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Sample records for high-q superconducting resonators

  1. Molybdenum-rhenium alloy based high-Q superconducting microwave resonators

    SciTech Connect

    Singh, Vibhor Schneider, Ben H.; Bosman, Sal J.; Merkx, Evert P. J.; Steele, Gary A.

    2014-12-01

    Superconducting microwave resonators (SMRs) with high quality factors have become an important technology in a wide range of applications. Molybdenum-Rhenium (MoRe) is a disordered superconducting alloy with a noble surface chemistry and a relatively high transition temperature. These properties make it attractive for SMR applications, but characterization of MoRe SMR has not yet been reported. Here, we present the fabrication and characterization of SMR fabricated with a MoRe 60–40 alloy. At low drive powers, we observe internal quality-factors as high as 700 000. Temperature and power dependence of the internal quality-factors suggest the presence of the two level systems from the dielectric substrate dominating the internal loss at low temperatures. We further test the compatibility of these resonators with high temperature processes, such as for carbon nanotube chemical vapor deposition growth, and their performance in the magnetic field, an important characterization for hybrid systems.

  2. High-Q Superconducting Coplanar Waveguide Resonators for Integration into Molecule Ion Traps

    DTIC Science & Technology

    2010-05-01

    quality factor. We fabricated the resonators as two dimensional coplanar waveguides in niobium on R-plane sapphire using optical lithography. Resist was...patterned on the niobium using optical lithography, developed then reactive-ion etched to transfer the pattern into the niobium . The resonators were...resonators as two dimensional coplanar waveguides in niobium on R-plane sapphire using optical lithography. Resist was patterned on the niobium using

  3. Tunable high-q superconducting notch filter

    DOEpatents

    Pang, C.S.; Falco, C.M.; Kampwirth, R.T.; Schuller, I.K.

    1979-11-29

    A superconducting notch filter is made of three substrates disposed in a cryogenic environment. A superconducting material is disposed on one substrate in a pattern of a circle and an annular ring connected together. The second substrate has a corresponding pattern to form a parallel plate capacitor and the second substrate has the circle and annular ring connected by a superconducting spiral that forms an inductor. The third substrate has a superconducting spiral that is placed parallel to the first superconducting spiral to form a transformer. Relative motion of the first substrate with respect to the second is effected from outside the cryogenic environment to vary the capacitance and hence the frequency of the resonant circuit formed by the superconducting devices.

  4. High Q Miniature Sapphire Acoustic Resonator

    NASA Technical Reports Server (NTRS)

    Wang, Rabi T.; Tjoelker, R. L.

    2010-01-01

    We have demonstrated high Q measurements in a room temperature Miniature Sapphire Acoustic Resonator (MSAR). Initial measurements of bulk acoustic modes in room temperature sapphire at 39 MHz have demonstrated a Q of 8.8 x 10(exp 6). The long term goal of this work is to integrate such a high Q resonator with small, low noise quartz oscillator electronics, providing a fractional frequency stability better than 1 x 10(exp -14) @ 1s.

  5. High Q silica microbubble resonators

    NASA Astrophysics Data System (ADS)

    Farnesi, D.; Barucci, A.; Berneschi, S.; Brenci, M.; Cosi, F.; Nunzi Conti, G.; Pelli, S.; Righini, G. C.; Soria, S.

    2012-01-01

    Microbubble resonators (MBRs) combine the unique properties of whispering gallery mode resonators with the intrinsic capability of integrated microfluidics. Here an improved fabrication method of MBRs is presented, based on the heating of a slightly pressurized capillary by a rotating arc discharge. Rotation of the electrodes ensures an homogeneous distribution of the heat all over the capillary surface. The demonstrated MBRs have Q factors up to 107 at 773 nm. Microbubbles were filled with water and aqueous solutions of ethanol in order to test the refractive index sensing capabilities of such resonators, which also show a good temporal stability.

  6. High-Q superconducting niobium cavities for gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    de Paula, L. A. N.; Furtado, S. R.; Aguiar, O. D.; Oliveira, N. F., Jr.; Castro, P. J.; Barroso, J. J.

    2014-10-01

    The main purpose of this work is to optimize the electric Q-factor of superconducting niobium klystron cavities to be used in parametric transducers of the Mario Schenberg gravitational wave detector. Many cavities were manufactured from niobium with relatively high tantalum impurities (1420 ppm) and they were cryogenically tested to determine their resonance frequencies, unloaded electrical quality factors (Q0) and electromagnetic couplings. These cavities were closed with a flat niobium plate with tantalum impurities below 1000 ppm and an unloaded electrical quality factors of the order of 105 have been obtained. AC conductivity of the order of 1012 S/m has been found for niobium cavities when matching experimental results with computational simulations. These values for the Q-factor would allow the detector to reach the quantum limit of sensitivity of ~ 10-22 Hz-1/2 in the near future, making it possible to search for gravitational waves around 3.2 kHz. The experimental tests were performed at the laboratories of the National Institute for Space Research (INPE) and at the Institute for Advanced Studies (IEAv - CTA).

  7. Engineered Carbon Nanotube Materials for High-Q Nanomechanical Resonators

    NASA Technical Reports Server (NTRS)

    Choi, Daniel S.; Hunt, Brian; Bronikowski, Mike; Epp, Larry; Hoenk, Michael; Hoppe, Dan; Kowalczyk, Bob; Wong, Eric; Xu, Jimmy; Adam, Douglas; Young, Rob

    2003-01-01

    This document represents a presentation offered by the Jet Propulsion Laboratory, with assistance from researchers from Brown University and Northrop Grumman. The presentation took place in Seoul, Korea in July 2003 and attempted to demonstrate the fabrication approach regarding the development of high quality factor (high-Q) mechanical oscillators (in the forms of a tunable nanotube resonator and a nanotube array radio frequency [RF] filter) aimed at signal processing and based on carbon nanotubes. The presentation also addressed parallel efforts to develop both in-plane single nanotube resonators as well as vertical array power devices.

  8. Preventing Raman Lasing in High-Q WGM Resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry; Maleki, Lute

    2007-01-01

    A generic design has been conceived to suppress the Raman effect in whispering- gallery-mode (WGM) optical resonators that have high values of the resonance quality factor (Q). Although it is possible to exploit the Raman effect (even striving to maximize the Raman gain to obtain Raman lasing), the present innovation is intended to satisfy a need that arises in applications in which the Raman effect inhibits the realization of the full potential of WGM resonators as frequency-selection components. Heretofore, in such applications, it has been necessary to operate high-Q WGM resonators at unattractively low power levels to prevent Raman lasing. (The Raman-lasing thresholds of WGM optical resonators are very low and are approximately proportional to Q(sup -2)). Heretofore, two ways of preventing Raman lasting at high power levels have been known, but both entail significant disadvantages: A resonator can be designed so that the optical field is spread over a relatively large mode volume to bring the power density below the threshold. For any given combination of Q and power level, there is certain mode volume wherein Raman lasing does not start. Unfortunately, a resonator that has a large mode volume also has a high spectral density, which is undesirable in a typical photonic application. A resonator can be cooled to the temperature of liquid helium, where the Raman spectrum is narrower and, therefore, the Raman gain is lower. However, liquid-helium cooling is inconvenient. The present design overcomes these disadvantages, making it possible to operate a low-spectral-density (even a single-mode) WGM resonator at a relatively high power level at room temperature, without risk of Raman lasing.

  9. High-Q 3D coaxial resonators for cavity QED

    NASA Astrophysics Data System (ADS)

    Yoon, Taekwan; Owens, John C.; Naik, Ravi; Lachapelle, Aman; Ma, Ruichao; Simon, Jonathan; Schuster, David I.

    Three-dimensional microwave resonators provide an alternative approach to transmission-line resonators used in most current circuit QED experiments. Their large mode volume greatly reduces the surface dielectric losses that limits the coherence of superconducting circuits, and the well-isolated and controlled cavity modes further suppress coupling to the environment. In this work, we focus on unibody 3D coaxial cavities which are only evanescently coupled and free from losses due to metal-metal interfaces, allowing us to reach extremely high quality-factors. We achieve quality-factor of up to 170 million using 4N6 Aluminum at superconducting temperatures, corresponding to an energy ringdown time of ~4ms. We extend our methods to other materials including Niobium, NbTi, and copper coated with Tin-Lead solder. These cavities can be further explored to study their properties under magnetic field or upon coupling to superconducting Josephson junction qubits, e.g. 3D transmon qubits. Such 3D cavity QED system can be used for quantum information applications, or quantum simulation in coupled cavity arrays.

  10. Ultra-High Q Acoustic Resonance in Superfluid ^4He

    NASA Astrophysics Data System (ADS)

    De Lorenzo, L. A.; Schwab, K. C.

    2017-02-01

    We report the measurement of the acoustic quality factor of a gram-scale, kilohertz-frequency superfluid resonator, detected through the parametric coupling to a superconducting niobium microwave cavity. For temperatures between 400 mK and 50 mK, we observe a T^{-4} temperature dependence of the quality factor, consistent with a 3-phonon dissipation mechanism. We observe Q factors up to 1.4× 10^8, consistent with the dissipation due to dilute ^3He impurities, and expect that significant further improvements are possible. These experiments are relevant to exploring quantum behavior and decoherence of massive macroscopic objects, the laboratory detection of continuous gravitational waves from pulsars, and the probing of possible limits to physical length scales.

  11. High Q silica microbubble resonators fabricated by arc discharge

    NASA Astrophysics Data System (ADS)

    Berneschi, S.; Farnesi, D.; Cosi, F.; Nunzi Conti, G.; Pelli, S.; Righini, G. C.; Soria, S.

    2011-09-01

    Microbubble resonators combine the unique properties of whispering gallery mode resonators with the intrinsic capability of integrated microfluidics. Here an improved fabrication method of microbubble resonators is presented, based on the heating of a slightly pressurized capillary by a rotating arc discharge. Rotation of the electrodes, moved out of a fiber splicer, ensures a homogeneous distribution of the heat all over the capillary surface. The demonstrated microbubble resonators have Q factors up to 6×107 at 1550nm. Microbubbles were filled with water and aqueous solutions of ethanol in order to test the refractive index sensing capabilities of such resonators, which also show a good temporal stability. The limit of detection of our microbubble resonator sensor is 10-6RIU.

  12. High Q silica microbubble resonators fabricated by arc discharge.

    PubMed

    Berneschi, S; Farnesi, D; Cosi, F; Conti, G Nunzi; Pelli, S; Righini, G C; Soria, S

    2011-09-01

    Microbubble resonators combine the unique properties of whispering gallery mode resonators with the intrinsic capability of integrated microfluidics. Here an improved fabrication method of microbubble resonators is presented, based on the heating of a slightly pressurized capillary by a rotating arc discharge. Rotation of the electrodes, moved out of a fiber splicer, ensures a homogeneous distribution of the heat all over the capillary surface. The demonstrated microbubble resonators have Q factors up to 6×10(7) at 1550 nm. Microbubbles were filled with water and aqueous solutions of ethanol in order to test the refractive index sensing capabilities of such resonators, which also show a good temporal stability. The limit of detection of our microbubble resonator sensor is 10(-6) RIU.

  13. Monolithic Cylindrical Fused Silica Resonators with High Q Factors

    PubMed Central

    Pan, Yao; Wang, Dongya; Wang, Yanyan; Liu, Jianping; Wu, Suyong; Qu, Tianliang; Yang, Kaiyong; Luo, Hui

    2016-01-01

    The cylindrical resonator gyroscope (CRG) is a typical Coriolis vibratory gyroscope whose performance is determined by the Q factor and frequency mismatch of the cylindrical resonator. Enhancing the Q factor is crucial for improving the rate sensitivity and noise performance of the CRG. In this paper, for the first time, a monolithic cylindrical fused silica resonator with a Q factor approaching 8 × 105 (ring-down time over 1 min) is reported. The resonator is made of fused silica with low internal friction and high isotropy, with a diameter of 25 mm and a center frequency of 3974.35 Hz. The structure of the resonator is first briefly introduced, and then the experimental non-contact characterization method is presented. In addition, the post-fabrication experimental procedure of Q factor improvement, including chemical and thermal treatment, is demonstrated. The Q factor improvement by both treatments is compared and the primary loss mechanism is analyzed. To the best of our knowledge, the work presented in this paper represents the highest reported Q factor for a cylindrical resonator. The proposed monolithic cylindrical fused silica resonator may enable high performance inertial sensing with standard manufacturing process and simple post-fabrication treatment. PMID:27483263

  14. All-optical Photonic Oscillator with High-Q Whispering Gallery Mode Resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy A.; Matsko, Andrey B.; Strekalov, Dmitry; Mohageg, Makan; Iltchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We demonstrated low threshold optical photonic hyper-parametric oscillator in a high-Q 10(exp 10) CaF2 whispering gallery mode resonator which generates stable 8.5 GHz signal. The oscillations result from the resonantly enhanced four wave mixing occurring due to Kerr nonlinearity of the material.

  15. Superconducting Materials Testing with a High-Q Copper RF Cavity

    SciTech Connect

    Tantawi, S.G.; Dolgashev, V.; Bowden, G.; Lewandowski, J.; Nantista, C.D.; Canabal, A.; Tajima, T.; Capmpisi, I.E.; /Oak Ridge

    2007-11-07

    Superconducting RF is of increasing importance in particle accelerators. We have developed a resonant cavity with high quality factor and an interchangeable wall for testing of superconducting materials. A compact TE01 mode launcher attached to the coupling iris selectively excites the azimuthally symmetric cavity mode, which allows a gap at the detachable wall and is free of surface electric fields that could cause field emission, multipactor, and RF breakdown. The shape of the cavity is tailored to focus magnetic field on the test sample. We describe cryogenic experiments conducted with this cavity. An initial experiment with copper benchmarked our apparatus. This was followed by tests with Nb and MgB2. In addition to characterizing the onset of superconductivity with temperature, our cavity can be resonated with a high power klystron to determine the surface magnetic field level sustainable by the material in the superconducting state. A feedback code is used to make the low level RF drive track the resonant frequency.

  16. Optical bistability in a high-Q racetrack resonator based on small SU-8 ridge waveguides.

    PubMed

    Jin, Li; Fu, Xin; Yang, Bo; Shi, Yaocheng; Dai, Daoxin

    2013-06-15

    A racetrack resonator with a high Q value (~34,000) is demonstrated experimentally based on small SU-8 optical ridge waveguides, which were fabricated with an improved etchless process. Optical bistability is observed in the present racetrack resonator even with a low input optical power (5.6-7.3 mW), which is attributed to the significant thermal nonlinear optical effect due to the high Q value and the large negative thermo-optical coefficient of SU-8. Theoretical modeling for the optical bistability is also given, and it agrees well with the experimental result.

  17. Guided mode resonance with extremely high Q-factors in terahertz metamaterials

    NASA Astrophysics Data System (ADS)

    Chen, Hang; Liu, Jianjun; Hong, Zhi

    2017-01-01

    We proposed and demonstrated that guided mode resonance (GMR) response with extremely high quality factor can be achieved in a planar terahertz metamaterial (MM) by rotating split ring resonators (SRRs) or moving the gaps of SRRs in a two-SRR composed MM. Furthermore, a novel extremely sharp asymmetric Fano resonance or electromagnetically induced transparency (EIT) like spectral response can be easily realized by manipulating the coherent interaction between this high Q GMR and the dipole resonance of MM. The new method can be extended to other ranges of the electromagnetic spectrum, and open new horizons for the design of ultra-high Q metamaterials for multifunctional applications, such as ultra-sensitive sensors, narrowband filters, or slow light based devices.

  18. Development of Ultra High Gradient and High Q{sub 0} Superconducting Radio Frequency Cavities

    SciTech Connect

    Geng, Rongli; Clemens, William A.; Follkie, James E.; Harris, Teena M.; Kushnick, Peter W.; Machie, Danny; Martin, Robert E.; Palczewski, Ari D.; Perry, Era A.; Slack, Gary L.; Williams, R. S.; Adolphsen, C.; Li, Z.; Hao, J. K.; Li, Y. M.; Liu, K. X.

    2013-06-01

    We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q{sub 0} superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q{sub 0} of 10{sup 10} at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q{sub 0} of 2-10{sup 10} at 2K.

  19. Droplet sensing using small and compact high-Q planar resonator based on impedance matching technique.

    PubMed

    Lee, Hee-Jo; Yook, Jong-Gwan

    2016-09-01

    In this paper, we demonstrate the sensing feasibility of the proposed high-Q resonator using a phosphate-buffered saline droplet at microwave frequencies. In the experimental results, the resonant frequency, signal level, and Q-factor of the S21-parameter with and without a 1-μl droplet were changed to about 230 MHz, 32 dB, and 1500, respectively. The resonator system was found to be suitable for droplet sensing with a small volume due to its small and compact scheme. This resonator system is expected to play an important role in droplet sensing with different dielectric constants.

  20. Droplet sensing using small and compact high-Q planar resonator based on impedance matching technique

    NASA Astrophysics Data System (ADS)

    Lee, Hee-Jo; Yook, Jong-Gwan

    2016-09-01

    In this paper, we demonstrate the sensing feasibility of the proposed high-Q resonator using a phosphate-buffered saline droplet at microwave frequencies. In the experimental results, the resonant frequency, signal level, and Q-factor of the S21-parameter with and without a 1-μl droplet were changed to about 230 MHz, 32 dB, and 1500, respectively. The resonator system was found to be suitable for droplet sensing with a small volume due to its small and compact scheme. This resonator system is expected to play an important role in droplet sensing with different dielectric constants.

  1. Tunable superconducting microstrip resonators

    NASA Astrophysics Data System (ADS)

    Adamyan, A. A.; Kubatkin, S. E.; Danilov, A. V.

    2016-04-01

    We report on a simple yet versatile design for a tunable superconducting microstrip resonator. Niobium nitride is employed as the superconducting material and aluminum oxide, produced by atomic layer deposition, as the dielectric layer. We show that the high quality of the dielectric material allows to reach the internal quality factors in the order of Qi˜104 in the single photon regime. Qi rapidly increases with the number of photons in the resonator N and exceeds 105 for N ˜10 -50 . A straightforward modification of the basic microstrip design allows to pass a current bias through the strip and to control its kinetic inductance. We achieve a frequency tuning δf =62 MHz around f0=2.4 GHz for a fundamental mode and δf =164 MHz for a third harmonic. This translates into a tuning parameter Qiδf /f0=150 . The presented design can be incorporated into essentially any superconducting circuitry operating at temperatures below 2.5 K.

  2. Stimulated Brillouin laser and frequency comb generation in high-Q microbubble resonators.

    PubMed

    Lu, Qijing; Liu, Sheng; Wu, Xiang; Liu, Liying; Xu, Lei

    2016-04-15

    We report on the stimulated Brillouin laser (SBL) and over-dense frequency comb generation in high-Q microbubble resonators (MBRs). Both first-order and cascaded SBL are achieved due to the rich high-order axial modes in the MBRs, although the free spectral range (FSR) of azimuthal mode of the MBR is severely mismatched with the Brillouin shift. The SBL is also generated by varying the internal pressure of MBR at fixed initially non-resonant pump light wavelength. In addition, over-dense frequency combs are realized with comb spacings that are one and two FSRs of aixal mode.

  3. High-Q AlN Contour Mode Resonators with Unattached, Voltage-Actuated Electrodes

    NASA Astrophysics Data System (ADS)

    Schneider, Robert Anthony

    High-Q narrowband filters at ultra-high frequencies hold promise for reducing noise and suppressing interferers in wireless transceivers, yet research efforts confront a daunting challenge. So far, no existing resonator technology can provide the simultaneous high-Q, high electromechanical coupling ( k2eff), frequency tunability, low motional resistance (Rx), stopband rejection, self-switchability, frequency accuracy, and power handling desired to select individual channels or small portions of a band over a wide RF range. Indeed, each technology provides only a subset of the desired properties. Recently introduced "capacitive-piezoelectric" resonators, i.e., piezoelectric resonators with non-contacting transduction electrodes, known for achieving very good Q's, have recently emerged (in the early 2010's) as a contender among existing technologies to address the needs of RF narrowband selection. Several reports of such devices, made from aluminum nitride (AlN), have demonstrated improved Q's over attached electrode counterparts at frequencies up to 1.2 GHz, albeit with reduced transduction efficiency due to the added capacitive gaps. Fabrication challenges, while still allowing for a glimpse of the promise of this technology, have, until now, hindered attempts at more complex devices than just simple resonators with improved Q's. This thesis project demonstrates several key improvements to capacitive-piezo technology, which, taken together, further bolster its case for deployment for frequency control applications. (Abstract shortened by ProQuest.).

  4. Coupling Light from a High-Q Microsphere Resonator Using a UV-induced Surface Grating

    NASA Technical Reports Server (NTRS)

    Ilchenko, V. S.; Starodubov, D. S.; Gorodetsky, M. L.; Maleki, L.; Feinberg, J.

    2000-01-01

    High-Q microspheres with whispering-gallery modes have very narrow resonances that can be used for fiber-optic filters, ultra-compact narrow-linewidth lasers and optical/microwave oscillators. Whispering-gallery modes were previously excited in microspheres using evanescent optical fields. The necessary phase synchronism was obtained by adjusting the incident angle of input light beam (prism coupler) or adjustment of the waveguide propagation constant (fiber taper coupler). For many applications, however, bulky near-field couplers are undesirable. They compromise the symmetry and generate stray fields. Also, the control of coupling is crucial for the performance of microsphere resonators: in analogy with radio frequency circuits, the loading Q-factor should be less than the intrinsic Q-factor, Q(sub L) less than or equal to Q(sub O). Ideally one should combine a stable coupling element and a resonator into a single microsphere component.

  5. Enhancing the resonance stability of a high-Q micro/nanoresonator by an optical means

    NASA Astrophysics Data System (ADS)

    Sun, Xuan; Luo, Rui; Zhang, Xi-Cheng; Lin, Qiang

    2016-02-01

    High-quality optical resonators underlie many important applications ranging from optical frequency metrology, precision measurement, nonlinear/quantum photonics, to diverse sensing such as detecting single biomolecule, electromagnetic field, mechanical acceleration/rotation, among many others. All these applications rely essentially on the stability of optical resonances, which, however, is ultimately limited by the fundamental thermal fluctuations of the devices. The resulting thermo-refractive and thermo-elastic noises have been widely accepted for nearly two decades as the fundamental thermodynamic limit of an optical resonator, limiting its resonance uncertainty to a magnitude 10-12 at room temperature. Here we report a novel approach that is able to significantly improve the resonance stability of an optical resonator. We show that, in contrast to the common belief, the fundamental temperature fluctuations of a high-Q micro/nanoresonator can be suppressed remarkably by pure optical means without cooling the device temperature, which we term as temperature squeezing. An optical wave with only a fairly moderate power launched into the device is able to produce strong photothermal backaction that dramatically suppresses the spectral intensity of temperature fluctuations by five orders of magnitudes and squeezes the overall level (root-mean-square value) of temperature fluctuations by two orders of magnitude. The proposed approach is universally applicable to various micro/nanoresonator platforms and the optimal temperature squeezing can be achieved with an optical Q around 106-107 that is readily available in various current devices. The proposed photothermal temperature squeezing is expected to have profound impact on broad applications of high-Q cavities in sensing, metrology, and integrated nonlinear/quantum photonics.

  6. Mid-infrared ultra-high-Q resonators based on fluoride crystalline materials

    PubMed Central

    Lecaplain, C.; Javerzac-Galy, C.; Gorodetsky, M. L.; Kippenberg, T. J.

    2016-01-01

    The unavailability of highly transparent materials in the mid-infrared has been the main limitation in the development of ultra-sensitive molecular sensors or cavity-based spectroscopy applications. Whispering gallery mode microresonators have attained ultra-high-quality (Q) factor resonances in the near-infrared and visible. Here we report ultra-high Q factors in the mid-infrared using polished alkaline earth metal fluoride crystals. Using an uncoated chalcogenide tapered fibre as a high-ideality coupler in the mid-infrared, we study via cavity ringdown technique the losses of BaF2, CaF2, MgF2 and SrF2 microresonators. We show that MgF2 is limited by multiphonon absorption by studying the temperature dependence of the Q factor. In contrast, in SrF2 and BaF2 the lower multiphonon absorption leads to ultra-high Q factors at 4.5 μm. These values correspond to an optical finesse of , the highest value achieved for any type of mid-infrared resonator to date. PMID:27869119

  7. Mid-infrared ultra-high-Q resonators based on fluoride crystalline materials

    NASA Astrophysics Data System (ADS)

    Lecaplain, C.; Javerzac-Galy, C.; Gorodetsky, M. L.; Kippenberg, T. J.

    2016-11-01

    The unavailability of highly transparent materials in the mid-infrared has been the main limitation in the development of ultra-sensitive molecular sensors or cavity-based spectroscopy applications. Whispering gallery mode microresonators have attained ultra-high-quality (Q) factor resonances in the near-infrared and visible. Here we report ultra-high Q factors in the mid-infrared using polished alkaline earth metal fluoride crystals. Using an uncoated chalcogenide tapered fibre as a high-ideality coupler in the mid-infrared, we study via cavity ringdown technique the losses of BaF2, CaF2, MgF2 and SrF2 microresonators. We show that MgF2 is limited by multiphonon absorption by studying the temperature dependence of the Q factor. In contrast, in SrF2 and BaF2 the lower multiphonon absorption leads to ultra-high Q factors at 4.5 μm. These values correspond to an optical finesse of , the highest value achieved for any type of mid-infrared resonator to date.

  8. Mid-infrared ultra-high-Q resonators based on fluoride crystalline materials.

    PubMed

    Lecaplain, C; Javerzac-Galy, C; Gorodetsky, M L; Kippenberg, T J

    2016-11-21

    The unavailability of highly transparent materials in the mid-infrared has been the main limitation in the development of ultra-sensitive molecular sensors or cavity-based spectroscopy applications. Whispering gallery mode microresonators have attained ultra-high-quality (Q) factor resonances in the near-infrared and visible. Here we report ultra-high Q factors in the mid-infrared using polished alkaline earth metal fluoride crystals. Using an uncoated chalcogenide tapered fibre as a high-ideality coupler in the mid-infrared, we study via cavity ringdown technique the losses of BaF2, CaF2, MgF2 and SrF2 microresonators. We show that MgF2 is limited by multiphonon absorption by studying the temperature dependence of the Q factor. In contrast, in SrF2 and BaF2 the lower multiphonon absorption leads to ultra-high Q factors at 4.5 μm. These values correspond to an optical finesse of , the highest value achieved for any type of mid-infrared resonator to date.

  9. Surface-resistance measurements using superconducting stripline resonators.

    PubMed

    Hafner, Daniel; Dressel, Martin; Scheffler, Marc

    2014-01-01

    We present a method to measure the absolute surface resistance of conductive samples at a set of GHz frequencies with superconducting lead stripline resonators at temperatures 1-6 K. The stripline structure can easily be applied for bulk samples and allows direct calculation of the surface resistance without the requirement of additional calibration measurements or sample reference points. We further describe a correction method to reduce experimental background on high-Q resonance modes by exploiting TEM-properties of the external cabling. We then show applications of this method to the reference materials gold, tantalum, and tin, which include the anomalous skin effect and conventional superconductivity. Furthermore, we extract the complex optical conductivity for an all-lead stripline resonator to find a coherence peak and the superconducting gap of lead.

  10. Fano resonances in a multimode waveguide coupled to a high-Q silicon nitride ring resonator.

    PubMed

    Ding, Dapeng; de Dood, Michiel J A; Bauters, Jared F; Heck, Martijn J R; Bowers, John E; Bouwmeester, Dirk

    2014-03-24

    Silicon nitride (Si3N4) optical ring resonators provide exceptional opportunities for low-loss integrated optics. Here we study the transmission through a multimode waveguide coupled to a Si3N4 ring resonator. By coupling single-mode fibers to both input and output ports of the waveguide we selectively excite and probe combinations of modes in the waveguide. Strong asymmetric Fano resonances are observed and the degree of asymmetry can be tuned through the positions of the input and output fibers. The Fano resonance results from the interference between modes of the waveguide and light that couples resonantly to the ring resonator. We develop a theoretical model based on the coupled mode theory to describe the experimental results. The large extension of the optical modes out of the Si3N4 core makes this system promising for sensing applications.

  11. Circular High-Q Resonating Isotropic Strain Sensors with Large Shift of Resonance Frequency under Stress

    PubMed Central

    Melik, Rohat; Unal, Emre; Perkgoz, Nihan Kosku; Puttlitz, Christian; Demir, Hilmi Volkan

    2009-01-01

    We present circular architecture bioimplant strain sensors that facilitate a strong resonance frequency shift with mechanical deformation. The clinical application area of these sensors is for in vivo assessment of bone fractures. Using a rectangular geometry, we obtain a resonance shift of 330 MHz for a single device and 170 MHz for its triplet configuration (with three side-by-side resonators on chip) under an applied load of 3,920 N. Using the same device parameters with a circular isotropic architecture, we achieve a resonance frequency shift of 500 MHz for the single device and 260 MHz for its triplet configuration, demonstrating substantially increased sensitivity. PMID:22303132

  12. Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping Recipes for High Q Cavities

    SciTech Connect

    Vostrikov, Alexander; Checchin, Mattia; Grassellino, Anna; Kim, Young-Kee; Romanenko, Alexander

    2015-06-01

    A study is presented on the superconducting properties of niobium used for the fabrication of the SRF cavities after treating by recently discovered nitrogen doping methods. Cylindrical niobium samples have been subjected to the standard surface treatments applied to the cavities (electro-polishing, l 20°C bake) and compared with samples treated by additional nitrogen doping recipes routinely used to reach ultra-high quality factor values (>3· 1010 at 2 K, 16 MV/m). The DC magnetization curves and the complex magnetic AC susceptibility have been measured. Evidence for the lowered field of first flux penetration after nitrogen doping is found suggesting a correlation with the lowered quench fields. Superconducting critical temperatures Tc = 9.25 K are found to be in agreement with previous measurements, and no strong effect on the critical surface field (Bd) from nitrogen doping was found.

  13. Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity.

    PubMed

    Lo, C K; Lai, W C; Cheng, J C

    2011-08-01

    A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (-20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.

  14. Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity

    NASA Astrophysics Data System (ADS)

    Lo, C. K.; Lai, W. C.; Cheng, J. C.

    2011-08-01

    A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (-20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.

  15. High-Q photonic resonators and electro-optic coupling using silicon-on-lithium-niobate.

    PubMed

    Witmer, Jeremy D; Valery, Joseph A; Arrangoiz-Arriola, Patricio; Sarabalis, Christopher J; Hill, Jeff T; Safavi-Naeini, Amir H

    2017-04-13

    Future quantum networks, in which superconducting quantum processors are connected via optical links, will require microwave-to-optical photon converters that preserve entanglement. A doubly-resonant electro-optic modulator (EOM) is a promising platform to realize this conversion. Here, we present our progress towards building such a modulator by demonstrating the optically-resonant half of the device. We demonstrate high quality (Q) factor ring, disk and photonic crystal resonators using a hybrid silicon-on-lithium-niobate material system. Optical Q factors up to 730,000 are achieved, corresponding to propagation loss of 0.8 dB/cm. We also use the electro-optic effect to modulate the resonance frequency of a photonic crystal cavity, achieving a electro-optic modulation coefficient between 1 and 2 pm/V. In addition to quantum technology, we expect that our results will be useful both in traditional silicon photonics applications and in high-sensitivity acousto-optic devices.

  16. Frequency-Temperature Compensation Techniques for High-Q Microwave Resonators

    NASA Astrophysics Data System (ADS)

    Hartnett, John G.; Tobar, Michael E.

    Low-noise high-stability resonator oscillators based on high-Q monolithic sapphire ``Whispering Gallery'' (WG)-mode resonators have become important devices for telecommunication, radar and metrological applications. The extremely high quality factor of sapphire, of 2 x10^5 at room temperature, 5 x10^7 at liquid nitrogen temperature and 5 x10^9 at liquid helium temperature has enabled the lowest phase noise and highly frequency-stable oscillators in the microwave regime to be constructed. To create an oscillator with exceptional frequency stability, the resonator must have its frequency-temperature dependence annulled at some temperature, as well as a high quality factor. The Temperature Coefficient of Permittivity (TCP) for sapphire is quite large, at 10-100parts per million/K above 77K. This mechanism allows temperature fluctuations to transform to resonator frequency fluctuations.A number of research groups worldwide have investigated various methods of compensating the TCP of a sapphire dielectric resonator at different temperatures. The usual electromagnetic technique of annulment involves the use of paramagnetic impurities contributing an opposite temperature coefficient of the magnetic susceptibility to the TCP. This technique has only been realized successfully in liquid helium environments. Near 4K the thermal expansion and permittivity effects are small and only small quantities of the paramagnetic ions are necessary to compensate the mode frequency. Compensation is due to impurity ions that were incidentally left over from the manufacturing process.Recently, there has been an effort to dispense with the need for liquid helium and make a compact flywheel oscillator for the new generation of primary frequency standards such as the cesium fountain at the Laboratoire Primaire du Temps et des Fréquences (LPTF), France. To achieve the stability limit imposed

  17. Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B.; Epp, Larry W.; Bagge, Leif

    2011-01-01

    High Q resonators are a critical component of stable, low-noise communication systems, radar, and precise timing applications such as atomic clocks. In electronic resonators based on Si integrated circuits, resistive losses increase as a result of the continued reduction in device dimensions, which decreases their Q values. On the other hand, due to the mechanical construct of bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators, such loss mechanisms are absent, enabling higher Q-values for both BAW and SAW resonators compared to their electronic counterparts. The other advantages of mechanical resonators are their inherently higher radiation tolerance, a factor that makes them attractive for NASA s extreme environment planetary missions, for example to the Jovian environments where the radiation doses are at hostile levels. Despite these advantages, both BAW and SAW resonators suffer from low resonant frequencies and they are also physically large, which precludes their integration into miniaturized electronic systems. Because there is a need to move the resonant frequency of oscillators to the order of gigahertz, new technologies and materials are being investigated that will make performance at those frequencies attainable. By moving to nanoscale structures, in this case vertically oriented, cantilevered carbon nanotubes (CNTs), that have larger aspect ratios (length/thickness) and extremely high elastic moduli, it is possible to overcome the two disadvantages of both bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators. Nano-electro-mechanical systems (NEMS) that utilize high aspect ratio nanomaterials exhibiting high elastic moduli (e.g., carbon-based nanomaterials) benefit from high Qs, operate at high frequency, and have small force constants that translate to high responsivity that results in improved sensitivity, lower power consumption, and im - proved tunablity. NEMS resonators have recently been demonstrated using topdown

  18. Meta-metallic coils and resonators: Methods for high Q-value resonant geometries

    NASA Astrophysics Data System (ADS)

    Mett, R. R.; Sidabras, J. W.; Hyde, J. S.

    2016-08-01

    A novel method of decreasing ohmic losses and increasing Q-value in metallic resonators at high frequencies is presented. The method overcomes the skin-depth limitation of rf current flow cross section. The method uses layers of conductive foil of thickness less than a skin depth and capacitive gaps between layers. The capacitive gaps can substantially equalize the rf current flowing in each layer, resulting in a total cross-sectional dimension for rf current flow many times larger than a skin depth. Analytic theory and finite-element simulations indicate that, for a variety of structures, the Q-value enhancement over a single thick conductor approaches the ratio of total conductor thickness to skin depth if the total number of layers is greater than one-third the square of the ratio of total conductor thickness to skin depth. The layer number requirement is due to counter-currents in each foil layer caused by the surrounding rf magnetic fields. We call structures that exhibit this type of Q-enhancement "meta-metallic." In addition, end effects due to rf magnetic fields wrapping around the ends of the foils can substantially reduce the Q-value for some classes of structures. Foil structures with Q-values that are substantially influenced by such end effects are discussed as are five classes of structures that are not. We focus particularly on 400 MHz, which is the resonant frequency of protons at 9.4 T. Simulations at 400 MHz are shown with comparison to measurements on fabricated structures. The methods and geometries described here are general for magnetic resonance and can be used at frequencies much higher than 400 MHz.

  19. Meta-metallic coils and resonators: Methods for high Q-value resonant geometries.

    PubMed

    Mett, R R; Sidabras, J W; Hyde, J S

    2016-08-01

    A novel method of decreasing ohmic losses and increasing Q-value in metallic resonators at high frequencies is presented. The method overcomes the skin-depth limitation of rf current flow cross section. The method uses layers of conductive foil of thickness less than a skin depth and capacitive gaps between layers. The capacitive gaps can substantially equalize the rf current flowing in each layer, resulting in a total cross-sectional dimension for rf current flow many times larger than a skin depth. Analytic theory and finite-element simulations indicate that, for a variety of structures, the Q-value enhancement over a single thick conductor approaches the ratio of total conductor thickness to skin depth if the total number of layers is greater than one-third the square of the ratio of total conductor thickness to skin depth. The layer number requirement is due to counter-currents in each foil layer caused by the surrounding rf magnetic fields. We call structures that exhibit this type of Q-enhancement "meta-metallic." In addition, end effects due to rf magnetic fields wrapping around the ends of the foils can substantially reduce the Q-value for some classes of structures. Foil structures with Q-values that are substantially influenced by such end effects are discussed as are five classes of structures that are not. We focus particularly on 400 MHz, which is the resonant frequency of protons at 9.4 T. Simulations at 400 MHz are shown with comparison to measurements on fabricated structures. The methods and geometries described here are general for magnetic resonance and can be used at frequencies much higher than 400 MHz.

  20. Quartz crystal and superconductive resonators and oscillators

    NASA Technical Reports Server (NTRS)

    Besson, R. S.

    1978-01-01

    A general overview of piezoelectric resonators is given with emphasis on evolution of the resonator design. Superconducting cavities and crystals at low temperature and the use of resonant frequencies are also discussed.

  1. Frequency-tunable superconducting resonators via nonlinear kinetic inductance

    SciTech Connect

    Vissers, M. R.; Hubmayr, J.; Sandberg, M.; Gao, J.; Chaudhuri, S.; Bockstiegel, C.

    2015-08-10

    We have designed, fabricated, and tested a frequency-tunable high-Q superconducting resonator made from a niobium titanium nitride film. The frequency tunability is achieved by injecting a DC through a current-directing circuit into the nonlinear inductor whose kinetic inductance is current-dependent. We have demonstrated continuous tuning of the resonance frequency in a 180 MHz frequency range around 4.5 GHz while maintaining the high internal quality factor Q{sub i} > 180 000. This device may serve as a tunable filter and find applications in superconducting quantum computing and measurement. It also provides a useful tool to study the nonlinear response of a superconductor. In addition, it may be developed into techniques for measurement of the complex impedance of a superconductor at its transition temperature and for readout of transition-edge sensors.

  2. High-Q cross-plate phononic crystal resonator for enhanced acoustic wave localization and energy harvesting

    NASA Astrophysics Data System (ADS)

    Yang, Aichao; Li, Ping; Wen, Yumei; Yang, Chao; Wang, Decai; Zhang, Feng; Zhang, Jiajia

    2015-05-01

    A high-Q cross-plate phononic crystal resonator (Cr-PCR) coupled with an electromechanical Helmholtz resonator (EMHR) is proposed to improve acoustic wave localization and energy harvesting. Owing to the strongly directional wave-scattering effect of the cross-plate corners, strong confinement of acoustic waves emerges. Consequently, the proposed Cr-PCR structure exhibits ∼353.5 times higher Q value and ∼6.1 times greater maximum pressure amplification than the phononic crystal resonator (Cy-PCR) (consisting of cylindrical scatterers) of the same size. Furthermore, the harvester using the proposed Cr-PCR and the EMHR has ∼22 times greater maximum output-power volume density than the previous harvester using Cy-PCR and EMHR structures.

  3. Design Considerations for High-Q Bandpass Microwave Oscillator Sensors Based Upon Resonant Amplification

    SciTech Connect

    Jones, Anthony M.; Kelly, James F.; Tedeschi, Jonathan R.; McCloy, John S.

    2014-06-23

    A series of microwave resonant oscillator sensors were designed and characterized using bandpass planar and volumetric electrical resonators having loaded quality factor (Q) values in the range of 2 to 20. The use of these resonators in positive feedback circuits yielded sensor Q-factors of up to 2 x 107, demonstrating Q-factor amplifications on the order of 106. It is shown that the Q-factor amplification can be increased in a positive feedback system through the selection of feedback loop group delay, allowing use of resonators with lower Qstat values. A low-frequency electromagnetic interference sensing application is demonstrated for two resonant oscillator configurations, showing considerable frequency sensitivity to 45 kHz emitters.

  4. Simultaneous electrical and optical readout of graphene-coated high Q silicon nitride resonators

    NASA Astrophysics Data System (ADS)

    Adiga, V. P.; De Alba, R.; Storch, I. R.; Yu, P. A.; Ilic, B.; Barton, R. A.; Lee, S.; Hone, J.; McEuen, P. L.; Parpia, J. M.; Craighead, H. G.

    2013-09-01

    Resonant mechanics of high quality factor (Q) graphene coated silicon nitride devices have been explored using optical and electrical transduction schemes. With the addition of the graphene layer, we retain the desirable mechanical properties of silicon nitride but utilize the electrical and optical properties of graphene to transduce and tune the resonant motion by both optical and electrical means. By positioning the graphene-on-silicon-nitride drums in a tunable optical cavity, we observe position dependent damping and resonant frequency control of the devices due to optical absorption by graphene.

  5. High-Q silicon-on-insulator optical rib waveguide racetrack resonators.

    PubMed

    Kiyat, Isa; Aydinli, Atilla; Dagli, Nadir

    2005-03-21

    In this work, detailed design and realization of high quality factor (Q) racetrack resonators based on silicon-on-insulator rib waveguides are presented. Aiming to achieve critical coupling, suitable waveguide geometry is determined after extensive numerical studies of bending loss. The final design is obtained after coupling factor calculations and estimation of propagation loss. Resonators with quality factors (Q) as high as 119000 has been achieved, the highest Q value for resonators based on silicon-on-insulator rib waveguides to date with extinction ratios as large as 12 dB.

  6. Radio frequency spectral characterization and model parameters extraction of high Q optical resonators

    PubMed Central

    Abdallah, Zeina; Boucher, Yann G.; Fernandez, Arnaud; Balac, Stéphane; Llopis, Olivier

    2016-01-01

    A microwave domain characterization approach is proposed to determine the properties of high quality factor optical resonators. This approach features a very high precision in frequency and aims to acquire a full knowledge of the complex transfer function (amplitude and phase) characterizing an optical resonator using a microwave vector network analyzer. It is able to discriminate between the different coupling regimes, from the under-coupling to the selective amplification, and it is used together with a model from which the main resonator parameters are extracted, i.e. coupling factor, intrinsic losses, phase slope, intrinsic and external quality factor. PMID:27251460

  7. High-Q nested resonator in an actively stabilized optomechanical cavity

    NASA Astrophysics Data System (ADS)

    Buters, F. M.; Heeck, K.; Eerkens, H. J.; Weaver, M. J.; Luna, F.; de Man, S.; Bouwmeester, D.

    2017-03-01

    Experiments involving micro- and nanomechanical resonators need to be carefully designed to reduce mechanical environmental noise. A small scale on-chip approach is to add a resonator to the system as a mechanical low-pass filter. However, the inherent low frequency of the low-pass filter causes the system to be easily excited mechanically. We solve this problem by applying active feedback to the resonator, thereby minimizing the motion with respect to the front mirror of an optomechanical cavity. Not only does this method actively stabilize the cavity length but it also retains the on-chip vibration isolation.

  8. High-Q silicon-on-insulator optical rib waveguide racetrack resonators

    NASA Astrophysics Data System (ADS)

    Kiyat, Isa; Aydinli, Atilla; Dagli, Nadir

    2005-03-01

    In this work, detailed design and realization of high quality factor (Q) racetrack resonators based on silicon-on-insulator rib waveguides are presented. Aiming to achieve critical coupling, suitable waveguide geometry is determined after extensive numerical studies of bending loss. The final design is obtained after coupling factor calculations and estimation of propagation loss. Resonators with quality factors (Q) as high as 119000 has been achieved, the highest Q value for resonators based on silicon-on-insulator rib waveguides to date with extinction ratios as large as 12 dB.

  9. Selective excitation of high-Q resonant modes in a bottle/quasi-cylindrical microresonator

    NASA Astrophysics Data System (ADS)

    Dong, Yongchao; Jin, Xueying; Wang, Keyi

    2016-08-01

    We fabricate a bottle/quasi-cylindrical microresonator by using a fusion splicer. This method does not require a real-time control of the translation stages and can easily fabricate a resonator with expected size and shape. Selective excitation of whispering gallery modes (WGMs) in the resonator is realized with a fiber taper coupled at various positions of the resonator along the bottle axis. Most importantly, we obtain a clean and regular spectrum with very high quality factor (Q) modes up to 3.1×107 in the quasi-cylindrical region of the resonator. Moreover, we package the coupling system into a whole device that can be moved freely. The vibration performance tests of the packaged device show that the coupling system with the taper coupled at the quasi-cylindrical region has a remarkable anti-vibration ability. The portability and robustness of the device make it attractive in practical applications.

  10. Monolithic integration of high-Q wedge resonators with vertically coupled waveguides

    NASA Astrophysics Data System (ADS)

    Ramiro-Manzano, Fernando; Prtljaga, Nikola; Pavesi, Lorenzo; Pucker, Georg; Ghulinyan, Mher

    2013-05-01

    Typical UHQ resonators, microspheres and microtoroids, lack the possibility of integration into lightwave circuits due to their planarity constrains. In this context, CMOS-compatible alternatives in the form of wedge resonators have been proposed. However, the mode retraction from the wedge cavity inhibits the possibility to side couple with integrated waveguides and therefore, halts the full integration within a planar lightwave circuit. In this work, we propose and demonstrate experimentally the complete integration of wedge resonators with vertically coupled dielectric bus waveguides. This coupling scheme permits to use arbitrary gaps, geometries and materials, enables simplified and precise control of the light injection into the cavity and opens the door to an industrial mass-fabrication of UHQ resonators.

  11. High Q silica microbubble resonators fabricated by heating a pressurized glass capillary

    NASA Astrophysics Data System (ADS)

    Yu, Zhe; Liu, Tiegen; Jiang, Junfeng; Liu, Kun; Chen, Wenjie; Zhang, Xuezhi; Lin, Xujun; Liu, Wenhui

    2014-11-01

    Microbubble resonators combine the unique properties of whispering gallery mode resonators with the capability of integrated microfluidics. The microbubble resonator is fabricated by heating the tapered tip of a pressurized glass capillary with oxyhydrogen flame. Firstly, a microtube with a diameter of 250um is stretched under heating of oxyhydrogen flame, the heating zone length is set to be 20mm and the length of stretch is set to be 7000um.Then nitrogen will be pumped in to the tapered microtube with the pressure of 0.1Mpa, the tapered tip will be heated by the oxyhydrogen flame continuously until a microbubble forms. An optical fiber taper with a diameter of 2 um, fabricated by stretching a single-mode optical fiber under flame was brought in contact with the microbubble to couple the light from a 1550nm tunable diode laser into the whispering gallery mode. The microbubble resonator has a Q factors up to 1.5 × 107 around 1550nm. Different concentrations of ethanol solution (from 5% to 30%) are filled into it in order to test the refractive index sensing capabilities of such resonator, which shows a sensitivity of 82nm/RIU.

  12. Ultralow loss, high Q, four port resonant couplers for quantum optics and photonics.

    PubMed

    Rokhsari, H; Vahala, K J

    2004-06-25

    We demonstrate a low-loss, optical four port resonant coupler (add-drop geometry), using ultrahigh Q (>10(8)) toroidal microcavities. Different regimes of operation are investigated by variation of coupling between resonator and fiber taper waveguides. As a result, waveguide-to-waveguide power transfer efficiency of 93% (0.3 dB loss) and nonresonant insertion loss of 0.02% (<0.001 dB) for narrow bandwidth (57 MHz) four port couplers are achieved in this work. The combination of low-loss, fiber compatibility, and wafer-scale design would be suitable for a variety of applications ranging from quantum optics to photonic networks.

  13. Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature

    SciTech Connect

    Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Tobar, M. E.; Galliou, S.; Bourquin, R.

    2014-12-04

    We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.8×10{sup 16} Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

  14. Neutral Pion Electroproduction in the Resonance Region at High $Q^2$

    SciTech Connect

    Villano, A N; Bosted, P E; Connell, S H; Dalton, M M; Jones, M K; Adams, G S; Afanasev, A; Ahmidouch, A; Angelescu, T; Arrington, J; Asaturyan, R; Baker, O K; Benmouna, N; Berman, B L; Breuer, H; Christy, M E; Cui, Y; Danagoulian, S; Day, D; Dodario, T; Dunne, J A; Dutta, D; El Khayari, N; Elliot, B; Ent, R; Fenker, H C; Frolov, V V; Gan, L; Gaskell, D; Gasparian, A; Grullon, S; Hafidi, K; Hinton, W; Holt, R J; Huber, G M; Hungerford, E; Joo, K; Kalantarians, N; Keppel, C E; Kinney, E R; Kubarovsky, V; Li, Y; Liang, Y; Lu, M; Lung, A; Mack, D; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Mkrtchhyan, H; Napolitano, J; Niculescu, G; Niculescu, I; Opper, A K; Pamela, P; Potterveld, D H; Reimer, Paul E; Reinhold, J; Roche, J; Rock, S E; Schulte, E; Segbefia, E; Smith, C; Smith, G R

    2009-09-01

    The process $ep \\to e^{\\prime}p^{\\prime}\\pi^0$ has been measured at $Q^2$ = 6.4 and 7.7 \\ufourmomts in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center of mass frame considering the process $\\gamma^{\\ast}p \\to p^{\\prime}\\pi^0$. Various details relating to the background subtractions, radiative corrections and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well known $\\Delta(1232)$ resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios $R_{EM}$ and $R_{SM}$ along with the magnetic transition form factor $G_M^{\\ast}$. It is found that the rapid fall off of the $\\Delta(1232)$ contribution continues into this region of momentum transfer and that other resonances

  15. Dispersion engineering of thick high-Q silicon nitride ring-resonators via atomic layer deposition.

    PubMed

    Riemensberger, Johann; Hartinger, Klaus; Herr, Tobias; Brasch, Victor; Holzwarth, Ronald; Kippenberg, Tobias J

    2012-12-03

    We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition. Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. The results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

  16. Tapered Glass-Fiber Microspike: High-Q Flexural Wave Resonator and Optically Driven Knudsen Pump

    NASA Astrophysics Data System (ADS)

    Pennetta, Riccardo; Xie, Shangran; Russell, Philip St. J.

    2016-12-01

    Appropriately designed optomechanical devices are ideal for making ultra-sensitive measurements. Here we report a fused-silica microspike that supports a flexural resonance with a quality factor greater than 100 000 at room temperature in vacuum. Fashioned by tapering single-mode fiber (SMF), it is designed so that the core-guided optical mode in the SMF evolves adiabatically into the fundamental mode of the air-glass waveguide at the tip. The very narrow mechanical linewidth (20 mHz) makes it possible to measure extremely small changes in resonant frequency. In a vacuum chamber at low pressure, the weak optical absorption of the glass is sufficient to create a temperature gradient along the microspike, which causes it to act as a microscopic Knudsen pump, driving a flow of gas molecules towards the tip where the temperature is highest. The result is a circulating molecular flow within the chamber. Momentum exchange between the vibrating microspike and the flowing molecules causes an additional restoring force that can be measured as a tiny shift in the resonant frequency. The effect is strongest when the mean free path of the gas molecules is comparable with the dimensions of the vacuum chamber. The system offers a novel means of monitoring the behavior of weakly absorbing optomechanical sensors operating in vacuum.

  17. Ultra-high-Q thin-silicon nitride strip-loaded ring resonators.

    PubMed

    Stefan, L; Bernard, M; Guider, R; Pucker, G; Pavesi, L; Ghulinyan, M

    2015-07-15

    We report on the design, fabrication, and characterization of thin Si3N4 ultra-high-quality (UHQ) factor ring resonators monolithically integrated on a silicon chip. The devices are based on a strip-loaded configuration and operate at both near-infrared (NIR) and third-telecom wavelengths. This approach allows us to use a guiding Si3N4 core that is one order of magnitude thinner than what has been reported in the past for obtaining similar device performances. Our strip-loaded devices benefit from the absence of physically etched lateral boundaries to show minute light scattering and, therefore, reducing significantly scattering-related losses. Consequently, UHQs of 3.7×10(6) in the NIR and high-quality factors of up to 9×10(5) in the C-band were measured for the guiding material thickness of 80 nm and 115 nm, respectively. These first results are subject to further improvements that may allow employing strip-loaded resonators in nonlinear frequency conversion or quantum computing schemes within the desired spectral range provided by the material transparency.

  18. Neutral pion electroproduction in the resonance region at high Q{sup 2}.

    SciTech Connect

    Villano, A. N.; Stoler, P.; Bosted, P. E.; Connell, S. H.; Dalton, M. M.; Arrington, J.; Hafidi, K.; Holt, R. J.; Schulte, E.; Reimer, P. E.; Zheng, X.; Physics; Rensselaer Polytechnic Inst.; Thomas Jefferson National Accelerator Facility; Univ. of the Johannesburg; Univ. of the Witwatersrand

    2009-09-01

    The process ep {yields} ep{pi}{sup 0} has been measured at Q{sup 2} = 6.4 and 7.7 (GeV/c{sup 2}){sup 2} in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center-of-mass frame considering the process {gamma}*p {yields} p{pi}{sup 0}. Various details relating to the background subtractions, radiative corrections, and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well-known {Delta}(1232) resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios R{sub EM} and R{sub SM} along with the magnetic transition form factor G*{sub M}. It is found that the rapid falloff of the {Delta}(1232) contribution continues into this region of momentum transfer and that other resonances may be making important contributions in this region.

  19. Neutral pion electroproduction in the resonance region at high Q{sup 2}

    SciTech Connect

    Villano, A. N.; Stoler, P.; Kubarovsky, V.; Adams, G. S.; Napolitano, J.; Bosted, P. E.; Jones, M. K.; Ent, R.; Fenker, H. C.; Gaskell, D.; Lung, A.; Mack, D.; Meekins, D. G.; Roche, J.; Smith, G. R.; Wojtsekhowski, B.; Wood, S. A.; Connell, S. H.; Dalton, M. M.; Ahmidouch, A.

    2009-09-15

    The process ep{yields}ep{pi}{sup 0} has been measured at Q{sup 2}=6.4 and 7.7 (GeV/c{sup 2}){sup 2} in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center-of-mass frame considering the process {gamma}*p{yields}p{pi}{sup 0}. Various details relating to the background subtractions, radiative corrections, and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well-known {delta}(1232) resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios R{sub EM} and R{sub SM} along with the magnetic transition form factor G{sub M}*. It is found that the rapid falloff of the {delta}(1232) contribution continues into this region of momentum transfer and that other resonances may be making important contributions in this region.

  20. High-Q AlN/SiO2 symmetric composite thin film bulk acoustic wave resonators.

    PubMed

    Artieda, Alvaro; Muralt, Paul

    2008-11-01

    High-Q, bulk acoustic wave composite resonators based on a symmetric layer sequence of SiO(2)-AlN-SiO(2) sandwiched between electrodes have been developed. Acoustic isolation was achieved by means of deep silicon etching to obtain membrane type thin film bulk acoustic wave resonators (TFBARs). Three different device versions were investigated. The SiO(2) film thicknesses were varied (0 nm, 70 nm, 310 nm, and 770 nm) while the piezoelectric AlN film had a constant thickness of 1.2 microm. The sputter-deposited AlN film grown on the amorphous, sputter-deposited SiO(2) layer exhibited a d(33,f) of 4.0 pm/V. Experimental results of quality factors (Q) and coupling coefficients (k(t)(2)) are in agreement with finite element calculations. A Q of 2000 is observed for the first harmonic of the 310 nm oxide devices. The most intense resonance of the 770 nm oxide device is the third harmonic reaching Q factors of 1450. The temperature drift reveals the impact of the SiO(2) layers, which is more pronounced on the first harmonic, reducing the TCF to 4 ppm/K for the 3rd harmonic of the 310 nm oxide devices.

  1. Single electron tunnelling through high-Q single-wall carbon nanotube NEMS resonators

    NASA Astrophysics Data System (ADS)

    Hüttel, A. K.; Meerwaldt, H. B.; Steele, G. A.; Poot, M.; Witkamp, B.; Kouwenhoven, L. P.; van der Zant, H. S. J.

    2010-12-01

    By first lithographically fabricating contact electrodes and then as last step growing carbon nanotubes with chemical vapour deposition across the ready-made chip, many potential contamination mechanisms for nanotube devices can be avoided. Combining this with pre-defined trenches on the chip, such that the nanotubes are freely suspended above the substrate, enables the formation of highly regular electronic systems. We show that, in addition, such suspended ultra-clean nanotubes provide excellent high-frequency and low-dissipation mechanical resonators. The motion detection mechanism of our experiment is discussed, and we measure the effect of Coulomb blockade and the back-action of single electron tunneling on the mechanical motion. In addition data on the mechanical higher modes is presented.

  2. Reduction of Simulation Times for High-Q Structures using the Resonance Equation

    DOE PAGES

    Hall, Thomas Wesley; Bandaru, Prabhakar R.; Rees, Daniel Earl

    2015-11-17

    Simulating steady state performance of high quality factor (Q) resonant RF structures is computationally difficult for structures with sizes on the order of more than a few wavelengths because of the long times (on the order of ~ 0.1 ms) required to achieve steady state in comparison with maximum time step that can be used in the simulation (typically, on the order of ~ 1 ps). This paper presents analytical and computational approaches that can be used to accelerate the simulation of the steady state performance of such structures. The basis of the proposed approach is the utilization of amore » larger amplitude signal at the beginning to achieve steady state earlier relative to the nominal input signal. Finally, the methodology for finding the necessary input signal is then discussed in detail, and the validity of the approach is evaluated.« less

  3. Reduction of Simulation Times for High-Q Structures using the Resonance Equation

    SciTech Connect

    Hall, Thomas Wesley; Bandaru, Prabhakar R.; Rees, Daniel Earl

    2015-11-17

    Simulating steady state performance of high quality factor (Q) resonant RF structures is computationally difficult for structures with sizes on the order of more than a few wavelengths because of the long times (on the order of ~ 0.1 ms) required to achieve steady state in comparison with maximum time step that can be used in the simulation (typically, on the order of ~ 1 ps). This paper presents analytical and computational approaches that can be used to accelerate the simulation of the steady state performance of such structures. The basis of the proposed approach is the utilization of a larger amplitude signal at the beginning to achieve steady state earlier relative to the nominal input signal. Finally, the methodology for finding the necessary input signal is then discussed in detail, and the validity of the approach is evaluated.

  4. High-Q microsphere resonators for angular velocity sensing in gyroscopes

    SciTech Connect

    An, Panlong; Zheng, Yongqiu; Yan, Shubin Xue, Chenyang Liu, Jun; Wang, Wanjun

    2015-02-09

    A resonator gyroscope based on the Sagnac effect is proposed using a core unit that is generated by water-hydrogen flame melting. The relationship between the quality factor Q and diameter D is revealed. The Q factor of the spectral lines of the microsphere cavity coupling system, which uses tapered fibers, is found to be 10{sup 6} or more before packaging with a low refractive curable ultraviolet polymer, although it drops to approximately 10{sup 5} after packaging. In addition, a rotating test platform is built, and the transmission spectrum and discriminator curves of a microsphere cavity with Q of 3.22×10{sup 6} are measured using a semiconductor laser (linewidth less than 1 kHz) and a real-time proportional-integral circuit tracking and feedback technique. Equations fitting the relation between the voltage and angular rotation rate are obtained. According to the experimentally measured parameters, the sensitivity of the microsphere-coupled system can reach 0.095{sup ∘}/s.

  5. Composite arrays of superconducting microstrip line resonators

    SciTech Connect

    Mohebbi, H. R. Miao, G. X.; Benningshof, O. W. B.; Taminiau, I. A. J.; Cory, D. G.

    2014-03-07

    A novel design of an array of half-wave superconductive microstrip resonators is described. The resonator is intended to be useful for electron spin resonance studies of thin film samples at cryogenic temperatures. It achieves a high quality factor, has a small mode-volume, and creates a uniform magnetic field in a plane above the resonator. The device is made of thin film Niobium on sapphire wafer and is tested with a static magnetic field. Variation of Q-factor versus the magnetic field's strength at different temperatures is reported and is in a good agreement with simulation when the loss due to the vortices is included. Also, the power-dependence response of the resonator is shown in experiments and is verified by capturing the nonlinearity associated with the surface impedance of the superconducting film into the circuit model of the device.

  6. High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms.

    PubMed

    Santis, Christos Theodoros; Steger, Scott T; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon

    2014-02-25

    The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 μm, achieved using a single-mode silicon resonator with Q of 10(6).

  7. HIgh-Q Optical Micro-cavity Resonators as High Sensitive Bio-chemical and Ultrasonic Sensors

    NASA Astrophysics Data System (ADS)

    Ling, Tao

    device's Q factor has been realized by shifting the device's working wavelength to near-visible wavelength and further reducing the device's sidewall roughness. A record new high Q-˜x105 has been measured and the device's NEP as low as 21Pa has been measured. Furthermore, a smaller size polymer microring device has been developed and fabricated to realize larger angle beam forming applications.

  8. Development of a broadband reflective T-filter for voltage biasing high-Q superconducting microwave cavities

    SciTech Connect

    Hao, Yu; Rouxinol, Francisco; LaHaye, M. D.

    2014-12-01

    We present the design of a reflective stop-band filter based on quasi-lumped elements that can be utilized to introduce large dc and low-frequency voltage biases into a low-loss superconducting coplanar waveguide (CPW) cavity. Transmission measurements of the filter are seen to be in good agreement with simulations and demonstrate insertion losses greater than 20 dB in the range of 3–10 GHz. Moreover, transmission measurements of the CPW's fundamental mode demonstrate that loaded quality factors exceeding 10{sup 5} can be achieved with this design for dc voltages as large as 20 V and for the cavity operated in the single-photon regime. This makes the design suitable for use in a number of applications including qubit-coupled mechanical systems and circuit QED.

  9. Nanoscale constrictions in superconducting coplanar waveguide resonators

    SciTech Connect

    Jenkins, Mark David; Naether, Uta; Ciria, Miguel; Zueco, David; Luis, Fernando; Sesé, Javier; Atkinson, James; Barco, Enrique del; Sánchez-Azqueta, Carlos; Majer, Johannes

    2014-10-20

    We report on the design, fabrication, and characterization of superconducting coplanar waveguide resonators with nanoscopic constrictions. By reducing the size of the center line down to 50 nm, the radio frequency currents are concentrated and the magnetic field in its vicinity is increased. The device characteristics are only slightly modified by the constrictions, with changes in resonance frequency lower than 1% and internal quality factors of the same order of magnitude as the original ones. These devices could enable the achievement of higher couplings to small magnetic samples or even to single molecular spins and have applications in circuit quantum electrodynamics, quantum computing, and electron paramagnetic resonance.

  10. Tunable Superconducting Split Ring Resonators

    DTIC Science & Technology

    2012-09-19

    devices and the associated dissipative losses therein. This way an almost dissipationless active supercon- ducting circuit with magnetic control...capacitance of the gap to form a resonator circuit . The advantage of such a circuit is its quite low resonance frequency compared to other structures...of similar size. Figure 1: A schematic SSRR (left) and an equivalent circuit (right). C is the gap and surface capacitance, LGC is the magnetic

  11. Tunable coupling between two superconducting resonators

    NASA Astrophysics Data System (ADS)

    Deppe, F.; Wulschner, F.; Baust, A.; Hoffmann, E.; Menzel, E. P.; Marx, A.; Gross, R.; Solano, E.; Zueco, D.; Garcia Ripoll, J.-J.

    2014-03-01

    During the last decade, tremendous progress has been made towards quantum computation and quantum simulation with superconducting circuits. In such architectures, the controlled exchange of information between two superconducting transmission line resonators via a tunable coupling is a useful tool. Here, we present experimental progress on such devices. Specifically, the coupling is mediated either by a superconducting flux qubit or by an RF SQUID. Our results allow us to analyze the tunable coupling in frequency and time domain. We acknowledge support from: the DFG via SFB 631; the German excellence initiative via NIM; the EU projects CCQED, PROMISCE, SCALEQIT; Spanish MINECO FIS2009-12773-C02-01, FIS2011-25167, FIS2012-36673-C03-02; UPV/EHU UFI 11/55; Basque Government IT472-10.

  12. Analysis and calibration techniques for superconducting resonators.

    PubMed

    Cataldo, Giuseppe; Wollack, Edward J; Barrentine, Emily M; Brown, Ari D; Moseley, S Harvey; U-Yen, Kongpop

    2015-01-01

    A method is proposed and experimentally explored for in-situ calibration of complex transmission data for superconducting microwave resonators. This cryogenic calibration method accounts for the instrumental transmission response between the vector network analyzer reference plane and the device calibration plane. Once calibrated, the observed resonator response is analyzed in detail by two approaches. The first, a phenomenological model based on physically realizable rational functions, enables the extraction of multiple resonance frequencies and widths for coupled resonators without explicit specification of the circuit network. In the second, an ABCD-matrix representation for the distributed transmission line circuit is used to model the observed response from the characteristic impedance and propagation constant. When used in conjunction with electromagnetic simulations, the kinetic inductance fraction can be determined with this method with an accuracy of 2%. Datasets for superconducting microstrip and coplanar-waveguide resonator devices were investigated and a recovery within 1% of the observed complex transmission amplitude was achieved with both analysis approaches. The experimental configuration used in microwave characterization of the devices and self-consistent constraints for the electromagnetic constitutive relations for parameter extraction are also presented.

  13. Parametric resonance in tunable superconducting cavities

    NASA Astrophysics Data System (ADS)

    Wustmann, Waltraut; Shumeiko, Vitaly

    2013-05-01

    We develop a theory of parametric resonance in tunable superconducting cavities. The nonlinearity introduced by the superconducting quantum interference device (SQUID) attached to the cavity and damping due to connection of the cavity to a transmission line are taken into consideration. We study in detail the nonlinear classical dynamics of the cavity field below and above the parametric threshold for the degenerate parametric resonance, featuring regimes of multistability and parametric radiation. We investigate the phase-sensitive amplification of external signals on resonance, as well as amplification of detuned signals, and relate the amplifier performance to that of linear parametric amplifiers. We also discuss applications of the device for dispersive qubit readout. Beyond the classical response of the cavity, we investigate small quantum fluctuations around the amplified classical signals. We evaluate the noise power spectrum both for the internal field in the cavity and the output field. Other quantum-statistical properties of the noise are addressed such as squeezing spectra, second-order coherence, and two-mode entanglement.

  14. Proof-of-principle demonstration of Nb{sub 3}Sn superconducting radiofrequency cavities for high Q{sub 0} applications

    SciTech Connect

    Posen, S. Liepe, M.; Hall, D. L.

    2015-02-23

    Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb{sub 3}Sn. In this paper, we present results for single cell cavities coated with Nb{sub 3}Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q{sub 0} out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q{sub 0} at quench of 8 × 10{sup 9}. In each case, the peak surface magnetic field at quench was well above H{sub c1}, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q{sub 0} values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb{sub 3}Sn cavities in future applications.

  15. Nonlinearly Coupled Superconducting Lumped Element Resonators

    NASA Astrophysics Data System (ADS)

    Collodo, Michele C.; Potočnik, Anton; Rubio Abadal, Antonio; Mondal, Mintu; Oppliger, Markus; Wallraff, Andreas

    We study SQUID-mediated tunable coupling between two superconducting on-chip resonators in the microwave frequency range. In this circuit QED implementation, we employ lumped-element type resonators, which consist of Nb thin film structured into interdigitated finger shunt capacitors and meander inductors. A SQUID, functioning as flux dependent and intrinsically nonlinear inductor, is placed as a coupling element together with an interdigitated capacitor between the two resonators (cf. A. Baust et al., Phys Rev. B 91 014515 (2015)). We perform a spectroscopic measurement in a dilution refrigerator and find the linear photon hopping rate between the resonators to be widely tunable as well as suppressible for an appropriate choice of parameters, which is made possible due to the interplay of inductively and capacitively mediated coupling. Vanishing linear coupling promotes nonlinear effects ranging from onsite- to cross-Kerr interaction. A dominating cross-Kerr interaction related to this configuration is notable, as it induces a unique quantum state. In the course of analog quantum simulations, such elementary building blocks can serve as a precursor for more complex geometries and thus pave the way to a number of novel quantum phases of light

  16. High-Q Wafer Level Package Based on Modified Tri-Layer Anodic Bonding and High Performance Getter and Its Evaluation for Micro Resonant Pressure Sensor

    PubMed Central

    Wang, Liying; Du, Xiaohui; Wang, Lingyun; Xu, Zhanhao; Zhang, Chenying; Gu, Dandan

    2017-01-01

    In order to achieve and maintain a high quality factor (high-Q) for the micro resonant pressure sensor, this paper presents a new wafer level package by adopting cross-layer anodic bonding technique of the glass/silicon/silica (GSS) stackable structure and integrated Ti getter. A double-layer structure similar to a silicon-on-insulator (SOI) wafer is formed after the resonant layer and the pressure-sensitive layer are bonded by silicon direct bonding (SDB). In order to form good bonding quality between the pressure-sensitive layer and the glass cap layer, the cross-layer anodic bonding technique is proposed for vacuum package by sputtering Aluminum (Al) on the combination wafer of the pressure-sensitive layer and the resonant layer to achieve electrical interconnection. The model and the bonding effect of this technique are discussed. In addition, in order to enhance the performance of titanium (Ti) getter, the prepared and activation parameters of Ti getter under different sputtering conditions are optimized and discussed. Based on the optimized results, the Ti getter (thickness of 300 nm to 500 nm) is also deposited on the inside of the glass groove by magnetron sputtering to maintain stable quality factor (Q). The Q test of the built testing system shows that the number of resonators with a Q value of more than 10,000 accounts for more than 73% of the total. With an interval of 1.5 years, the Q value of the samples remains almost constant. It proves the proposed cross-layer anodic bonding and getter technique can realize high-Q resonant structure for long-term stable operation. PMID:28300752

  17. Test of the FDTD accuracy in the analysis of the scattering resonances associated with high-Q whispering-gallery modes of a circular cylinder.

    PubMed

    Boriskin, Artem V; Boriskina, Svetlana V; Rolland, Anthony; Sauleau, Ronan; Nosich, Alexander I

    2008-05-01

    Our objective is the assessment of the accuracy of a conventional finite-difference time-domain (FDTD) code in the computation of the near- and far-field scattering characteristics of a circular dielectric cylinder. We excite the cylinder with an electric or magnetic line current and demonstrate the failure of the two-dimensional FDTD algorithm to accurately characterize the emission rate and the field patterns near high-Q whispering-gallery-mode resonances. This is proven by comparison with the exact series solutions. The computational errors in the emission rate are then studied at the resonances still detectable with FDTD, i.e., having Q-factors up to 10(3).

  18. Pulsed-laser excitation of acoustic modes in open high-Q photoacoustic resonators for trace gas monitoring: results for C2H4

    NASA Astrophysics Data System (ADS)

    Brand, Christian; Winkler, Andreas; Hess, Peter; Miklós, András; Bozóki, Zoltán; Sneider, János

    1995-06-01

    The pulsed excitation of acoustic resonances was studied with a continuously monitoring photoacoustic detector system. Acoustic waves were generated in C2H4/N 2 gas mixtures by light absorption of the pulses from a transversely excited atmospheric CO2 laser. The photoacoustic part consisted of high-Q cylindrical resonators (Q factor 820 for the first radial mode in N2) and two adjoining variable acoustic filter systems. The time-resolved signal was Fourier transformed to a frequency spectrum of high resolution. For the first radial mode a Lorentzian profile was fitted to the measured data. The outside noise suppression and the signal-to-noise ratio were investigated in a normal laboratory environment in the flow-through mode. The acoustic and electric filter system combined with the

  19. Ultra-high frequency, high Q/volume micromechanical resonators in a planar AlN phononic crystal

    NASA Astrophysics Data System (ADS)

    Ghasemi Baboly, M.; Alaie, S.; Reinke, C. M.; El-Kady, I.; Leseman, Z. C.

    2016-07-01

    This paper presents the first design and experimental demonstration of an ultrahigh frequency complete phononic crystal (PnC) bandgap aluminum nitride (AlN)/air structure operating in the GHz range. A complete phononic bandgap of this design is used to efficiently and simultaneously confine elastic vibrations in a resonator. The PnC structure is fabricated by etching a square array of air holes in an AlN slab. The fabricated PnC resonator resonates at 1.117 GHz, which corresponds to an out-of-plane mode. The measured bandgap and resonance frequencies are in very good agreement with the eigen-frequency and frequency-domain finite element analyses. As a result, a quality factor/volume of 7.6 × 1017/m3 for the confined resonance mode was obtained that is the largest value reported for this type of PnC resonator to date. These results are an important step forward in achieving possible applications of PnCs for RF communication and signal processing with smaller dimensions.

  20. Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy.

    PubMed

    Ooe, Hiroaki; Fujii, Mikihiro; Tomitori, Masahiko; Arai, Toyoko

    2016-02-01

    High-Q factor retuned fork (RTF) force sensors made from quartz tuning forks, and the electric circuits for the sensors, were evaluated and optimized to improve the performance of non-contact atomic force microscopy (nc-AFM) performed under ultrahigh vacuum (UHV) conditions. To exploit the high Q factor of the RTF sensor, the oscillation of the RTF sensor was excited at its resonant frequency, using a stray capacitance compensation circuit to cancel the excitation signal leaked through the stray capacitor of the sensor. To improve the signal-to-noise (S/N) ratio in the detected signal, a small capacitor was inserted before the input of an operational (OP) amplifier placed in an UHV chamber, which reduced the output noise from the amplifier. A low-noise, wideband OP amplifier produced a superior S/N ratio, compared with a precision OP amplifier. The thermal vibrational density spectra of the RTF sensors were evaluated using the circuit. The RTF sensor with an effective spring constant value as low as 1000 N/m provided a lower minimum detection limit for force differentiation. A nc-AFM image of a Si(111)-7 × 7 surface was produced with atomic resolution using the RTF sensor in a constant frequency shift mode; tunneling current and energy dissipation images with atomic resolution were also simultaneously produced. The high-Q factor RTF sensor showed potential for the high sensitivity of energy dissipation as small as 1 meV/cycle and the high-resolution analysis of non-conservative force interactions.

  1. Improved transmission performance resulting from the reduced chirp of a semiconductor laser coupled to an external high-Q resonator

    SciTech Connect

    Cartledge, J.C. )

    1990-05-01

    The coupling of a Fabry--Perot laser to an external high-{ital Q} resonator, whose resonance frequencies are not altered by changes in the carrier density, yields a dynamic single-longitudinal-mode laser with a significantly reduced transient frequency chirp. The improvement in the receiver sensitivity due to the reduced chirp is examined for NRZ and RZ intensity modulation, direct detection systems operating in the 1.55-{mu}m wavelength region with conventional single-mode optical fiber. The methodology involves a solving modified rate equations numerically for the optical power and phase of the external resonator laser in response to an injected current waveform, modeling the signal transmission properties of single-mode optical fibers by convolution and modulus squared operations, and using a truncated pulse train approximation to evaluate the probability of error in the presence of intersymbol interference, shot noise, APD multiplication noise, and preamplifier circuit noise.

  2. Hybrid III-V on Si grating as a broadband reflector and a high-Q resonator

    NASA Astrophysics Data System (ADS)

    Chung, Il-Sug; Taghizadeh, Alireza; Park, Gyeong Cheol

    2016-03-01

    Hybrid grating (HG) with a high-refractive-index cap layer added onto a high contrast grating (HCG), can provide a high reflectance close 100 % over a broader wavelength range than HCGs, or work as a ultrahigh quality (Q) factor resonator. The reflection and resonance properties of HGs have been investigated and the mechanisms leading to these properties are discussed. A HG reflector sample integrating a III-V cap layer with InGaAlAs quantum wells onto a Si grating has been fabricated and its reflection property has been characterized. The HG-based lasers have a promising prospect for silicon photonics light source or high-speed laser applications.

  3. Azimuthal-order variations of surface-roughness-induced mode splitting and scattering loss in high-Q microdisk resonators.

    PubMed

    Li, Qing; Eftekhar, Ali A; Xia, Zhixuan; Adibi, Ali

    2012-05-01

    We report an experimental observation of strong variations of quality factor and mode splitting among whispering-gallery modes with the same radial order and different azimuthal orders in a scattering-limited microdisk resonator. A theoretical analysis based on the statistical properties of the surface roughness reveals that mode splittings for different azimuthal orders are uncorrelated, and variations of mode splitting and quality factor among the same radial mode family are possible. Simulation results agree well with the experimental observations.

  4. Theory of RF superconductivity for resonant cavities

    NASA Astrophysics Data System (ADS)

    Gurevich, Alex

    2017-03-01

    An overview of a theory of electromagnetic response of superconductors in strong radio-frequency (RF) electromagnetic fields is given with the emphasis on applications to superconducting resonant cavities for particle accelerators. The paper addresses fundamentals of the BCS surface resistance, the effect of subgap states and trapped vortices on the residual surface resistance at low RF fields, and a nonlinear surface resistance at strong fields, particularly the effect of the RF field suppression of the surface resistance. These issues are essential for the understanding of the field dependence of high quality factors Q({B}a)∼ {10}10{--}{10}11 achieved on the Nb cavities at 1.3–2 K in strong RF fields B a close to the depairing limit, and the extended Q({B}a) rise which has been observed on Ti and N-treated Nb cavities. Possible ways of further increase of Q({B}a) and the breakdown field by optimizing impurity concentration at the surface and by multilayer nanostructuring with materials other than Nb are discussed.

  5. Tunable sub-gap radiation detection with superconducting resonators

    NASA Astrophysics Data System (ADS)

    Dupré, O.; Benoît, A.; Calvo, M.; Catalano, A.; Goupy, J.; Hoarau, C.; Klein, T.; Le Calvez, K.; Sacépé, B.; Monfardini, A.; Levy-Bertrand, F.

    2017-04-01

    We have fabricated planar amorphous indium oxide superconducting resonators ({T}{{c}}∼ 2.8 K) that are sensitive to frequency-selective radiation in the range of 7–10 GHz. Those values lay far below twice the superconducting gap that is worth about 200 GHz. The photon detection consists in a shift of the fundamental resonance frequency. We show that the detected frequency can be adjusted by modulating the total length of the superconducting resonator. We attribute those observations to the excitation of higher-order resonance modes. The coupling between the fundamental lumped and the higher order distributed resonance is due to the kinetic inductance nonlinearity with current. These devices, that we have called sub-gap kinetic inductance detectors, are to be distinguished from the standard kinetic inductance detectors in which quasi-particles are generated when incident light breaks down Cooper pairs.

  6. A platform for multiplexed sensing of biomolecules using high-Q microring resonator arrays with differential readout and integrated microfluidics

    NASA Astrophysics Data System (ADS)

    Wright, J. B.; Brener, I.; Westlake, K. R.; Branch, D. W.; Shaw, M. J.; Vawter, G. A.

    2010-02-01

    We demonstrate chemical/biological sensor arrays based on high quality factor evanescent microring waveguide resonators in a process that is compatible with CMOS fabrication, glass microfluidic integration, and robust surface chemistry ligand attachment. We cancel out any fluctuations due to liquid temperature variations through a differential dual sensor design. Using laser locking servo techniques we attain detection sensitivities in the ng/ml range. This combination of silicon photonic sensors, robust packaging, high sensitivity and arrayed design is capable of providing a platform for multiplexed chem-bio sensing of molecules suspended in solution.

  7. Nonlinearity of superconducting transmission line and microstrip resonator

    SciTech Connect

    Vendik, O.G.; Vendik, I.B.; Samoilova, T.B.

    1997-02-01

    The simplest model of nonlinear response of a superconducting thin film is used for modeling the nonlinear phenomena in a superconducting transmission line and a microstrip resonator. The specified characteristic power of the transmission line is suggested to use as a fitting parameter for numerical description of the microstrip line nonlinearity at microwaves. Quantitative agreement of simulated and experimental data has been obtained for the incident power dependent transmission coefficient of a microstrip line section and a high quality microstrip resonator. Numerical results have also been obtained for the power of the third harmonic radiated from the nonlinear resonator.

  8. Noise from Two-Level Systems in Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Neill, C.; Barends, R.; Chen, Y.; Chiaro, B.; Jeffrey, E.; Kelly, J.; Mariantoni, M.; Megrant, A.; Mutus, J.; Ohya, S.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T.; Cleland, A. N.; Martinis, J. M.

    2013-03-01

    Two-level systems (TLSs) present in amorphous dielectrics and surface interfaces are a significant source of decoherence in superconducting qubits. Linear microwave resonators offer a valuable instrument for characterizing the strongly power-dependent response of these TLSs. Using quarter-wavelength coplanar waveguide resonators, we monitored the microwave response of the resonator at a single near-resonant frequency versus time at varying microwave drive powers. We observe a time dependent variation of the resonator's internal dissipation and resonance frequency. The amplitude of these variations saturates with power in a manner similar to loss from TLSs. These results provide a means for quantifying the number and distribution of TLSs.

  9. A high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging.

    PubMed

    Luo, Zhenyu; Chen, Deyong; Wang, Junbo; Li, Yinan; Chen, Jian

    2014-12-16

    This paper presents a high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging. An approach to maintaining high-vacuum conditions by integrating the MEMS fabrication process with getter material preparation is presented in this paper. In this device, the pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in "H" type doubly-clamped micro resonant beams, leading to a resonance frequency shift. The device geometries were optimized using FEM simulation and a 4-inch SOI wafer was used for device fabrication, which required only three photolithographic steps. In the device fabrication, a non-evaporable metal thin film as the getter material was sputtered on a Pyrex 7740 glass wafer, which was then anodically bonded to the patterned SOI wafer for vacuum packaging. Through-glass via holes predefined in the glass wafer functioned as the electrical interconnections between the patterned SOI wafer and the surrounding electrical components. Experimental results recorded that the Q-factor of the resonant beam was beyond 22,000, with a differential sensitivity of 89.86 Hz/kPa, a device resolution of 10 Pa and a nonlinearity of 0.02% F.S with the pressure varying from 50 kPa to 100 kPa. In addition, the temperature drift coefficient was less than -0.01% F.S/°C in the range of -40 °C to 70 °C, the long-term stability error was quantified as 0.01% F.S over a 5-month period and the accuracy of the microsensor was better than 0.01% F.S.

  10. A High-Q Resonant Pressure Microsensor with Through-Glass Electrical Interconnections Based on Wafer-Level MEMS Vacuum Packaging

    PubMed Central

    Luo, Zhenyu; Chen, Deyong; Wang, Junbo; Li, Yinan; Chen, Jian

    2014-01-01

    This paper presents a high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging. An approach to maintaining high-vacuum conditions by integrating the MEMS fabrication process with getter material preparation is presented in this paper. In this device, the pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in “H” type doubly-clamped micro resonant beams, leading to a resonance frequency shift. The device geometries were optimized using FEM simulation and a 4-inch SOI wafer was used for device fabrication, which required only three photolithographic steps. In the device fabrication, a non-evaporable metal thin film as the getter material was sputtered on a Pyrex 7740 glass wafer, which was then anodically bonded to the patterned SOI wafer for vacuum packaging. Through-glass via holes predefined in the glass wafer functioned as the electrical interconnections between the patterned SOI wafer and the surrounding electrical components. Experimental results recorded that the Q-factor of the resonant beam was beyond 22,000, with a differential sensitivity of 89.86 Hz/kPa, a device resolution of 10 Pa and a nonlinearity of 0.02% F.S with the pressure varying from 50 kPa to 100 kPa. In addition, the temperature drift coefficient was less than −0.01% F.S/°C in the range of −40 °C to 70 °C, the long-term stability error was quantified as 0.01% F.S over a 5-month period and the accuracy of the microsensor was better than 0.01% F.S. PMID:25521385

  11. Broadband architecture for galvanically accessible superconducting microwave resonators

    NASA Astrophysics Data System (ADS)

    Bosman, Sal J.; Singh, Vibhor; Bruno, Alessandro; Steele, Gary A.

    2015-11-01

    In many hybrid quantum systems, a superconducting circuit is required, which combines DC-control with a coplanar waveguide (CPW) microwave resonator. The strategy thus far for applying a DC voltage or current bias to microwave resonators has been to apply the bias through a symmetry point in such a way that it appears as an open circuit for certain frequencies. Here, we introduce a microwave coupler for superconducting CPW cavities in the form of a large shunt capacitance to ground. Such a coupler acts as a broadband mirror for microwaves while providing galvanic connection to the center conductor of the resonator. We demonstrate this approach with a two-port λ/4-transmission resonator with linewidths in the MHz regime ( Q ˜103 ) that shows no spurious resonances and apply a voltage bias up to 80 V without affecting the quality factor of the resonator. This resonator coupling architecture, which is simple to engineer, fabricate, and analyse, could have many potential applications in experiments involving superconducting hybrid circuits.

  12. YBCO superconducting ring resonators at millimeter-wave frequencies

    NASA Technical Reports Server (NTRS)

    Chorey, Christopher M.; Kong, Keon-Shik; Bhasin, Kul B.; Warner, J. D.; Itoh, Tatsuo

    1991-01-01

    Microstrip ring resonators operating at 35 GHz were fabricated from laser ablated YBCO films deposited on lanthanum aluminate substrates. They were measured over a range of temperatures and their performances compared to identical resonators made of evaporated gold. Below 60 Kelvin the superconducting strip performed better than the gold, reaching an unloaded Q approximately 1.5 times that of gold at 25 K. A shift in the resonant frequency follows the form predicted by the London equations. The Phenomenological Loss Equivalence Method is applied to the ring resonator and the theoretically calculated Q values are compared to the experimental results.

  13. Multigap superconductivity and barrier-driven resonances in superconducting nanofilms with an inner potential barrier

    NASA Astrophysics Data System (ADS)

    Doria, Mauro M.; Cariglia, Marco; Perali, Andrea

    2016-12-01

    We study the crossover in a zero-temperature superconducting nanofilm from a single to a double superconducting slab induced by a barrier in the middle. We use the Bogoliubov-de Gennes (BdG) equations in the Anderson approximation to show that the single-phase superconducting ground state of this heterostructure is intrinsically multigapped and has a new type of resonance caused by the strength of the barrier, thus distinct from the Thompson-Blatt shape resonance which is caused by tuning the thickness of the film. The simplest theoretical framework able to describe a finite height and very thin tunable insulating potential barrier in the middle is provided by a δ -function potential. In this framework, the even single-particle states are affected by the insulating barrier, whereas the odd ones are not. The new type of resonance, hereafter called barrier-driven resonance, is caused by the crossing of the even single-particle states through the Fermi surface. The lift of the even-odd degeneracy at the barrier reconfigures the pairing interaction and leads to a multigapped superconducting state with barrier-driven resonances.

  14. Lorentzian crater in superconducting microwave resonators with inserted nanowires

    NASA Astrophysics Data System (ADS)

    Bezryadin, Alexey; Brenner, Matthew W.; Gopalakrishnan, Sarang; Ku, Jaseung; Shah, Nayana; Goldbart, Paul M.

    2011-03-01

    We report on observations of nonequilibrium pulsing states in microwave (i.e., GHz) coplanar waveguide(CPW) resonators consisting of superconducting MoGe strips interrupted by a trench and connected by one or more suspended superconducting nanowires. The Lorentzian resonance peak shows a ``crater'' when driven past the critical current of the nanowire, leading to a ``pulsing'' state. In the pulsing state, the supercurrent grows until it reaches the critical current, at which point all stored energy quickly dissipates through Joule heating. We develop a phenomenological model of resonator-nanowire systems, which explains the experimental data quantitatively. For the case of resonators comprising two parallel nanowires and subject to an external magnetic field, we find field-driven oscillations of the onset power for crater formation, as well as the occurrence of a new state, in which the periodic pulsing effect is such that only the weaker wire participates in the dissipation process.

  15. Photon-induced thermal effects in superconducting coplanar waveguide resonators

    NASA Astrophysics Data System (ADS)

    Wang, Yiwen; Zhou, Pinjia; Wei, Lianfu; Li, Haijie; Zhang, Beihong; Zhang, Miao; Wei, Qiang; Fang, Yurong; Cao, Chunhai

    2013-10-01

    We experimentally investigated the optical responses of a superconducting niobium resonator. It was found that, with increasing radiation power, the resonance frequency increases monotonically below around 500 mK, decreases monotonically above around 1 K, and exhibits a nonmonotonic behavior at around 700 mK. These observations show that one can operate the irradiated resonator in three temperature regimes, depending on whether two-level system (TLS) effects or kinetic inductance effects dominate. Furthermore, we found that the optical responses at ultra-low temperatures can be qualitatively regarded as a photon-induced thermalization effect of TLSs, which could be utilized to achieve thermal sensitive photon detections.

  16. Quantum logical gates with four-level superconducting quantum interference devices coupled to a superconducting resonator

    SciTech Connect

    He Xiaoling; Luo Junyan; Yang Chuiping; Li Sheng; Han Siyuan

    2010-08-15

    We propose a way for realizing a two-qubit controlled phase gate with superconducting quantum interference devices (SQUIDs) coupled to a superconducting resonator. In this proposal, the two lowest levels of each SQUID serve as the logical states and two intermediate levels of each SQUID are used for the gate realization. We show that neither adjustment of SQUID level spacings during the gate operation nor uniformity in SQUID parameters is required by this proposal. In addition, this proposal does not require the adiabatic passage or a second-order detuning and thus the gate is much faster.

  17. Observation of superconductivity in hydrogen sulfide from nuclear resonant scattering.

    PubMed

    Troyan, Ivan; Gavriliuk, Alexander; Rüffer, Rudolf; Chumakov, Alexander; Mironovich, Anna; Lyubutin, Igor; Perekalin, Dmitry; Drozdov, Alexander P; Eremets, Mikhail I

    2016-03-18

    High-temperature superconductivity remains a focus of experimental and theoretical research. Hydrogen sulfide (H2S) has been reported to be superconducting at high pressures and with a high transition temperature. We report on the direct observation of the expulsion of the magnetic field in H2S compressed to 153 gigapascals. A thin (119)Sn film placed inside the H2S sample was used as a sensor of the magnetic field. The magnetic field on the (119)Sn sensor was monitored by nuclear resonance scattering of synchrotron radiation. Our results demonstrate that an external static magnetic field of about 0.7 tesla is expelled from the volume of (119)Sn foil as a result of the shielding by the H2S sample at temperatures between 4.7 K and approximately 140 K, revealing a superconducting state of H2S.

  18. Anomalous Behavior of High Quality Factor Planar Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Megrant, Anthony; Chen, Zijun; Chiaro, Ben; Dunsworth, Andrew; Quintana, Chris; Campbell, Brooks; Kelly, Julian; Barends, Rami; Chen, Yu; Jeffrey, Evan; Mutus, Josh; Neill, Charles; O'Malley, Peter; Sank, Daniel; Vainsencher, Amit; Wenner, Jim; White, Ted; Bochmann, Jorg; Hoi, Iochun; Palmstrom, Christopher; Martinis, John; Cleland, Andrew

    2014-03-01

    Superconducting coplanar waveguide resonators have proven to be invaluable tools in studying some of the decoherence mechanisms found in superconducting qubits. Surface two-level states tend to dominate decoherence at temperatures below Tc/10 and at very low microwave powers, assuming loss through other channels (e.g. quasiparticles, vortices, and radiation loss) has been mitigated through proper shielding and design. I will present recent measurements of resonators whose behavior diverges significantly from the standard two-level state model at low temperatures and low excitation energies, resulting in startling behavior of the internal quality factor. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), through the Army Research Office grant W911NF-09-1-0375.

  19. Superconducting Microwave Resonator Arrays for Submillimeter/Far-Infrared Imaging

    NASA Astrophysics Data System (ADS)

    Noroozian, Omid

    Superconducting microwave resonators have the potential to revolutionize submillimeter and far-infrared astronomy, and with it our understanding of the universe. The field of low-temperature detector technology has reached a point where extremely sensitive devices like transition-edge sensors are now capable of detecting radiation limited by the background noise of the universe. However, the size of these detector arrays are limited to only a few thousand pixels. This is because of the cost and complexity of fabricating large-scale arrays of these detectors that can reach up to 10 lithographic levels on chip, and the complicated SQUID-based multiplexing circuitry and wiring for readout of each detector. In order to make substantial progress, next-generation ground-based telescopes such as CCAT or future space telescopes require focal planes with large-scale detector arrays of 104--10 6 pixels. Arrays using microwave kinetic inductance detectors (MKID) are a potential solution. These arrays can be easily made with a single layer of superconducting metal film deposited on a silicon substrate and pattered using conventional optical lithography. Furthermore, MKIDs are inherently multiplexable in the frequency domain, allowing ˜ 10 3 detectors to be read out using a single coaxial transmission line and cryogenic amplifier, drastically reducing cost and complexity. An MKID uses the change in the microwave surface impedance of a superconducting thin-film microresonator to detect photons. Absorption of photons in the superconductor breaks Cooper pairs into quasiparticles, changing the complex surface impedance, which results in a perturbation of resonator frequency and quality factor. For excitation and readout, the resonator is weakly coupled to a transmission line. The complex amplitude of a microwave probe signal tuned on-resonance and transmitted on the feedline past the resonator is perturbed as photons are absorbed in the superconductor. The perturbation can be

  20. Photon transfer in a system of coupled superconducting microwave resonators

    NASA Astrophysics Data System (ADS)

    Muirhead, C. M.; Gunupudi, B.; Colclough, M. S.

    2016-08-01

    A novel scheme is proposed for the study of energy transfer in a pair of coupled thin film superconducting microwave resonators. We show that the transfer could be achieved by modulating the kinetic inductance and that this has a number of advantages over earlier theoretical and experimental schemes, which use modulation of capacitance by vibrating nanobars or membranes. We show that the proposed scheme lends itself to the study of the classical analogues of Rabi and Landau-Zener-Stueckelberg oscillations and Landau-Zener transitions using experimentally achievable parameters. We consider a number of ways in which energy transfer (photon shuttle) between the two resonators could be achieved experimentally.

  1. Superconductivity

    NASA Astrophysics Data System (ADS)

    Yeo, Yung K.

    Many potential high-temperature superconductivity (HTS) military applications have been demonstrated by low-temperature superconductivity systems; they encompass high efficiency electric drives for naval vessels, airborne electric generators, energy storage systems for directed-energy weapons, electromechanical launchers, magnetic and electromagnetic shields, and cavity resonators for microwave and mm-wave generation. Further HST applications in militarily relevant fields include EM sensors, IR focal plane arrays, SQUIDs, magnetic gradiometers, high-power sonar sources, and superconducting antennas and inertial navigation systems. The development of SQUID sensors will furnish novel magnetic anomaly detection methods for ASW.

  2. Loss mechanisms in superconducting thin film microwave resonators

    SciTech Connect

    Goetz, Jan Haeberlein, Max; Wulschner, Friedrich; Zollitsch, Christoph W.; Meier, Sebastian; Fischer, Michael; Fedorov, Kirill G.; Menzel, Edwin P.; Deppe, Frank; Eder, Peter; Xie, Edwar; Gross, Rudolf; Marx, Achim

    2016-01-07

    We present a systematic analysis of the internal losses of superconducting coplanar waveguide microwave resonators based on niobium thin films on silicon substrates. In particular, we investigate losses introduced by Nb/Al interfaces in the center conductor, which is important for experiments where Al based Josephson junctions are integrated into Nb based circuits. We find that these interfaces can be a strong source for two-level state (TLS) losses, when the interfaces are not positioned at current nodes of the resonator. In addition to TLS losses, for resonators including Al, quasiparticle losses become relevant above 200 mK. Finally, we investigate how losses generated by eddy currents in conductive material on the backside of the substrate can be minimized by using thick enough substrates or metals with high conductivity on the substrate backside.

  3. Analysis of whispering-gallery superconducting dielectric resonator modes

    SciTech Connect

    Zhou Shiping; Jabbar, A. )

    1991-06-01

    The whispering-gallery (WG) modes of a superconducting dielectric resonator (SDR) based on a sapphire cylindrical dielectric resonator and a YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} shielding cylinder were studied. A method for the determination of the resonant frequencies and the maximum quality factor of such modes is presented. Calculations have shown that most of the mode energy could be confined between the caustic surface of the WG modes provided the dimensions of the SDR are properly selected, and a magnitude of 10{sup 9} for Q of the SDR could be estimated. A phenomenal explanation is given to account for such outstanding microwave behavior.

  4. Electron Spin Resonance at the Level of 1 04 Spins Using Low Impedance Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Eichler, C.; Sigillito, A. J.; Lyon, S. A.; Petta, J. R.

    2017-01-01

    We report on electron spin resonance measurements of phosphorus donors localized in a 200 μ m2 area below the inductive wire of a lumped element superconducting resonator. By combining quantum limited parametric amplification with a low impedance microwave resonator design, we are able to detect around 2 ×1 04 spins with a signal-to-noise ratio of 1 in a single shot. The 150 Hz coupling strength between the resonator field and individual spins is significantly larger than the 1-10 Hz coupling rates obtained with typical coplanar waveguide resonator designs. Because of the larger coupling rate, we find that spin relaxation is dominated by radiative decay into the resonator and dependent upon the spin-resonator detuning, as predicted by Purcell.

  5. Characterizing a Superconducting Resonator with Frequency-Compensated Tunable Coupling

    NASA Astrophysics Data System (ADS)

    Wenner, James; Campbell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; Hoi, I.-C.; Kelly, J.; Megrant, A.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Vainsencher, A.; White, T. C.; Barends, R.; Chen, Y.; Fowler, A. G.; Jeffrey, E.; Mutus, J. Y.; Roushan, P.; Sank, D.; Martinis, John M.

    2015-03-01

    Deterministic quantum state transfer between devices on different chips requires the ability to transfer quantum states between traveling qubits and fixed logic qubits. Reflections must be minimized to avoid energy loss and phase interference; this requires tunable coupling to an inter-chip line while the two devices are at equal frequencies. To achieve this, we present a 6GHz superconducting coplanar resonator with tunable coupling to a 50 Ohm transmission line. We compensate for the resulting shift in resonator frequency by simultaneously tuning a second SQUID. We further demonstrate the device coherence and the ability both to release a single-frequency shaped pulse into the transmission line and to efficiently capture a shaped pulse, prerequisites for efficient inter-chip deterministic quantum state transfer.

  6. Nuclear Magnetic Resonance Study of High Temperature Superconductivity

    NASA Astrophysics Data System (ADS)

    Mounce, Andrew M.

    The high temperature superconductors HgBa2CuO 4+delta (Hg1201) and Bi2SrCa2Cu2O 8+delta (Bi2212) have been treated with 17O for both nuclear magnetic resonance (NMR) sensitivity and various electronic properties. Subsequently, NMR experiments were performed on Hg1201 and Bi2212 to reveal the nature of the pseudogap, in the normal state, and vortex phases, in the superconducting state. NMR has been performed on 17O in an underdoped Hg1201 crystal with a superconducting transition transition temperature of 74 K to look for circulating orbital currents proposed theoretically and inferred from neutron scattering. The measurements reveal narrow spectra which preclude static local fields in the pseudogap phase at the apical site, suggesting that the moments observed with neutrons are fluctuating or the orbital current ordering is not the correct model for the neutron scattering observation. The fine detail of the NMR frequency shifts at the apical oxygen site are consistent with a dipolar field from the Cu+2 site and diamagnetism below the superconducting transition. It has been predicted that superconducting vortices should be electrically charged and that this effect is particularly enhanced for high temperature superconductors. Here it is shown that the Abrikosov vortex lattice, characteristic of the mixed state of superconductors, will become unstable at sufficiently high magnetic field if there is charge trapped on the vortex core for highly anisotropic superconductors. NMR measurements of the magnetic fields generated by vortices in Bi2212 single crystals provide evidence for an electro-statically driven vortex lattice reconstruction with the magnitude of charge on each vortex pancake of 2x10-3e, depending on doping, in line with theoretical estimates. Competition with magnetism is at the heart of high temperature superconductivity, most intensely felt near a vortex core. To investigate vortex magnetism spatially resolved NMR has been used, finding a strongly non

  7. Observation of the fundamental Nyquist noise limit in an ultra-high Q-factor cryogenic bulk acoustic wave cavity

    SciTech Connect

    Goryachev, Maxim Ivanov, Eugene N.; Tobar, Michael E.; Kann, Frank van; Galliou, Serge

    2014-10-13

    Thermal Nyquist noise fluctuations of high-Q bulk acoustic wave cavities have been observed at cryogenic temperatures with a DC superconducting quantum interference device amplifier. High Q modes with bandwidths of few tens of milliHz produce thermal fluctuations with a signal-to-noise ratio of up to 23 dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high (Q > 10{sup 8} at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.

  8. First high gradient test results of a dressed 325 MHz superconducting single spoke resonator at Fermilab

    SciTech Connect

    Webber, R.C.; Khabiboulline, T.; Madrak, R.; Nicol, T.; Ristori, L.; Soyars, W.; Wagner, R.; /Fermilab

    2010-09-01

    A new superconducting RF cavity test facility has been commissioned at Fermilab in conjunction with first tests of a 325 MHz, {beta} = 0.22 superconducting single-spoke cavity dressed with a helium jacket and prototype tuner. The facility is described and results of full gradient, CW cavity tests with a high Q{sub ext} drive coupler are reported. Sensitivities to Q disease and externally applied magnetic fields were investigated. Results are compared to bare cavity results obtained prior to hydrogen degassing and welding into the helium jacket.

  9. Project X superconducting spoke resonator test cryostat 2 K conversion

    NASA Astrophysics Data System (ADS)

    Chen, M.; Dalesandro, A.; Hansen, B.; Klebaner, A.; Nicol, T.; Orlov, Y.; Peterson, T.

    2014-01-01

    Superconducting spoke resonators (SSR1 and SSR2) envisioned for Project X will be developed in Fermilab and operated at temperatures down to 2 K in continuous wave (CW) mode. Each spoke cavity will be tested individually in a cryostat that replicates conditions in the longer multi-cavity cryomodules. This test cryostat has all the features of the longer cryomodules - magnetic shielding, 80 K thermal shield, multi-layer insulation, support post, and input coupler [1]. Fermilab is in the processing of retrofitting the existing test cryostat which was originally designed for operation at 4.5 K. This paper describes the design of the conversion of the current test cryostat, flexible transfer lines, helium relief system and cryogenics interface.

  10. Quasiparticle spin resonance and coherence in superconducting aluminium

    NASA Astrophysics Data System (ADS)

    Quay, C. H. L.; Weideneder, M.; Chiffaudel, Y.; Strunk, C.; Aprili, M.

    2015-10-01

    Conventional superconductors were long thought to be spin inert; however, there is now increasing interest in both (the manipulation of) the internal spin structure of the ground-state condensate, as well as recently observed long-lived, spin-polarized excitations (quasiparticles). We demonstrate spin resonance in the quasiparticle population of a mesoscopic superconductor (aluminium) using novel on-chip microwave detection techniques. The spin decoherence time obtained (~100 ps), and its dependence on the sample thickness are consistent with Elliott-Yafet spin-orbit scattering as the main decoherence mechanism. The striking divergence between the spin coherence time and the previously measured spin imbalance relaxation time (~10 ns) suggests that the latter is limited instead by inelastic processes. This work stakes out new ground for the nascent field of spin-based electronics with superconductors or superconducting spintronics.

  11. Characterizing and reducing microfabrication-induced loss in superconducting devices, Part I: Resonators

    NASA Astrophysics Data System (ADS)

    Dunsworth, Andrew; Megrant, A.; Chen, Z.; Quintana, C.; Burkett, B.; Kelly, J.; Barends, R.; Fowler, A.; Jeffrey, E.; White, T.; Sank, D.; Mutus, J.; Campbell, B.; Chen, Y.; Chiaro, B.; Neill, C.; O'Malley, P. J. J.; Roushan, P.; Vainsencher, A.; Wenner, J.; Martinis, J. M.

    Planar and 3D superconducting qubits have previously been shown to be limited by microfabrication induced loss. Using finite element simulations, we have identified a major source of this decoherence in superconducting qubits. Furthermore, we experimentally verified this dominant loss channel using a novel resonator based approach, which we call 'Hydra' resonators. We fully characterized and then substantially reduced this loss channel using these Hydra resonators. I will report on these measurements and their implications on improving the coherence of superconducting qubits. This work is supported by Google inc.

  12. Superconducting Pb stripline resonators in parallel magnetic field and their application for microwave spectroscopy

    NASA Astrophysics Data System (ADS)

    Ebensperger, Nikolaj G.; Thiemann, Markus; Dressel, Martin; Scheffler, Marc

    2016-11-01

    Planar superconducting microwave resonators are key elements in a variety of technical applications and also act as sensitive probes for microwave spectroscopy of various materials of interest in present solid state research. Here superconducting Pb is a suitable material as a basis for microwave stripline resonators. To utilize Pb stripline resonators in a variable magnetic field (e.g. in ESR measurements), the electrodynamics of such resonators in a finite magnetic field has to be fully understood. Therefore we performed microwave transmission measurements (with ample applied power to work in linear response) on superconducting Pb stripline resonators in a variable, parallel magnetic field. We determined surface resistance, penetration depth, as well as real and imaginary parts, {σ }1 and {σ }2, of the complex conductivity of superconducting Pb as a function of a magnetic field. Here we find features reminiscent of those in temperature-dependent measurements, such as a maximum in {σ }1 (coherence peak). At magnetic fields above the critical field of this type-I superconductor we still find a low-loss microwave response, which we assign to remaining superconductivity in the form of filaments within the Pb. Hysteresis effects are found in the quality factor of resonances once the swept magnetic field has exceeded the critical magnetic field. This is due to normal conducting areas that are pinned and can therefore persist in the superconducting phase. Besides zero-field-cooling we show an alternative way to eliminate these even at T\\lt {T}c. Based on our microwave data, we also determine the critical magnetic field and the critical temperature of Pb in a temperature range between 1.6 K and 6.5 K and magnetic fields up to 140 mT, showing good agreement with BCS predictions. We also study a Sn sample in a Pb resonator to demonstrate the applicability of superconducting Pb stripline resonators in the experimental study of other (super-)conducting materials in a

  13. Evidence of a Nonequilibrium Distribution of Quasiparticles in the Microwave Response of a Superconducting Aluminum Resonator

    NASA Astrophysics Data System (ADS)

    de Visser, P. J.; Goldie, D. J.; Diener, P.; Withington, S.; Baselmans, J. J. A.; Klapwijk, T. M.

    2014-01-01

    In a superconductor, absorption of photons with an energy below the superconducting gap leads to redistribution of quasiparticles over energy and thus induces a strong nonequilibrium quasiparticle energy distribution. We have measured the electrodynamic response, quality factor, and resonant frequency of a superconducting aluminium microwave resonator as a function of microwave power and temperature. Below 200 mK, both the quality factor and resonant frequency decrease with increasing microwave power, consistent with the creation of excess quasiparticles due to microwave absorption. Counterintuitively, above 200 mK, the quality factor and resonant frequency increase with increasing power. We demonstrate that the effect can only be understood by a nonthermal quasiparticle distribution.

  14. In-situ electron paramagnetic resonance studies of paramagnetic point defects in superconducting microwave resonators

    NASA Astrophysics Data System (ADS)

    Zhang, Shengke; Kopas, Cameron; Wagner, Brian; Queen, Daniel; Newman, N.

    2016-09-01

    The physical nature and concentration of paramagnetic point defects in the dielectrics of superconducting planar microwave resonators have been determined using in-situ electron paramagnetic resonance spectroscopy. To perform this work, the quality factor of parallel plate and stripline resonators was measured as a function of the magnitude of a magnetic-field applied parallel to the electrode surfaces. YBa2Cu3O7-δ thin film electrodes proved to be a preferred choice over Nb and MgB2 because they are readily available and have a small surface resistance (Rs) up to high temperatures (˜77 K) and magnetic fields (i.e., <1 T). Stripline resonators with a widely used high performance microwave dielectric, Co2+-doped Ba(Zn1/3Nb2/3)O3, are shown to have losses dominated by d-electron spin-excitations in exchange-coupled Co2+ point-defect clusters, even in the absence of an applied magnetic field. A significant enhanced microwave loss in stripline and parallel plate resonators is found to correlate with the presence of paramagnetic Mn2+ dopants in Ba(Zn1/3Ta2/3)O3 ceramics and dangling bond states in amorphous Si thin films, although the identification of the dominant loss mechanism(s) in these dielectrics requires further investigation.

  15. Microtesla magnetic resonance imaging with a superconducting quantum interference device

    SciTech Connect

    McDermott, Robert; Lee, SeungKyun; ten Haken, Bennie; Trabesinger, Andreas H.; Pines, Alexander; Clarke, John

    2004-03-15

    We have constructed a magnetic resonance imaging (MRI) scanner based on a dc Superconducting QUantum Interference Device (SQUID) configured as a second-derivative gradiometer. The magnetic field sensitivity of the detector is independent of frequency; it is therefore possible to obtain high-resolution images by prepolarizing the nuclear spins in a field of 300 mT and detecting the signal at 132 fYT, corresponding to a proton Larmor frequency of 5.6 kHz. The reduction in the measurement field by a factor of 10,000 compared with conventional scanners eliminates inhomogeneous broadening of the nuclear magnetic resonance lines, even in fields with relatively poor homogeneity. The narrow linewidths result in enhanced signal-to-noise ratio and spatial resolution for a fixed strength of the magnetic field gradients used to encode the image. We present two-dimensional images of phantoms and pepper slices, obtained in typical magnetic field gradients of 100 fYT/m, with a spatial resolution of about 1mm. We further demonstrate a slice-selected image of an intact pepper. By varying the time delay between removal of the polarizing field and initiation of the spin echo sequence we acquire T1-weighted contrast images of water phantoms, some of which are doped with a paramagnetic salt; here, T1 is the nuclear spin-lattice relaxation time. The techniques presented here could readily be adapted to existing multichannel SQUID systems used for magnetic source imaging of brain signals. Further potential applications include low-cost systems for tumor screening and imaging peripheral regions of the body.

  16. Storage and on-demand release of microwaves using superconducting resonators with tunable coupling

    SciTech Connect

    Pierre, Mathieu Svensson, Ida-Maria; Raman Sathyamoorthy, Sankar; Johansson, Göran; Delsing, Per

    2014-06-09

    We present a system which allows to tune the coupling between a superconducting resonator and a transmission line. This storage resonator is addressed through a second, coupling resonator, which is frequency-tunable and controlled by a magnetic flux applied to a superconducting quantum interference device. We experimentally demonstrate that the lifetime of the storage resonator can be tuned by more than three orders of magnitude. A field can be stored for 18 μs when the coupling resonator is tuned off resonance and it can be released in 14 ns when the coupling resonator is tuned on resonance. The device allows capture, storage, and on-demand release of microwaves at a tunable rate.

  17. Optical-Fiber-Illuminated Response of a Superconducting Microwave Resonator Below 1 K

    NASA Astrophysics Data System (ADS)

    Voigt, Kristen; Hertzberg, J. B.; Dutta, S. K.; Hoffman, J. E.; Grover, J. A.; Lee, J.; Solano, P.; Budoyo, R. P.; Ballard, C.; Anderson, J. R.; Lobb, C. J.; Rolston, S. L.; Wellstood, F. C.

    As a step towards building a hybrid quantum system that couples superconducting elements to neutral atoms trapped on a tapered optical nanofiber, we have studied how the presence of the fiber dielectric and light scattered from a fiber affect the response of a translatable thin-film lumped-element superconducting Al microwave resonator that is cooled to 15 mK. The resonator has a resonance frequency of about 6 GHz, a quality factor Q 2 x 105, and is mounted inside a 3D Al superconducting cavity. An optical fiber is tapered to a 60 um diameter and passes through two small holes in the 3D cavity such that it sits near the resonator. The 3D cavity is mounted on an x-z piezo-translation stage that allows us to change the relative position of the thin-film resonator and fiber. When the resonator is brought closer to the fiber, the resonance frequency decreases slightly due to the presence of the fiber dielectric. When 200 uW of 780 nm light is sent through the fiber, about 100 pW/mm is Rayleigh-scattered from the fiber. This causes a position-dependent illumination of the resonator, affecting its resonance frequency and Q. We compare our results to a model of the resonator response that includes the generation, diffusion, and recombination of quasiparticles in the resonator and find that the frequency response allows us to track the position of the fiber to within 10 um.

  18. Dissipative processes in superconducting nanodevices: Nanowire-resonators, shunted nanowires, and graphene proximity junctions

    NASA Astrophysics Data System (ADS)

    Brenner, Matthew W.

    The topic of superconducting nanowires has recently been an interesting field of research which has included the study of the superconductor to insulator transition (SIT), the observation of macroscopic quantum behavior such as quantum phase slips (QPS), and the potential use of nanowires as qubits. Superconducting coplanar microwave waveguide resonators have also become a popular way of studying superconducting junctions and qubits, as they provide an extremely low noise environment. For example, superconducting two-dimensional Fabry-Perot resonators have been used by other groups to make non-demolition measurements of a qubit. The motivation of this thesis will be the merging of the fields of superconducting nanowires and the technique of using superconducting microwave resonators to study junctions by incorporating a nanowire into the resonator itself at a current anti-node. By doing this, the nonlinear effects of the nanowire can be studied which may find application in single photon detectors, mixers, and the readout of qubits. We also employ the technique of molecular templating to fabricate some of the thinnest superconducting nanowires ever studied (down to ˜ 5 nm in diameter in some cases). In this thesis, we extend the understanding of the nonlinear properties of a nanowire-resonator system and investigate a new type of nonlinearity that involves a pulsing regime between the superconducting and normal phases of the nanowire. We develop a model, which describes the results quantitatively and by modeling the system, we are able to extract information regarding the relaxation time of the nanowire back into the superconducting state. We also study double nanowire-resonator systems where two closely spaced parallel nanowires interrupt the resonator center conductor and form a loop where vortex tunneling processes can occur. Using a double nanowire-resonator we are able to observe the Little-Parks effect at low temperatures (where the resistance of the wires

  19. Mechanical resonance characteristics of a high-{Tc} superconducting levitation system

    SciTech Connect

    Sugiura, Toshihiko; Fujimori, Hideki

    1996-05-01

    This research deals with dynamic response of a permanent magnet freely levitated above an excited high-{Tc} superconductor. Evaluation of dynamic characteristics is required in mechanical design of high-{Tc} superconducting levitation systems. Their dynamics is coupled with Type-II superconducting phenomena. By a numerical approach based on some macroscopic models they evaluate mechanical resonance characteristics of a superconducting levitation system. Numerical results show some nonlinear properties and effect of the flux flow in Type-II superconductor, which are observed in experiments or predicted by analyses.

  20. Chip Mount Design as a Dissipation-Limiting Factor in High Quality Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Campbell, Brooks; Barends, R.; Bochmann, J.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Hoi, I.; Jeffrey, E.; Kelly, J.; Megrant, A.; Mutus, J.; Neil, C.; O'Malley, P.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T.; Cleland, A. N.; Martinis, J. M.

    2014-03-01

    Superconducting quantum computing technology continues to make progress with regards to both materials quality and circuit complexity. We have found that chip mount design can become a coherence-limiting factor for superconducting coplanar resonators with an internal quality factor above 1 million. Understanding the impact of chip-to-mount coupling will aid in both proper mount design for higher density circuits as well as the further improvement of coherence times. These coplanar resonators provide an ideal test circuit as they are sensitive to a variety of loss mechanisms including radiation, infrared light, and magnetic fields which also affect more complex superconducting circuits. I will present results relating the coherence and performance of resonators to box design, box material, and chip layout.

  1. Coherently Opening a High-Q Cavity

    NASA Astrophysics Data System (ADS)

    Tufarelli, Tommaso; Ferraro, Alessandro; Serafini, Alessio; Bose, Sougato; Kim, M. S.

    2014-04-01

    We propose a general framework to effectively "open" a high-Q resonator, that is, to release the quantum state initially prepared in it in the form of a traveling electromagnetic wave. This is achieved by employing a mediating mode that scatters coherently the radiation from the resonator into a one-dimensional continuum of modes such as a waveguide. The same mechanism may be used to "feed" a desired quantum field to an initially empty cavity. Switching between an open and "closed" resonator may then be obtained by controlling either the detuning of the scatterer or the amount of time it spends in the resonator. First, we introduce the model in its general form, identifying (i) the traveling mode that optimally retains the full quantum information of the resonator field and (ii) a suitable figure of merit that we study analytically in terms of the system parameters. Then, we discuss two feasible implementations based on ensembles of two-level atoms interacting with cavity fields. In addition, we discuss how to integrate traditional cavity QED in our proposal using three-level atoms.

  2. A graph-theoretical representation of multiphoton resonance processes in superconducting quantum circuits

    PubMed Central

    Jooya, Hossein Z.; Reihani, Kamran; Chu, Shih-I

    2016-01-01

    We propose a graph-theoretical formalism to study generic circuit quantum electrodynamics systems consisting of a two level qubit coupled with a single-mode resonator in arbitrary coupling strength regimes beyond rotating-wave approximation. We define colored-weighted graphs, and introduce different products between them to investigate the dynamics of superconducting qubits in transverse, longitudinal, and bidirectional coupling schemes. The intuitive and predictive picture provided by this method, and the simplicity of the mathematical construction, are demonstrated with some numerical studies of the multiphoton resonance processes and quantum interference phenomena for the superconducting qubit systems driven by intense ac fields. PMID:27869230

  3. A graph-theoretical representation of multiphoton resonance processes in superconducting quantum circuits

    NASA Astrophysics Data System (ADS)

    Jooya, Hossein Z.; Reihani, Kamran; Chu, Shih-I.

    2016-11-01

    We propose a graph-theoretical formalism to study generic circuit quantum electrodynamics systems consisting of a two level qubit coupled with a single-mode resonator in arbitrary coupling strength regimes beyond rotating-wave approximation. We define colored-weighted graphs, and introduce different products between them to investigate the dynamics of superconducting qubits in transverse, longitudinal, and bidirectional coupling schemes. The intuitive and predictive picture provided by this method, and the simplicity of the mathematical construction, are demonstrated with some numerical studies of the multiphoton resonance processes and quantum interference phenomena for the superconducting qubit systems driven by intense ac fields.

  4. Phase and amplitude stabilization of beam-loaded superconducting resonators

    SciTech Connect

    Delayen, J.R.

    1992-01-01

    A model has been developed to analyze the static and dynamic behavior of superconducting accelerating cavities operated in self-excited loops in the presence of phase and amplitude feedback, ponderomotive effects, and beam loading. This is an extension of an earlier analysis of the stabilization of superconducting cavities which has been the basis of the control system of several superconducting accelerators but did not include beam loading. Conditions have been derived to ensure static and dynamic stability in the presence of ponderomotive effects (coupling between the mechanical and electromagnetic modes of the cavity through the radiation pressure). Expressions for the effect of fluctuations of cavity frequency and beam amplitude and phase on the cavity-field amplitude and phase and beam-energy gain have been obtained.

  5. Phase and amplitude stabilization of beam-loaded superconducting resonators

    SciTech Connect

    Delayen, J.R.

    1992-10-01

    A model has been developed to analyze the static and dynamic behavior of superconducting accelerating cavities operated in self-excited loops in the presence of phase and amplitude feedback, ponderomotive effects, and beam loading. This is an extension of an earlier analysis of the stabilization of superconducting cavities which has been the basis of the control system of several superconducting accelerators but did not include beam loading. Conditions have been derived to ensure static and dynamic stability in the presence of ponderomotive effects (coupling between the mechanical and electromagnetic modes of the cavity through the radiation pressure). Expressions for the effect of fluctuations of cavity frequency and beam amplitude and phase on the cavity-field amplitude and phase and beam-energy gain have been obtained.

  6. Sequentially evaporated thin film YBa2Cu3O(7-x) superconducting microwave ring resonator

    NASA Technical Reports Server (NTRS)

    Rohrer, Norman J.; To, Hing Y.; Valco, George J.; Bhasin, Kul B.; Chorey, Chris; Warner, Joseph D.

    1990-01-01

    There is great interest in the application of thin film high temperature superconductors in high frequency electronic circuits. A ring resonator provides a good test vehicle for assessing the microwave losses in the superconductor and for comparing films made by different techniques. Ring resonators made of YBa2Cu3O(7-x) have been investigated on LaAlO3 substrates. The superconducting thin films were deposited by sequential electron beam evaporation of Cu, Y, and BaF2 with a post anneal. Patterning of the superconducting film was done using negative photolithography. A ring resonator was also fabricated from a thin gold film as a control. Both resonators had a gold ground plane on the backside of the substrate. The ring resonators' reflection coefficients were measured as a function of frequency from 33 to 37 GHz at temperatures ranging from 20 K to 68 K. The resonator exhibited two resonances which were at 34.5 and 35.7 GHz at 68 K. The resonant frequencies increased with decreasing temperature. The magnitude of the reflection coefficients was in the calculation of the unloaded Q-values. The performance of the evaporated and gold resonator are compared with the performance of a laser ablated YBa2Cu3O(7-x) resonator. The causes of the double resonance are discussed.

  7. Superconducting resonator used as a phase and energy detector for linac setup

    NASA Astrophysics Data System (ADS)

    Lobanov, Nikolai R.

    2016-07-01

    Booster linacs for tandem accelerators and positive ion superconducting injectors have matured into standard features of many accelerator laboratories. Both types of linac are formed as an array of independently-phased resonators operating at room temperature or in a superconducting state. Each accelerating resonator needs to be individually set in phase and amplitude for optimum acceleration efficiency. The modularity of the linac allows the velocity profile along the structure to be tailored to accommodate a wide range charge to mass ratio. The linac setup procedure, described in this paper, utilizes a superconducting resonator operating in a beam bunch phase detection mode. The main objective was to derive the full set of phase distributions for quick and efficient tuning of the entire accelerator. The phase detector was operated in overcoupling mode in order to minimize de-tuning effects of microphonic background. A mathematical expression was derived to set a limit on resonator maximum accelerating field during the crossover search to enable extracting unambiguous beam phase data. A set of equations was obtained to calculate the values of beam phase advance and energy gain produced by accelerating resonators. An extensive range of linac setting up configurations was conducted to validate experimental procedures and analytical models. The main application of a superconducting phase detector is for fast tuning for beams of ultralow intensities, in particular in the straight section of linac facilities.

  8. Performance and modeling of superconducting ring resonators at millimeter-wave frequencies

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Chorey, C. M.; Warner, J. D.; Romanofsky, R. R.; Heinen, V. O.; Kong, K. S.; Lee, H. Y.; Itoh, T.

    1990-01-01

    Microstrip ring resonators operating at 35 GHz were fabricated from laser ablated YBCO thin films deposited on lanthanum aluminate substrates. They were measured over a range of temperatures and their performance compared to identical resonators made of evaporated gold. Below 60 Kelvin the superconducting strip performed better than the gold, reaching an unloaded Q approximately 1.5 times that of gold at 25 K. A shift in the resonant frequency follows the form predicted by the London equations. The Phenomenological Loss Equivalence Method is applied to the ring resonator and the theoretically calculated Q values are compared to the experimental results.

  9. Dielectric surface loss in superconducting resonators with flux-trapping holes

    NASA Astrophysics Data System (ADS)

    Chiaro, B.; Megrant, A.; Dunsworth, A.; Chen, Z.; Barends, R.; Campbell, B.; Chen, Y.; Fowler, A.; Hoi, I. C.; Jeffrey, E.; Kelly, J.; Mutus, J.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Martinis, John M.

    2016-10-01

    Surface distributions of two level system (TLS) defects and magnetic vortices are limiting dissipation sources in superconducting quantum circuits. Arrays of flux-trapping holes are commonly used to eliminate loss due to magnetic vortices, but may increase dielectric TLS loss. We find that dielectric TLS loss increases by approximately 25% for resonators with a hole array beginning 2 μ {{m}} from the resonator edge, while the dielectric loss added by holes further away was below measurement sensitivity. Other forms of loss were not affected by the holes. Additionally, we estimate the loss due to residual magnetic effects to be 9× {10}-10 {μ {{T}}}-1 for resonators patterned with flux-traps and operated in magnetic fields up to 5 μ {{T}}. This is orders of magnitude below the total loss of the best superconducting coplanar waveguide resonators.

  10. Simulation of the superconducting multiturn flux transformer integrated with a coplanar resonator

    NASA Astrophysics Data System (ADS)

    Yi, H. R.; Zhang, Y.; Klein, N.

    2000-06-01

    The analysis of the structure of a superconducting multiturn flux transformer integrated with a coplanar resonator for radio-frequency superconducting quantum interference devices is described. Electromagnetic simulations indicate that the loss is dominated by the high loss tangent of the dielectric film used for the separation of the upper and lower superconducting films. The simulated current distribution at its resonant frequency shows that the highest current density is distributed on the multiturn input coil. This current distribution leads to a very high loss when the loss tangent of the dielectric film is high. However, for the same loss tangent of the dielectric film, it is possible to get a reasonably high unloaded quality factor by providing a normal shunt for the multiturn input coil.

  11. Superconductive quantum interference magnetometer with high sensitivity achieved by an induced resonance

    SciTech Connect

    Vettoliere, A.; Granata, C.

    2014-08-15

    A fully integrated low noise superconducting quantum interference device (SQUID) in a magnetometer configuration is presented. An intrinsic high voltage responsivity as high as 500 μV/Φ{sub 0} has been obtained by introducing a resonance in the voltage – magnetic flux characteristic. This resonance is induced by an integrated superconducting coil surrounding the pick-up coil and connected to one end of the SQUID output. The SQUID magnetometer exhibits a spectral density of magnetic field noise as low as 3 fT/Hz{sup 1/2}. In order to verify the suitability of the magnetometer, measurements of bandwidth and slew rate have been performed and compared with those of the same device without the resonance and with additional positive feedback. Due to their good characteristics such devices can be employed in a large number of applications including biomagnetism.

  12. Superconductive quantum interference magnetometer with high sensitivity achieved by an induced resonance.

    PubMed

    Vettoliere, A; Granata, C

    2014-08-01

    A fully integrated low noise superconducting quantum interference device (SQUID) in a magnetometer configuration is presented. An intrinsic high voltage responsivity as high as 500 μV/Φ0 has been obtained by introducing a resonance in the voltage - magnetic flux characteristic. This resonance is induced by an integrated superconducting coil surrounding the pick-up coil and connected to one end of the SQUID output. The SQUID magnetometer exhibits a spectral density of magnetic field noise as low as 3 fT/Hz(1/2). In order to verify the suitability of the magnetometer, measurements of bandwidth and slew rate have been performed and compared with those of the same device without the resonance and with additional positive feedback. Due to their good characteristics such devices can be employed in a large number of applications including biomagnetism.

  13. In situ broadband cryogenic calibration for two-port superconducting microwave resonators.

    PubMed

    Yeh, Jen-Hao; Anlage, Steven M

    2013-03-01

    We introduce an improved microwave calibration method for use in a cryogenic environment, based on a traditional three-standard calibration, the Thru-Reflect-Line (TRL) calibration. The modified calibration method takes advantage of additional information from multiple measurements of an ensemble of realizations of a superconducting resonator, as a new pseudo-Open standard, to correct errors in the TRL calibration. We also demonstrate an experimental realization of this in situ broadband cryogenic calibration system utilizing cryogenic switches. All calibration measurements are done in the same thermal cycle as the measurement of the resonator (requiring only an additional 20 min), thus avoiding 4 additional thermal cycles for traditional TRL calibration (which would require an additional 12 days). The experimental measurements on a wave-chaotic microwave billiard verify that the new method significantly improves the measured scattering matrix of a high-quality-factor superconducting resonator.

  14. Space applications of superconductivity - Resonators for high stability oscillators and other applications

    NASA Technical Reports Server (NTRS)

    Stein, S. R.

    1980-01-01

    The potential applications of superconductivity in space are examined. It is shown that superconducting oscillators have achieved better frequency stability that any other device for averaging times of 10 s to 1000 s. Such a high stability results from the use of solid niobium resonators having Q factors greater that 10 to the 10th. Oscillators of this type have direct applications as clocks and spectrally pure sources. In addition, they may also be used for accurate measurements of many physical quantities and to perform a variety of experiments on fundamental constants, relativity, and gravity waves.

  15. An Analysis Method for Superconducting Resonator Parameter Extraction with Complex Baseline Removal

    NASA Technical Reports Server (NTRS)

    Cataldo, Giuseppe

    2014-01-01

    A new semi-empirical model is proposed for extracting the quality (Q) factors of arrays of superconducting microwave kinetic inductance detectors (MKIDs). The determination of the total internal and coupling Q factors enables the computation of the loss in the superconducting transmission lines. The method used allows the simultaneous analysis of multiple interacting discrete resonators with the presence of a complex spectral baseline arising from reflections in the system. The baseline removal allows an unbiased estimate of the device response as measured in a cryogenic instrumentation setting.

  16. Superconductivity

    DTIC Science & Technology

    1989-07-01

    SUPERCONDUCTIVITY HIGH-POWER APPLICATIONS Electric power generation/transmission Energy storage Acoustic projectors Weapon launchers Catapult Ship propulsion • • • Stabilized...temperature superconductive shields could be substantially enhanced by use of high-Tc materials. 27 28 NRAC SUPERCONDUCTIVITY SHIP PROPULSION APPLICATIONS...motor shown in the photograph. As a next step in the evolution of electric-drive ship propulsion technology, DTRC has proposed to scale up the design

  17. A cryogen-free ultralow-field superconducting quantum interference device magnetic resonance imaging system

    SciTech Connect

    Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob

    2014-09-15

    Magnetic resonance imaging (MRI) at microtesla fields using superconducting quantum interference device (SQUID) detection has previously been demonstrated, and advantages have been noted. Although the ultralow-field SQUID MRI technique would not need the heavy superconducting magnet of conventional MRI systems, liquid helium required to cool the low-temperature detector still places a significant burden on its operation. We have built a prototype cryocooler-based SQUID MRI system that does not require a cryogen. The SQUID detector and the superconducting gradiometer were cooled down to 3.7 K and 4.3 K, respectively. We describe the prototype design, characterization, a phantom image, and areas of further improvements needed to bring the imaging performance to parity with conventional MRI systems.

  18. A cryogen-free ultralow-field superconducting quantum interference device magnetic resonance imaging system.

    PubMed

    Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob

    2014-09-01

    Magnetic resonance imaging (MRI) at microtesla fields using superconducting quantum interference device (SQUID) detection has previously been demonstrated, and advantages have been noted. Although the ultralow-field SQUID MRI technique would not need the heavy superconducting magnet of conventional MRI systems, liquid helium required to cool the low-temperature detector still places a significant burden on its operation. We have built a prototype cryocooler-based SQUID MRI system that does not require a cryogen. The SQUID detector and the superconducting gradiometer were cooled down to 3.7 K and 4.3 K, respectively. We describe the prototype design, characterization, a phantom image, and areas of further improvements needed to bring the imaging performance to parity with conventional MRI systems.

  19. Design of the superconducting magnet for 9.4 Tesla whole-body magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Li, Y.; Wang, Q.; Dai, Y.; Ni, Z.; Zhu, X.; Li, L.; Zhao, B.; Chen, S.

    2017-02-01

    A superconducting magnet for 9.4 Tesla whole-body magnetic resonance imaging is designed and fabricated in Institute of Electrical Engineering, Chinese Academy of Sciences. In this paper, the electromagnetic design methods of the main coils and compensating coils are presented. Sensitivity analysis is performed for all superconducting coils. The design of the superconducting shimming coils is also presented and the design of electromagnetic decoupling of the Z2 coils from the main coils is introduced. Stress and strain analysis with both averaged and detailed models is performed with finite element method. A quench simulation code with anisotropic continuum model and control volume method is developed by us and is verified by experimental study. By means of the quench simulation code, the quench protection system for the 9.4 T magnet is designed for the main coils, the compensating coils and the shimming coils. The magnet cryostat design with zero helium boiling-off technology is also introduced.

  20. High-Kinetic-Inductance Superconducting Nanowire Resonators for Circuit QED in a Magnetic Field

    NASA Astrophysics Data System (ADS)

    Samkharadze, N.; Bruno, A.; Scarlino, P.; Zheng, G.; DiVincenzo, D. P.; DiCarlo, L.; Vandersypen, L. M. K.

    2016-04-01

    We present superconducting microwave-frequency resonators based on NbTiN nanowires. The small cross section of the nanowires minimizes vortex generation, making the resonators resilient to magnetic fields. Measured intrinsic quality factors exceed 2 ×105 in a 6-T in-plane magnetic field and 3 ×104 in a 350-mT perpendicular magnetic field. Because of their high characteristic impedance, these resonators are expected to develop zero-point voltage fluctuations one order of magnitude larger than in standard coplanar waveguide resonators. These properties make the nanowire resonators well suited for circuit QED experiments needing strong coupling to quantum systems with small electric dipole moments and requiring a magnetic field, such as electrons in single and double quantum dots.

  1. Phase diagram and neutron spin resonance of superconducting NaFe1 -xCuxAs

    NASA Astrophysics Data System (ADS)

    Tan, Guotai; Song, Yu; Zhang, Rui; Lin, Lifang; Xu, Zhuang; Tian, Long; Chi, Songxue; Graves-Brook, M. K.; Li, Shiliang; Dai, Pengcheng

    2017-02-01

    We use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe1 -xCuxAs single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near x ≈2 % with the suppression of stripe-type magnetic order in NaFeAs. Upon further increasing Cu concentration the system becomes insulating, culminating in an antiferromagnetically ordered insulating phase near x ≈50 % . Using transport measurements, we demonstrate that the resistivity in NaFe1 -xCuxAs exhibits non-Fermi-liquid behavior near x ≈1.8 % . Our inelastic neutron scattering experiments reveal a single neutron spin resonance mode exhibiting weak dispersion along c axis in NaFe0.98Cu0.02As . The resonance is high in energy relative to the superconducting transition temperature Tc but weak in intensity, likely resulting from impurity effects. These results are similar to other iron pnictides superconductors despite that the superconducting phase in NaFe1 -xCuxAs is continuously connected to an antiferromagnetically ordered insulating phase near x ≈50 % with significant electronic correlations. Therefore, electron correlations is an important ingredient of superconductivity in NaFe1 -xCuxAs and other iron pnictides.

  2. On-chip quantum optics with quantum dots and superconducting resonators

    NASA Astrophysics Data System (ADS)

    Deng, Guang-Wei; Guo, Guo-Ping; Guo, Guang-Can

    2016-11-01

    Benefit from the recent nanotechnology process, people can integrate different nanostructures on a single chip. Particularly, quantum dots (QD), which behave as artificial atoms, have been shown to couple with a superconducting resonator, indicating that quantum-dot based quantum chip has a highly scalable possibility. Here we show a quantum chip architecture by combining graphene quantum dots and superconducting resonators together. A double quantum dot (DQD) and a microwave hybrid system can be described by the Jaynes-Cummings model, while a multi-quantum-dots system is conformed to the Tavis-Cummings model. These simple quantum optics models are experimentally realized in our device, providing a compelling platform for both graphene study and potential applications.

  3. Space applications of superconductivity

    NASA Technical Reports Server (NTRS)

    Sullivan, D. B.; Vorreiter, J. W.

    1979-01-01

    Some potential applications of superconductivity in space are summarized, e.g., the use of high field magnets for cosmic ray analysis or energy storage and generation, space applications of digital superconducting devices, such as the Josephson switch and, in the future, a superconducting computer. Other superconducting instrumentation which could be used in space includes: low frequency superconducting sensors, microwave and infrared detectors, instruments for gravitational studies, and high-Q cavities for use as stabilizing elements in clocks and oscillators.

  4. Enhanced electromechanical coupling of a nanomechanical resonator to coupled superconducting cavities.

    PubMed

    Li, Peng-Bo; Li, Hong-Rong; Li, Fu-Li

    2016-01-12

    We investigate the electromechanical coupling between a nanomechanical resonator and two parametrically coupled superconducting coplanar waveguide cavities that are driven by a two-mode squeezed microwave source. We show that, with the selective coupling of the resonator to the cavity Bogoliubov modes, the radiation-pressure type coupling can be greatly enhanced by several orders of magnitude, enabling the single photon strong coupling to be reached. This allows the investigation of a number of interesting phenomena such as photon blockade effects and the generation of nonclassical quantum states with electromechanical systems.

  5. Microwave-induced excess quasiparticles in superconducting resonators measured through correlated conductivity fluctuations

    NASA Astrophysics Data System (ADS)

    de Visser, P. J.; Baselmans, J. J. A.; Yates, S. J. C.; Diener, P.; Endo, A.; Klapwijk, T. M.

    2012-04-01

    We have measured the number of quasiparticles and their lifetime in aluminium superconducting microwave resonators. The number of excess quasiparticles below 160 mK decreases from 72 to 17 μm-3 with a 6 dB decrease of the microwave power. The quasiparticle lifetime increases accordingly from 1.4 to 3.5 ms. These properties of the superconductor were measured through the spectrum of correlated fluctuations in the quasiparticle system and condensate of the superconductor, which show up in the resonator amplitude and phase, respectively. Because uncorrelated noise sources vanish, fluctuations in the superconductor can be studied with a sensitivity close to the vacuum noise.

  6. Superconducting resonator and Rydberg atom hybrid system in the strong coupling regime

    NASA Astrophysics Data System (ADS)

    Yu, Deshui; Landra, Alessandro; Valado, María Martínez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer

    2016-12-01

    We propose a promising hybrid quantum system, where a highly excited atom strongly interacts with a superconducting L C oscillator via the electric field of capacitor. An external electrostatic field is applied to tune the energy spectrum of the atom. The atomic qubit is implemented by two eigenstates near an avoided-level crossing in the dc Stark map of a Rydberg atom. Varying the electrostatic field brings the atomic-qubit transition on or off resonance with respect to the microwave resonator, leading to a strong atom-resonator coupling with an extremely large cooperativity. Like the nonlinearity induced by Josephson junctions in superconducting circuits, the large atom-resonator interface disturbs the harmonic potential of the resonator, resulting in an artificial two-level particle. Different universal two-qubit logic gates can also be performed on our hybrid system within the space where an atomic qubit couples to a single photon with an interaction strength much larger than any relaxation rates, opening the door to the cavity-mediated state transmission.

  7. Bifurcation, mode coupling and noise in a nonlinear multimode superconducting microwave resonator

    NASA Astrophysics Data System (ADS)

    Tancredi, G.; Ithier, G.; Meeson, P. J.

    2013-08-01

    The addition of nonlinearity to an harmonic resonator provides a route to complex dynamical behaviour of resonant modes, including coupling between them. We present a superconducting device that makes use of the nonlinearity of Josephson junctions to introduce a controlled, tunable, nonlinear inductance to a thin film coplanar waveguide resonator. Considering the device as a potential quantum optical component in the microwave regime, we create a sensitive bifurcation amplifier and then demonstrate spectroscopy of other resonant modes via the intermode coupling. We find that the sensitivity of the device approaches within a factor two quantitative agreement with a quantum model by Dykman but is limited by a noise that has its source(s) on-chip.

  8. Coupling of a locally implanted rare-earth ion ensemble to a superconducting micro-resonator

    SciTech Connect

    Wisby, I. Tzalenchuk, A. Ya.; Graaf, S. E. de; Adamyan, A.; Kubatkin, S. E.; Gwilliam, R.; Meeson, P. J.; Lindström, T.

    2014-09-08

    We demonstrate the coupling of rare-earth ions locally implanted in a substrate (Gd{sup 3+} in Al{sub 2}O{sub 3}) to a superconducting NbN lumped-element micro-resonator. The hybrid device is fabricated by a controlled ion implantation of rare-earth ions in well-defined micron-sized areas, aligned to lithographically defined micro-resonators. The technique does not degrade the internal quality factor of the resonators which remain above 10{sup 5}. Using microwave absorption spectroscopy, we observe electron-spin resonances in good agreement with numerical modelling and extract corresponding coupling rates of the order of 1 MHz and spin linewidths of 50–65 MHz.

  9. Ultra-thin superconducting film coated silicon nitride nanowire resonators for low-temperature applications

    NASA Astrophysics Data System (ADS)

    Sebastian, Abhilash; Zhelev, Nikolay; de Alba, Roberto; Parpia, Jeevak

    We demonstrate fabrication of high stress silicon nitride nanowire resonators with a thickness and width of less than 50 nm intended to be used as probes for the study of superfluid 3He. The resonators are fabricated as doubly-clamped wires/beams using a combination of electron-beam lithography and wet/dry etching techniques. We demonstrate the ability to suspend (over a trench of depth ~8 µm) wires with a cross section as small as 30 nm, covered with a 20 nm superconducting film, and having lengths up to 50 µm. Room temperature resonance measurements were carried out by driving the devices using a piezo stage and detecting the motion using an optical interferometer. The results show that metalizing nano-mechanical resonators not only affects their resonant frequencies but significantly reduce their quality factor (Q). The devices are parametrically pumped by modulating the system at twice its fundamental resonant frequency, which results in observed amplification of the signal. The wires show self-oscillation with increasing modulation strength. The fabricated nanowire resonators are intended to be immersed in the superfluid 3He. By tracking the resonant frequency and the Q of the various modes of the wire versus temperature, we aim to probe the superfluid gap structure.

  10. Velocimetry of superconducting vortices based on stroboscopic resonances

    PubMed Central

    Jelić, Ž. L.; Milošević, M. V.; Silhanek, A. V.

    2016-01-01

    An experimental determination of the mean vortex velocity in superconductors mostly relies on the measurement of flux-flow resistance with magnetic field, temperature, or driving current. In the present work we introduce a method combining conventional transport measurements and a frequency-tuned flashing pinning potential to obtain reliable estimates of the vortex velocity. The proposed device is characterized using the time-dependent Ginzburg-Landau formalism, where the velocimetry method exploits the resonances in mean vortex dissipation when temporal commensuration occurs between the vortex crossings and the flashing potential. We discuss the sensitivity of the proposed technique on applied current, temperature and heat diffusion, as well as the vortex core deformations during fast motion. PMID:27774995

  11. Velocimetry of superconducting vortices based on stroboscopic resonances

    NASA Astrophysics Data System (ADS)

    Jelić, Ž. L.; Milošević, M. V.; Silhanek, A. V.

    2016-10-01

    An experimental determination of the mean vortex velocity in superconductors mostly relies on the measurement of flux-flow resistance with magnetic field, temperature, or driving current. In the present work we introduce a method combining conventional transport measurements and a frequency-tuned flashing pinning potential to obtain reliable estimates of the vortex velocity. The proposed device is characterized using the time-dependent Ginzburg-Landau formalism, where the velocimetry method exploits the resonances in mean vortex dissipation when temporal commensuration occurs between the vortex crossings and the flashing potential. We discuss the sensitivity of the proposed technique on applied current, temperature and heat diffusion, as well as the vortex core deformations during fast motion.

  12. Error analysis for intrinsic quality factor measurement in superconducting radio frequency resonators

    NASA Astrophysics Data System (ADS)

    Melnychuk, O.; Grassellino, A.; Romanenko, A.

    2014-12-01

    In this paper, we discuss error analysis for intrinsic quality factor (Q0) and accelerating gradient (Eacc) measurements in superconducting radio frequency (SRF) resonators. The analysis is applicable for cavity performance tests that are routinely performed at SRF facilities worldwide. We review the sources of uncertainties along with the assumptions on their correlations and present uncertainty calculations with a more complete procedure for treatment of correlations than in previous publications [T. Powers, in Proceedings of the 12th Workshop on RF Superconductivity, SuP02 (Elsevier, 2005), pp. 24-27]. Applying this approach to cavity data collected at Vertical Test Stand facility at Fermilab, we estimated total uncertainty for both Q0 and Eacc to be at the level of approximately 4% for input coupler coupling parameter β1 in the [0.5, 2.5] range. Above 2.5 (below 0.5) Q0 uncertainty increases (decreases) with β1 whereas Eacc uncertainty, in contrast with results in Powers [in Proceedings of the 12th Workshop on RF Superconductivity, SuP02 (Elsevier, 2005), pp. 24-27], is independent of β1. Overall, our estimated Q0 uncertainty is approximately half as large as that in Powers [in Proceedings of the 12th Workshop on RF Superconductivity, SuP02 (Elsevier, 2005), pp. 24-27].

  13. Error analysis for intrinsic quality factor measurement in superconducting radio frequency resonators.

    PubMed

    Melnychuk, O; Grassellino, A; Romanenko, A

    2014-12-01

    In this paper, we discuss error analysis for intrinsic quality factor (Q0) and accelerating gradient (Eacc) measurements in superconducting radio frequency (SRF) resonators. The analysis is applicable for cavity performance tests that are routinely performed at SRF facilities worldwide. We review the sources of uncertainties along with the assumptions on their correlations and present uncertainty calculations with a more complete procedure for treatment of correlations than in previous publications [T. Powers, in Proceedings of the 12th Workshop on RF Superconductivity, SuP02 (Elsevier, 2005), pp. 24-27]. Applying this approach to cavity data collected at Vertical Test Stand facility at Fermilab, we estimated total uncertainty for both Q0 and Eacc to be at the level of approximately 4% for input coupler coupling parameter β1 in the [0.5, 2.5] range. Above 2.5 (below 0.5) Q0 uncertainty increases (decreases) with β1 whereas Eacc uncertainty, in contrast with results in Powers [in Proceedings of the 12th Workshop on RF Superconductivity, SuP02 (Elsevier, 2005), pp. 24-27], is independent of β1. Overall, our estimated Q0 uncertainty is approximately half as large as that in Powers [in Proceedings of the 12th Workshop on RF Superconductivity, SuP02 (Elsevier, 2005), pp. 24-27].

  14. Precise Frequency Measurements Using a Superconducting Cavity Stabilized Oscillator

    NASA Technical Reports Server (NTRS)

    Strayer, D. M.; Yeh, N.-C.; Jiang, W.; Anderson, V. L.; Asplund, N.

    1999-01-01

    Many physics experiments call on improved resolution to better define the experimental results, thus improving tests of theories. Modern microwave technology combined with high-Q resonators can achieve frequency readout and control with resolutions up to a part in 10(exp 18). When the physical quantity in question in the experiment can be converted to a frequency or a change in frequency, a high-stability microwave oscillator can be applied to obtain state-of-the-art precision. In this work we describe the overall physical concepts and the required experimental procedures for optimizing a high-resolution frequency measurement system that employs a high-Q superconducting microwave cavity and a low-noise frequency synthesizer. The basic approach is to resolve the resonant frequencies of a high-Q (Q > 10(exp 10)) cavity to extremely high precision (one part in 10(exp 17)- 10(exp 18)). Techniques for locking the synthesizer frequency to a resonant frequency of the superconducting cavity to form an ultra-stable oscillator are described. We have recently set up an ultra-high-vacuum high-temperature annealing system to process superconducting niobium cavities, and have been able to consistently achieve Q > 10(exp 9). We have integrated high-Q superconducting cavities with a low-noise microwave synthesizer in a phase-locked-loop to verify the frequency stability of the system. Effects that disturb the cavity resonant frequency (such as the temperature fluctuations and mechanical vibrations) and methods to mitigate those effects are also considered. Applicability of these techniques to experiments will be discussed, and our latest experimental progress in achieving high-resolution frequency measurements using the superconducting-cavity-stabilized-oscillator will be presented.

  15. Roadmap for the design of a superconducting electron cyclotron resonance ion source for Spiral2

    SciTech Connect

    Thuillier, T.; Angot, J.; Lamy, T.; Peaucelle, C.

    2012-02-15

    A review of today achieved A/Q = 3 heavy ions beams is proposed. The daily operation A/Q = 3 ion beam intensities expected at Spiral2 are at the limit or above best record 3rd generation electron cyclotron resonance ion source (ECRIS) intensities. The necessity to build a new fully superconducting to fulfill these requirements is outlined. A discussion on the volume of the future source is proposed and the minimum value of 12 liters is derived. An analysis of the x-ray absorption superconducting ECRIS is presented based on VENUS experimental data and geometry. This study underlines the necessity to include a complete x-ray study at the time of source conception. The specifications foreseen for the new ECRIS are presented, followed with the roadmap for the design.

  16. Protection layers on a superconducting microwave resonator toward a hybrid quantum system

    NASA Astrophysics Data System (ADS)

    Lee, Jongmin; Park, Dong Hun

    2015-10-01

    We propose a protection scheme of a superconducting microwave resonator to realize a hybrid quantum system, where cold neutral atoms are coupled with a single microwave photon through magnetic dipole interaction at an interface inductor. The evanescent field atom trap, such as a waveguide/nanofiber atom trap, brings both surface-scattered photons and absorption-induced broadband blackbody radiation which result in quasiparticles and a low quality factor at the resonator. A proposed multiband protection layer consists of pairs of two dielectric layers and a thin nanogrid conductive dielectric layer above the interface inductor. We show numerical simulations of quality factors and reflection/absorption spectra, indicating that the proposed multilayer structure can protect a lumped-element microwave resonator from optical photons and blackbody radiation while maintaining a reasonably high quality factor.

  17. Protection layers on a superconducting microwave resonator toward a hybrid quantum system

    SciTech Connect

    Lee, Jongmin; Park, Dong Hun

    2015-10-07

    We propose a protection scheme of a superconducting microwave resonator to realize a hybrid quantum system, where cold neutral atoms are coupled with a single microwave photon through magnetic dipole interaction at an interface inductor. The evanescent field atom trap, such as a waveguide/nanofiber atom trap, brings both surface-scattered photons and absorption-induced broadband blackbody radiation which result in quasiparticles and a low quality factor at the resonator. A proposed multiband protection layer consists of pairs of two dielectric layers and a thin nanogrid conductive dielectric layer above the interface inductor. We show numerical simulations of quality factors and reflection/absorption spectra, indicating that the proposed multilayer structure can protect a lumped-element microwave resonator from optical photons and blackbody radiation while maintaining a reasonably high quality factor.

  18. Results of RIKEN superconducting electron cyclotron resonance ion source with 28 GHz.

    PubMed

    Higurashi, Y; Ohnishi, J; Nakagawa, T; Haba, H; Tamura, M; Aihara, T; Fujimaki, M; Komiyama, M; Uchiyama, A; Kamigaito, O

    2012-02-01

    We measured the beam intensity of highly charged heavy ions and x-ray heat load for RIKEN superconducting electron cyclotron resonance ion source with 28 GHz microwaves under the various conditions. The beam intensity of Xe(20+) became maximum at B(min) ∼ 0.65 T, which was ∼65% of the magnetic field strength of electron cyclotron resonance (B(ECR)) for 28 GHz microwaves. We observed that the heat load of x-ray increased with decreasing gas pressure and field gradient at resonance zone. It seems that the beam intensity of highly charged heavy ions with 28 GHz is higher than that with 18 GHz at same RF power.

  19. Superconductivity:

    NASA Astrophysics Data System (ADS)

    Sacchetti, N.

    In this paper a short historical account of the discovery of superconductivity and of its gradual development is given. The physical interpretation of its various aspects took about forty years (from 1911 to 1957) to reach a successful description of this phenomenon in terms of a microscopic theory At the very end it seemed that more or less everything could be reasonably interpreted even if modifications and refinements of the original theory were necessary. In 1986 the situation changed abruptly when a cautious but revolutionary paper appeared showing that superconductivity was found in certain ceramic oxides at temperatures above those up to then known. A rush of frantic experimental activity started world-wide and in less than one year it was shown that superconductivity is a much more widespread phenomenon than deemed before and can be found at temperatures well above the liquid air boiling point. The complexity and the number of the substances (mainly ceramic oxides) involved call for a sort of modern alchemy if compounds with the best superconducting properties are to be manufactured. We don't use the word alchemy in a deprecatory sense but just to emphasise that till now nobody can say why these compounds are what they are: superconductors.

  20. Production of a highly charged uranium ion beam with RIKEN superconducting electron cyclotron resonance ion source

    SciTech Connect

    Higurashi, Y.; Ohnishi, J.; Nakagawa, T.; Haba, H.; Fujimaki, M.; Komiyama, M.; Kamigaito, O.; Tamura, M.; Aihara, T.; Uchiyama, A.

    2012-02-15

    A highly charged uranium (U) ion beam is produced from the RIKEN superconducting electron cyclotron resonance ion source using 18 and 28 GHz microwaves. The sputtering method is used to produce this U ion beam. The beam intensity is strongly dependent on the rod position and sputtering voltage. We observe that the emittance of U{sup 35+} for 28 GHz microwaves is almost the same as that for 18 GHz microwaves. It seems that the beam intensity of U ions produced using 28 GHz microwaves is higher than that produced using 18 GHz microwaves at the same Radio Frequency (RF) power.

  1. The third generation superconducting 28 GHz electron cyclotron resonance ion source VENUS (invited)

    SciTech Connect

    Lyneis, C.; Leitner, D.; Leitner, M.; Taylor, C.; Abbott, S.

    2010-02-15

    VENUS is a third generation electron cyclotron resonance (ECR) ion source, which incorporates a high field superconducting NbTi magnet structure, a 28 GHz gryotron microwave source and a state of the art closed cycle cryosystem. During the decade from initial concept to regular operation, it has demonstrated both the feasibility and the performance levels of this new generation of ECR ion sources and required innovation on magnet construction, plasma chamber design, and beam transport. In this paper, the development, performance, and major innovations are described as well as a look to the potential to construct a fourth generation ECR ion source.

  2. Simulation and beamline experiments for the superconducting electron cyclotron resonance ion source VENUS

    SciTech Connect

    Todd, Damon S.; Leitner, Daniela; Lyneis, Claude M.; Grote, David P.

    2008-02-15

    The particle-in-cell code WARP has been enhanced to incorporate both two- and three-dimensional sheath extraction models giving WARP the capability of simulating entire ion beam transport systems including the extraction of beams from plasma sources. In this article, we describe a method of producing initial ion distributions for plasma extraction simulations in electron cyclotron resonance (ECR) ion sources based on experimentally measured sputtering on the source biased disk. Using this initialization method, we present preliminary results for extraction and transport simulations of an oxygen beam and compare them with experimental beam imaging on a quartz viewing plate for the superconducting ECR ion source VENUS.

  3. Decoherence and interferometric sensitivity of boson sampling in superconducting resonator networks

    NASA Astrophysics Data System (ADS)

    Goldstein, Samuel; Korenblit, Simcha; Bendor, Ydan; You, Hao; Geller, Michael R.; Katz, Nadav

    2017-01-01

    Multiple bosons undergoing coherent evolution in a coupled network of sites constitute a so-called quantum walk system. The simplest example of such a two-particle interference is the celebrated Hong-Ou-Mandel interference. When scaling to larger boson numbers, simulating the exact distribution of bosons has been shown, under reasonable assumptions, to be exponentially hard. We analyze the feasibility and expected performance of a globally connected superconducting resonator based quantum walk system, using the known characteristics of state-of-the-art components. We simulate the sensitivity of such a system to decay processes and to perturbations and compare with coherent input states.

  4. Cantilever anemometer based on a superconducting micro-resonator: application to superfluid turbulence.

    PubMed

    Salort, J; Monfardini, A; Roche, P-E

    2012-12-01

    We present a new type of cryogenic local velocity probe that operates in liquid helium (1 K < T < 4.2 K) and achieves a spatial resolution of ≈ 0.1 mm. The operating principle is based on the deflection of a micro-machined silicon cantilever which reflects the local fluid velocity. Deflection is probed using a superconducting niobium micro-resonator sputtered on the sensor and used as a strain gauge. We present the working principle and the design of the probe, as well as calibration measurements and velocity spectra obtained in a turbulent helium flow above and below the superfluid transition.

  5. Controllable frequency comb generation in a tunable superconducting coplanar waveguide resonator

    NASA Astrophysics Data System (ADS)

    You, J. Q.; Wang, Shuaipeng; Wang, Yipu; Zhang, Dengke; Luo, Xiaoqing; Chen, Zhen; Li, Tiefu

    Frequency combs have attracted considerable interest because they are extremely useful in a wide range of applications, such as optical metrology and high precision spectroscopy. Here we report the design and characterization of a controllable frequency comb generated in a tunable superconducting coplanar waveguide resonator in the microwave regime. Both the center frequency and teeth density of the comb are precisely controllable. The teeth spacing can be adjusted from Hz to MHz. The experimental results can be well explained via theoretical analysis. This work is supported by the NSAF Grant No. U1330201, the NSFC Grant No. 91421102, and the MOST 973 Program Grant Nos. 2014CB848700 and 2014CB921401.

  6. Development of an 18 GHz superconducting electron cyclotron resonance ion source at RCNP.

    PubMed

    Yorita, Tetsuhiko; Hatanaka, Kichiji; Fukuda, Mitsuhiro; Kibayashi, Mitsuru; Morinobu, Shunpei; Okamura, Hiroyuki; Tamii, Atsushi

    2008-02-01

    An 18 GHz superconducting electron cyclotron resonance ion source has recently been developed and installed in order to extend the variety and the intensity of ions at the RCNP coupled cyclotron facility. Production of several ions such as O, N, Ar, Kr, etc., is now under development and some of them have already been used for user experiments. For example, highly charged heavy ion beams like (86)Kr(21+,23+) and intense (16)O(5+,6+) and (15)N(6+) ion beams have been provided for experiments. The metal ion from volatile compounds method for boron ions has been developed as well.

  7. Extremely high Q -factor metamaterials due to anapole excitation

    NASA Astrophysics Data System (ADS)

    Basharin, Alexey A.; Chuguevsky, Vitaly; Volsky, Nikita; Kafesaki, Maria; Economou, Eleftherios N.

    2017-01-01

    We have designed and fabricated a metamaterial consisting of planar metamolecules which exhibit unusual, almost perfect anapole behavior in the sense that the electric dipole radiation is almost canceled by the toroidal dipole one, producing thus an extremely high Q -factor at the resonance frequency. Thus we have demonstrated theoretically and experimentally that metamaterials approaching ideal anapole behavior have very high Q -factor. The size of the system, at the millimeter range, and the parasitic magnetic quadrupole radiation are the factors limiting the size of the Q -factor. In spite of the very low radiation losses the estimated local fields at the metamolecules are extremely high, of the order of 104 higher than the external incoming field.

  8. Progress of superconducting electron cyclotron resonance ion sources at Institute of Modern Physics (IMP)

    SciTech Connect

    Sun, L. Feng, Y. C.; Zhang, W. H.; Zhang, X. Z.; Cao, Y.; Wu, W.; Yang, T. J.; Zhao, B.; Zhao, H. W.; Ma, L. Z.; Xia, J. W.; Lu, W.; Zhao, Y. Y.; Xie, D.

    2014-02-15

    Superconducting ECR ion sources can produce intense highly charged ion beams for the application in heavy ion accelerators. Superconducting Electron Resonance ion source with Advanced Design (SECRAL) is one of the few fully superconducting ECR ion sources that has been successfully built and put into routine operation for years. With enormous efforts and R and D work, promising results have been achieved with the ion source. Heated by the microwave power from a 7 kW/24 GHz gyrotron microwave generator, very intense highly charged gaseous ion beams have been produced, such as 455 eμA Xe{sup 27+}, 236 eμA Xe{sup 30+}, and 64 eμA Xe{sup 35+}. Since heavy metallic ion beams are being more and more attractive and important for many accelerator projects globally, intensive studies have been made to produce highly charged heavy metal ion beams, such as those from bismuth and uranium. Recently, 420 eμA Bi{sup 30+} and 202 eμA U{sup 33+} have been produced with SECRAL source. This paper will present the latest results with SECRAL, and the operation status will be discussed as well. An introduction of recently started SECRAL II project will also be given in the presentation.

  9. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

    PubMed Central

    Huang, H. Y.; Jia, C. J.; Chen, Z. Y.; Wohlfeld, K.; Moritz, B.; Devereaux, T. P.; Wu, W. B.; Okamoto, J.; Lee, W. S.; Hashimoto, M.; He, Y.; Shen, Z. X.; Yoshida, Y.; Eisaki, H.; Mou, C. Y.; Chen, C. T.; Huang, D. J.

    2016-01-01

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors. PMID:26794437

  10. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

    SciTech Connect

    Huang, H. Y.; Jia, C. J.; Chen, Z. Y.; Wohlfeld, K.; Moritz, B.; Devereaux, T. P.; Wu, W. B.; Okamoto, J.; Lee, W. S.; Hashimoto, M.; He, Y.; Shen, Z. X.; Yoshida, Y.; Eisaki, H.; Mou, C. Y.; Chen, C. T.; Huang, D. J.

    2016-01-22

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors.

  11. Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

    DOE PAGES

    Huang, H. Y.; Jia, C. J.; Chen, Z. Y.; ...

    2016-01-22

    Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi1.5Pb0.6Sr1.54CaCu2O8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast,more » the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-Tc cuprate superconductors.« less

  12. First results of 28 GHz superconducting electron cyclotron resonance ion source for KBSI accelerator

    SciTech Connect

    Park, Jin Yong; Lee, Byoung-Seob; Choi, Seyong; Kim, Seong Jun; Ok, Jung-Woo; Yoon, Jang-Hee; Kim, Hyun Gyu; Shin, Chang Seouk; Hong, Jonggi; Bahng, Jungbae; Won, Mi-Sook

    2016-02-15

    The 28 GHz superconducting electron cyclotron resonance (ECR) ion source has been developed to produce a high current heavy ion for the linear accelerator at KBSI (Korea Basic Science Institute). The objective of this study is to generate fast neutrons with a proton target via a p(Li,n)Be reaction. The design and fabrication of the essential components of the ECR ion source, which include a superconducting magnet with a liquid helium re-condensed cryostat and a 10 kW high-power microwave, were completed. The waveguide components were connected with a plasma chamber including a gas supply system. The plasma chamber was inserted into the warm bore of the superconducting magnet. A high voltage system was also installed for the ion beam extraction. After the installation of the ECR ion source, we reported the results for ECR plasma ignition at ECRIS 2014 in Russia. Following plasma ignition, we successfully extracted multi-charged ions and obtained the first results in terms of ion beam spectra from various species. This was verified by a beam diagnostic system for a low energy beam transport system. In this article, we present the first results and report on the current status of the KBSI accelerator project.

  13. Resonating Valence Bonds and Mean-Field d-Wave Superconductivity in Graphite

    SciTech Connect

    Black-Schaffer, Annica M.

    2010-04-27

    We investigate the possibility of inducing superconductivity in a graphite layer by electronic correlation effects. We use a phenomenological microscopic Hamiltonian which includes nearest neighbor hopping and an interaction term which explicitly favors nearest neighbor spin-singlets through the well-known resonance valence bond (RVB) character of planar organic molecules. Treating this Hamiltonian in mean-field theory, allowing for bond-dependent variation of the RVB order parameter, we show that both s- and d-wave superconducting states are possible. The d-wave solution belongs to a two-dimensional representation and breaks time reversal symmetry. At zero doping there exists a quantum critical point at the dimensionless coupling J/t = 1.91 and the s- and d-wave solutions are degenerate for low temperatures. At finite doping the d-wave solution has a significantly higher T{sub c} than the s-wave solution. By using density functional theory we show that the doping induced from sulfur absorption on a graphite layer is enough to cause an electronically driven d-wave superconductivity at graphite-sulfur interfaces. We also discuss applying our results to the case of the intercalated graphites as well as the validity of a mean-field approach.

  14. First results of 28 GHz superconducting electron cyclotron resonance ion source for KBSI accelerator

    NASA Astrophysics Data System (ADS)

    Park, Jin Yong; Lee, Byoung-Seob; Choi, Seyong; Kim, Seong Jun; Ok, Jung-Woo; Yoon, Jang-Hee; Kim, Hyun Gyu; Shin, Chang Seouk; Hong, Jonggi; Bahng, Jungbae; Won, Mi-Sook

    2016-02-01

    The 28 GHz superconducting electron cyclotron resonance (ECR) ion source has been developed to produce a high current heavy ion for the linear accelerator at KBSI (Korea Basic Science Institute). The objective of this study is to generate fast neutrons with a proton target via a p(Li,n)Be reaction. The design and fabrication of the essential components of the ECR ion source, which include a superconducting magnet with a liquid helium re-condensed cryostat and a 10 kW high-power microwave, were completed. The waveguide components were connected with a plasma chamber including a gas supply system. The plasma chamber was inserted into the warm bore of the superconducting magnet. A high voltage system was also installed for the ion beam extraction. After the installation of the ECR ion source, we reported the results for ECR plasma ignition at ECRIS 2014 in Russia. Following plasma ignition, we successfully extracted multi-charged ions and obtained the first results in terms of ion beam spectra from various species. This was verified by a beam diagnostic system for a low energy beam transport system. In this article, we present the first results and report on the current status of the KBSI accelerator project.

  15. Progress of superconducting electron cyclotron resonance ion sources at Institute of Modern Physics (IMP)

    NASA Astrophysics Data System (ADS)

    Sun, L.; Lu, W.; Feng, Y. C.; Zhang, W. H.; Zhang, X. Z.; Cao, Y.; Zhao, Y. Y.; Wu, W.; Yang, T. J.; Zhao, B.; Zhao, H. W.; Ma, L. Z.; Xia, J. W.; Xie, D.

    2014-02-01

    Superconducting ECR ion sources can produce intense highly charged ion beams for the application in heavy ion accelerators. Superconducting Electron Resonance ion source with Advanced Design (SECRAL) is one of the few fully superconducting ECR ion sources that has been successfully built and put into routine operation for years. With enormous efforts and R&D work, promising results have been achieved with the ion source. Heated by the microwave power from a 7 kW/24 GHz gyrotron microwave generator, very intense highly charged gaseous ion beams have been produced, such as 455 eμA Xe27+, 236 eμA Xe30+, and 64 eμA Xe35+. Since heavy metallic ion beams are being more and more attractive and important for many accelerator projects globally, intensive studies have been made to produce highly charged heavy metal ion beams, such as those from bismuth and uranium. Recently, 420 eμA Bi30+ and 202 eμA U33+ have been produced with SECRAL source. This paper will present the latest results with SECRAL, and the operation status will be discussed as well. An introduction of recently started SECRAL II project will also be given in the presentation.

  16. Progress of superconducting electron cyclotron resonance ion sources at Institute of Modern Physics (IMP).

    PubMed

    Sun, L; Lu, W; Feng, Y C; Zhang, W H; Zhang, X Z; Cao, Y; Zhao, Y Y; Wu, W; Yang, T J; Zhao, B; Zhao, H W; Ma, L Z; Xia, J W; Xie, D

    2014-02-01

    Superconducting ECR ion sources can produce intense highly charged ion beams for the application in heavy ion accelerators. Superconducting Electron Resonance ion source with Advanced Design (SECRAL) is one of the few fully superconducting ECR ion sources that has been successfully built and put into routine operation for years. With enormous efforts and R&D work, promising results have been achieved with the ion source. Heated by the microwave power from a 7 kW/24 GHz gyrotron microwave generator, very intense highly charged gaseous ion beams have been produced, such as 455 eμA Xe(27+), 236 eμA Xe(30+), and 64 eμA Xe(35+). Since heavy metallic ion beams are being more and more attractive and important for many accelerator projects globally, intensive studies have been made to produce highly charged heavy metal ion beams, such as those from bismuth and uranium. Recently, 420 eμA Bi(30+) and 202 eμA U(33+) have been produced with SECRAL source. This paper will present the latest results with SECRAL, and the operation status will be discussed as well. An introduction of recently started SECRAL II project will also be given in the presentation.

  17. Development of superconducting resonators for the Argonne heavy-ion linac

    SciTech Connect

    Shepard, K.W.

    1981-01-01

    Recent developments include a method for conditioning resonators which has produced a significant increase in accelerating gradient and also a design for a split-ring resonator with an optimum particle velocity of 0.16 c. Results of using a 1500 watt rf source to condition superconducting split-ring resonators are described. By repetitively pulsing for a few msec to field levels as high as an 8 MV/m effective accelerating field E/sub a/, electron loading at high field levels has been substantially reduced. After such conditioning, continuous operation at E/sub a/ > 6 MV/m, corresponding to a peak surface electric field of 30 MV/m, has been obtained. A split-ring resonator designed for an optimum particle velocity ..beta.. = v/c = 0.16 is also described. The 145.5 MHz resonator is contained in the same 16 inch diameter, 14 inch length housing used for the ..beta.. = 0.1 Argonne split-ring. In design of the split ring element, a 20% reduction in peak surface electric field has been achieved with no significant increase in surface magnetic field.

  18. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements.

    PubMed

    de Graaf, S E; Danilov, A V; Adamyan, A; Kubatkin, S E

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 μV, approaching low enough photon population (N ∼ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10(-20) F/Hz, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy.

  19. A study of two-level system defects in dielectric films using superconducting resonators

    NASA Astrophysics Data System (ADS)

    Khalil, Moe Shwan

    In this dissertation I describe measurements of dielectric loss at microwave frequencies due to two level systems (TLS) using superconducting resonators. Most measurements were performed in a dilution refrigerator at temperatures between 30 and 200 mK and all resonators discussed were fabricated with thin-film superconducting aluminum. I derive the transmission through a non-ideal (mismatched) resonant circuit and find that in general the resonance line-shape is asymmetric. I describe an analysis method for extracting the internal quality factor (Q i), the diameter correction method (DCM), and compare it to a commonly used phenomenological method, the phi rotation method (phiRM). I analytically find that the phiRM deterministically overestimates Qi when the asymmetry of the resonance line-shape is high. Four coplanar resonator geometries were studied, with frequencies spanning 5-7 GHz. They were all superconducting aluminum fabricated on sapphire and silicon substrates. These include a quasi-lumped element resonator, a coplanar strip transmission line resonator, and two hybrid designs that contain both a coplanar strip and a quasi-lumped element. Measured Qi's were as high as 2 x 105 for single photon excitations and there was no systematic variation in loss between quasi-lumped and coplanar strip resonance modes. I also measured the microwave loss tangent of several atomic layer deposition (ALD) grown dielectrics and obtained secondary ion mass spectrometry (SIMS) measurements of the same films. I found that hydrogen defect concentrations were correlated with low temperature microwave loss. In amorphous films that showed excess hydrogen defects on the surface, two independent TLS distributions were required to fit the loss tangent, one for the surface and one for the bulk. In crystalline dielectrics where hydrogen contamination was uniform throughout the bulk, a single bulk TLS distribution was sufficient. Finally, I measured the TLS loss in 250 nm thick HD

  20. Large Dispersive Shift of Cavity Resonance Induced by a Superconducting Flux Qubit in the Straddling Regime

    NASA Astrophysics Data System (ADS)

    Inomata, Kunihiro; Yamamoto, Tsuyoshi; Billangeon, Pierre-M.; Lin, Zhirong; Nakamura, Yasunobu; Tsai, Jaw-Shen; Koshino, Kazuki

    2013-03-01

    We demonstrate enhancement of the dispersive frequency shift in a coplanar waveguide resonator induced by a capacitively coupled superconducting flux qubit in the straddling regime. The magnitude of the observed shift, 80 MHz for the qubit-resonator detuning of 5 GHz, is quantitatively explained by the generalized Rabi model which takes into account the contribution of the qubit higher energy levels. By applying the enhanced dispersive shift to the qubit readout, we achieved 90 % contrast of the Rabi oscillations which is mainly limited by the energy relaxation of the qubit. We also discuss the qubit readout using a Josephson parametric amplifier. This work was supported by the MEXT Kakenhi ``Quantum Cybernetics'', the JSPS through its FIRST Program, and the NICT Commissioned Research.

  1. Quantum state transfer and controlled-phase gate on one-dimensional superconducting resonators assisted by a quantum bus

    PubMed Central

    Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo

    2016-01-01

    We propose a quantum processor for the scalable quantum computation on microwave photons in distant one-dimensional superconducting resonators. It is composed of a common resonator R acting as a quantum bus and some distant resonators rj coupled to the bus in different positions assisted by superconducting quantum interferometer devices (SQUID), different from previous processors. R is coupled to one transmon qutrit, and the coupling strengths between rj and R can be fully tuned by the external flux through the SQUID. To show the processor can be used to achieve universal quantum computation effectively, we present a scheme to complete the high-fidelity quantum state transfer between two distant microwave-photon resonators and another one for the high-fidelity controlled-phase gate on them. By using the technique for catching and releasing the microwave photons from resonators, our processor may play an important role in quantum communication as well. PMID:26907366

  2. Superconducting qubit as a quantum transformer routing entanglement between a microscopic quantum memory and a macroscopic resonator

    SciTech Connect

    Kemp, Alexander; Saito, Shiro; Semba, Kouichi; Munro, William J.; Nemoto, Kae

    2011-09-01

    We demonstrate experimentally the creation and measurement of an entangled state between a microscopic two-level system (TLS), formed by a defect in an oxide layer, and a macroscopic superconducting resonator, where their indirect interaction is mediated by an artificial atom, a superconducting persistent current qubit (PCQB). Under appropriate conditions, we found the coherence time of the TLS, the resonator, and the entangled state of these two are significantly longer than the Ramsey dephasing time of PCQB itself. This demonstrates that a PCQB can be used as a quantum transformer to address high coherence microscopic quantum memories by connecting them to macroscopic quantum buses.

  3. Superconducting magnet performance for 28 GHz electron cyclotron resonance ion source developed at the Korea Basic Science Institute

    SciTech Connect

    Park, Jin Yong; Choi, Seyong; Lee, Byoung-Seob; Yoon, Jang-Hee; Ok, Jung-Woo; Shin, Chang Seouk; Won, Mi-Sook; Kim, Byoung Chul; Ahn, Jung Keun

    2014-02-15

    A superconducting magnet for use in an electron cyclotron resonance ion source was developed at the Korea Basic Science Institute. The superconducting magnet is comprised of three solenoids and a hexapole magnet. According to the design value, the solenoid magnets can generate a mirror field, resulting in axial magnetic fields of 3.6 T at the injection area and 2.2 T at the extraction region. A radial field strength of 2.1 T can also be achieved by hexapole magnet on the plasma chamber wall. NbTi superconducting wire was used in the winding process following appropriate techniques for magnet structure. The final assembly of the each magnet involved it being vertically inserted into the cryostat to cool down the temperature using liquid helium. The performance of each solenoid and hexapole magnet was separately verified experimentally. The construction of the superconducting coil, the entire magnet assembly for performance testing and experimental results are reported herein.

  4. High-Q terahertz reconfigurable metamaterials using graphene

    NASA Astrophysics Data System (ADS)

    Arezoomandan, Sara; Sensale Rodriguez, Berardi

    2016-09-01

    We propose and discuss high-Q reconfigurable metamaterials based on graphene. The key components of the device are periodic concentric metallic ring resonators with interdigitated fingers, which are placed in-between the rings and provide for the large Q in the metamaterial, as well as several strategically located gaps where active graphene sheets are placed. We can easily adjust the frequency response of the metamaterial by means of varying a couple of parameters, such as the ring dimensions, number of fingers, etc., but also dynamically by means of varying conductivity in graphene.

  5. High-Q gold and silicon nitride bilayer nanostrings

    NASA Astrophysics Data System (ADS)

    Biswas, T. S.; Suhel, A.; Hauer, B. D.; Palomino, A.; Beach, K. S. D.; Davis, J. P.

    2012-08-01

    Low-mass, high-Q, silicon nitride nanostrings are at the cutting edge of nanomechanical devices for sensing applications. Here we show that the addition of a chemically functionalizable gold overlayer does not adversely affect the Q of the fundamental out-of-plane mode. Instead the device retains its mechanical responsiveness while gaining sensitivity to molecular bonding. Furthermore, differences in thermal expansion within the bilayer give rise to internal stresses that can be electrically controlled. In particular, an alternating current (AC) excites resonant motion of the nanostring. This AC thermoelastic actuation is simple, robust, and provides an integrated approach to sensor actuation.

  6. Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators.

    PubMed

    Götz, K J G; Blien, S; Stiller, P L; Vavra, O; Mayer, T; Huber, T; Meier, T N G; Kronseder, M; Strunk, Ch; Hüttel, A K

    2016-04-01

    Molybdenum rhenium alloy thin films can exhibit superconductivity up to critical temperatures of T(c)=15K. At the same time, the films are highly stable in the high-temperature methane/hydrogen atmosphere typically required to grow single wall carbon nanotubes. We characterize molybdenum rhenium alloy films deposited via simultaneous sputtering from two sources, with respect to their composition as function of sputter parameters and their electronic dc as well as GHz properties at low temperature. Specific emphasis is placed on the effect of the carbon nanotube growth conditions on the film. Superconducting coplanar waveguide resonators are defined lithographically; we demonstrate that the resonators remain functional when undergoing nanotube growth conditions, and characterize their properties as function of temperature. This paves the way for ultra-clean nanotube devices grown in situ onto superconducting coplanar waveguide circuit elements.

  7. Exact Tuning of High-Q Optical Microresonators by Use of UV

    NASA Technical Reports Server (NTRS)

    Savchankov, Anaotliy; Maleki, Lute; Iltchenko, Vladimir; Handley, Timothy

    2006-01-01

    In one of several alternative approaches to the design and fabrication of a "whispering-gallery" optical microresonator of high resonance quality (high Q), the index of refraction of the resonator material and, hence, the resonance frequencies. In this approach, a microresonator structure is prepared by forming it from an ultraviolet-sensitive material. Then the structure is subjected to controlled exposure to UV light while its resonance frequencies are monitored.

  8. Noise-tunable nonlinearity in a dispersively coupled diffusion-resonator system using superconducting circuits

    NASA Astrophysics Data System (ADS)

    Rhén, Christin; Isacsson, Andreas

    2017-01-01

    The harmonic oscillator is one of the most widely used model systems in physics: an indispensable theoretical tool in a variety of fields. It is well known that an otherwise linear oscillator can attain novel and nonlinear features through interaction with another dynamical system. We investigate such an interacting system: a superconducting LC-circuit dispersively coupled to a superconducting quantum interference device (SQUID). We find that the SQUID phase behaves as a classical two-level system, whose two states correspond to one linear and one nonlinear regime for the LC-resonator. As a result, the circuit’s response to forcing can become multistable. The strength of the nonlinearity is tuned by the level of noise in the system, and increases with decreasing noise. This tunable nonlinearity could potentially find application in the field of sensitive detection, whereas increased understanding of the classical harmonic oscillator is relevant for studies of the quantum-to-classical crossover of Jaynes-Cummings systems.

  9. Physics and material science of ultra-high quality factor superconducting resonator

    NASA Astrophysics Data System (ADS)

    Vostrikov, Alexander

    The nitrogen doping into niobium superconducting radio frequency cavity walls aiming to improve the fundamental mode quality factor is the subject of the research in the given work. Quantitative nitrogen diffusion into niobium model calculating the concentration profile was developed. The model estimations were confirmed with secondary ion mass spectrometry technique measurements. The model made controlled nitrogen doping recipe optimization possible. As a result the robust reproducible recipe for SRF cavity walls treatment with nitrogen doping was developed. The cavities produced with optimized recipe met LCLS--II requirements on quality factor of 2. · 10 10 at acceleration field of 16~MV/m. The microscopic effects of nitrogen doping on superconducting niobium properties were studied with low energy muon spin rotation technique and magnetometer measurements. No significant effect of nitrogen on the following features was found: electron mean free path, magnetic field penetration depth, and upper and surface critical magnetic fields. It was detected that for nitrogen doped niobium samples magnetic flux starts to penetrate inside the superconductor at lower external magnetic field value compared to the low temperature baked niobium ones. This explains lower quench field of SRF cavities treated with nitrogen. Quality factor improvement of fundamental mode forced to analyze the high order mode (HOM) impact on the particle beam dynamics. Both resonant and cumulative effects caused by monopole and dipole HOMs respectively are found to be negligible within the requirements for LCLS--II.

  10. Noise-tunable nonlinearity in a dispersively coupled diffusion-resonator system using superconducting circuits

    PubMed Central

    Rhén, Christin; Isacsson, Andreas

    2017-01-01

    The harmonic oscillator is one of the most widely used model systems in physics: an indispensable theoretical tool in a variety of fields. It is well known that an otherwise linear oscillator can attain novel and nonlinear features through interaction with another dynamical system. We investigate such an interacting system: a superconducting LC-circuit dispersively coupled to a superconducting quantum interference device (SQUID). We find that the SQUID phase behaves as a classical two-level system, whose two states correspond to one linear and one nonlinear regime for the LC-resonator. As a result, the circuit’s response to forcing can become multistable. The strength of the nonlinearity is tuned by the level of noise in the system, and increases with decreasing noise. This tunable nonlinearity could potentially find application in the field of sensitive detection, whereas increased understanding of the classical harmonic oscillator is relevant for studies of the quantum-to-classical crossover of Jaynes-Cummings systems. PMID:28120946

  11. Design of a superconducting volume coil for magnetic resonance microscopy of the mouse brain

    NASA Astrophysics Data System (ADS)

    Nouls, John C.; Izenson, Michael G.; Greeley, Harold P.; Johnson, G. Allan

    2008-04-01

    We present the design process of a superconducting volume coil for magnetic resonance microscopy of the mouse brain at 9.4 T. The yttrium barium copper oxide coil has been designed through an iterative process of three-dimensional finite-element simulations and validation against room temperature copper coils. Compared to previous designs, the Helmholtz pair provides substantially higher B1 homogeneity over an extended volume of interest sufficiently large to image biologically relevant specimens. A custom-built cryogenic cooling system maintains the superconducting probe at 60 ± 0.1 K. Specimen loading and probe retuning can be carried out interactively with the coil at operating temperature, enabling much higher through-put. The operation of the probe is a routine, consistent procedure. Signal-to-noise ratio in a mouse brain increased by a factor ranging from 1.1 to 2.9 as compared to a room-temperature solenoid coil optimized for mouse brain microscopy. We demonstrate images encoded at 10 × 10 × 20 μm for an entire mouse brain specimen with signal-to-noise ratio of 18 and a total acquisition time of 16.5 h, revealing neuroanatomy unseen at lower resolution. Phantom measurements show an effective spatial resolution better than 20 μm.

  12. Physics and material science of ultra-high quality factor superconducting resonator

    SciTech Connect

    Vostrikov, Alexander

    2015-08-01

    The nitrogen doping into niobium superconducting radio frequency cavity walls aiming to improve the fundamental mode quality factor is the subject of the research in the given work. Quantitative nitrogen diffusion into niobium model calculating the concentration profile was developed. The model estimations were confirmed with secondary ion mass spectrometry technique measurements. The model made controlled nitrogen doping recipe optimization possible. As a result the robust reproducible recipe for SRF cavity walls treatment with nitrogen doping was developed. The cavities produced with optimized recipe met LCLS–II requirements on quality factor of 2.7 ∙ 1010 at acceleration field of 16 MV/m. The microscopic effects of nitrogen doping on superconducting niobium properties were studied with low energy muon spin rotation technique and magnetometer measurements. No significant effect of nitrogen on the following features was found: electron mean free path, magnetic field penetration depth, and upper and surface critical magnetic fields. It was detected that for nitrogen doped niobium samples magnetic flux starts to penetrate inside the superconductor at lower external magnetic field value compared to the low temperature baked niobium ones. This explains lower quench field of SRF cavities treated with nitrogen. Quality factor improvement of fundamental mode forced to analyze the high order mode (HOM) impact on the particle beam dynamics. Both resonant and cumulative effects caused by monopole and dipole HOMs respectively are found to be negligible within the requirements for LCLS–II.

  13. Earth's core and inner-core resonances from analysis of VLBI nutation and superconducting gravimeter data

    NASA Astrophysics Data System (ADS)

    Rosat, S.; Lambert, S. B.; Gattano, C.; Calvo, M.

    2017-01-01

    Geophysical parameters of the deep Earth's interior can be evaluated through the resonance effects associated with the core and inner-core wobbles on the forced nutations of the Earth's figure axis, as observed by very long baseline interferometry (VLBI), or on the diurnal tidal waves, retrieved from the time-varying surface gravity recorded by superconducting gravimeters (SGs). In this paper, we inverse for the rotational mode parameters from both techniques to retrieve geophysical parameters of the deep Earth. We analyse surface gravity data from 15 SG stations and VLBI delays accumulated over the last 35 yr. We show existing correlations between several basic Earth parameters and then decide to inverse for the rotational modes parameters. We employ a Bayesian inversion based on the Metropolis-Hastings algorithm with a Markov-chain Monte Carlo method. We obtain estimates of the free core nutation resonant period and quality factor that are consistent for both techniques. We also attempt an inversion for the free inner-core nutation (FICN) resonant period from gravity data. The most probable solution gives a period close to the annual prograde term (or S1 tide). However the 95 per cent confidence interval extends the possible values between roughly 28 and 725 d for gravity, and from 362 to 414 d from nutation data, depending on the prior bounds. The precisions of the estimated long-period nutation and respective small diurnal tidal constituents are hence not accurate enough for a correct determination of the FICN complex frequency.

  14. Earth's core and inner core resonances from analysis of VLBI nutation and superconducting gravimeter data

    NASA Astrophysics Data System (ADS)

    Rosat, S.; Lambert, S. B.; Gattano, C.; Calvo, M.

    2016-10-01

    Geophysical parameters of the deep Earth's interior can be evaluated through the resonance effects associated with the core and inner-core wobbles on the forced nutations of the Earth's figure axis, as observed by very long baseline interferometry (VLBI), or on the diurnal tidal waves, retrieved from the time-varying surface gravity recorded by superconducting gravimeters (SGs). In this paper, we inverse for the rotational mode parameters from both techniques to retrieve geophysical parameters of the deep Earth. We analyze surface gravity data from 15 SG stations and VLBI delays accumulated over the last 35 years. We show existing correlations between several basic Earth parameters and then decide to inverse for the rotational modes parameters. We employ a Bayesian inversion based on the Metropolis-Hastings algorithm with a Markov Chain Monte Carlo method. We obtain estimates of the free core nutation (FCN) resonant period and quality factor that are consistent for both techniques. We also attempt an inversion for the free inner core nutation (FICN) resonant period from gravity data. The most probable solution gives a period close to the annual prograde term (or S1 tide). However the 95% confidence interval extend the possible values between roughly 28 days and 725 days for gravity, and from 362 to 414 days from nutation data, depending on the prior bounds. The precisions of the estimated long-period nutation and respective small diurnal tidal constituents are hence not accurate enough for a correct determination of the FICN complex frequency.

  15. Controllable quantum dynamics of inhomogeneous nitrogen-vacancy center ensembles coupled to superconducting resonators

    PubMed Central

    Song, Wan-lu; Yang, Wan-li; Yin, Zhang-qi; Chen, Chang-yong; Feng, Mang

    2016-01-01

    We explore controllable quantum dynamics of a hybrid system, which consists of an array of mutually coupled superconducting resonators (SRs) with each containing a nitrogen-vacancy center spin ensemble (NVE) in the presence of inhomogeneous broadening. We focus on a three-site model, which compared with the two-site case, shows more complicated and richer dynamical behavior, and displays a series of damped oscillations under various experimental situations, reflecting the intricate balance and competition between the NVE-SR collective coupling and the adjacent-site photon hopping. Particularly, we find that the inhomogeneous broadening of the spin ensemble can suppress the population transfer between the SR and the local NVE. In this context, although the inhomogeneous broadening of the spin ensemble diminishes entanglement among the NVEs, optimal entanglement, characterized by averaging the lower bound of concurrence, could be achieved through accurately adjusting the tunable parameters. PMID:27627994

  16. Superconducting quantum interference device microsusceptometer balanced over a wide bandwidth for nuclear magnetic resonance applications

    SciTech Connect

    Vinante, A. Falferi, P.; Mezzena, R.

    2014-10-15

    Superconducting Quantum Interference Device (SQUID) microsusceptometers have been widely used to study magnetic properties of materials at microscale. As intrinsically balanced devices, they could also be exploited for direct SQUID-detection of nuclear magnetic resonance (NMR) from micron sized samples, or for SQUID readout of mechanically detected NMR from submicron sized samples. Here, we demonstrate a double balancing technique that enables achievement of very low residual imbalance of a SQUID microsusceptometer over a wide bandwidth. In particular, we can generate ac magnetic fields within the SQUID loop as large as 1 mT, for frequencies ranging from dc up to a few MHz. As an application, we demonstrate direct detection of NMR from {sup 1}H spins in a glycerol droplet placed directly on top of the 20 μm SQUID loops.

  17. Magnetic resonance imaging using a superconducting magnet with an off-center homogeneous field zone

    NASA Astrophysics Data System (ADS)

    Sekino, Masaki; Miyazoe, Akihisa; Ohsaki, Hiroyuki; Hisatsune, Tatsuhiro; Ozaki, Osamu; Kiyoshi, Tsukasa; Wada, Hitoshi

    2011-04-01

    We previously fabricated superconducting magnet component coils that were asymmetrically arranged along the coil axis. In this study, we performed magnetic resonance imaging (MRI) using this magnet. The magnet consisted of seven coils wound up with NbTi wires, generating a homogeneous field zone at 29 mm off-center along the longitudinal axis. A gradient coil, a radio frequency coil, and other hardware were installed for MRI measurements. MRI of water in a sample tube and of a vegetable was performed using a spin-echo method under a static field of 0.77 T. If this concept of magnet design were extended to develop a larger MRI system for the human brain, a subject would have a wide field of vision and could move the hands during imaging.

  18. Radiation and Resonant Frequency of Superconducting Annular Ring Microstrip Antenna on Uniaxial Anisotropic Media

    NASA Astrophysics Data System (ADS)

    Barkat, Ouarda; Benghalia, Abdelmadjid

    2009-10-01

    In this work, the full-wave method is used for computing the resonant frequency, the bandwidth, and radiation pattern of High temperature superconductor, or an imperfectly conducting annular ring microstrip, which is printed on uniaxial anisotropic substrate. Galerkin’s method is used in the resolution of the electric field integral equation. The TM set of modes issued from the cavity model theory are used to expand the unknown currents on the patch. Numerical results concerning the effect of the anisotropic substrates on the antenna performance are presented and discussed. It is found that microstrip superconducting could give high efficiency with high gain in millimeter wavelengths. Results are compared with previously published data and are found to be in good agreement.

  19. Decrease of the surface resistance in superconducting niobium resonator cavities by the microwave field

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Gurevich, Alexander V.

    2014-03-03

    Measurements of the quality factor, Q, of Nb superconducting microwave resonators often show that Q increases by {approx_equal} 10%–30% with increasing radio-frequency (rf) field, H, up to {approx} 15-20 mT. Recent high temperature heat treatments can amplify this rf field-induced increase of Q up to {approx_equal} 50%–100% and extend it to much higher fields, but the mechanisms of the enhancement of Q(H) remain unclear. Here, we suggest a method to reveal these mechanisms by measuring temperature dependencies of Q at different rf field amplitudes. We show that the increase of Q(H) does not come from a field dependent quasi-particles activation energy or residual resistance, but rather results from the smearing of the density of state by the rf field.

  20. Nb3Sn superconducting magnets for electron cyclotron resonance ion sources

    SciTech Connect

    Ferracin, P.; Caspi, S.; Felice, H.; Leitner, D.; Lyneis, C. M.; Prestemon, S.; Sabbi, G. L.; Todd, D. S.

    2009-05-04

    Electron cyclotron resonance (ECR) ion sources are an essential component of heavy-ion accelerators. Over the past few decades advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to remarkable performance improvements of ECR ion sources. Currently third generation high field superconducting ECR ion sources operating at frequencies around 28 GHz are the state of the art ion injectors and several devices are either under commissioning or under design around the world. At the same time, the demand for increased intensities of highly charged heavy ions continues to grow, which makes the development of even higher performance ECR ion sources a necessity. To extend ECR ion sources to frequencies well above 28 GHz, new magnet technology will be needed in order to operate at higher field and force levels. The superconducting magnet program at LBNL has been developing high field superconducting magnets for particle accelerators based on Nb{sub 3}Sn superconducting technology for several years. At the moment, Nb{sub 3}Sn is the only practical conductor capable of operating at the 15 T field level in the relevant configurations. Recent design studies have been focused on the possibility of using Nb{sub 3}Sn in the next generation of ECR ion sources. In the past, LBNL has worked on the VENUS ECR, a 28 GHz source with solenoids and a sextupole made with NbTi operating at fields of 6-7 T. VENUS has now been operating since 2004. We present in this paper the design of a Nb{sub 3}Sn ECR ion source optimized to operate at an rf frequency of 56 GHz with conductor peak fields of 13-15 T. Because of the brittleness and strain sensitivity of Nb{sub 3}Sn- , particular care is required in the design of the magnet support structure, which must be capable of providing support to the coils without overstressing the conductor. In this paper, we present the main features of the support structure, featuring an external aluminum shell

  1. Nb{sub 3}Sn superconducting magnets for electron cyclotron resonance ion sources

    SciTech Connect

    Ferracin, P.; Caspi, S.; Felice, H.; Leitner, D.; Lyneis, C. M.; Prestemon, S.; Sabbi, G. L.; Todd, D. S.

    2010-02-15

    Electron cyclotron resonance (ECR) ion sources are an essential component of heavy-ion accelerators. Over the past few decades advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to remarkable performance improvements of ECR ion sources. Currently third generation high field superconducting ECR ion sources operating at frequencies around 28 GHz are the state of the art ion injectors and several devices are either under commissioning or under design around the world. At the same time, the demand for increased intensities of highly charged heavy ions continues to grow, which makes the development of even higher performance ECR ion sources a necessity. To extend ECR ion sources to frequencies well above 28 GHz, new magnet technology will be needed in order to operate at higher field and force levels. The superconducting magnet program at LBNL has been developing high field superconducting magnets for particle accelerators based on Nb{sub 3}Sn superconducting technology for several years. At the moment, Nb{sub 3}Sn is the only practical conductor capable of operating at the 15 T field level in the relevant configurations. Recent design studies have been focused on the possibility of using Nb{sub 3}Sn in the next generation of ECR ion sources. In the past, LBNL has worked on the VENUS ECR, a 28 GHz source with solenoids and a sextupole made with NbTi operating at fields of 6-7 T. VENUS has now been operating since 2004. We present in this paper the design of a Nb{sub 3}Sn ECR ion source optimized to operate at an rf frequency of 56 GHz with conductor peak fields of 13-15 T. Because of the brittleness and strain sensitivity of Nb{sub 3}Sn, particular care is required in the design of the magnet support structure, which must be capable of providing support to the coils without overstressing the conductor. In this paper, we present the main features of the support structure, featuring an external aluminum shell

  2. Nb3Sn superconducting magnets for electron cyclotron resonance ion sources.

    PubMed

    Ferracin, P; Caspi, S; Felice, H; Leitner, D; Lyneis, C M; Prestemon, S; Sabbi, G L; Todd, D S

    2010-02-01

    Electron cyclotron resonance (ECR) ion sources are an essential component of heavy-ion accelerators. Over the past few decades advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to remarkable performance improvements of ECR ion sources. Currently third generation high field superconducting ECR ion sources operating at frequencies around 28 GHz are the state of the art ion injectors and several devices are either under commissioning or under design around the world. At the same time, the demand for increased intensities of highly charged heavy ions continues to grow, which makes the development of even higher performance ECR ion sources a necessity. To extend ECR ion sources to frequencies well above 28 GHz, new magnet technology will be needed in order to operate at higher field and force levels. The superconducting magnet program at LBNL has been developing high field superconducting magnets for particle accelerators based on Nb(3)Sn superconducting technology for several years. At the moment, Nb(3)Sn is the only practical conductor capable of operating at the 15 T field level in the relevant configurations. Recent design studies have been focused on the possibility of using Nb(3)Sn in the next generation of ECR ion sources. In the past, LBNL has worked on the VENUS ECR, a 28 GHz source with solenoids and a sextupole made with NbTi operating at fields of 6-7 T. VENUS has now been operating since 2004. We present in this paper the design of a Nb(3)Sn ECR ion source optimized to operate at an rf frequency of 56 GHz with conductor peak fields of 13-15 T. Because of the brittleness and strain sensitivity of Nb(3)Sn, particular care is required in the design of the magnet support structure, which must be capable of providing support to the coils without overstressing the conductor. In this paper, we present the main features of the support structure, featuring an external aluminum shell pretensioned with water

  3. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator

    SciTech Connect

    Park, Bum-Sik Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-15

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper.

  4. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator.

    PubMed

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper.

  5. Superconducting qubit as a probe of squeezing in a nonlinear resonator

    NASA Astrophysics Data System (ADS)

    Boissonneault, Maxime; Doherty, A. C.; Ong, F. R.; Bertet, P.; Vion, D.; Esteve, D.; Blais, A.

    2014-02-01

    In addition to their central role in quantum information processing, qubits have proven to be useful tools in a range of other applications such as enhanced quantum sensing and as spectrometers of quantum noise. Here we show that a superconducting qubit strongly coupled to a nonlinear resonator can act as a probe of quantum fluctuations of the intraresonator field. Building on previous work [M. Boissoneault et al., Phys. Rev. A 85, 022305 (2012), 10.1103/PhysRevA.85.022305], we derive an effective master equation for the qubit which takes into account squeezing of the resonator field. We show how sidebands in the qubit excitation spectrum that are predicted by this model can reveal information about the squeezing factor r. The main results of this paper have already been successfully compared to experimental data [F. R. Ong et al., Phys. Rev. Lett. 110, 047001 (2013), 10.1103/PhysRevLett.110.047001], and we present here the details of the derivations.

  6. Electronic model for CoO2 layer based systems: chiral resonating valence bond metal and superconductivity.

    PubMed

    Baskaran, G

    2003-08-29

    Takada et al. have reported superconductivity in layered Na(x)CoO(2)yH(2)O (T(c) approximately equal to 5 K). We model a reference neutral CoO2 layer as an orbitally nondegenerate spin-1/2 antiferromagnetic Mott insulator on a triangular lattice and Na(x)CoO(2)yH(2)O as electron doped Mott insulators described by a t-J model. It is suggested that at optimal doping chiral spin fluctuations enhanced by the dopant dynamics lead to a gapful d-wave superconducting state. A chiral resonating valence bond (RVB) metal, a parity and time (PT) reversal violating state with condensed RVB gauge fields, with a possible weak ferromagnetism, and low temperature p-wave superconductivity are also suggested at higher dopings.

  7. Squeezing the fundamental temperature fluctuations of a high-Q microresonator

    NASA Astrophysics Data System (ADS)

    Sun, Xuan; Luo, Rui; Zhang, Xi-Cheng; Lin, Qiang

    2017-02-01

    Temperature fluctuations of an optical resonator underlie a fundamental limit of its cavity stability. Here we show that the fundamental temperature fluctuations of a high-Q microresonator can be suppressed remarkably by pure optical means without cooling the device temperature. An optical wave launched into the cavity is able to produce strong photothermal backaction which dramatically suppresses the spectral intensity of temperature fluctuations and squeezes its overall level by orders of magnitude. The proposed photothermal temperature squeezing is expected to significantly improve the stability of optical resonances, with potentially profound impact on broad applications of high-Q cavities in sensing, metrology, and nonlinear and quantum optics.

  8. Tunnel-diode resonator and nuclear magnetic resonance studies of low-dimensional magnetic and superconducting systems

    SciTech Connect

    Yeninas, Steven Lee

    2013-01-01

    This thesis emphasizes two frequency-domain techniques which uniquely employ radio frequency (RF) excitations to investigate the static and dynamic properties of novel magnetic and superconducting materials.

  9. High Q at Low and Medium Field

    SciTech Connect

    Gianluigi Ciovati

    2004-09-22

    The surface resistance of a bulk niobium superconducting rf cavity as function of the surface magnetic field is often characterized by three peculiar dependencies at low, medium and high field. Understanding the causes and the physics behind these anomalous behaviors is important to improve the performance of superconducting cavities used in particle accelerators. In this paper attention will be focused on low and medium field regions by presenting experimental results of several cavity test series and reviewing the models that try to explain these non-linearities of the surface resistance.

  10. Status report of the 28 GHz superconducting electron cyclotron resonance ion source VENUS (invited)

    SciTech Connect

    Leitner, D.; Lyneis, C.M.; Loew, T.; Todd, D.S.; Virostek, S.; Tarvainen, O.

    2006-03-15

    The superconducting versatile electron cyclotron resonance (ECR) ion source for nuclear science (VENUS) is a next generation superconducting ECR ion source designed to produce high-current, high-charge-state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the rare isotope accelerator (RIA) front end, where the goal is to produce intense beams of medium-charge-state ions. Example beams for the RIA accelerator are 15 p {mu}A of Kr{sup 17+}(260 e {mu}A), 12 p {mu}A of Xe{sup 20+} (240 e {mu}A of Xe{sup 20+}), and 8 p {mu}A of U{sup 28+}(230 e {mu}A). To achieve these high currents, VENUS has been optimized for operation at 28 GHz, reaching maximal confinement fields of 4 and 3 T axially and over 2.2 T on the plasma chamber wall radially. After a commissioning phase at 18 GHz, the source started the 28 GHz operation in the summer of 2004. During that ongoing 28 GHz commissioning process, record ion-beam intensities have been extracted. For instance, measured extracted currents for the low to medium charge states were 270 e {mu}A of Xe{sup 27+} and 245 e {mu}A of Bi{sup 29+}, while for the higher charge states 15 e {mu}A of Xe{sup 34+}, 15 e {mu}A of Bi{sup 41+}, and 0.5 e {mu}A of Bi{sup 50+} could be produced. Results from the ongoing 28 GHz commissioning as well as results using double-frequency heating with 18 and 28 GHz for oxygen and xenon are presented. The effect of the minimum B field on the ion source performance has been systematically measured for 18 and 28 GHz. In both cases the performance peaked at a minimum B field of about 80% of the resonance field. In addition, a strong dependence of the x-ray flux and energy on the minimum B field value was found.

  11. scraps: An open-source Python-based analysis package for analyzing and plotting superconducting resonator data

    SciTech Connect

    Carter, Faustin Wirkus; Khaire, Trupti S.; Novosad, Valentyn; Chang, Clarence L.

    2016-11-07

    We present "scraps" (SuperConducting Analysis and Plotting Software), a Python package designed to aid in the analysis and visualization of large amounts of superconducting resonator data, specifically complex transmission as a function of frequency, acquired at many different temperatures and driving powers. The package includes a least-squares fitting engine as well as a Monte-Carlo Markov Chain sampler for sampling the posterior distribution given priors, marginalizing over nuisance parameters, and estimating covariances. A set of plotting tools for generating publication-quality figures is also provided in the package. Lastly, we discuss the functionality of the software and provide some examples of its utility on data collected from a niobium-nitride coplanar waveguide resonator fabricated at Argonne National Laboratory.

  12. scraps: An open-source Python-based analysis package for analyzing and plotting superconducting resonator data

    DOE PAGES

    Carter, Faustin Wirkus; Khaire, Trupti S.; Novosad, Valentyn; ...

    2016-11-07

    We present "scraps" (SuperConducting Analysis and Plotting Software), a Python package designed to aid in the analysis and visualization of large amounts of superconducting resonator data, specifically complex transmission as a function of frequency, acquired at many different temperatures and driving powers. The package includes a least-squares fitting engine as well as a Monte-Carlo Markov Chain sampler for sampling the posterior distribution given priors, marginalizing over nuisance parameters, and estimating covariances. A set of plotting tools for generating publication-quality figures is also provided in the package. Lastly, we discuss the functionality of the software and provide some examples of itsmore » utility on data collected from a niobium-nitride coplanar waveguide resonator fabricated at Argonne National Laboratory.« less

  13. Diffusion tensor imaging using a high-temperature superconducting resonator in a 3 T magnetic resonance imaging for a spontaneous rat brain tumor

    NASA Astrophysics Data System (ADS)

    Lin, In-Tsang; Yang, Hong-Chang; Chen, Jyh-Horng

    2013-02-01

    This study investigates the peri-tumor signal abnormalities of a spontaneous brain tumor in a rat by using a 4 cm high-temperature superconducting (HTS) surface resonator. Fractional anisotropy (FA) values derived from diffusion tensor imaging reflect the interstitial characteristic of the peri-lesional tissues of brain tumors. Low FA indicates interstitial tumor infiltration and tissue injury, while high FA indicates better tissue integrity. Better delineation of tissue contents obtained by the HTS surface resonator at 77 K may facilitate therapeutic strategy and improve clinical outcomes.

  14. Investigation of relativistic runaway electrons in electron cyclotron resonance heating discharges on Korea Superconducting Tokamak Advanced Research

    SciTech Connect

    Kang, C. S.; Lee, S. G.

    2014-07-15

    The behavior of relativistic runaway electrons during Electron Cyclotron Resonance Heating (ECRH) discharges is investigated in the Korea Superconducting Tokamak Advanced Research device. The effect of the ECRH on the runaway electron population is discussed. Observations on the generation of superthermal electrons during ECRH will be reported, which will be shown to be consistent with existing theory for the development of a superthermal electron avalanche during ECRH [A. Lazaros, Phys. Plasmas 8, 1263 (2001)].

  15. Entanglement generation of nitrogen-vacancy centers via coupling to nanometer-sized resonators and a superconducting interference device

    SciTech Connect

    Chen Qiong; Xu Zhenyu; Feng Mang

    2010-07-15

    We present a potential scheme to entangle negatively charged nitrogen-vacancy (N-V) centers in distance using nanomechanical resonators (NAMRs) and a common superconducting quantum interference device (SQUID). By virtually exciting the vibrational modes of the NAMRs, we show the effective coupling between the N-V centers and the SQUID, which is a promising step toward large-sized quantum-information processing with separate N-V centers.

  16. Nuclear magnetic resonance with dc SQUID (Super-conducting QUantum Interference Device) preamplifiers

    SciTech Connect

    Fan, N.Q.; Heaney, M.B.; Clark, J.; Newitt, D.; Wald, L.; Hahn, E.L.; Bierlecki, A.; Pines, A.

    1988-08-01

    Sensitive radio-frequency (rf) amplifiers based on dc Superconducting QUantum Interface Devices (SQUIDS) are available for frequencies up to 200 MHz. At 4.2 K, the gain and noise temperature of a typical tuned amplifier are 18.6 +- 0.5 dB and 1.7 +- 0.5 K at 93 MHz. These amplifiers are being applied to a series of novel experiments on nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR). The high sensitivity of these amplifiers was demonstrated in the observation of ''nuclear spin noise'', the emission of photons by /sup 35/Cl nuclei in a state of zero polarization. In the more conventional experiments in which one applies a large rf pulse to the spins, a Q-spoiler, consisting of a series array of Josephson junctions, is used to reduce the Q of the input circuit to a very low value during the pulse. The Q-spoiler enables the circuit to recover quickly after the pulse, and has been used in an NQR experiment to achieve a sensitivity of about 2 /times/ 10/sup 16/ nuclear Bohr magnetons in a single free precession signal with a bandwidth of 10 kHz. In a third experiment, a sample containing /sup 35/Cl nuclei was placed in a capacitor and the signal detected electrically using a tuned SQUID amplifier and Q-spoiler. In this way, the electrical polarization induced by the precessing Cl nuclear quadrupole moments was detected: this is the inverse of the Stark effect in NQR. Two experiments involving NMR have been carried out. In the first, the 30 MHz resonance in /sup 119/Sn nuclei is detected with a tuned amplifier and Q-spoiler, and a single pulse resolution of 10/sup 18/ nuclear Bohr magnetons in a bandwidth of 25 kHz has been achieved. For the second, a low frequency NMR system has been developed that uses an untuned input circuit coupled to the SQUID. The resonance in /sup 195/Pt nuclei has been observed at 55 kHz in a field of 60 gauss. 23 refs., 11 figs.

  17. Excited baryon form factors at high Q{sup 2}

    SciTech Connect

    Stoler, Paul; Adams, G.; Frolov, V.; Klusman, M.; Napolitano, J.; Nozar, M.; Price, J.; Stoler, P.; Witkowski, M.; Ahmidouch, A.; Assamagan, K.; Avery, S.; Baker, K.; Eden, T.; Gueye, P.; Hinton, W.; Keppel, C.; Madey, R.; Niculescu, G.; Niculescu, I.

    1997-05-20

    The role of resonance electroproduction at high Q{sup 2} is discussed in the context of exclusive reactions, as well as the alternative theoretical models which are proposed to treat exclusive reactions in the few GeV{sup 2}/c{sup 2} region of momentum transfer. Jefferson Lab experiment 94-014, which measured the excitation of the {delta}(1232) and S{sub 11}(1535) via the reactions p(e,e{sup '}p){pi}{sup 0} and p(e,e{sup '}p){eta} respectively at Q{sup 2}{approx}2.8 and 4 GeV{sup 2}/c{sup 2} is described, and the state of analysis reported.

  18. Excited baryon form factors at high Q{sup 2}

    SciTech Connect

    Paul Stoler; Gary Adams; Abdellah Ahmidouch; Chris Armstrong; K. Assamagan; Steven Avery; K. Baker; Peter Bosted; Volker Burkert; Jim Dunne; Tom Eden; Rolf Ent; V. Frolov; David Gaskell; P. Gueye; Wendy Hinton; Cynthia Keppel; Wooyoung Kim; Michael Klusman; Doug Koltenuk; David Mack; Richard Madey; David Meekins; Ralph Minehart; Joseph Mitchell; Hamlet Mkrtchyan; James Napolitano; Gabriel Niculescu; Ioana Niculescu; Mina Nozar; John Price; Vardan Tadevosyan; Liguang Tang; Michael Witkowski; Stephen Wood

    1998-05-01

    The role of resonance electroproduction at high Q{sup 2} is discussed in the context of exclusive reactions, as well as the alternative theoretical models which are proposed to treat exclusive reactions in the few GeV{sup 2}/c{sup 2} region of momentum transfer. Jefferson Lab experiment 94-014, which measured the excitation of the Delta (1232) and S{sub 11}(1535) via the reactions p(e,e{sup '}p)pi{sup 0} and p(e,e{sup '}p)eta respectively at Q{sup 2} {approx} 2.8 and 4 GeV{sup 2}/c{sup 2} is described, and the state of analysis reported.

  19. High Q BPS Monopole Bags are Urchins

    NASA Astrophysics Data System (ADS)

    Evslin, Jarah; Gudnason, Sven Bjarke

    2014-01-01

    It has been known for 30 years that 't Hooft-Polyakov monopoles of charge Q greater than one cannot be spherically symmetric. Five years ago, Bolognesi conjectured that, at some point in their moduli space, BPS monopoles can become approximately spherically symmetric in the high Q limit. In this paper, we determine the sense in which this conjecture is correct. We consider an SU(2) gauge theory with an adjoint scalar field, and numerically find configurations with Q units of magnetic charge and a mass which is roughly linear in Q, for example, in the case Q = 81 we present a configuration whose energy exceeds the BPS bound by about 54%. These approximate solutions are constructed by gluing together Q cones, each of which contains a single unit of magnetic charge. In each cone, the energy is largest in the core, and so a constant energy density surface contains Q peaks and thus resembles a sea urchin.

  20. Identifying capacitive and inductive loss in lumped element superconducting hybrid titanium nitride/aluminum resonators

    NASA Astrophysics Data System (ADS)

    Vissers, Michael R.; Weides, Martin P.; Kline, Jeffrey S.; Sandberg, Martin; Pappas, David P.

    2012-07-01

    We present a method to systematically locate and extract capacitive and inductive losses in superconducting resonators at microwave frequencies by use of mixed-material, lumped element devices. In these devices, ultra-low loss titanium nitride was progressively replaced with aluminum in the inter-digitated capacitor and meandered inductor elements. By measuring the power dependent loss at 50 mK as the Al/TiN fraction in each element is increased, we find that at low electric field, i.e., in the single photon limit, the loss is two level system in nature and is correlated with the amount of Al capacitance rather than the Al inductance. In the high electric field limit, the remaining loss is linearly related to the product of the Al area times its inductance and is likely due to quasiparticles generated by stray IR radiation. At elevated temperature, additional loss is correlated with the amount of Al in the inductance, with a power independent TiN-Al interface loss term that exponentially decreases as the temperature is reduced. The TiN-Al interface loss is vanishingly small at the 50 mK base temperature.

  1. A simulation of X-ray shielding for a superconducting electron cyclotron resonance ion source

    SciTech Connect

    Park, Jin Yong; Won, Mi-Sook; Lee, Byoung-Seob; Yoon, Jang-Hee; Choi, Seyong; Ok, Jung-Woo; Choi, Jeong-Sik; Kim, Byoung-Chul

    2014-02-15

    It is generally assumed that large amounts of x-rays are emitted from the ion source of an Electron Cyclotron Resonance (ECR) instrument. The total amount of x-rays should be strictly limited to avoid the extra heat load to the cryostat of the superconducting ECR ion source, since they are partly absorbed by the cold mass into the cryostat. A simulation of x-ray shielding was carried out to determine the effective thickness of the x-ray shield needed via the use of Geant4. X-ray spectra of the 10 GHz Nanogan ECR ion source were measured as a function of the thickness variation in the x-ray shield. The experimental results were compared with Geant4 results to verify the effectiveness of the x-ray shield. Based on the validity in the case of the 10 GHz ECR ion source, the x-ray shielding results are presented by assuming the spectral temperature of the 28 GHz ECR ion source.

  2. First results from the new RIKEN superconducting electron cyclotron resonance ion source (invited).

    PubMed

    Nakagawa, T; Higurashi, Y; Ohnishi, J; Aihara, T; Tamura, M; Uchiyama, A; Okuno, H; Kusaka, K; Kidera, M; Ikezawa, E; Fujimaki, M; Sato, Y; Watanabe, Y; Komiyama, M; Kase, M; Goto, A; Kamigaito, O; Yano, Y

    2010-02-01

    The next generation heavy ion accelerator facility, such as the RIKEN radio isotope (RI) beam factory, requires an intense beam of high charged heavy ions. In the past decade, performance of the electron cyclotron resonance (ECR) ion sources has been dramatically improved with increasing the magnetic field and rf frequency to enhance the density and confinement time of plasma. Furthermore, the effects of the key parameters (magnetic field configuration, gas pressure, etc.) on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and modern superconducting (SC) technology, we successfully constructed the new 28 GHz SC-ECRIS, which has a flexible magnetic field configuration to enlarge the ECR zone and to optimize the field gradient at ECR point. Using it, we investigated the effect of ECR zone size, magnetic field configuration, and biased disk on the beam intensity of the highly charged heavy ions with 18 GHz microwaves. In this article, we present the structure of the ion source and first experimental results with 18 GHz microwave in detail.

  3. ESR spectrometer with a loop-gap resonator for cw and time resolved studies in a superconducting magnet.

    PubMed

    Simon, Ferenc; Murányi, Ferenc

    2005-04-01

    The design and performance of an electron spin resonance spectrometer operating at 3 and 9 GHz microwave frequencies combined with a 9-T superconducting magnet are described. The probehead contains a compact two-loop, one gap resonator, and is inside the variable temperature insert of the magnet enabling measurements in the 0-9T magnetic field and 1.5-400 K temperature range. The spectrometer allows studies on systems where resonance occurs at fields far above the g approximately 2 paramagnetic condition such as in antiferromagnets. The low quality factor of the resonator allows time resolved experiments such as, e.g., longitudinally detected ESR. We demonstrate the performance of the spectrometer on the NaNiO2 antiferromagnet, the MgB2 superconductor, and the RbC60 conducting alkaline fulleride polymer.

  4. Potential Applications of Microtesla Magnetic Resonance ImagingDetected Using a Superconducting Quantum Interference Device

    SciTech Connect

    Myers, Whittier Ryan

    2006-01-01

    This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 μT. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes the sample spins and an untuned second-order superconducting gradiometer coupled to a low transition temperature superconducting quantum interference device (SQUID) detects the subsequent 5.6-kHz spin precession. Imaging sequences including multiple echoes and partial Fourier reconstruction are developed. Calculating the SNR of prepolarized SQUID-detected MRI shows that three-dimensional Fourier imaging yields higher SNR than slice-selection imaging. An experimentally demonstrated field-cycling pulse sequence and post-processing algorithm mitigate image artifacts caused by concomitant gradients in low-field MRI. The magnetic field noise of SQUID untuned detection is compared to the noise of SQUID tuned detection, conventional Faraday detection, and the Nyquist noise generated by conducting biological samples. A second-generation microtesla MRI system employing a low-noise SQUID is constructed to increase SNR. A 2.4-m cubic, eddy-current shield with 6-mm thick aluminum walls encloses the experiment to attenuate external noise. The measured noise is 0.75 fT Hz-1/2 referred to the bottom gradiometer loop. Solenoids wound from 30-strand braided wire to decrease Nyquist noise and cooled by either liquid nitrogen or water polarize the spins. Copper wire coils wound on wooden supports produce the imaging magnetic fields and field gradients. Water phantom images with 0.8 x 0.8 x 10 mm3 resolution have a SNR of 6. Three-dimensional 1.6 x 1.9 x 14 mm3 images of bell peppers and 3 x 3 x 26 mm3 in vivo images of the human arm are presented. Since contrast based on the transverse spin relaxation rate (T1) is enhanced at low magnetic fields, microtesla MRI could potentially be used for tumor imaging. The

  5. Ultra-high Q sphere-like cavities for cascaded stimulated Brillouin lasing

    NASA Astrophysics Data System (ADS)

    Che, Kaijun; Zhang, Pan; Guo, Changlei; Tang, Deyu; Ren, Changyan; Xu, Huiying; Luo, Zhengqian; Cai, Zhiping

    2017-03-01

    High Q microsphere optical cavity is usually fabricated from a single mode fiber. Here, we propose a new method to fabricate sphere-like cavity by melting the tip of rotating quartz-rod with a CO2 laser. The cavities with diameter from 200 μm to 700 μm and resonant Q factors above 108 are obtained. Due to the rich resonances of the sphere-like cavity, up to 15-order cascaded stimulated Brillouin lasings(SBL) near 1.55 μm are observed in a cavity with a diameter of 760 μm by simply tuning the pump wavelength to a finely-selected resonance. We wish the ultra-high Q cavities with rich resonances and bulk rod mount can have practical applications in nonlinear optics and microwave photonics as an optical component.

  6. Fabrication of high-Q lithium niobate microresonators using femtosecond laser micromachining

    PubMed Central

    Lin, Jintian; Xu, Yingxin; Fang, Zhiwei; Wang, Min; Song, Jiangxin; Wang, Nengwen; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2015-01-01

    We report on fabrication of high-Q lithium niobate (LN) whispering-gallery-mode (WGM) microresonators suspended on silica pedestals by femtosecond laser direct writing followed by focused ion beam (FIB) milling. The micrometer-scale (diameter ~82 μm) LN resonator possesses a Q factor of ~2.5 × 105 around 1550 nm wavelength. The combination of femtosecond laser direct writing with FIB enables high-efficiency, high-precision nanofabrication of high-Q crystalline microresonators. PMID:25627294

  7. Probing the density of states of two-level tunneling systems in silicon oxide films using superconducting lumped element resonators

    SciTech Connect

    Skacel, S. T.; Kaiser, Ch.; Wuensch, S.; Siegel, M.; Rotzinger, H.; Lukashenko, A.; Jerger, M.; Weiss, G.; Ustinov, A. V.

    2015-01-12

    We have investigated dielectric losses in amorphous silicon oxide (a-SiO) thin films under operating conditions of superconducting qubits (mK temperatures and low microwave powers). For this purpose, we have developed a broadband measurement setup employing multiplexed lumped element resonators using a broadband power combiner and a low-noise amplifier. The measured temperature and power dependences of the dielectric losses are in good agreement with those predicted for atomic two-level tunneling systems (TLS). By measuring the losses at different frequencies, we found that the TLS density of states is energy dependent. This had not been seen previously in loss measurements. These results contribute to a better understanding of decoherence effects in superconducting qubits and suggest a possibility to minimize TLS-related decoherence by reducing the qubit operation frequency.

  8. Ten Ghz YBa2Cu3O(7-Delta) Superconducting Ring Resonators on NdGaO3 Substrates

    NASA Technical Reports Server (NTRS)

    To, H. Y.; Valco, G. J.; Bhasin, K. B.

    1993-01-01

    YBa2Cu3O(7-delta) thin films were formed on NdGaO3 substrates by laser ablation. Critical temperatures greater than 89 K and critical current densities exceeding 2 x 10(exp 8) Acm(sub -2) at 77 K were obtained. The microwave performance of films patterned into microstrip ring resonators with gold ground planes was measured. An unloaded quality factor six times larger than that of a gold resonator of identical geometry was achieved. The unloaded quality factor decreased below 70 K for both the superconducting and gold resonators due to increasing dielectric losses in the substrate. The temperature dependence of the loss tangent of NdGaO3 was extracted from the measurements.

  9. A superconducting hydrogen maser resonator made from electrophoretic YBa sub 2 Cu sub 3 O sub 7 minus. delta

    SciTech Connect

    Opie, D.; Schone, H. . Dept. of Physics); Hein, M.; Muller, G.; Piel, H.; Wehler, D. ); Folen, V.; Wolf, S. )

    1991-03-01

    This paper reports on a compact loop-gap hydrogen maser resonator constructed by electrophoretic deposition of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) onto silver. The resonator is tuned to operate at the hyperfine transition frequency of hydrogen (1.42 GHz). This device is considered to be the first step towards a superconducting cavity for a compact hydrogen maser to be used in the Global Positioning System (GPS). The required miniaturization of the resonator reduces its Q value. This effect can be compensated for by the low surface resistance of YBCO at 77 K. Large and curved polycrystalline YBCO layers can be obtained by the electrophoretic deposition technique. In this contribution we report on the construction and the test of High Temperature Superconductor Space Experiment (HTSSE).

  10. Planar Lithographed Superconducting LC Resonators for Frequency-Domain Multiplexed Readout Systems

    NASA Astrophysics Data System (ADS)

    Rotermund, K.; Barch, B.; Chapman, S.; Hattori, K.; Lee, A.; Palaio, N.; Shirley, I.; Suzuki, A.; Tran, C.

    2016-07-01

    Cosmic microwave background (CMB) polarization experiments are increasing the number of transition edge sensor (TES) bolometers to increase sensitivity. In order to maintain low thermal loading of the sub-Kelvin stage, the frequency-domain multiplexing (FDM) factor has to increase accordingly. FDM is achieved by placing TES bolometers in series with inductor-capacitor (LC) resonators, which select the readout frequency. The multiplexing factor can be raised with a large total readout bandwidth and small frequency spacing between channels. The inductance is kept constant to maintain a uniform readout bandwidth across detectors, while the maximum acceptable value is determined by bolometer stability. Current technology relies on commercially available ceramic chip capacitors. These have high scatter in their capacitance thereby requiring large frequency spacing. Furthermore, they have high equivalent series resistance (ESR) at higher frequencies and are time consuming and tedious to hand assemble via soldering. A solution lies in lithographed, planar spiral inductors (currently in use by some experiments) combined with interdigitated capacitors on a silicon (Si) substrate. To maintain reasonable device dimensions, we have reduced trace and gap widths of the LCs to 4 \\upmu m. We increased the inductance from 16 to 60 \\upmu H to achieve a higher packing density, a requirement for FDM systems with large multiplexing factors. Additionally, the Si substrate yields low ESR values across the entire frequency range and lithography makes mass production of LC pairs possible. We reduced mutual inductance between inductors by placing them in a checkerboard pattern with the capacitors, thereby increasing physical distances between adjacent inductors. We also reduce magnetic coupling of inductors with external sources by evaporating a superconducting ground plane onto the backside of the substrate. We report on the development of lithographed LCs in the 1-5 MHz range for use

  11. Tunnel-diode resonator and nuclear magnetic resonance studies of low-dimensional magnetic and superconducting systems

    NASA Astrophysics Data System (ADS)

    Yeninas, Steven Lee

    This thesis emphasizes two frequency-domain techniques which uniquely employ radio frequency (RF) excitations to investigate the static and dynamic properties of novel magnetic and superconducting materials. The first technique is a tunnel-diode resonator (TDR) which detects bulk changes in the dynamic susceptibility, chi = dM/dH. The capability of TDR to operate at low temperatures (less than 100 mK) and high fields (up to 65 T in pulsed fields) was critical for investigations of the antiferromagnetically correlated magnetic molecules Cr12Cu2 and Cr12 Ln4 (Ln = Y, Eu, Gd, Tb, Dy, Ho, Er, Yb), and the superconductor SrFe2(As1--xPx) 2 (x = 0.35). Investigations of Cr12Cu 2 and Cr12Ln4 demonstrates the first implementation of TDR to experimentally investigate the lowlying energy spectra of magnetic molecules in pulsed magnetic fields. Zeeman splitting of the quantum spin states results in transitions between field-dependent ground state energy levels observed as peaks in dM/dH at 600 mK, and demonstrate good agreement with theoretical calculations using a isotropic Heisenberg spin Hamiltonian. Increasing temperature to 2.5 K, TDR reveals a rich spectrum of frequency-dependent level crossings from thermally populated excited states which cannot be observed by conventional static magnetometry techniques. The last study presented uses TDR in pulsed fields to determine the temperature-dependent upper-critical field Hc2 to investigate the effects of columnar defects arising from heavy ion irradiation of SrFe2(As 1--xPx)2. Results suggest irradiation uniformly suppresses Tc and Hc2, and does not introduce additional features on H c2(T) and the shapes of the anisotropic Hc2 curves indicates a nodal superconducting gap. The second technique is nuclear magnetic resonance (NMR) which yields site specific magnetic and electronic information arising from hyperfine interactions for select magnetic nuclei. NMR spectra and nuclear spin-lattice relaxation measurements are reported

  12. Superconducting Cavity Electromechanics on a Silicon-on-Insulator Platform

    NASA Astrophysics Data System (ADS)

    Dieterle, Paul B.; Kalaee, Mahmoud; Fink, Johannes M.; Painter, Oskar

    2016-07-01

    Fabrication processes involving anhydrous hydrofluoric vapor etching are developed to create high-Q aluminum superconducting microwave resonators on free-standing silicon membranes formed from a silicon-on-insulator wafer. Using this fabrication process, a high-impedance 8.9-GHz coil resonator is coupled capacitively with a large participation ratio to a 9.7-MHz micromechanical resonator. Two-tone microwave spectroscopy and radiation pressure backaction are used to characterize the coupled system in a dilution refrigerator down to temperatures of Tf=11 mK , yielding a measured electromechanical vacuum coupling rate of g0/2 π =24.6 Hz and a mechanical resonator Q factor of Qm=1.7 ×1 07. Microwave backaction cooling of the mechanical resonator is also studied, with a minimum phonon occupancy of nm≈16 phonons being realized at an elevated fridge temperature of Tf=211 mK .

  13. High-Q plasmonic bottle microresonator

    NASA Astrophysics Data System (ADS)

    Mohd Nasir, M. Narizee; Ding, Ming; Murugan, G. Senthil; Zervas, Michalis N.

    2014-03-01

    In this paper, we demonstrate a hybrid plasmonic bottle microresonator (PBMR) which supports whispering gallery modes (WGMs) along with surface plasmon waves (SPWs) for high performance optical sensor applications. The BMR was fabricated through "soften-and-compress" technique with a thin gold layer deposited on top of the resonator. A polarization-resolved measurement was set-up in order to fully characterize the fabricated PBMR. Initially, the uncoated BMR with waist diameter of 181 μm, stem diameter of 125 μm and length of 400 μm was fabricated and then gold film was deposited on the surface. Due to surface curvature, the gold film covering half of the BMR had a characteristic meniscus shape and maximum thickness of 30 nm. The meniscus provides appropriately tapered edges which facilitate the adiabatic transformation of BMR WGMs to SPWs and vice versa. This results in low transition losses, which combined with partially-metal-coated resonator, can result in high hybrid-PBMR Q's. The transmission spectra of the hybrid PBMR are dramatically different to the original uncoated BMR. Under TE(TM) excitation, the PBMR showed composite resonances with Q of ~2100(850) and almost identical ~ 3 nm FSR. We have accurately fitted the observed transmission resonances with Lorentzian-shaped curves and showed that the TE and TM excitations are actually composite resonances comprise of two and three partially overlapping resonances with Q's in excess of 2900 and 2500, respectively. To the best of our knowledge these are the highest Qs observed in plasmonic microcavities.

  14. Using a Superconducting Resonator with Frequency-Compensated Tunable Coupling to Transfer a Quantum State Deterministically and Directly

    NASA Astrophysics Data System (ADS)

    Wenner, James; Neill, C.; Quintana, C.; Campbell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; O'Malley, P.; Vainsencher, A.; White, T.; Barends, R.; Chen, Y.; Fowler, A.; Jeffrey, E.; Kelly, J.; Lucero, E.; Megrant, A.; Mutus, J.; Neeley, M.; Roushan, P.; Sank, D.; Martinis, John M.

    Deterministic direct quantum state transfer between devices on different chips requires the ability to transfer quantum states between traveling qubits and fixed logic qubits. Reflections must be minimized to avoid energy loss and phase interference; this requires tunable coupling to an inter-chip line while the two devices are at equal frequencies. To achieve this, we use a 6GHz superconducting coplanar resonator with tunable coupling to a 50 Ohm transmission line. We compensate for the resulting shift in resonator frequency by simultaneously tuning a second SQUID. We measure the device coherence and demonstrate the ability to release a single-frequency shaped pulse into the transmission line, efficiently capture a shaped pulse, and deterministically and directly transfer a quantum state.

  15. Piezoelectric tunable microwave superconducting cavity

    NASA Astrophysics Data System (ADS)

    Carvalho, N. C.; Fan, Y.; Tobar, M. E.

    2016-09-01

    In the context of engineered quantum systems, there is a demand for superconducting tunable devices, able to operate with high-quality factors at power levels equivalent to only a few photons. In this work, we developed a 3D microwave re-entrant cavity with such characteristics ready to provide a very fine-tuning of a high-Q resonant mode over a large dynamic range. This system has an electronic tuning mechanism based on a mechanically amplified piezoelectric actuator, which controls the resonator dominant mode frequency by changing the cavity narrow gap by very small displacements. Experiments were conducted at room and dilution refrigerator temperatures showing a large dynamic range up to 4 GHz and 1 GHz, respectively, and were compared to a finite element method model simulated data. At elevated microwave power input, nonlinear thermal effects were observed to destroy the superconductivity of the cavity due to the large electric fields generated in the small gap of the re-entrant cavity.

  16. Twin photon pairs in a high-Q silicon microresonator

    SciTech Connect

    Rogers, Steven; Lu, Xiyuan; Jiang, Wei C.; Lin, Qiang

    2015-07-27

    We report the generation of high-purity twin photon pairs through cavity-enhanced non-degenerate four-wave mixing (FWM) in a high-Q silicon microdisk resonator. Twin photon pairs are created within the same cavity mode and are consequently expected to be identical in all degrees of freedom. The device is able to produce twin photons at telecommunication wavelengths with a pair generation rate as large as (3.96 ± 0.03) × 10{sup 5} pairs/s, within a narrow bandwidth of 0.72 GHz. A coincidence-to-accidental ratio of 660 ± 62 was measured, the highest value reported to date for twin photon pairs, at a pair generation rate of (2.47 ± 0.04) × 10{sup 4} pairs/s. Through careful engineering of the dispersion matching window, we have reduced the ratio of photons resulting from degenerate FWM to non-degenerate FWM to less than 0.15.

  17. Orbital selective neutron spin resonance in underdoped superconducting NaFe0.985Co0.015As

    NASA Astrophysics Data System (ADS)

    Wang, Weiyi; Park, J. T.; Yu, Rong; Li, Yu; Song, Yu; Zhang, Zongyuan; Ivanov, Alexandre; Kulda, Jiri; Dai, Pengcheng

    2017-03-01

    We use neutron scattering to study the electron-doped superconducting NaFe0.985Co0.015As (Tc=14 K), which has coexisting static antiferromagnetic (AF) order (TN=31 K) and exhibits two neutron spin resonances (Er 1≈3.5 meV and Er 2≈6 meV) at the in-plane AF ordering wave vector QAF=Q1=(1 ,0 ) in reciprocal space. In the twinned state below the tetragonal-to-orthorhombic structural transition Ts, both resonance modes appear at Q1 but cannot be distinguished from Q2=(0 ,1 ) . By detwinning the single crystal with uniaxial pressure along the orthorhombic b axis, we find that both resonances appear only at Q1 with vanishing intensity at Q2. Since electronic bands of the orbital dx z and dy z characters split below Ts with the dx z band sinking ˜10 meV below the Fermi surface, our results indicate that the neutron spin resonances in NaFe0.985Co0.015As arise mostly from quasiparticle excitations between the hole and electron Fermi surfaces with the dy z orbital character.

  18. Coupling Ideality of Integrated Planar High-Q Microresonators

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Martin H. P.; Liu, Junqiu; Geiselmann, Michael; Kippenberg, Tobias J.

    2017-02-01

    Chip-scale optical microresonators with integrated planar optical waveguides are useful building blocks for linear, nonlinear, and quantum-optical photonic devices alike. Loss reduction through improving fabrication processes results in several integrated microresonator platforms attaining quality (Q ) factors of several millions. Beyond the improvement of the quality factor, the ability to operate the microresonator with high coupling ideality in the overcoupled regime is of central importance. In this regime, the dominant source of loss constitutes the coupling to a single desired output channel, which is particularly important not only for quantum-optical applications such as the generation of squeezed light and correlated photon pairs but also for linear and nonlinear photonics. However, to date, the coupling ideality in integrated photonic microresonators is not well understood, in particular, design-dependent losses and their impact on the regime of high ideality. Here we investigate design-dependent parasitic losses described by the coupling ideality of the commonly employed microresonator design consisting of a microring-resonator waveguide side coupled to a straight bus waveguide, a system which is not properly described by the conventional input-output theory of open systems due to the presence of higher-order modes. By systematic characterization of multimode high-Q silicon nitride microresonator devices, we show that this design can suffer from low coupling ideality. By performing 3D simulations, we identify the coupling to higher-order bus waveguide modes as the dominant origin of parasitic losses which lead to the low coupling ideality. Using suitably designed bus waveguides, parasitic losses are mitigated with a nearly unity ideality and strong overcoupling (i.e., a ratio of external coupling to internal resonator loss rate >9 ) are demonstrated. Moreover, we find that different resonator modes can exchange power through the coupler, which, therefore

  19. On application of superconducting resonators for reconstruction of proton injector for nuclotron complex

    NASA Astrophysics Data System (ADS)

    Aliev, K. A.; Polozov, S. M.; Samoshin, A. V.; Toporkov, S. E.; Kulevoy, T. V.; Kropachev, G. N.; Butenko, A. V.; Monchinskiy, V. A.; Sidorin, A. O.; Trubnikov, G. V.

    2016-12-01

    The possibility of replacing LU-20 drift tube linac, the injector for Nuclotron accelerator complex, with a superconducting proton accelerator with an output energy of up to 50 MeV consisting of a sequence of independently phased cavities and solenoids is considered. The results of choosing the general layout of the accelerator and the beam dynamics simulation are presented.

  20. Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL.

    PubMed

    Zhao, H W; Sun, L T; Zhang, X Z; Guo, X H; Cao, Y; Lu, W; Zhang, Z M; Yuan, P; Song, M T; Zhao, H Y; Jin, T; Shang, Y; Zhan, W L; Wei, B W; Xie, D Z

    2008-02-01

    There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e microA of O(7+), 505 e microA of Xe(20+), 306 e microA of Xe(27+), and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

  1. The preliminary tests of the superconducting electron cyclotron resonance ion source DECRIS-SC2.

    PubMed

    Efremov, A; Bekhterev, V; Bogomolov, S; Drobin, V; Loginov, V; Lebedev, A; Yazvitsky, N; Yakovlev, B

    2012-02-01

    A new compact version of the "liquid He-free" superconducting ECR ion source, to be used as an injector of highly charged heavy ions for the MC-400 cyclotron, is designed and built at the Flerov Laboratory of Nuclear Reactions in collaboration with the Laboratory of High Energy Physics of JINR. The axial magnetic field of the source is created by the superconducting magnet and the NdFeB hexapole is used for the radial plasma confinement. The microwave frequency of 14 GHz is used for ECR plasma heating. During the first tests, the source shows a good enough performance for the production of medium charge state ions. In this paper, we will present the design parameters and the preliminary results with gaseous ions.

  2. Controllable coupling between a nanomechanical resonator and a coplanar-waveguide resonator via a superconducting flux qubit

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Jin, Da-Yu; Jing, Jun; Lam, Chi-Hang; You, J. Q.

    2015-09-01

    We study a tripartite quantum system consisting of a coplanar-waveguide (CPW) resonator and a nanomechanical resonator (NAMR) connected by a flux qubit, where the flux qubit has a large detuning from both resonators. By a unitary transformation and a second-order approximation, we obtain a strong and controllable (i.e., magnetic-field-dependent) effective coupling between the NAMR and the CPW resonator. Due to the strong coupling, vacuum Rabi splitting can be observed from the voltage-fluctuation spectrum of the CPW resonator. We further study the properties of single-photon transport as inferred from the reflectance or equivalently the transmittance. We show that the reflectance and the corresponding phase-shift spectra both exhibit doublet of narrow spectral features due to vacuum Rabi splitting. By tuning the external magnetic field, the reflectance and the phase shift can be varied from 0 to 1 and -π to π , respectively. The results indicate that this hybrid quantum system can act as a quantum router.

  3. Theoretical estimates of maximum fields in superconducting resonant radio frequency cavities: stability theory, disorder, and laminates

    NASA Astrophysics Data System (ADS)

    Liarte, Danilo B.; Posen, Sam; Transtrum, Mark K.; Catelani, Gianluigi; Liepe, Matthias; Sethna, James P.

    2017-03-01

    Theoretical limits to the performance of superconductors in high magnetic fields parallel to their surfaces are of key relevance to current and future accelerating cavities, especially those made of new higher-T c materials such as Nb3Sn, NbN, and MgB2. Indeed, beyond the so-called superheating field {H}{sh}, flux will spontaneously penetrate even a perfect superconducting surface and ruin the performance. We present intuitive arguments and simple estimates for {H}{sh}, and combine them with our previous rigorous calculations, which we summarize. We briefly discuss experimental measurements of the superheating field, comparing to our estimates. We explore the effects of materials anisotropy and the danger of disorder in nucleating vortex entry. Will we need to control surface orientation in the layered compound MgB2? Can we estimate theoretically whether dirt and defects make these new materials fundamentally more challenging to optimize than niobium? Finally, we discuss and analyze recent proposals to use thin superconducting layers or laminates to enhance the performance of superconducting cavities. Flux entering a laminate can lead to so-called pancake vortices; we consider the physics of the dislocation motion and potential re-annihilation or stabilization of these vortices after their entry.

  4. Enhancement in low field nuclear magnetic resonance with a high-Tc superconducting quantum interference device and hyperpolarized 3He

    NASA Astrophysics Data System (ADS)

    Liao, Shu-Hsien; Yang, Hong-Chang; Horng, Herng-Er; Chen, Hsin-Hsien; Yang, Shieh-Yueh; Chen, Ming-Jye; Yang, Chang-Hau

    2008-09-01

    In this work, we present a design that improves signals produced by nuclear magnetic resonance (NMR) and magnetic resonance imaging by using optical pumping and a high-Tc superconducting quantum interference device (SQUID) magnetometer. In our design for a NMR detection system, a pickup coil is coupled to the spin procession of a H3e nucleus; the input coil is coupled to a high-Tc SQUID magnetometer; and the capacitor is connected in series to form a tank circuit resonating at the Larmor frequency of the H3e nucleus in the measuring field. A signal-to-noise ratio gain of 2.67 over a conventional Faraday detection coil was obtained with the high-Tc SQUID detection system in a measuring magnetic field equaling 0.1128 mT, at which the central frequency was 3.66 kHz for H3e nucleus. The improvement in the NMR signal for large-size, hyperpolarized H3e coupled to a high-Tc SQUID-based spectrometer in low magnetic fields at room temperature is significant compared to that without flux coupling. This result may be of interest given its potential for use in a low field imager.

  5. Superconducting Resonators Development for the FRIB and ReA Linacs at MSU: Recent Achievements and Future Goals

    SciTech Connect

    Facco, A; Binkowski, J; Compton, C; Crisp, J L; Dubbs, L J; Elliot, K; Harle, L L; Hodek, M; Johnson, M J; Leitner, D; Leitner, M; Malloch, I M; Miller, S J; Oweiss, R; Popielarski, J; Popielarski, L; Saito, K; Wei, J; Wlodarczak, J; Xu, Y; Zhang, Y; Zheng, Z; Burrill, A; Davis, G K; Macha, K; Reilly, A V

    2012-07-01

    The superconducting driver and post-accelerator linacs of the FRIB project, the large scale radioactive beam facility under construction at MSU, require the construction of about 400 low-{beta} Quarter-wave (QWR) and Half-wave resonators (HWR) with four different optimum velocities. 1st and 2nd generation prototypes of {beta}{sub 0} = 0.041 and 0.085 QWRs and {beta}{sub 0} = 0.53 HWRs have been built and tested, and have more than fulfilled the FRIB and ReA design goals. The present cavity surface preparation at MSU allowed production of low-{beta} cavities nearly free from field emission. The first two cryostats of {beta}{sub 0} = 0.041 QWRs are now in operation in the ReA3 linac. A 3rd generation design of the FRIB resonators allowed to further improve the cavity parameters, reducing the peak magnetic field in operation and increasing the possible operation gradient, with consequent reduction of the number of required resonators. The construction of the cavities for FRIB, which includes three phases for each cavity type (development, pre-production and production runs) has started. Cavity design, construction, treatment and performance will be described and discussed.

  6. TlCaBaCuO high Tc superconducting microstrip ring resonators designed for 12 GHz

    NASA Technical Reports Server (NTRS)

    Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

    1993-01-01

    Microwave properties of sputtered Tl-Ca-Ba-Cu-O thin films were investigated by designing, fabricating, and testing microstrip ring resonators. Ring resonators designed for 12 GHz fundamental resonance frequency, were fabricated and tested. From the unloaded Q values for the resonators, the surface resistance was calculated by separating the conductor losses from the total losses. The penetration depth was obtained from the temperature dependence of resonance frequency, assuming that the shift in resonance frequency is mainly due to the temperature dependence of penetration depth. The effective surface resistance at 12 GHz and 77 K was determined to be between 1.5 and 2.75 mOmega, almost an order lower than Cu at the same temperature and frequency. The effective penetration depth at 0 K is approximately 7000 A.

  7. High-Q filters with complete transports using quasiperiodic rings with spin-orbit interaction

    SciTech Connect

    Qiu, R. Z.; Chen, C. H.; Tsao, C. W.; Hsueh, W. J.

    2014-09-15

    A high Q filter with complete transports is achieved using a quasiperiodic Thue-Morse array of mesoscopic rings with spin-orbit interaction. As the generation order of the Thue-Morse array increases, not only does the Q factor of the resonance peak increase exponentially, but the number of sharp resonance peaks also increases. The maximum Q factor for the electronic filter of a Thue-Morse array is much greater than that in a periodic array, for the same number of the rings.

  8. Studies of emittance of multiply charged ions extracted from high temperature superconducting electron cyclotron resonance ion source, PKDELIS

    SciTech Connect

    Rodrigues, G.; Lakshmy, P. S.; Kumar, Sarvesh; Mandal, A.; Kanjilal, D.; Roy, A.; Baskaran, R.

    2010-02-15

    For the high current injector project at Inter University Accelerator Centre, a high temperature superconducting electron cyclotron resonance (ECR) ion source, PKDELIS, would provide the high charge state ions. The emittance of the ECR ion source is an important parameter to design further beam transport system and to match the acceptances of the downstream radio frequency quadrupole and drift tube linac accelerators of the high current injector. The emittance of the analyzed beam of PKDELIS ECR source has been measured utilizing the three beam size technique. A slit and two beam profile monitors positioned at fixed distances from each other were used to measure the beam size. The digitized beam profiles have been analyzed to determine the emittance of various multiply charged ions. The variation of emittance with gas mixing, ultrahigh frequency power, and extraction energy are discussed in this presentation.

  9. Observations of compound sawteeth in ion cyclotron resonant heating plasma using ECE imaging on experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Hussain, Azam; Zhao, Zhenling; Xie, Jinlin; Zhu, Ping; Liu, Wandong; Ti, Ang

    2016-04-01

    The spatial and temporal evolutions of compound sawteeth were directly observed using 2D electron cyclotron emission imaging on experimental advanced superconducting tokamak. The compound sawtooth consists of partial and full collapses. After partial collapse, the hot core survives as only a small amount of heat disperses outwards, whereas in the following full collapse a large amount of heat is released and the hot core dissipates. The presence of two q = 1 surfaces was not observed. Instead, the compound sawtooth occurs mainly at the beginning of an ion cyclotron resonant frequency heating pulse and during the L-H transition phase, which may be related to heat transport suppression caused by a decrease in electron heat diffusivity.

  10. Electron Tunneling Studies of MOLYBDENUM(1-X) Rhenium(x): Enhancement of Superconductivity by a Resonance Mode.

    NASA Astrophysics Data System (ADS)

    Shum, Danny Pak-Chum

    It is well-known that a heavy impurity atom in a lattice of light atoms induces a lower frequency in-band resonance mode in the vibrational spectrum. The exact effect of such a mode on the lat- tice spectrum has not previously been reported and effects of such modes on superconductivity have not previously been described. Sputtered thin films of bcc Mo(,1-x)Re(,x), 0.2 < x < 0.4, have been pre- pared for this study because the Re atom is almost twice as heavy as Mo. High quality MoRe/Al(,2)O(,3)/Pb tunnel junctions on these films have been made with an in situ deposited and subsequently oxidized thin Al layer as barrier. Three phonon peaks were observed directly in the dV/dI and d('2)V/dI('2) curves. The (alpha)('2)F((omega)) spectra, determined from the data through the Eliashberg theory of superconductivity, all show an anomalous low energy peak, in addition to the Mo-derived transverse and longitudinal phonon peaks. This peak appears near 14 meV, in agreement with the Brout-Visscher theory and with neu- tron scattering data which first indicated the Re resonance mode in Mo(,.85)Re(,.15). We show that the resonance mode contributes strongly to (alpha)('2)F((omega)) and to strong coupling (delta)(=2(DELTA)/k(,B)T(,c) - 3.53) > 0. (delta) increases with (lamda)(,R), the Re contribution to the electron-phonon coupling con- stant (lamda). The dependences of the anomalous softening and width of the resonance mode on (lamda)(,R) fit the Yu-Anderson theory of local pho- non screening by a Fermi gas of electrons treated as Tomonago. bosons. These results explain the low N(0), high T(,c) behavior of Mo(,.6)Re(,.4). *DOE Report IS-T-1246. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.

  11. Physics of Limiting Phenomena in Superconducting Microwave Resonators: Vortex Dissipation, Ultimate Quench and Quality Factor Degradation Mechanisms

    SciTech Connect

    Checchin, Mattia

    2016-01-01

    Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the

  12. Physics of Limiting Phenomena in Superconducting Microwave Resonators: Vortex Dissipation, Ultimate Quench and Quality Factor Degradation Mechanisms

    SciTech Connect

    Checchin, Mattia

    2016-12-01

    Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the

  13. High Temperature Superconductivity Space Experiment (HTSSE). Hybrid HTS/Dielectric Resonator Bandpass Filter

    DTIC Science & Technology

    1992-04-02

    enlarged ( limited by waveguide moding) or the metal walls replaced by HTS material . HTS walls are particularly attractive since they can be placed...an order of magnitude the resistive losses of filters, waveguide feeds, and transmission lines. Significant reduction in size and weight of these...suspending a dielectric resonator inside a waveguide cavity below cutoff. One of the basic advantages of a dielectric resonator as compared to a

  14. Automation of Data Analysis Programs Used in the Cryogenic Characterization of Superconducting Microwave Resonators

    NASA Technical Reports Server (NTRS)

    Creason, A. S.; Miranda, F. A.

    1996-01-01

    Knowledge of the microwave properties at cryogenic temperatures of components fabricated using High-Temperature-Superconductors (HTS) is useful in the design of HTS-based microwave circuits. Therefore, fast and reliable characterization techniques have been developed to study the aforementioned properties. In this paper, we discuss computer analysis techniques employed in the cryogenic characterization of HTS-based resonators. The revised data analysis process requires minimal user input. and organizes the data in a form that is easily accessible by the user for further examination. These programs retrieve data generated during the cryogenic characterization at microwave frequencies of HTS based resonators and use it to calculate parameters such as the loaded and unloaded quality factors (Q and Q(sub o), respectively), the resonant frequency (f(sub o)), and the coupling coefficient (k), which are important quantities in the evaluation of HTS resonators. While the data are also stored for further use, the programs allow the user to obtain a graphical representation of any of the measured parameters as a function of temperature soon after the completion of the cryogenic measurement cycle. Although these programs were developed to study planar HTS-based resonators operating in the reflection mode, they could also be used in the cryogenic characterization of two ports (i.e., reflection/transmission) resonators.

  15. Comparisons between the 35 mm Quadrature Surface Resonator at 300 K and the 40 mm High-Temperature Superconducting Surface Resonator at 77 K in a 3T MRI Imager

    PubMed Central

    Song, Manli; Chen, Jyh-Horng; Chen, Ji; Lin, In-Tsang

    2015-01-01

    This study attempts to compare the signal-to-noise ratio (SNR) of the 40 mm High-Temperature Superconducting (HTS) surface resonator at 77 K and the 35 mm commercial quadrature (QD) surface resonator at 300 K in a 3 Tesla (T) MRI imager. To aquire images for the comparison, we implemented a phantom experiment using the 40 mm diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) HTS surface resonator, the 35 mm commercial QD surface resonator and the 40 mm professionally-made copper surface resonator. The HTS surface resonator at 77 K provided a 1.43-fold SNR gain over the QD surface resonator at 300 K and provided a 3.84-fold SNR gain over the professionally-made copper surface resonator at 300 K on phantom images. The results agree with the predictions, and the difference between the predicted SNR gains and measured SNR gains is 1%. Although the geometry of the HTS surface resonator is different from the QD surface resonator, its SNR is still higher. The results demonstrate that a higher image quality can be obtained with the HTS surface resonator at 77 K. With the HTS surface resonator, the SNR can be improved, suggesting that the HTS surface resonator is a potentially helpful diagnostic tool for MRI imaging in various applications. PMID:25812124

  16. Distinguishing S-plus-minus and S-plus-plus electron pairing symmetries by neutron spin resonances in superconducting Sodium-Iron-Cobalt-Arsenic (transitional temperature = 18 Kelvin)

    SciTech Connect

    Das, Tanmoy; Balatsky, Alexander V.; Zhang, Chenglin; Li, Haifeng; Su, Yiki; Nethertom, Tucker; Redding, Caleb; Carr, Scott; Schneidewind, Astrid; Faulhaber, Enrico; Li, Shiliang; Yao, Daoxin; Bruckel, Thomas; Dai, Pengchen; Sobolev, Oleg

    2012-06-05

    A determination of the superconducting (SC) electron pairing symmetry forms the basis for establishing a microscopic mechansim for superconductivity. For iron pnictide superconductors, the s{sup {+-}}-pairing symmetry theory predicts the presence of a sharp neutron spin resonance at an energy below the sum of hole and electron SC gap energies (E {le} 2{Delta}). Although the resonances have been observed for various iron pnictide superconductors, they are broad in energy and can also be interpreted as arising from the s{sup ++}-pairing symmetry with E {ge} 2{Delta}. Here we use inelastic neutron scattering to reveal a sharp resonance at E = 7 meV in the SC NaFe{sub 0.935}Co{sub 0.045}As (T{sub c} = 18 K). By comparing our experiments with calculated spin-excitations spectra within the s{sup {+-}} and s{sup ++}-pairing symmetries, we conclude that the resonance in NaFe{sub 0.935}Co{sub 0.045}As is consistent with the s{sup {+-}}-pairing symmetry, thus eliminating s{sup ++}-pairing symmetry as a candidate for superconductivity.

  17. One-step resonant controlled-phase gate on distant transmon qutrits in different 1D superconducting resonators

    PubMed Central

    Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo; Lu Long, Gui

    2015-01-01

    We propose a scheme to construct the controlled-phase (c-phase) gate on distant transmon qutrits hosted in different resonators inter-coupled by a connected transmon qutrit. Different from previous works for entanglement generation and information transfer on two distant qubits in a dispersive regime in the similar systems, our gate is constructed in the resonant regime with one step. The numerical simulation shows that the fidelity of our c-phase gate is 99.5% within 86.3 ns. As an interesting application of our c-phase gate, we propose an effective scheme to complete a conventional square lattice of two-dimensional surface code layout for fault-tolerant quantum computing on the distant transmon qutrits. The four-step coupling between the nearest distant transmon qutrits, small coupling strengths of the distant transmon qutrits, and the non-population on the connection transmon qutrit can reduce the interactions among different parts of the layout effectively, which makes the layout be integrated with a large scale in an easier way. PMID:26486426

  18. Normal modes of a superconducting transmission-line resonator with embedded lumped element circuit components

    NASA Astrophysics Data System (ADS)

    Mortensen, Henrik Lund; Mølmer, Klaus; Andersen, Christian Kraglund

    2016-11-01

    We present a method to identify the coupled, normal modes of a superconducting transmission line with an embedded lumped element circuit. We evaluate the effective transmission-line nonlinearities in the case of Kerr-like Josephson interactions in the circuit and in the case where the embedded circuit constitutes a qubit degree of freedom, which is Rabi coupled to the field in the transmission line. Our theory quantitatively accounts for the very high and positive Kerr nonlinearities observed in a recent experiment [M. Rehák, P. Neilinger, M. Grajcar, G. Oelsner, U. Hübner, E. Il'ichev, and H.-G. Meyer, Appl. Phys. Lett. 104, 162604 (2014), 10.1063/1.4873719], and we can evaluate the accomplishments of modified versions of the experimental circuit.

  19. Magnetic Resonance in Spin Glasses, Superconductivity of Thin Aluminum Films and Models for Transport Properties of One-Dimensional Systems

    NASA Astrophysics Data System (ADS)

    Elliott, Jeffrey Holden

    This thesis reports on three separate investigations in solid state physics. The first is electron paramagnetic resonance in the spin glass Ag:Mn. EPR measurements were performed at two resonance frequencies, concentrating on temperatures above the glass transition temperature. The measured linewidth appears to diverge at T(,g) for low resonance frequencies. This is the first observation of a sharp feature in the EPR behavior of spin glasses at the magnetic susceptibility transition temperature. These results will be compared with recently proposed phenomenological and microscopic theories. The second topic reported in this thesis is the superconducting transition of thin aluminum films. These films were investigated as a function of grain size and thickness. The transition temperature was enhanced over the bulk value, in agreement with many previous investigations of granular aluminum. This study differs from most in the sample preparation--evaporation, photolithography and anodization. This allows a better understanding of the sample geometry on the level of a grain size, which in turn allows better comparison to the many theories proposed to explain the enhancement. The third topic reported in this thesis is an extension of the variable rate hopping theory applied in one dimension to N-ME-Qn(TCNQ)(,2). This model is a classical one used to explain both the DC and AC electrical conductivity of organic conductors. The temperature dependence of the model does not agree with experiment at low temperatures. Tunneling has been added to the hopping. This increases the conductivity at low temperatures, and results in excellent agreement with the experimental conductivity over the measured temperature range. The model also predicts that the frequency dependence of the conductivity varies as (omega)(' 1/2) at low frequencies. This long time tail prediction agrees with the measured dielectric constant of N-Me-iso-Qn(TCNQ)(,2).

  20. DC superconducting quantum interference device usable in nuclear quadrupole resonance and zero field nuclear magnetic spectrometers

    DOEpatents

    Fan, Non Q.; Clarke, John

    1993-01-01

    A spectrometer for measuring the nuclear quadrupole resonance spectra or the zero-field nuclear magnetic resonance spectra generated by a sample is disclosed. The spectrometer uses an amplifier having a dc SQUID operating in a flux-locked loop for generating an amplified output as a function of the intensity of the signal generated by the sample. The flux-locked loop circuit includes an integrator. The amplifier also includes means for preventing the integrator from being driven into saturation. As a result, the time for the flux-locked loop to recover from the excitation pulses generated by the spectrometer is reduced.

  1. DC superconducting quantum interference device usable in nuclear quadrupole resonance and zero field nuclear magnetic spectrometers

    DOEpatents

    Fan, N.Q.; Clarke, J.

    1993-10-19

    A spectrometer for measuring the nuclear quadrupole resonance spectra or the zero-field nuclear magnetic resonance spectra generated by a sample is disclosed. The spectrometer uses an amplifier having a dc SQUID operating in a flux-locked loop for generating an amplified output as a function of the intensity of the signal generated by the sample. The flux-locked loop circuit includes an integrator. The amplifier also includes means for preventing the integrator from being driven into saturation. As a result, the time for the flux-locked loop to recover from the excitation pulses generated by the spectrometer is reduced. 7 figures.

  2. Tailoring Surface Impurity Content to Maximize Q-factors of Superconducting Resonators

    SciTech Connect

    Martinello, Martina; Checchin, Mattia; Grassellino, Anna; Melnychuk, Oleksandr; Posen, Sam; Romanenko, Alexander; Sergatskov, Dmitri; Zasadzinski, John

    2016-06-01

    Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of flux trapped, depends on the mean free path. A variety of 1.3 GHz cavities with different surface treatments (EP, 120 C bake and different N-doping) were studied in order to cover the largest range of mean free path nowadays achievable, from few to thousands of nanometers. A bell shaped trend appears for the range of mean free path studied. Over doped cavities falls at the maximum of this curve defining the largest values of sensitivity. In addition, we have also studied the trend of the BCS surface resistance contribution as a function of mean free path, revealing that N-doped cavities follow close to the theoretical minimum of the BCS surface resistance as a function of the mean free path. Adding these results together we unveil that optimal N-doping treatment allows to maximize Q-factor at 2 K and 16 MV/m until the magnetic field fully trapped during the cavity cooldown stays below 10 mG.

  3. Collective Nature of Spin Excitations in Superconducting Cuprates Probed by Resonant Inelastic X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Minola, M.; Dellea, G.; Gretarsson, H.; Peng, Y. Y.; Lu, Y.; Porras, J.; Loew, T.; Yakhou, F.; Brookes, N. B.; Huang, Y. B.; Pelliciari, J.; Schmitt, T.; Ghiringhelli, G.; Keimer, B.; Braicovich, L.; Le Tacon, M.

    2015-05-01

    We used resonant inelastic x-ray scattering (RIXS) with and without analysis of the scattered photon polarization, to study dispersive spin excitations in the high temperature superconductor YBa2Cu3O6 +x over a wide range of doping levels (0.1 ≤x ≤1 ). The excitation profiles were carefully monitored as the incident photon energy was detuned from the resonant condition, and the spin excitation energy was found to be independent of detuning for all x . These findings demonstrate that the largest fraction of the spin-flip RIXS profiles in doped cuprates arises from magnetic collective modes, rather than from incoherent particle-hole excitations as recently suggested theoretically [Benjamin et al. Phys. Rev. Lett. 112, 247002 (2014)]. Implications for the theoretical description of the electron system in the cuprates are discussed.

  4. Controllable generation of two-mode-entangled states in two-resonator circuit QED with a single gap-tunable superconducting qubit

    NASA Astrophysics Data System (ADS)

    Ma, Sheng-Li; Li, Zhen; Fang, Ai-Ping; Li, Peng-Bo; Gao, Shao-Yan; Li, Fu-Li

    2014-12-01

    We study controllable generation of two-mode-entangled states in a circuit QED setup, which consists of two spatially separated superconducting transmission line resonators and a single gap-tunable superconducting qubit. Two sharp coupling sidebands are induced when the artificial atom is suitably driven by a bichromatic microwave field. The two resonators can have squeezing-type interactions with the qubit via the coupling sidebands. If the two resonators are not degenerate, we show that the two resonators can be cooled down into the two-mode squeezed vacuum via dissipation of the qubit. The generation of the two-mode squeezed state is based on a dissipative state-engineering process, which explores the energy relaxation of the qubit as a resource. Moreover, the scheme does not need both the specific preparation of the initial state and the designed special dynamical process of the system. If the resonators are degenerate, we show that entangled coherent states of the resonators can be generated by use of the unitary dynamical evolution process of the system and the state-projection measurement. Moreover, macro entangled coherent states of the resonators with huge photons can in principle be created if the resonators and the qubit have sufficiently long lifetimes. The present scheme has two remarkable features: (1) only a single qubit is used in the generation of the two-mode squeezed state; and (2) the ultrastrong coupling condition and initializing the resonators in coherent states are not required. These make the present scheme more simple and feasible in experimental implementation.

  5. Splitting of high-Q Mie modes induced by light backscattering in silica microspheres

    NASA Astrophysics Data System (ADS)

    Weiss, D. S.; Sandoghdar, V.; Hare, J.; Lefèvre-Seguin, V.; Raimond, J.-M.; Haroche, S.

    1995-09-01

    We have observed that very high- Q Mie resonances in silica microspheres are split into doublets. This splitting is attributed to internal backscattering that couples the two degenerate whispering-gallery modes propagating in opposite directions along the sphere equator. We have studied this doublet structure by high-resolution spectroscopy. Time-decay measurements have also been performed and show a beat note corresponding to the coupling rate between the clockwise and counterclockwise modes. A simple model of coupled oscillators describes our data well, and the backscattering efficiency that we measure is consistent with what is observed in optical fibers.

  6. Superconductivity in Medicine

    NASA Astrophysics Data System (ADS)

    Alonso, Jose R.; Antaya, Timothy A.

    2012-01-01

    Superconductivity is playing an increasingly important role in advanced medical technologies. Compact superconducting cyclotrons are emerging as powerful tools for external beam therapy with protons and carbon ions, and offer advantages of cost and size reduction in isotope production as well. Superconducting magnets in isocentric gantries reduce their size and weight to practical proportions. In diagnostic imaging, superconducting magnets have been crucial for the successful clinical implementation of magnetic resonance imaging. This article introduces each of those areas and describes the role which superconductivity is playing in them.

  7. Enhancement of nuclear magnetic resonance in microtesla magnetic field with prepolarization field detected with high-Tc superconducting quantum interference device

    NASA Astrophysics Data System (ADS)

    Yang, Hong-Chang; Liao, Shu-Hsien; Horng, Herng-Er; Kuo, Shing-Ling; Chen, Hsin-Hsien; Yang, S. Y.

    2006-06-01

    We applied prepolarization field and high-Tc superconducting quantum interference device (SQUID) detector to enhance nuclear magnetic resonance signal in a microtesla magnetic field. The minimum measuring magnetic field is 8.9μT at which the proton resonance frequency is 380Hz. The specificity instrumentation and the difficulty of using a high-Tc SQUID with prepolarization field were investigated. We applied gradient field to perform one-dimensional proton imaging in a microtesla magnetic field. Additionally, low field high-Tc SQUID-based NMR systems are promising in biomagnetic research due to its use, for example, in imaging with hyperpolarized noble gas.

  8. Fast, low-power manipulation of spin ensembles in superconducting microresonators

    SciTech Connect

    Sigillito, A. J. Malissa, H.; Tyryshkin, A. M.; Houck, A. A.; Lyon, S. A.; Riemann, H.; Abrosimov, N. V.; Becker, P.; Pohl, H.-J.; Thewalt, M. L. W.; Itoh, K. M.; Morton, J. J. L.; Schuster, D. I.

    2014-06-02

    We demonstrate the use of high-Q superconducting coplanar waveguide (CPW) microresonators to perform rapid manipulations on a randomly distributed spin ensemble using very low microwave power (400 nW). This power is compatible with dilution refrigerators, making microwave manipulation of spin ensembles feasible for quantum computing applications. We also describe the use of adiabatic microwave pulses to overcome microwave magnetic field (B{sub 1}) inhomogeneities inherent to CPW resonators. This allows for uniform control over a randomly distributed spin ensemble. Sensitivity data are reported showing a single shot (no signal averaging) sensitivity to 10{sup 7} spins or 3×10{sup 4}spins/√(Hz) with averaging.

  9. Inverse design of high-Q wave filters in two-dimensional phononic crystals by topology optimization.

    PubMed

    Dong, Hao-Wen; Wang, Yue-Sheng; Zhang, Chuanzeng

    2017-04-01

    Topology optimization of a waveguide-cavity structure in phononic crystals for designing narrow band filters under the given operating frequencies is presented in this paper. We show that it is possible to obtain an ultra-high-Q filter by only optimizing the cavity topology without introducing any other coupling medium. The optimized cavity with highly symmetric resonance can be utilized as the multi-channel filter, raising filter and T-splitter. In addition, most optimized high-Q filters have the Fano resonances near the resonant frequencies. Furthermore, our filter optimization based on the waveguide and cavity, and our simple illustration of a computational approach to wave control in phononic crystals can be extended and applied to design other acoustic devices or even opto-mechanical devices.

  10. Characterization of etch pits found on a large-grain bulk niobium superconducting radio-frequency resonant cavity

    SciTech Connect

    Zhao, Xin; Ciovati, G.; Bieler, T. R.

    2010-12-15

    The performance of superconducting radio-frequency (SRF) resonant cavities made of bulk niobium is limited by nonlinear localized effects. Surface analysis of regions of higher power dissipation is thus of intense interest. Such areas (referred to as “hotspots”) were identified in a large-grain single-cell cavity that had been buffered-chemical polished and dissected for examination by high resolution electron microscopy, electron backscattered diffraction microscopy (EBSD), and optical microscopy. Pits with clearly discernible crystal facets were observed in both “hotspot” and “coldspot” specimens. The pits were found in-grain, at bicrystal boundaries, and on tricrystal junctions. They are interpreted as etch pits induced by crystal defects (e.g. dislocations). All coldspots examined had a qualitatively lower density of etch pits or relatively smooth tricrystal boundary junctions. EBSD mapping revealed the crystal orientation surrounding the pits. Locations with high pit density are correlated with higher mean values of the local average misorientation angle distributions, indicating a higher geometrically necessary dislocation content. In addition, a survey of the samples by energy dispersive x-ray analysis did not show any significant contamination of the samples’ surface. In conclusion, the local magnetic field enhancement produced by the sharp-edge features observed on the samples is not sufficient to explain the observed degradation of the cavity quality factor, which starts at peak surface magnetic field as low as 20 mT.

  11. Characterization of etch pits found on a large-grain bulk niobium superconducting radio-frequency resonant cavity

    DOE PAGES

    Zhao, Xin; Ciovati, G.; Bieler, T. R.

    2010-12-15

    The performance of superconducting radio-frequency (SRF) resonant cavities made of bulk niobium is limited by nonlinear localized effects. Surface analysis of regions of higher power dissipation is thus of intense interest. Such areas (referred to as “hotspots”) were identified in a large-grain single-cell cavity that had been buffered-chemical polished and dissected for examination by high resolution electron microscopy, electron backscattered diffraction microscopy (EBSD), and optical microscopy. Pits with clearly discernible crystal facets were observed in both “hotspot” and “coldspot” specimens. The pits were found in-grain, at bicrystal boundaries, and on tricrystal junctions. They are interpreted as etch pits induced bymore » crystal defects (e.g. dislocations). All coldspots examined had a qualitatively lower density of etch pits or relatively smooth tricrystal boundary junctions. EBSD mapping revealed the crystal orientation surrounding the pits. Locations with high pit density are correlated with higher mean values of the local average misorientation angle distributions, indicating a higher geometrically necessary dislocation content. In addition, a survey of the samples by energy dispersive x-ray analysis did not show any significant contamination of the samples’ surface. In conclusion, the local magnetic field enhancement produced by the sharp-edge features observed on the samples is not sufficient to explain the observed degradation of the cavity quality factor, which starts at peak surface magnetic field as low as 20 mT.« less

  12. Growth of single-crystal Al layers on GaAs and Si substrates for microwave superconducting resonators

    NASA Astrophysics Data System (ADS)

    Tournet, J.; Gosselink, D.; Jaikissoon, M.; Miao, G.-X.; Langenberg, D.; Mariantoni, M.; Wasilewski, Zr

    Thin Al layers on dielectrics are essential building blocks of circuits used in the quest for scalable quantum computing systems. While molecular beam epitaxy (MBE) has been shown to produce the highest quality Al layers, further reduction of losses in superconducting resonators fabricated from them is highly desirable. Defects at the Al-substrate interface are likely the key source of losses. Here we report on the optimization of MBE growth of Al layers on GaAs and Si substrates. Si surfaces were prepared by in-situ high temperature substrate annealing. For GaAs, defects typically remaining on the substrate surfaces after oxide desorption were overgrown with GaAs or GaAs/AlAs superlattice buffer layers. Such surface preparation steps were followed by cooling process to below 0°C, precisely controlled to obtain targeted surface reconstructions. Deposition of 110 nm Al layers was done at subzero temperatures and monitored with RHEED at several azimuths simultaneously. The resulting layers were characterized by HRXRD, AFM and Nomarski. Single crystal, near-atomically smooth layers of Al(110) were demonstrated on GaAs(001)-2x4 surface whereas Al(111) of comparable quality was formed on Si(111)-1x1 and 7x7 surfaces.

  13. Evaluation of radio frequency microcoils as nuclear magnetic resonance detectors in low-homogeneity high-field superconducting magnets

    NASA Astrophysics Data System (ADS)

    Wright, A. C.; Neideen, T. A.; Magin, R. L.; Norcross, J. A.

    1998-11-01

    We describe here experiments evaluating the performance of solenoidal radio frequency probes having submillimeter dimensions (microcoils) as detectors for liquid nuclear magnetic resonance (NMR) in very low-homogeneity (100 ppm/cm) magnetic fields. Performance is based on the measured H2O linewidth. A series of solenoidal microcoils having sample volumes 8, 53, and 593 nl were filled with distilled H2O and evaluated for smallest obtainable unshimmed NMR spectral linewidths in a vertical bore superconducting magnet, stabilized at 5.9 T (1H frequency=250 MHz). The smallest microcoil (472 μm diameter) gave a smallest H2O linewidth of 525 Hz, 25 times smaller than that from a standard 5.7 mm probe. Linewidth increased approximately as the square root of sample volume. For comparison, shimmed H2O linewidths using the same microcoils in a high-homogeneity (0.1 ppm/cm) NMR magnet were also measured. Shimmed linewidths in the high-homogeneity magnet were two orders of magnitude smaller and exhibited a similar dependence on volume. The results demonstrate that by using microcoils the volume over which the polarizing magnetic field must meet a specified homogeneity can be significantly reduced, which would be advantageous for smaller, less expensive NMR systems.

  14. Production of highly charged heavy ions by 18 GHz superconducting electron cyclotron resonance at Research Center for Nuclear Physics.

    PubMed

    Yorita, Tetsuhiko; Hatanaka, Kichiji; Fukuda, Mitsuhiro; Kibayashi, Mitsuru; Morinobu, Shunpei; Okamura, Hiroyuki; Tamii, Atsushi

    2010-02-01

    An 18 GHz superconducting electron cyclotron resonance ion source has been installed as a subject of the azimuthally varying field cyclotron upgrade project (K. Hatanaka et al., in Proceedings of the 17th International Conference on Cyclotrons and Their Applications, Tokyo, Japan, 18-22 October 2004, pp. 115-117), in order to increase beam currents and to extend the variety of ions. The production development of several ions has been performed since 2006 and some of them have already been used for user experiments [T. Yorita et al., Rev. Sci. Instrum. 79, 02A311 (2008)]. Further optimizations for each component such as the material of plasma electrode, material, and shape of bias probe and mirror field have been continued and more intense ion beams have been obtained for O, N, and Ar. For the purpose of obtaining highly charged Xe with several microamperes, the optimization of position and shape of plasma electrode and bias disk has also been done and highly charged Xe(32+) beam has been obtained successfully.

  15. Quantum charge pumping through resonant crossed Andreev reflection in a superconducting hybrid junction of silicene

    NASA Astrophysics Data System (ADS)

    Paul, Ganesh C.; Saha, Arijit

    2017-01-01

    We theoretically investigate the phenomena of adiabatic quantum charge pumping through a normal-insulator-superconductor-insulator-normal (NISIN) setup of silicene within the scattering matrix formalism. Assuming a thin barrier limit, we consider the strength of the two barriers (χ1 and χ2) as the two pumping parameters in the adiabatic regime. Within this geometry, we obtain crossed Andreev reflection (CAR) with probability unity in the χ1-χ2 plane without concomitant transmission or elastic co-tunneling. Tunability of the band gap at the Dirac point by applying an external electric field perpendicular to the silicene sheet and variation of the chemical potential at the normal silicene region, open up the possibility of achieving either a perfect CAR or transmission process through our setup. This resonant behavior is periodic with the barrier strengths. We analyze the behavior of the pumped charge through the NISIN structure as a function of the pumping strength and angles of the incident electrons. We show that large (Q ˜2 e ) pumped charge can be obtained through our geometry when the pumping contour encloses either the CAR or transmission resonance in the pumping parameter space. We discuss possible experimental feasibility of our theoretical predictions.

  16. Applications of High-Q Microresonators in Cavity Optomechanics and Nonlinear Photonics

    NASA Astrophysics Data System (ADS)

    Jiang, Wei C.

    Optical microresonators confining light to small volumes are indispensable for a great variety of studies and applications. This thesis is devoted to a study of cavity optomechanical and nonlinear optical phenomena in high-Q microresonators with different materials and structures. Based on that, it proposes and demonstrates several novel schemes and device platforms that exhibit great potential for various applications ranging from frequency metrology and quantum photonics, to information processing and sensing. The thesis starts with a demonstration of a high-frequency (above 1 GHz) regenerative optomechanical oscillator based on a 2-mum-radius high-Q silicon microdisk resonator in the silicon-on-insulator platform with an ultra-low threshold pump power at room temperature and atmosphere. It then continues to explore the cavity optomechanics in single-crystal lithium niobate. A compact lithium niobate microdisk optomechanical resonator with high optical and mechanical qualities, large optomechanical coupling, and high mechanical frequency is achieved, enabling the demonstration of regenerative oscillation in the ambience. Meanwhile, I propose and investigate a novel approach for single molecule detection that utilizes the optical spring effect in a high-Q coherent optomechanical oscillator to dramatically enhance the sensing resolution by orders of magnitude compared with conventional resonator-based approaches. In particular, a high-Q silica microsphere is employed to experimentally demonstrate the detection of single Bovine Serum Albumin proteins with a molecular weight of 66 kDalton at a signal-to-noise ratio of 16.8. On the other hand, the thesis focuses on the theoretical and experimental investigation of the generation of high-purity bright photon pairs in a silicon microdisk based on the cavity enhanced four-wave mixing. The device is able to produce multiple photon pairs at different wavelengths in the telecom band with a high spectral brightness of 6.24 x

  17. Localized high-Q modes in conical microcavities

    NASA Astrophysics Data System (ADS)

    Lin, Xing; Fang, Wei

    2016-12-01

    We carry out three-dimensional (3D) numerical simulation on a conical microcavity with a half-angle of 11 degree, where there exists high-Q modes by introducing a thin high refractive index film on a conical surface. Our study reveals that, rather than the surface profile of the microcavity, the effective radius plays crucial role in whether the cavity may support localized modes. Specifically, the change of high refractive index film thickness creates an additional angular momentum barrier, so that the conical microcavity may sustain localized high-Q modes. Our study offers a new degree of freedom to control the properties of 3D microcavities, which is useful for microlaser or sensor applications.

  18. Catastrophic sliding bifurcations and onset of oscillations in a superconducting resonator.

    PubMed

    Jeffrey, M R; Champneys, A R; di Bernardo, M; Shaw, S W

    2010-01-01

    This paper presents a general analysis and a concrete example of the catastrophic case of a discontinuity-induced bifurcation in so-called Filippov nonsmooth dynamical systems. Such systems are characterized by discontinuous jumps in the right-hand sides of differential equations across a phase space boundary and are often used as physical models of stick-slip motion and relay control. Sliding bifurcations of periodic orbits have recently been shown to underlie the onset of complex dynamics including chaos. In contrast to previously analyzed cases, in this work a periodic orbit is assumed to graze the boundary of a repelling sliding region, resulting in its abrupt destruction without any precursive change in its stability or period. Necessary conditions for the occurrence of such catastrophic grazing-sliding bifurcations are derived. The analysis is illustrated in a piecewise-smooth model of a stripline resonator, where it can account for the abrupt onset of self-modulating current fluctuations. The resonator device is based around a ring of NbN containing a microbridge bottleneck, whose switching between normal and super conducting states can be modeled as discontinuous, and whose fast temperature versus slow current fluctuations are modeled by a slow-fast timescale separation in the dynamics. By approximating the slow component as Filippov sliding, explicit conditions are derived for catastrophic grazing-sliding bifurcations, which can be traced out as parameters vary. The results are shown to agree well with simulations of the slow-fast model and to offer a simple explanation of one of the key features of this experimental device.

  19. Evidence of Spin Resonance Signal in Oxygen Free Superconducting CaFe0.88Co0.12AsF: An Inelastic Neutron Scattering Study

    NASA Astrophysics Data System (ADS)

    Price, Stephen; Su, Yixi; Xiao, Yinguo; Adroja, Devashibhai T.; Guidi, Tatiana; Mittal, Ranjan; Nandi, Shibabrata; Matsuishi, Satoru; Hosono, Hideo; Brückel, Thomas

    2013-10-01

    The spin excitation spectrum of optimally doped superconducting CaFe0.88Co0.12AsF (Tc˜ 22 K) was studied by means of time-of-flight (ToF) inelastic neutron scattering experiments on a powder sample for temperatures above and below Tc and energies up to 15 meV. In the superconducting state, the spin resonance signal is observed as an enhancement of spectral weight of particle hole excitations of approximately 1.5 times relative to normal state excitations. The resonance energy ER˜ 7 meV scales to Tc via 3.7 kBTc which is in reasonable agreement to the scaling relation reported for other Fe-based compositions. For energies below 5 meV the spectrum of spin flip particle hole excitations in the superconducting state exhibits a strong reduction in spectral weight, indicating the opening of the spin gap. Nonetheless, a complete suppression of magnetic response cannot be observed. In contrast, the normal state spin excitations are not gapped and strongly two dimensional spin fluctuations persist up to temperatures at least as high as 150 K.

  20. Measuring the Charge of a Single Dielectric Nanoparticle Using a High-Q Optical Microresonator

    NASA Astrophysics Data System (ADS)

    Chen, You-Ling; Jin, Wei-Liang; Xiao, Yun-Feng; Zhang, Xuming

    2016-10-01

    Measuring the charge of a nanoparticle is of great importance in many fields including optics, astronomy, biochemistry, atmospheric science, environmental engineering, and dusty plasma. Here, we propose to use a high-Q whispering-gallery-mode (WGM) optical microresonator to detect the surface and bulk charge of a dielectric nanoparticle. Because of the modification of nanoparticle conductivity induced by the surplus electrons, both the coupling strength between the nanoparticle and the WGM and the dissipation changes compared with the case of a neutral nanoparticle. The charge density can be inferred from the transmission spectrum of the WGM microresonator. By monitoring the mode splitting, the linewidth broadening or the resonance dip value of the transmission spectrum, surface (bulk) electron density as low as 0.007 nm-2 (0.001 nm-3) can be detected for nanoparticles with negative (positive) electron affinity. The high sensitivity is attributed to the ultranarrow resonance linewidth and small mode volume of the microresonator.

  1. Selective tuning of high-Q silicon photonic crystal nanocavities via laser-assisted local oxidation.

    PubMed

    Chen, Charlton J; Zheng, Jiangjun; Gu, Tingyi; McMillan, James F; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee; Wong, Chee Wei

    2011-06-20

    We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 μm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ∼ 30 mW laser powers. Over this tuning range, the cavity Qs decreases from 3.2×10(5) to 1.2×10(5). Numerical simulations model the temperature distributions in the silicon photonic crystal membrane and the cavity resonance shift from oxidation.

  2. High-Q contacted ring microcavities with scatterer-avoiding “wiggler” Bloch wave supermode fields

    SciTech Connect

    Liu, Yangyang Popović, Miloš A.

    2014-05-19

    High-Q ring resonators with contacts to the waveguide core provide a versatile platform for various applications in chip-scale optomechanics, thermo-, and electro-optics. We propose and demonstrate azimuthally periodic contacted ring resonators based on multi-mode Bloch matching that support contacts on both the inner and outer radius edges with small degradation to the optical quality factor (Q). Radiative coupling between degenerate modes of adjacent radial spatial order leads to imaginary frequency (Q) splitting and a scatterer avoiding high-Q “wiggler” supermode field. We experimentally measure Qs up to 258 000 in devices fabricated in a silicon device layer on buried oxide undercladding and up to 139 000 in devices fully suspended in air using an undercut step. Wiggler supermodes are true modes of the microphotonic system that offer additional degrees of freedom in electrical, thermal, and mechanical design.

  3. The superconducting cavity stability ruby maser oscillator

    NASA Technical Reports Server (NTRS)

    Dick, G. J.; Strayer, D. M.

    1985-01-01

    Analysis of an application of the rudy maser to a superconducting Cavity Stabilized oscillator shows many attractive features. These derive from the mechancial stability inherent in an all-cryogenic design and from the properties of the ruby maser itself. A multiple-cavity design has been developed to allow physical separation of the high-Q superconducting cavity and the ruby element with its requried applied magnetic field. Mode selection is accomplished in this design by tuning the ruby by means of the applied field. We conclude that such an oscillator would perform well, even with cavity Q's as low as 10 to the 8th power allowing the use of a superconductor-on-sapphire resonator with its greater rigidity and lower thermal expansion. A first test of the Superconducting Cavity Stabilized Maser Oscillator (SCSMO) confirms the efficacy of the multiple-cavity design and the applicability of the ruby maser. Frequency variation less than 4x10 to the minus 11th power was measured in the stabilized mode and is attributed to the reference oscillator and to instabilities in the pump source. Variation of 10 to the minus 10th power was observed in the low-Q unstabilized mode, again attributable to pump fluctuations. Even so, direct scaling to a Q of 10 the 9th power predicts a stability better than 10 to the minus 15th power. Together with results showing the lowest losses to date in sapphire at microwave frequencies, and preliminary experiments on superconductor-on-sapphire resonators, frequency stability, levels as low as 10 to the minus 17th power are indicated.

  4. Anisotropic phantom to calibrate high-q diffusion MRI methods

    NASA Astrophysics Data System (ADS)

    Komlosh, M. E.; Benjamini, D.; Barnett, A. S.; Schram, V.; Horkay, F.; Avram, A. V.; Basser, P. J.

    2017-02-01

    A silicon oil-filled glass capillary array is proposed as an anisotropic diffusion MRI phantom. Together with a computational/theoretical pipeline these provide a gold standard for calibrating and validating high-q diffusion MRI experiments. The phantom was used to test high angular resolution diffusion imaging (HARDI) and double pulsed-field gradient (d-PFG) MRI acquisition schemes. MRI-based predictions of microcapillary diameter using both acquisition schemes were compared with results from optical microscopy. This phantom design can be used for quality control and quality assurance purposes and for testing and validating proposed microstructure imaging experiments and the processing pipelines used to analyze them.

  5. Development work for a superconducting linear collider

    NASA Technical Reports Server (NTRS)

    Matheisen, Axel

    1995-01-01

    For future linear e(+)e(-) colliders in the TeV range several alternatives are under discussion. The TESLA approach is based on the advantages of superconductivity. High Q values of the accelerator structures give high efficiency for converting RF power into beam power. A low resonance frequency for the RF structures can be chosen to obtain a large number of electrons (positrons) per bunch. For a given luminosity the beam dimensions can be chosen conservatively which leads to relaxed beam emittance and tolerances at the final focus. Each individual superconducting accelerator component (resonator cavity) of this linear collider has to deliver an energy gain of 25 MeV/m to the beam. Today s.c. resonators are in use at CEBAF/USA, at DESY/Germany, Darmstadt/Germany KEK/Japan and CERN/Geneva. They show acceleration gradients between 5 MV/m and 10 MV/m. Encouraging experiments at CEA Saclay and Cornell University showed acceleration gradients of 20 MV/m and 25 MV/m in single and multicell structures. In an activity centered at DESY in Hamburg/Germany the TESLA collaboration is constructing a 500 MeV superconducting accelerator test facility (TTF) to demonstrate that a linear collider based on this technique can be built in a cost effective manner and that the necessary acceleration gradients of more than 15 MeV/m can be reached reproducibly. The test facility built at DESY covers an area of 3.000 m2 and is divided into 3 major activity areas: (1) The testlinac, where the performance ofthe modular components with an electron beam passing the 40 m long acceleration section can be demonstrated. (2) The test area, where all individual resonators are tested before installation into a module. (3) The preparation and assembly area, where assembly of cavities and modules take place. We report here on the design work to reach a reduction of costs compared to actual existing superconducting accelerator structures and on the facility set up to reach high acceleration gradients in

  6. The combination of high Q factor and chirality in twin cavities and microcavity chain.

    PubMed

    Song, Qinghai; Zhang, Nan; Zhai, Huilin; Liu, Shuai; Gu, Zhiyuan; Wang, Kaiyang; Sun, Shang; Chen, Zhiwei; Li, Meng; Xiao, Shumin

    2014-09-29

    Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities.

  7. The combination of high Q factor and chirality in twin cavities and microcavity chain

    PubMed Central

    Song, Qinghai; Zhang, Nan; Zhai, Huilin; Liu, Shuai; Gu, Zhiyuan; Wang, Kaiyang; Sun, Shang; Chen, Zhiwei; Li, Meng; Xiao, Shumin

    2014-01-01

    Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities. PMID:25262881

  8. Characterization of magnetic nanoparticles as contrast agents in magnetic resonance imaging using high-Tc superconducting quantum interference devices in microtesla magnetic fields

    NASA Astrophysics Data System (ADS)

    Liao, Shu-Hsien; Yang, Hong-Chang; Horng, Herng-Er; Yang, S. Y.

    2009-02-01

    In this paper, we characterize the spin-lattice relaxation T1, spin-spin relaxation T2, and effective relaxation rate ΓMF of magnetic fluids for magnetic resonance imaging using a high-Tc superconducting quantum interference device (SQUID) in microtesla magnetic fields. When the magnetic susceptibility of the magnetic fluid was increased, a broadening of proton nuclear magnetic resonance spectra and a growing spin-lattice relaxation T1 as well as spin-spin relaxation T2 were observed. The effective relaxation rate ΓMF increased monotonically from 0 to 13 s-1 when the magnetic susceptibility of the magnetic fluids, relative to tap water, was increased from 0 to 0.0015 emu g-1. We demonstrate the magnetic fluid as an image contrast via a high-Tc SQUID in microtesla magnetic fields.

  9. Maintaining high-Q in an optical microresonator coated with high-aspect-ratio gold nanorods

    NASA Astrophysics Data System (ADS)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2013-10-01

    We report methods to coat fused-silica microresonators with solution-grown high-aspect-ratio (AR) gold nanorods (NRs). Microresonators coated using our method maintain an optical quality factor (Q) greater than 107 after coating. The more successful method involves silanization of the surface of the microresonator with 3-mercaptopropylmethyldimethoxysilane (MPMDMS), to enable the adhesion of gold NRs. The high-AR NR-coated microresonator combines the field enhancement of localized surface plasmon resonances with the cavity-enhanced evanescent components of high-Q whispering-gallery modes, making it useful for plasmonic sensing applications in the infrared. By coating with NRs having a different aspect ratio, the enhancement regime can be selected within a wide range of wavelengths.

  10. Enhanced Raman scattering of single nanoparticles in a high-Q whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Liu, Rui-Shan; Jin, Wei-Liang; Yu, Xiao-Chong; Liu, Yong-Chun; Xiao, Yun-Feng

    2015-04-01

    We study Raman scattering of single nanoparticles coupled to a high-Q whispering-gallery microresonator. It is found that cavity resonances greatly enhance the Raman signal, and the enhancement factor is as high as 108. Unlike the noncavity case, the signal power exhibits a nonmonotonic dependence on particle size, and it reaches the maximum when the Rayleigh scattering loss and the cavity intrinsic loss are comparable. We further analyze how the Raman signal intensity is influenced by different parameters including cavity quality factors and taper-cavity coupling strength. The detection limit of observing single-nanoparticle Raman signal is discussed finally. As a potential application, this mechanism may provide an alternative way to detect specific biological targets without the need of precovered biorecognitions.

  11. Label-free detection with high-Q microcavities: a review of biosensing mechanisms for integrated devices

    PubMed Central

    Yang, Lan

    2015-01-01

    Optical microcavities that confine light in high-Q resonance promise all of the capabilities required for a successful next-generation microsystem biodetection technology. Label-free detection down to single molecules as well as operation in aqueous environments can be integrated cost-effectively on microchips, together with other photonic components, as well as electronic ones. We provide a comprehensive review of the sensing mechanisms utilized in this emerging field, their physics, engineering and material science aspects, and their application to nanoparticle analysis and biomolecular detection. We survey the most recent developments such as the use of mode splitting for self-referenced measurements, plasmonic nanoantennas for signal enhancements, the use of optical force for nanoparticle manipulation as well as the design of active devices for ultra-sensitive detection. Furthermore, we provide an outlook on the exciting capabilities of functionalized high-Q microcavities in the life sciences. PMID:26918228

  12. Label-free detection with high-Q microcavities: a review of biosensing mechanisms for integrated devices.

    PubMed

    Vollmer, Frank; Yang, Lan

    2012-12-01

    Optical microcavities that confine light in high-Q resonance promise all of the capabilities required for a successful next-generation microsystem biodetection technology. Label-free detection down to single molecules as well as operation in aqueous environments can be integrated cost-effectively on microchips, together with other photonic components, as well as electronic ones. We provide a comprehensive review of the sensing mechanisms utilized in this emerging field, their physics, engineering and material science aspects, and their application to nanoparticle analysis and biomolecular detection. We survey the most recent developments such as the use of mode splitting for self-referenced measurements, plasmonic nanoantennas for signal enhancements, the use of optical force for nanoparticle manipulation as well as the design of active devices for ultra-sensitive detection. Furthermore, we provide an outlook on the exciting capabilities of functionalized high-Q microcavities in the life sciences.

  13. High-Q whispering-gallery mode sensor in liquids

    NASA Astrophysics Data System (ADS)

    Nadeau, Jay L.; Ilchenko, Vladimir S.; Kossakovski, Dmitri; Bearman, Gregory H.; Maleki, Lute

    2002-06-01

    Optical sensing of biomolecules on microfabricated glass surfaces requires surface coatings that minimize nonspecific binding while preserving the optical properties of the sensor. Microspheres with whispering-gallery (WG) modes can achieve quality factor (Q) levels many orders of magnitude greater than those of other WG-based microsensors: greater than 1010 in air, and greater than 109 in a variety of solvents, including methanol, H2O and phosphate buffered saline (PBS). The presence of dyes that absorb in the wavelength of the WG excitation in the evanescent zone can cause this Q value to drop by almost 3 orders of magnitude. Silanization of the surface with mercapto-terminal silanes is compatible with high Q (>109), but chemical cross-linking of streptavidin reduces the Q to 105-106 due to build-up of a thick, irregular layer of protein. However, linkage of biotin to the silane terminus preserves the Q at a ~2x107 and yields a reactive surface sensitive to avidin-containing ligands in a concentration-dependent manner. Improvements in the reliability of the surface chemistry show promise for construction of an ultrasensitive biosensor.

  14. Unconventional superconductivity and electron correlations in the cobalt oxyhydrate Na0.35CoO2.yH2O from nuclear quadrupole resonance.

    PubMed

    Fujimoto, Tatsuya; Zheng, Guo-qing; Kitaoka, Y; Meng, R L; Cmaidalka, J; Chu, C W

    2004-01-30

    We report a careful 59Co nuclear quadrupolar resonance measurement on the recently discovered cobalt oxyhydrate Na0.35CoO2.yH(2)O superconductor from T=40 K down to 0.2 K. We find that in the normal state the spin-lattice relaxation rate 1/T(1) follows a Curie-Weiss type temperature (T) variation, 1/T(1)T=C/(T-theta), with theta=-42 K, suggesting two-dimensional antiferromagnetic spin correlations. Below T(c)=3.9 K, 1/T(1) decreases with no coherence peak and follows a T(n) dependence with n approximately 2.2 down to approximately 2.0 K but crosses over to a 1/T(1) proportional to T variation below T=1.4 K, which suggests non-s-wave superconductivity. The data in the superconducting state are most consistent with the existence of line nodes in the gap function.

  15. Spectrum of a Resonator Coupled to a Driven Superconducting Qubit in the Strong Dispersive Regime of Circuit Quantum Electrodynamics

    NASA Astrophysics Data System (ADS)

    Chong, Yonuk; Hong, Hyun-Gue; Ha, Dong-Gwang

    The resonator spectrum in the strong dispersive coupling regime of circuit-QED has been a useful nondestructive indicator of a stationary qubit state. Here we present experimental observation of the further modification of the resonator spectrum as the qubit undergoes the dynamic transition by a resonant driving field. The quartet resonance associated with the polarized qubit is observed for the resonant driving at one-photon as well as the multi-photon transition in a 3D transmon qubit. The evolution of the resonance as a function of the driving power and the detuning of the driving field is well understood by a simple model which is based on the analytic diagonalization of Hamiltonian and described in terms of dressed states, Lamb shift, and AC Stark shift.

  16. Type-I superconductor pick-up coil in superconducting quantum interference device-based ultra-low field nuclear magnetic resonance

    SciTech Connect

    Hwang, Seong-min Kim, Kiwoong; Kyu Yu, Kwon; Lee, Seong-Joo; Hyun Shim, Jeong; Körber, Rainer; Burghoff, Martin

    2014-02-10

    In ultra-low field nuclear magnetic resonance (ULF-NMR) with strong prepolarization field (B{sub p}), type-II superconducting pick-up coils may be vulnerable to flux pinning from the strong B{sub p}. Pick-up coils made of NbTi, Nb, and Pb were evaluated in terms of acquired NMR signal quality. The type-II pick-up coils showed degraded signals above 61 mT maximum exposure, while the Pb pick-up coil exhibited no such degradation. Furthermore, a negative counter pulse following a strong B{sub p} was shown to follow magnetic hysteresis loop to unpin the trapped flux in the type-II pick-up coil and restore the NMR signal.

  17. Resonant inelastic x-ray scattering study of charge excitations in superconducting and nonsuperconducting PrFeAsO₁₋y

    SciTech Connect

    Jarrige, I.; Nomura, T.; Ishii, K.; Gretarsson, H.; Kim, Y.-J.; Kim, J.; Upton, M.; Casa, D.; Gog, T.; Ishikado, M.; Fukuda, T.; Yoshida, M.; Hill, J. P.; Liu, X.; Hiraoka, N.; Tsuei, K. D.; Shamoto, S.

    2012-09-05

    We report the first observation by momentum-resolved resonant inelastic x-ray scattering of charge excitations in an iron-based superconductor and its parent compound, PrFeAsO₀.₇ and PrFeAsO, respectively, with two main results. First, using calculations based on a 16-band dp model, we show that the energy of the lowest-lying excitations, identified as dd interband transitions of dominant xz,yz orbital character, exhibits a dramatic dependence on electron correlation. This enables us to estimate the Coulomb repulsion U and Hund's coupling J, and to highlight the role played by J in these peculiar orbital-dependent electron correlation effects. Second, we show that short-range antiferromagnetic correlations, which are a prerequisite to the occurrence of these excitations at the Γ point, are still present in the superconducting state.

  18. Resonant inelastic x-ray scattering study of charge excitations in superconducting and nonsuperconducting PrFeAsO₁₋y

    DOE PAGES

    Jarrige, I.; Nomura, T.; Ishii, K.; ...

    2012-09-05

    We report the first observation by momentum-resolved resonant inelastic x-ray scattering of charge excitations in an iron-based superconductor and its parent compound, PrFeAsO₀.₇ and PrFeAsO, respectively, with two main results. First, using calculations based on a 16-band dp model, we show that the energy of the lowest-lying excitations, identified as dd interband transitions of dominant xz,yz orbital character, exhibits a dramatic dependence on electron correlation. This enables us to estimate the Coulomb repulsion U and Hund's coupling J, and to highlight the role played by J in these peculiar orbital-dependent electron correlation effects. Second, we show that short-range antiferromagnetic correlations,more » which are a prerequisite to the occurrence of these excitations at the Γ point, are still present in the superconducting state.« less

  19. Thermocurrents and their role in high Q cavity performance

    NASA Astrophysics Data System (ADS)

    Eichhorn, R.; Daly, C.; Furuta, F.; Ganshyn, A.; Ge, M.; Gonnella, D.; Hall, D.; Ho, V.; Hoffstaetter, G. H.; Liepe, M.; May-Mann, J.; O'Connell, T.; Posen, S.; Quigley, P.; Sears, J.; Veshcherevich, V.

    2016-01-01

    Over the past years it became evident that the quality factor of a superconducting cavity is not only determined by its surface preparation procedure, but is also influenced by the way the cavity is cooled down. Moreover, different data sets exist, some of which indicate that a slow cooldown through the critical temperature is favorable while other data states the exact opposite. Even though there were speculations and some models about the role of thermocurrents and flux-pinning, the difference in behavior remained a mystery. In this paper we will present a consistent theoretical model which we confirmed by data that describes the role of thermocurrents, driven by temperature gradients and material transitions. We will clearly show how they impact the quality factor of a cavity, discuss our findings, relate it to findings at other labs and develop mitigation strategies which especially address the issue of achieving high quality factors of so-called nitrogen doped cavities in horizontal tests.

  20. Fano resonances in prism-coupled multimode square micropillar resonators

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Tong; Zhou, Linjie; Poon, Andrew W.

    2005-06-01

    We report Fano resonances in a multimode square glass micropillar resonator; the resonances were obtained by using angle-resolved prism coupling. Our experiments reveal characteristically asymmetric line shapes of high-Q resonances and of detuned low-Q resonances in multimode reflection spectra. The asymmetric resonance line shapes evolve for an approximately pi phase within a 0.5° range of reflection angles. We model our observed asymmetric multimode resonances by the far-field interference between a light wave that is evanescently coupled with a high-Q mode orbit and a coherent light wave that is refractively coupled with a detuned low-Q mode orbit.

  1. A signal input coil made of superconducting thin film for improved signal-to-noise ratio in a high-Tc SQUID-based ultra-low field nuclear magnetic resonance system

    NASA Astrophysics Data System (ADS)

    Chen, Kuen-Lin; Hsu, Chin-Wei; Ku, Yue-Bai; Chen, Hsin-Hsien; Liao, Shu-Hsien; Wang, Li-Min; Horng, Herng-Er; Yang, Hong-Chang

    2013-11-01

    Resonant coupling schemes are commonly used in SQUID-based ultra-low field (ULF) nuclear magnetic resonance (NMR) systems to couple the spin relaxation signals from samples to the SQUID. Generally, in NMR systems, a resonant coupling scheme is composed of two solenoid coils which are made of enamel insulated wires and a capacitor connected in series. In this work, we tried to replace the metal solenoid input coil with a planar high-Tc superconducting spiral coil to improve the signal-to-noise ratio (SNR) of the ULF NMR signal. A measurement of the free induction decay signal of water protons was performed to demonstrate the improved performance of the system. This improvement is due to the fact that the planar superconducting spiral coil possesses a higher mutual inductance with the SQUID. Therefore, it is a promising way to enhance the SNR of high-Tc SQUID-based ULF NMR/MRI systems.

  2. Two-component uniform spin susceptibility of superconducting HgBa2CuO4+δ single crystals measured using 63Cu and 199Hg nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Haase, Jürgen; Rybicki, Damian; Slichter, Charles P.; Greven, Martin; Yu, Guichuan; Li, Yuan; Zhao, Xudong

    2012-03-01

    63Cu and 199Hg nuclear magnetic resonance shifts for an optimally doped and underdoped HgBa2CuO4+δ single crystal are reported, and the temperature dependence dictates a two-component description of the uniform spin susceptibility. The first component, associated with the pseudogap phenomenon in the NMR shifts, decreases at room temperature and continues to drop as the temperature is lowered, without a drastic change at the transition temperature into the superconducting state. The second component is temperature independent above the superconducting transition temperature and vanishes rapidly below it. It is a substantial part of the total T-dependent susceptibility measured at both nuclei.

  3. Superconducting Transition at 38 K in Insulating-Overdoped La2CuO4-La1:64Sr0:36CuO4 Superlattices: Evidence for Interface Electronic Redistribution from Resonant Soft X-Ray Scattering

    SciTech Connect

    Smadici, S.; Bozovic, I.; Lee, J. C. T.; Wang, S.; Abbamonte, P.; Logvenov, G.; Gozar, A.; Deville Cavellin, C.

    2009-03-12

    We use resonant soft x-ray scattering (RSXS) to quantify the hole distribution in a superlattice of insulating La{sub 2}CuO{sub 4} (LCO) and overdoped La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO). Despite its nonsuperconducting constituents, this structure is superconducting with T{sub c} = 38 K. We found that the conducting holes redistribute electronically from LSCO to the LCO layers. The LCO layers were found to be optimally doped, suggesting they are the main drivers of superconductivity. Our results demonstrate the utility of RSXS for separating electronic from structural effects at oxide interfaces.

  4. Spin resonance in the superconducting state of Li1 -xFexODFe1 -ySe observed by neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Davies, N. R.; Rahn, M. C.; Walker, H. C.; Ewings, R. A.; Woodruff, D. N.; Clarke, S. J.; Boothroyd, A. T.

    2016-10-01

    We have performed inelastic neutron-scattering measurements on a powder sample of the superconductor lithium iron selenide hydroxide Li1 -xFexODFe1 -ySe (x ≃0.16 ,y ≃0.02 ,Tc=41 K ) . The spectrum shows an enhanced intensity below Tc over an energy range of 0.64 ×2 Δ superconducting gap, and has maxima at the wave vectors Q1≃1.46 and Q2≃1.97 Å-1 . The behavior of this feature is consistent with the spin-resonance mode found in other unconventional superconductors, and in particular strongly resembles the spin resonance observed in the spectrum of another molecular-intercalated iron selenide Li0.6(ND2)0.2(ND3)0.8Fe2Se2 . The signal can be described with a characteristic two-dimensional wave-vector (π ,0.67 π ) in the Brillouin zone of the iron square lattice, consistent with the nesting vector between electron Fermi sheets.

  5. Superconductivity and magnetic fluctuations in Cd(2))Re(2)O(7) via Cd nuclear magnetic resonance and re nuclear quadrupole resonance.

    PubMed

    Vyaselev, O; Arai, K; Kobayashi, K; Yamazaki, J; Kodama, K; Takigawa, M; Hanawa, M; Hiroi, Z

    2002-07-01

    We report Cd nuclear magnetic resonance (NMR) and Re nuclear quadrupole resonance (NQR) studies on Cd(2)Re(2)O(7), the first superconductor among pyrochlore oxides (T(c) approximately 1 K). The Re NQR spectrum at zero magnetic field below 100 K rules out any magnetic or charge order. The spin-lattice relaxation rate below T(c) exhibits a pronounced coherence peak and follows the weak-coupling BCS theory with nearly isotropic energy gap. The results of Cd NMR point to a moderate ferromagnetic enhancement at high temperatures followed by a rapid decrease of the density of states below the structural transition temperature of 200 K.

  6. Electron density distribution in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides studied by double nuclear magnetic resonance methods

    SciTech Connect

    Piskunov, Yu. V. Ogloblichev, V. V.; Arapova, I. Yu.; Sadykov, A. V.; Gerashchenko, A. P.; Verkhovskii, S. V.

    2011-11-15

    The effect of charge disorder on the formation of an inhomogeneous state of the electron system in the conduction band in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides is investigated experimentally by NMR methods. The NMR spectra of {sup 17}O are measured systematically, and the contributions from {sup 17}O atoms with different cation nearest surroundings are identified. It is found that microscopic regions with an elevated spin density of charge carriers are formed within two coordination spheres near antimony ions. Nuclei of the superconducting phase of the oxide (regions with an elevated antimony concentration) microscopically distributed over the sample are detected in compounds with x = 0.25 and 0.33. Experiments in which a double resonance signal of the spin echo of {sup 17}O-{sup 207}Pb and {sup 17}O-{sup 121}Sb are measured in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides are carried out for the first time. The constants of indirect heteronuclear spin-spin {sup 17}O-{sup 207}Pb interaction are determined as functions of the local Knight shift {sub 207}Ks. The estimates of the constants of the indirect interaction between the nuclei of the nearest neighbors (O-Pb and Pb-Pb atoms) and analysis of evolution of the NMR spectra of {sup 17}O upon a change in the antimony concentration are convincing evidence in favor of the development of a microscopically inhomogeneous state of the electron system in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides.

  7. ARTEMIS-B: A room-temperature test electron cyclotron resonance ion source for the National Superconducting Cyclotron Laboratory at Michigan State University

    SciTech Connect

    Machicoane, G.; Cole, D.; Ottarson, J.; Stetson, J.; Zavodszky, P.

    2006-03-15

    The current scheme for ion-beam injection into the coupled cyclotron accelerator at the NSCL involves the use of two electron cyclotron resonance (ECR) ion sources. The first one is a 6.4 GHz fully superconducting that will be replaced within two years by SUSI, a third generation 18 GHz superconducting ECR ion source. The other source, ARTEMIS, is a room-temperature source based on the AECR-U design and built in collaboration with the University of Jyvaeskylae in 1999. Due to cyclotron operation constraint, very little time can be allowed to ion source development and optics studies of the cyclotron injection beam line. In this context, NSCL has decided to build ARTEMIS-B an exact replica of its room-temperature ECR ion source. The goal of this project is threefold. One is to improve the overall reliability of cyclotron operation through tests and studies of various ion source parameters that could benefit beam stability, tuning reproducibility, and of course overall extracted currents performance. Second is to implement and test modifications or upgrade made to the ion source: extraction geometry, new resistive or rf oven design, dual frequency use, liner, etc. Finally, this test source will be used to study various ion optics schemes such as electrostatic quadrupole doublet or triplet at the source extraction or the use of a correction sextupole and assess their effect on the ion beam through the use of an emittance scanner and imaging viewer that will be incorporated into ARTEMIS-B beam line. This article reviews the design and construction of ARTEMIS-B along with some initial commissioning results.

  8. Superconducting linacs: some recent developments

    SciTech Connect

    Bollinger, L.M.

    1985-01-01

    The paper is a review of superconducting linacs that are of interest for heavy-ion acceleration. Most of the paper is concerned with energy boosters for projectiles from tandem electrostatic accelerators, the only application for which superconducting linacs are now used for heavy-ion acceleration. There is also a brief discussion of the concept of a superconducting injector linac being developed as a replacement of the tandem in a multi-stage acceleration system. Throughout, the emphasis is on the technology of the superconducting linac, including some attention to the relationships between resonator design parameters and accelerator performance characteristics. 21 refs., 14 figs., 3 tabs.

  9. Spin Texture and Spin Dynamics in Superconducting Cuprates Near the Phase Transition Revealed by the Electron Paramagnetic Resonance

    NASA Astrophysics Data System (ADS)

    Kochelaev, B. I.

    2016-12-01

    A short review of experimental results and theoretical models of the spin texture and spin dynamics in superconducting cuprates near the phase transition developed on the basis of the EPR measurements is given. Distortions of the long-range antiferromagnetic order in the YBa_2Cu_3O_{6+y} were investigated for y=0.1-0.4 using Yb^{3+} ions as the EPR probe. In weakly doped samples with y=0.1, a strong anisotropy of the EPR linewidth is revealed which was related to the indirect spin-spin interaction between the ytterbium ions via antiferromagnetic spin-waves. In the case of the doping level y=0.2-0.3, the EPR signal consists of narrow and broad lines, which were attributed to formation of charged domain walls. A theoretical analysis is well consistent with experimental results for the case of coplanar elliptical domain walls. A discussion of possible reasons for the observed unusual planar oxygen isotope effect on a critical temperature T_c related to charge heterogeneity in underdoped cuprates is given.

  10. MEMS scanning laser projection based on high-Q vacuum packaged 2D-resonators

    NASA Astrophysics Data System (ADS)

    Hofmann, U.; Eisermann, C.; Quenzer, H.-J.; Janes, J.; Schroeder, C.; Schwarzelbach, O.; Jensen, B.; Ratzmann, L.; Giese, T.; Senger, F.; Hagge, J.; Weiss, M.; Wagner, B.; Benecke, W.

    2011-03-01

    Small size, low power consumption and the capability to produce sharp images without need of an objective make MEMS scanning laser based pico-projectors an attractive solution for embedded cell-phone projection displays. To fulfil the high image resolution demands the MEMS scanning mirror has to show large scan angles, a large mirror aperture size and a high scan frequency. An additional important requirement in pico-projector applications is to minimize power consumption of the MEMS scanner to enable a long video projection time. Typically high losses in power are caused by gas damping. For that reason Fraunhofer ISIT has established a fabrication process for 2D-MEMS mirrors that includes vacuum encapsulation on 8-inch wafers. Quality factors as high as 145,000 require dedicated closed loop phase control electronics to enable stable image projection even at rapidly changing laser intensities. A capacitive feedback signal is the basis for controlling the 2D MEMS oscillation and for synchronising the laser sources. This paper reports on fabrication of two-axis wafer level vacuum packaged scanning micromirrors and its use in a compact laser projection display. The paper presents different approaches of overcoming the well-known reflex problem of packaged MEMS scanning mirrors.

  11. Raman lasing in As₂S₃ high-Q whispering gallery mode resonators.

    PubMed

    Vanier, Francis; Rochette, Martin; Godbout, Nicolas; Peter, Yves-Alain

    2013-12-01

    We report the first observation of a nonlinear process in a chalcogenide microresonator. Raman scattering and stimulated Raman scattering leading to laser oscillation is observed in microspheres made of As₂S₃. The coupled pump power threshold is as low as 13 μW using a pump wavelength of 1550 nm. The quality factor of the chalcogenide microresonator is also the highest ever reported with Q>7×10(7).

  12. Studies of extraction and transport system for highly charged ion beam of 18 GHz superconducting electron cyclotron resonance ion source at Research Center for Nuclear Physics

    SciTech Connect

    Yorita, T. Hatanaka, K.; Fukuda, M.; Ueda, H.; Yasuda, Y.; Morinobu, S.; Tamii, A.; Kamakura, K.

    2014-02-15

    An 18 GHz superconducting electron cyclotron resonance ion source is installed to increase beam currents and to extend the variety of ions especially for highly charged heavy ions which can be accelerated by cyclotrons of Research Center for Nuclear Physics (RCNP), Osaka University. The beam production developments of several ions from B to Xe have been already done [T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 79, 02A311 (2008) and T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 81, 02A332 (2010)] and the further studies for those beam extraction and its transport have been done in order to increase the beam current more. The plasma electrode, extraction electrode, and einzel lens are modified. Especially extraction electrode can be applied minus voltage for the beam extraction and it works well to improve the extracted beam current. The extraction voltage dependences of transmission and emittance also have been studied for beam current improvement which is injected into azimuthally varying field cyclotron at RCNP.

  13. Studies of extraction and transport system for highly charged ion beam of 18 GHz superconducting electron cyclotron resonance ion source at Research Center for Nuclear Physics

    NASA Astrophysics Data System (ADS)

    Yorita, T.; Hatanaka, K.; Fukuda, M.; Ueda, H.; Yasuda, Y.; Morinobu, S.; Tamii, A.; Kamakura, K.

    2014-02-01

    An 18 GHz superconducting electron cyclotron resonance ion source is installed to increase beam currents and to extend the variety of ions especially for highly charged heavy ions which can be accelerated by cyclotrons of Research Center for Nuclear Physics (RCNP), Osaka University. The beam production developments of several ions from B to Xe have been already done [T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 79, 02A311 (2008) and T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 81, 02A332 (2010)] and the further studies for those beam extraction and its transport have been done in order to increase the beam current more. The plasma electrode, extraction electrode, and einzel lens are modified. Especially extraction electrode can be applied minus voltage for the beam extraction and it works well to improve the extracted beam current. The extraction voltage dependences of transmission and emittance also have been studied for beam current improvement which is injected into azimuthally varying field cyclotron at RCNP.

  14. Studies of extraction and transport system for highly charged ion beam of 18 GHz superconducting electron cyclotron resonance ion source at Research Center for Nuclear Physics.

    PubMed

    Yorita, T; Hatanaka, K; Fukuda, M; Ueda, H; Yasuda, Y; Morinobu, S; Tamii, A; Kamakura, K

    2014-02-01

    An 18 GHz superconducting electron cyclotron resonance ion source is installed to increase beam currents and to extend the variety of ions especially for highly charged heavy ions which can be accelerated by cyclotrons of Research Center for Nuclear Physics (RCNP), Osaka University. The beam production developments of several ions from B to Xe have been already done [T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 79, 02A311 (2008) and T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 81, 02A332 (2010)] and the further studies for those beam extraction and its transport have been done in order to increase the beam current more. The plasma electrode, extraction electrode, and einzel lens are modified. Especially extraction electrode can be applied minus voltage for the beam extraction and it works well to improve the extracted beam current. The extraction voltage dependences of transmission and emittance also have been studied for beam current improvement which is injected into azimuthally varying field cyclotron at RCNP.

  15. Superconductive wire

    DOEpatents

    Korzekwa, David A.; Bingert, John F.; Peterson, Dean E.; Sheinberg, Haskell

    1995-01-01

    A superconductive article is made by inserting a rigid mandrel into an internal cavity of a first metallic tube, said tube having an interior surface and an exterior surface, said interior surface defining the interior cavity, forming a layer of a superconductive material or superconductive precursor upon the exterior surface of said first metallic tube, machining the layer of superconductive material or superconductive precursor to a predetermined diameter to form an intermediate article configured for insertion into a second metallic tube having an interior diameter corresponding to the predetermined diameter, inserting the machined intermediate article into a second metallic tube having an internal diameter corresponding to the predetermined diameter of the intermediate article to form a composite intermediate article, reducing or ironing the composite intermediate article to a predetermined cross-sectional diameter, and sintering the reduced or ironed composite intermediate article at temperatures and for time sufficient for the superconductive material or superconductive precursor to exhibit superconductivity.

  16. Superconductive wire

    DOEpatents

    Korzekwa, D.A.; Bingert, J.F.; Peterson, D.E.; Sheinberg, H.

    1995-07-18

    A superconductive article is made by inserting a rigid mandrel into an internal cavity of a first metallic tube, said tube having an interior surface and an exterior surface, said interior surface defining the interior cavity, forming a layer of a superconductive material or superconductive precursor upon the exterior surface of said first metallic tube, machining the layer of superconductive material or superconductive precursor to a predetermined diameter to form an intermediate article configured for insertion into a second metallic tube having an interior diameter corresponding to the predetermined diameter, inserting the machined intermediate article into a second metallic tube having an internal diameter corresponding to the predetermined diameter of the intermediate article to form a composite intermediate article, reducing or ironing the composite intermediate article to a predetermined cross-sectional diameter, and sintering the reduced or ironed composite intermediate article at temperatures and for time sufficient for the superconductive material or superconductive precursor to exhibit superconductivity. 2 figs.

  17. Superconducting transistor

    DOEpatents

    Gray, Kenneth E.

    1979-01-01

    A superconducting transistor is formed by disposing three thin films of superconducting material in a planar parallel arrangement and insulating the films from each other by layers of insulating oxides to form two tunnel junctions. One junction is biased above twice the superconducting energy gap and the other is biased at less than twice the superconducting energy gap. Injection of quasiparticles into the center film by one junction provides a current gain in the second junction.

  18. Fiber-Optic Refractometer Based on an Etched High-Q π-Phase-Shifted Fiber-Bragg-Grating

    PubMed Central

    Zhang, Qi; Ianno, Natale J.; Han, Ming

    2013-01-01

    We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q π-phase-shifted fiber-Bragg-grating (πFBG) that is chemically etched to the core of the fiber. Due to the π phase-shift, a strong πFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched πFBG demonstrated here has a diameter of ∼9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the etched πFBG features an extremely narrow notch with a linewidth of only 2.1 pm in water centered at ∼1,550 nm, corresponding to a Q-factor of 7.4 × 105, which allows for potentially significantly improved sensitivity over refractometers based on regular fiber Bragg gratings. PMID:23845932

  19. High-Q microresonators as lasing elements for silicon photonics

    NASA Astrophysics Data System (ADS)

    Borselli, Matthew

    Although the concept of constructing active optical waveguides in crystalline silicon has existed for over twenty years, it is only in the past few years that silicon photonics has been given serious attention as a, displacing technology. Fueled by the predicted saturation of "Moore's Law" within the next decade, universities and industries from all over the world are exploring the possibilities of creating truly integrated silicon opto-electronic devices in a cost effective manner. Some of the most promising silicon photonics technologies are chip-to-chip and intra-chip optical interconnects. Now that compact high-speed modulators in silicon have been achieved, the limiting factor in the widespread adoption of optical interconnects is the lack of practical on-chip optical sources. These sources are critical for the generation of the many wavelengths of light necessary for high-speed communication between the logical elements between and within microprocessors. Unfortunately, crystalline silicon is widely known as a poor emitter because of its indirect bandgap. This thesis focuses on the many challenges in generating silicon-based laser sources. As most CMOS compatible gain materials possess at most 1 dB/cm of gain, much of our work has been devoted to minimizing the optical losses in silicon optical microresonators. Silicon microdisk resonators fabricated from silicon-on-insulator wafers were employed to study and minimize the different sources of scattering and absorption present in high-index contrast Si microcavities. These microdisks supported whispering-gallery modes with quality factors as high as 5 x 106, close to the bulk limit of lightly doped silicon wafers. An external silica fiber taper probe was developed to test the microcavities in a rapid wafer-scale manner. Analytic theory and numerical simulation aided in the optimization of the cavity design and interpretation of experimental results. After successfully developing surface chemistry treatments

  20. White noise of Nb-based microwave superconducting quantum interference device multiplexers with NbN coplanar resonators for readout of transition edge sensors

    SciTech Connect

    Kohjiro, Satoshi; Hirayama, Fuminori; Yamamori, Hirotake; Nagasawa, Shuichi; Fukuda, Daiji; Hidaka, Mutsuo

    2014-06-14

    White noise of dissipationless microwave radio frequency superconducting quantum interference device (RF-SQUID) multiplexers has been experimentally studied to evaluate their readout performance for transition edge sensor (TES) photon counters ranging from near infrared to gamma ray. The characterization has been carried out at 4 K, first to avoid the low-frequency fluctuations present at around 0.1 K, and second, for a feasibility study of readout operation at 4 K for extended applications. To increase the resonant Q at 4 K and maintain low noise SQUID operation, multiplexer chips consisting of niobium nitride (NbN)-based coplanar-waveguide resonators and niobium (Nb)-based RF-SQUIDs have been developed. This hybrid multiplexer exhibited 1 × 10{sup 4} ≤ Q ≤ 2 × 10{sup 4} and the square root of spectral density of current noise referred to the SQUID input √S{sub I} = 31 pA/√Hz. The former and the latter are factor-of-five and seven improvements from our previous results on Nb-based resonators, respectively. Two-directional readout on the complex plane of the transmission component of scattering matrix S{sub 21} enables us to distinguish the flux noise from noise originating from other sources, such as the cryogenic high electron mobility transistor (HEMT) amplifier. Systematic noise measurements with various microwave readout powers P{sub MR} make it possible to distinguish the contribution of noise sources within the system as follows: (1) The achieved √S{sub I} is dominated by the Nyquist noise from a resistor at 4 K in parallel to the SQUID input coil which is present to prevent microwave leakage to the TES. (2) The next dominant source is either the HEMT-amplifier noise (for small values of P{sub MR}) or the quantization noise due to the resolution of 300-K electronics (for large values of P{sub MR}). By a decrease of these noise levels to a degree that is achievable by current technology, we predict that the

  1. White noise of Nb-based microwave superconducting quantum interference device multiplexers with NbN coplanar resonators for readout of transition edge sensors

    NASA Astrophysics Data System (ADS)

    Kohjiro, Satoshi; Hirayama, Fuminori; Yamamori, Hirotake; Nagasawa, Shuichi; Fukuda, Daiji; Hidaka, Mutsuo

    2014-06-01

    White noise of dissipationless microwave radio frequency superconducting quantum interference device (RF-SQUID) multiplexers has been experimentally studied to evaluate their readout performance for transition edge sensor (TES) photon counters ranging from near infrared to gamma ray. The characterization has been carried out at 4 K, first to avoid the low-frequency fluctuations present at around 0.1 K, and second, for a feasibility study of readout operation at 4 K for extended applications. To increase the resonant Q at 4 K and maintain low noise SQUID operation, multiplexer chips consisting of niobium nitride (NbN)-based coplanar-waveguide resonators and niobium (Nb)-based RF-SQUIDs have been developed. This hybrid multiplexer exhibited 1 × 104 ≤ Q ≤ 2 × 104 and the square root of spectral density of current noise referred to the SQUID input √SI = 31 pA/√Hz. The former and the latter are factor-of-five and seven improvements from our previous results on Nb-based resonators, respectively. Two-directional readout on the complex plane of the transmission component of scattering matrix S21 enables us to distinguish the flux noise from noise originating from other sources, such as the cryogenic high electron mobility transistor (HEMT) amplifier. Systematic noise measurements with various microwave readout powers PMR make it possible to distinguish the contribution of noise sources within the system as follows: (1) The achieved √SI is dominated by the Nyquist noise from a resistor at 4 K in parallel to the SQUID input coil which is present to prevent microwave leakage to the TES. (2) The next dominant source is either the HEMT-amplifier noise (for small values of PMR) or the quantization noise due to the resolution of 300-K electronics (for large values of PMR). By a decrease of these noise levels to a degree that is achievable by current technology, we predict that the microwave RF-SQUID multiplexer can exhibit √SI ≤ 5 pA/√Hz, i.e., close to √SI of

  2. Optimization of high-Q coupled nanobeam cavity for label-free sensing.

    PubMed

    Yaseen, Mohammad Tariq; Yang, Yi-Chun; Shih, Min-Hsiung; Chang, Yia-Chung

    2015-10-13

    We numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (FEM) simulations. We showed that when two PhC NB cavities separated by a small gap are evanescently coupled, the variation in the gap width significantly changes the coupling efficiency between the two coupled NB cavities and the resulting resonant frequencies split. Experimentally, we fabricated laterally-coupled PhC NB cavities using (InGaAsP) layer on the InP substrate. For sensing, we showed that the laterally coupled PhC NB cavities sensor exhibits higher sensitivity than the single PhC NB cavity. The higher sensitivity of laterally coupled PhC NB cavities is due to the strong evanescent coupling between nearby PhC NB cavities, which depends on the gap width and it is attributed to the large confinement of the electromagnetic field in the gap (air or liquid). As a result of the lateral coupling, both even (symmetric) and odd (asymmetric) modes exist. We show that even modes are more sensitive than odd modes. In addition, higher-order modes exhibit higher sensitivity. Hence, we characterized and examined the fabricated PhC NB cavity as a label-free biosensor, and it exhibits high figure of merit due to its high Q-factor. This illustrates a potentially useful method for optical sensing at nanoscale.

  3. Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing

    PubMed Central

    Yaseen, Mohammad Tariq; Yang, Yi-Chun; Shih, Min-Hsiung; Chang, Yia-Chung

    2015-01-01

    We numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (FEM) simulations. We showed that when two PhC NB cavities separated by a small gap are evanescently coupled, the variation in the gap width significantly changes the coupling efficiency between the two coupled NB cavities and the resulting resonant frequencies split. Experimentally, we fabricated laterally-coupled PhC NB cavities using (InGaAsP) layer on the InP substrate. For sensing, we showed that the laterally coupled PhC NB cavities sensor exhibits higher sensitivity than the single PhC NB cavity. The higher sensitivity of laterally coupled PhC NB cavities is due to the strong evanescent coupling between nearby PhC NB cavities, which depends on the gap width and it is attributed to the large confinement of the electromagnetic field in the gap (air or liquid). As a result of the lateral coupling, both even (symmetric) and odd (asymmetric) modes exist. We show that even modes are more sensitive than odd modes. In addition, higher-order modes exhibit higher sensitivity. Hence, we characterized and examined the fabricated PhC NB cavity as a label-free biosensor, and it exhibits high figure of merit due to its high Q-factor. This illustrates a potentially useful method for optical sensing at nanoscale. PMID:26473870

  4. Experimental study of a multipactor discharge on a dielectrics surface in a high-Q microwave cavity

    SciTech Connect

    Ivanov, O. A.; Lobaev, M. A.; Isaev, V. A.; Vikharev, A. L.

    2010-04-15

    Results from experimental studies of multipactor discharges on the surfaces of various dielectrics placed in a high-Q cylindrical microwave cavity excited at the TE{sub 013} mode in the X-band are presented. The thresholds for the onset and maintenance of a multipactor discharge on quartz, polycrystalline diamond, lithium fluoride, and Teflon surfaces possessing different roughness are determined. It is shown that, in such a resonance system, a steady multipactor discharge can operate without transition into the stage of microwave breakdown of the desorbed gas. It is found that, due to long-term action of the discharge, a thin carbon-containing film is deposited on the dielectric surface, which leads to an increase in the breakdown threshold.

  5. Purcell enhancement of fast-dephasing spontaneous emission from electron-hole droplets in high-Q silicon photonic crystal nanocavities

    NASA Astrophysics Data System (ADS)

    Sumikura, Hisashi; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

    2016-11-01

    We have observed electron-hole droplet emission enhanced by silicon photonic crystal nanocavities with different Q values and simulated their Purcell effect using a semiclassical theory considering the temporal dephasing of the emission. When the photon loss rate of the nanocavities is smaller than the dephasing rate of the emission, the cavity-enhanced integrated photoluminescence (PL) intensity is unchanged by the cavity Q value. This is because the Purcell enhancement of the spontaneous emission rate is saturated in a high-Q region. In contrast, the peak intensity of the cavity-enhanced PL is proportional to the cavity Q value without saturation. These results suggest that a high-Q nanocavity is suitable for fabricating bright narrowband light emitting devices that concentrate the broadband emission energy of fast-dephasing emitters in a narrowband cavity resonance.

  6. Hourglass Dispersion and Resonance of Magnetic Excitations in the Superconducting State of the Single-Layer Cuprate HgBa_{2}CuO_{4+δ} Near Optimal Doping.

    PubMed

    Chan, M K; Tang, Y; Dorow, C J; Jeong, J; Mangin-Thro, L; Veit, M J; Ge, Y; Abernathy, D L; Sidis, Y; Bourges, P; Greven, M

    2016-12-30

    We use neutron scattering to study magnetic excitations near the antiferromagnetic wave vector in the underdoped single-layer cuprate HgBa_{2}CuO_{4+δ} (superconducting transition temperature T_{c}≈88  K, pseudogap temperature T^{*}≈220  K). The response is distinctly enhanced below T^{*} and exhibits a Y-shaped dispersion in the pseudogap state, whereas the superconducting state features an X-shaped (hourglass) dispersion and a further resonancelike enhancement. A large spin gap of about 40 meV is observed in both states. This phenomenology is reminiscent of that exhibited by bilayer cuprates. The resonance spectral weight, irrespective of doping and compound, scales linearly with the putative binding energy of a spin exciton described by an itinerant-spin formalism.

  7. Hourglass Dispersion and Resonance of Magnetic Excitations in the Superconducting State of the Single-Layer Cuprate HgBa2 CuO4 +δ Near Optimal Doping

    NASA Astrophysics Data System (ADS)

    Chan, M. K.; Tang, Y.; Dorow, C. J.; Jeong, J.; Mangin-Thro, L.; Veit, M. J.; Ge, Y.; Abernathy, D. L.; Sidis, Y.; Bourges, P.; Greven, M.

    2016-12-01

    We use neutron scattering to study magnetic excitations near the antiferromagnetic wave vector in the underdoped single-layer cuprate HgBa2CuO4 +δ (superconducting transition temperature Tc≈88 K , pseudogap temperature T*≈220 K ). The response is distinctly enhanced below T* and exhibits a Y -shaped dispersion in the pseudogap state, whereas the superconducting state features an X -shaped (hourglass) dispersion and a further resonancelike enhancement. A large spin gap of about 40 meV is observed in both states. This phenomenology is reminiscent of that exhibited by bilayer cuprates. The resonance spectral weight, irrespective of doping and compound, scales linearly with the putative binding energy of a spin exciton described by an itinerant-spin formalism.

  8. Superconducting Cable

    DOEpatents

    Hughey, Raburn L.; Sinha, Uday K.; Reece, David S.; Muller, Albert C.

    2005-07-22

    In order to provide a flexible oxide superconducting cable which is reduced in AC loss, tape-shaped superconducting wires covered with a stabilizing metal are wound on a flexible former. The superconducting wires are preferably laid on the former at a bending strain of not more than 0.2%. In laying on the former, a number of tape-shaped superconducting wires are laid on a core member in a side-by-side manner, to form a first layer. A prescribed number of tape-shaped superconducting wires are laid on top of the first layer in a side-by-side manner, to form a second layer. The former may be made of a metal, plastic, reinforced plastic, polymer, or a composite and provides flexibility to the superconducting wires and the cable formed therewith.

  9. Superconducting Cable

    DOEpatents

    Hughey, Raburn L.; Sinha, Uday K.; Reece, David S.; Muller, Albert C.

    2005-03-08

    In order to provide a flexible oxide superconducting cable which is reduced in AC loss, tape-shaped superconducting wires covered with a stabilizing metal are wound on a flexible former. The superconducting wires are preferably laid on the former at a bending strain of not more than 0.2%. In laying on the former, a number of tape-shaped superconducting wires are laid on a core member in a side-by-side manner, to form a first layer. A prescribed number of tape-shaped superconducting wires are laid on top of the first layer in a side-by-side manner, to form a second layer. The former may be made of a metal, plastic, reinforced plastic, polymer, or a composite and provides flexibility to the superconducting wires and the cable formed therewith.

  10. Making Superconducting Welds between Superconducting Wires

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I.; Eom, Byeong Ho

    2008-01-01

    A technique for making superconducting joints between wires made of dissimilar superconducting metals has been devised. The technique is especially suitable for fabrication of superconducting circuits needed to support persistent electric currents in electromagnets in diverse cryogenic applications. Examples of such electromagnets include those in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems and in superconducting quantum interference devices (SQUIDs). Sometimes, it is desirable to fabricate different parts of a persistent-current-supporting superconducting loop from different metals. For example, a sensory coil in a SQUID might be made of Pb, a Pb/Sn alloy, or a Cu wire plated with Pb/Sn, while the connections to the sensory coil might be made via Nb or Nb/Ti wires. Conventional wire-bonding techniques, including resistance spot welding and pressed contact, are not workable because of large differences between the hardnesses and melting temperatures of the different metals. The present technique is not subject to this limitation. The present technique involves the use (1) of a cheap, miniature, easy-to-operate, capacitor-discharging welding apparatus that has an Nb or Nb/Ti tip and operates with a continuous local flow of gaseous helium and (2) preparation of a joint in a special spark-discharge welding geometry. In a typical application, a piece of Nb foil about 25 m thick is rolled to form a tube, into which is inserted a wire that one seeks to weld to the tube (see figure). The tube can be slightly crimped for mechanical stability. Then a spark weld is made by use of the aforementioned apparatus with energy and time settings chosen to melt a small section of the niobium foil. The energy setting corresponds to the setting of a voltage to which the capacitor is charged. In an experiment, the technique was used to weld an Nb foil to a copper wire coated with a Pb/Sn soft solder, which is superconducting. The joint was evaluated as

  11. Superconducting Materials

    NASA Technical Reports Server (NTRS)

    1995-01-01

    After working with Lewis Research Center and Jet Propulsion Laboratory, Superconducting Technologies, Inc. (STI) adapted NASA requirements and refined its own standard production recipe. STI uses high temperature superconducting (HTS) materials in its basic products: high quality thin films, circuits and components. Applications include microwave circuits for radar to reduce interference.

  12. Superconducting structure

    DOEpatents

    Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

    2003-04-01

    A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

  13. Superconducting Structure

    DOEpatents

    Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

    2005-09-13

    A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

  14. Spectral investigation of hot-spot and cavity resonance effects on the terahertz radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal mesa structures

    NASA Astrophysics Data System (ADS)

    Kadowaki, Kazuo; Watanabe, Chiharu; Minami, Hidetoshi; Yamamoto, Takashi; Kashiwagi, Takanari; Klemm, Richard

    2014-03-01

    Terahertz (THz) electromagnetic radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ mesa structures in the case of single mesa and series-connected mesas is investigated by the FTIR spectroscopic technique while observing its temperature distribution simultaneously by a SiC photoluminescence technique. Changing the bias level, sudden jumps of the hot-spot position were clearly observed. Although the radiation intensity changes drastically associated with the jump of the hot spot position, the frequency is unaffected as long as the voltage per junction is kept constant. Since the frequency of the intense radiation satisfies the cavity resonance condition, we confirmed that the cavity resonance is of primarily importance for the synchronization of whole intrinsic Josephson junctions in the mesa for high power radiation. This work was supported in part by the Grant-in-Aid for challenging Exploratory Research, the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

  15. High-temperature superconducting radiofrequency probe for magnetic resonance imaging applications operated below ambient pressure in a simple liquid-nitrogen cryostat

    NASA Astrophysics Data System (ADS)

    Lambert, Simon; Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Darrasse, Luc

    2013-05-01

    The present work investigates the joined effects of temperature and static magnetic field on the electrical properties of a 64 MHz planar high-temperature superconducting (HTS) coil, in order to enhance the signal-to-noise ratio (SNR) in nuclear magnetic resonance (NMR) applications with a moderate decrease of the HTS coil temperature (THTS). Temperature control is provided with accuracy better than 0.1 K from 80 to 66 K by regulating the pressure of the liquid nitrogen bath of a dedicated cryostat. The actual temperature of the HTS coil is obtained using a straightforward wireless method that eliminates the risks of coupling electromagnetic interference to the HTS coil and of disturbing the static magnetic field by DC currents near the region of interest. The resonance frequency ( f0) and the quality factor (Q) of the HTS coil are measured as a function of temperature in the 0-4.7 T field range with parallel and orthogonal orientations relative to the coil plane. The intrinsic HTS coil sensitivity and the detuning effect are then analyzed from the Q and f0 data. In the presence of the static magnetic field, the initial value of f0 in Earth's field could be entirely recovered by decreasing THTS, except for the orthogonal orientation above 1 T. The improvement of Q by lowering THTS was substantial. From 80 to 66 K, Q was multiplied by a factor of 6 at 1.5 T in orthogonal orientation. In parallel orientation, the maximum measured improvement of Q from 80 K to 66 K was a factor of 2. From 80 to 66 K, the improvement of the RF sensitivity relative to the initial value at the Earth's field and ambient pressure was up to 4.4 dB in parallel orientation. It was even more important in orthogonal orientation and continued to increase, up to 8.4 dB, at the maximum explored field of 1.5 T. Assuming that the noise contributions from the RF receiver are negligible, the SNR improvement using enhanced HTS coil cooling in NMR experiments was extracted from Q measurements either

  16. Coupling an Ensemble of Electrons on Superfluid Helium to a Superconducting Circuit

    NASA Astrophysics Data System (ADS)

    Yang, Ge; Fragner, A.; Koolstra, G.; Ocola, L.; Czaplewski, D. A.; Schoelkopf, R. J.; Schuster, D. I.

    2016-01-01

    The quantized lateral motional states and the spin states of electrons trapped on the surface of superfluid helium have been proposed as basic building blocks of a scalable quantum computer. Circuit quantum electrodynamics allows strong dipole coupling between electrons and a high-Q superconducting microwave resonator, enabling such sensitive detection and manipulation of electron degrees of freedom. Here, we present the first realization of a hybrid circuit in which a large number of electrons are trapped on the surface of superfluid helium inside a coplanar waveguide resonator. The high finesse of the resonator allows us to observe large dispersive shifts that are many times the linewidth and make fast and sensitive measurements on the collective vibrational modes of the electron ensemble, as well as the superfluid helium film underneath. Furthermore, a large ensemble coupling is observed in the dispersive regime during experiment, and it shows excellent agreement with our numeric model. The coupling strength of the ensemble to the cavity is found to be ≈1 MHz per electron, indicating the feasibility of achieving single electron strong coupling.

  17. High-Q band edge mode of plasmonic crystals studied by cathodoluminescence

    NASA Astrophysics Data System (ADS)

    Honda, Masahiro; Yamamoto, Naoki

    2014-02-01

    We have investigated the quality factor (Q-factor) of the band edge modes in the plasmonic crystal by a cathodoluminescence technique. We have found that the Q-factor at the Γ point depends on the terrace width (D)/period (P) ratio of the plasmonic crystal. The finite-difference time-domain methods predict that the band edge mode at D/P = 3/4 has a high-Q-factor (Q ˜ 250 by Palik's permittivity data and Q ˜ 530 by Johnson and Christy's data). The beam-scan spectral images allowed us to visualize the standing surface plasmon polariton waves at the band edge energies, and a high-Q-factor of ˜200 was observed at D/P ˜ 3/4.

  18. Modal analysis of Bragg onion resonators

    NASA Astrophysics Data System (ADS)

    Xu, Yong; Liang, Wei; Yariv, Amnon; Fleming, James G.; Lin, Shawn-Yu

    2004-03-01

    From analysis of the high Q modes in a Bragg onion resonator with an omnidirectional reflector cladding, we establish a close analogy between such a resonator and a spherical hollow cavity in perfect metal. We demonstrate that onion resonators are ideal for applications that require a large spontaneous-emission factor ß, such as thresholdless lasers and single-photon devices.

  19. Lateral acoustic wave resonator comprising a suspended membrane of low damping resonator material

    DOEpatents

    Olsson, Roy H.; El-Kady; , Ihab F.; Ziaei-Moayyed, Maryam; Branch; , Darren W.; Su; Mehmet F.,; Reinke; Charles M.,

    2013-09-03

    A very high-Q, low insertion loss resonator can be achieved by storing many overtone cycles of a lateral acoustic wave (i.e., Lamb wave) in a lithographically defined suspended membrane comprising a low damping resonator material, such as silicon carbide. The high-Q resonator can sets up a Fabry-Perot cavity in a low-damping resonator material using high-reflectivity acoustic end mirrors, which can comprise phononic crystals. The lateral overtone acoustic wave resonator can be electrically transduced by piezoelectric couplers. The resonator Q can be increased without increasing the impedance or insertion loss by storing many cycles or wavelengths in the high-Q resonator material, with much lower damping than the piezoelectric transducer material.

  20. Superconducting terahertz metamaterials

    SciTech Connect

    Chen, Hou-tong; Singh, Ranjan; O' Hara, John F; Azad, Abul K; Trugman, Stuart A; Jia, Quanxi; Taylor, Antoinette J

    2010-01-01

    During the past ten years subwavelength metallic structures have enabled metamaterials exhibiting exotic physical properties that are not possible or difficult to realize using naturally occurring materials, This bottom-up metamaterial approach is particularly attractive in the terahertz (THz) frequency range, where the THz gap is inherently associated with the lack of materials with appropriate reponse. In fact THz metamaterial devices have accomplished unprecedented performance towards practical applications. In these devices, the key is to incorporate natural materials, e,g, semiconductors, as the metamaterial substrates or integration parts of metamaterial structures. The active or dynamic tunability of metamaterials is through the application of external stimuli such as temperature, photoexcitation, or electric field. to modify the capacitive gaps in split-ring resonators (SRRs), It becomes clear that we would not be able to do much on the metallic SRRs, i.e. the metal conductivity and therefore the inductance largely remain constant not affected by external stimuli. Recently, there has been increasing interest in superconducting metamaterials towards loss reduction. Significant Joule losses have often prevented resonant metal metamaterials from achieving proposed applications. particularly in the optical frequency range. At low temperatures, superconducting materials possess superior conductivity than metals at frequencies up to THz. and therefore it is expected that superconducting melamaterials will have a lower loss than metal metamatetials, More interestingly, superconductors exhibit tunable complex conductivity over a wide range of values through change of temperature and application of photoexcitation, electrical currents and magnetic fields. Therefore, we would expect correspondingly tunable metamaterials. which originate from the superconducting materials composing the metamaterial, in contrast to tuning the metamaterial embedded environment.

  1. Superconducting Memristors

    NASA Astrophysics Data System (ADS)

    Peotta, Sebastiano; Di Ventra, Massimiliano

    2014-09-01

    In his original work, Josephson predicted that a phase-dependent conductance should be present in superconducting tunnel junctions, an effect difficult to detect, mainly because it is hard to single it out from the usual nondissipative Josephson current. We propose a solution for this problem that consists of using different superconducting materials to realize the two junctions of a superconducting interferometer. According to the Ambegaokar-Baratoff relation the two junctions have different conductances if the critical currents are equal, thus the Josephson current can be suppressed by fixing the magnetic flux in the loop at half of a flux quantum without canceling the phase-dependent conductance. Our proposal can be used to study the phase-dependent conductance, an effect present in principle in all superconducting weak links. From the standpoint of nonlinear circuit theory, such a device is in fact an ideal memristor with possible applications to memories and neuromorphic computing in the framework of ultrafast and low-energy-consumption superconducting digital circuits.

  2. Superconducting magnets

    SciTech Connect

    Willen, E.; Dahl, P.; Herrera, J.

    1985-01-01

    This report provides a self-consistent description of a magnetic field in the aperture of a superconducting magnet and details how this field can be calculated in a magnet with cos theta current distribution in the coils. A description of an apparatus that can be used to measure the field uniformity in the aperture has been given. Finally, a detailed description of the magnet being developed for use in the Superconducting Super Collider is given. When this machine is built, it will be by far the largest application of superconductivity to date and promises to make possible the experimental discoveries needed to understand the basic laws of nature governing the world in which we live.

  3. Design and fabrication of a superconducting magnet for an 18 GHz electron cyclotron resonance ion∕photon source NFRI-ECRIPS.

    PubMed

    You, H-J; Jang, S-W; Jung, Y-H; Lho, T-H; Lee, S-J

    2012-02-01

    A superconducting magnet was designed and fabricated for an 18 GHz ECR ion∕photon source, which will be installed at National Fusion Research Institute (NFRI) in South Korea. The magnetic system consists of a set of four superconducting coils for axial mirror field and 36 pieces of permanent magnets for hexapolar field. The superconducting coils with a cryocooler (1.5 W @ 4.2 K) allow one to reach peak mirror fields of 2.2 T in the injection and those of 1.5 T in the extraction regions on the source axis, and the resultant hexapolar field gives 1.35 T on the plasma chamber wall. The unbalanced magnetic force between the coils and surrounding yoke has been minimized to 16 ton by a coil arrangement and their electrical connection, and then was successfully suspended by 12 strong thermal insulating supports made of large numbers of carbon fibers. In order to block radiative thermal losses, multilayer thermal insulations are covered on the coil windings as well as 40-K aluminum thermal shield. Also new schemes of quench detection and safety system (coil divisions, quench detection coils, and heaters) were employed. For impregnation of the windings a special epoxy has been selected and treated to have a higher breaking strength and a higher thermal conductivity, which enables the superconductors to be uniformly and rapidly cooled down or heated during a quench.

  4. Design and fabrication of a superconducting magnet for an 18 GHz electron cyclotron resonance ion/photon source NFRI-ECRIPS

    SciTech Connect

    You, H.-J.; Jang, S.-W.; Jung, Y.-H.; Lho, T.-H.; Lee, S.-J.

    2012-02-15

    A superconducting magnet was designed and fabricated for an 18 GHz ECR ion/photon source, which will be installed at National Fusion Research Institute (NFRI) in South Korea. The magnetic system consists of a set of four superconducting coils for axial mirror field and 36 pieces of permanent magnets for hexapolar field. The superconducting coils with a cryocooler (1.5 W - 4.2 K) allow one to reach peak mirror fields of 2.2 T in the injection and those of 1.5 T in the extraction regions on the source axis, and the resultant hexapolar field gives 1.35 T on the plasma chamber wall. The unbalanced magnetic force between the coils and surrounding yoke has been minimized to 16 ton by a coil arrangement and their electrical connection, and then was successfully suspended by 12 strong thermal insulating supports made of large numbers of carbon fibers. In order to block radiative thermal losses, multilayer thermal insulations are covered on the coil windings as well as 40-K aluminum thermal shield. Also new schemes of quench detection and safety system (coil divisions, quench detection coils, and heaters) were employed. For impregnation of the windings a special epoxy has been selected and treated to have a higher breaking strength and a higher thermal conductivity, which enables the superconductors to be uniformly and rapidly cooled down or heated during a quench.

  5. PREFACE: Superconducting materials Superconducting materials

    NASA Astrophysics Data System (ADS)

    Charfi Kaddour, Samia; Singleton, John; Haddad, Sonia

    2011-11-01

    The discovery of superconductivity in 1911 was a great milestone in condensed matter physics. This discovery has resulted in an enormous amount of research activity. Collaboration among chemists and physicists, as well as experimentalists and theoreticians has given rise to very rich physics with significant potential applications ranging from electric power transmission to quantum information. Several superconducting materials have been synthesized. Crucial progress was made in 1987 with the discovery of high temperature superconductivity in copper-based compounds (cuprates) which have revealed new fascinating properties. Innovative theoretical tools have been developed to understand the striking features of cuprates which have remained for three decades the 'blue-eyed boy' for researchers in superconductor physics. The history of superconducting materials has been notably marked by the discovery of other compounds, particularly organic superconductors which despite their low critical temperature continue to attract great interest regarding their exotic properties. Last but not least, the recent observation of superconductivity in iron-based materials (pnictides) has renewed hope in reaching room temperature superconductivity. However, despite intense worldwide studies, several features related to this phenomenon remain unveiled. One of the fundamental key questions is the mechanism by which superconductivity takes place. Superconductors continue to hide their 'secret garden'. The new trends in the physics of superconductivity have been one of the two basic topics of the International Conference on Conducting Materials (ICoCoM2010) held in Sousse,Tunisia on 3-7 November 2010 and organized by the Tunisian Physical Society. The conference was a nice opportunity to bring together participants from multidisciplinary domains in the physics of superconductivity. This special section contains papers submitted by participants who gave an oral contribution at ICoCoM2010

  6. Demonstration of superconducting micromachined cavities

    SciTech Connect

    Brecht, T. Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J.

    2015-11-09

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.

  7. Superconducting Microelectronics.

    ERIC Educational Resources Information Center

    Henry, Richard W.

    1984-01-01

    Discusses superconducting microelectronics based on the Josephson effect and its advantages over conventional integrated circuits in speed and sensitivity. Considers present uses in standards laboratories (voltage) and in measuring weak magnetic fields. Also considers future applications in superfast computer circuitry using Superconducting…

  8. On-chip spectroscopy with thermally tuned high-Q photonic crystal cavities

    SciTech Connect

    Liapis, Andreas C. Gao, Boshen; Siddiqui, Mahmudur R.; Shi, Zhimin; Boyd, Robert W.

    2016-01-11

    Spectroscopic methods are a sensitive way to determine the chemical composition of potentially hazardous materials. Here, we demonstrate that thermally tuned high-Q photonic crystal cavities can be used as a compact high-resolution on-chip spectrometer. We have used such a chip-scale spectrometer to measure the absorption spectra of both acetylene and hydrogen cyanide in the 1550 nm spectral band and show that we can discriminate between the two chemical species even though the two materials have spectral features in the same spectral region. Our results pave the way for the development of chip-size chemical sensors that can detect toxic substances.

  9. High-Q silicon-on-insulator slot photonic crystal cavity infiltrated by a liquid

    SciTech Connect

    Caër, Charles; Le Roux, Xavier; Cassan, Eric

    2013-12-16

    We report the experimental realization of a high-Q slot photonic crystal cavity in Silicon-On-Insulator (SOI) configuration infiltrated by a liquid. Loaded Q-factor of 23 000 is measured at telecom wavelength. The intrinsic quality factor inferred from the transmission spectrum is higher than 200 000, which represents a record value for slot photonic crystal cavities on SOI, whereas the maximum of intensity of the cavity is roughly equal to 20% of the light transmitted in the waveguide. This result makes filled slot photonic crystal cavities very promising for silicon-based light emission and ultrafast nonlinear optics.

  10. First results from the Cornell high Q cw full linac cryo- module

    NASA Astrophysics Data System (ADS)

    Eichhorn, R.; Furuta, F.; He, Y.; Ge, M.; Hoffstaetter, G.; O'Connell, T.; Quigley, P.; Sabol, D.; Sears, J.; Smith, E.; Liepe, M.; Markham, S.; Bullock, B.; Elmore, B.; Kaufman, J.; Conway, J.; Veshcherevich, V.

    2015-12-01

    Cornell University has finished building a 10 m long superconducting accelerator module as a prototype of the main linac of a proposed ERL facility. This module houses 6 superconducting cavities- operated at 1.8 K in continuous wave (CW) mode - with individual HOM absorbers and one magnet/ BPM section. In pushing the limits, a high quality factor of the cavities (2•1010) and high beam currents (100 mA accelerated plus 100 mA decelerated) were targeted. The design of the cryomodule and the results of components tested before assembly will be presented in this paper.

  11. Modulating sub-THz radiation with current in superconducting metamaterial.

    PubMed

    Savinov, V; Fedotov, V A; Anlage, S M; de Groot, P A J; Zheludev, N I

    2012-12-14

    We show that subterahertz transmission of the superconducting metamaterial, an interlinked two-dimensional network of subwavelength resonators connected by a continuous superconducting wire loop, can be dynamically modulated by passing electrical current through it. We have identified the main mechanisms of modulation that correspond to the suppression of the superconductivity in the network by magnetic field and heat dissipation. Using the metamaterial fabricated from thin niobium film, we were able to demonstrate a transmission modulation depth of up to 45% and a bandwidth of at least 100 kHz. The demonstrated approach may be implemented with other superconducting materials at frequencies below the superconducting gap in the THz and subterahertz bands.

  12. Hyper-Parametric Oscillations in a Whispering Gallery Mode Fluorite Resonator

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Strekalov, Dmitry; Mohageg, Makan; Ilchenko, Vladimir; Matsko, Andrey; Maleki, Lute

    2004-01-01

    This viewgraph presentation summarizes the hyper-parametric oscillations observations of the fluorite resonator. The reporters have observed various nonlinear effects in ultra-high Q crystalline whispering gallery mode (WGM) resonators. In particular, it was demonstrated a low threshold optical hyper-parametric oscillations in a high-Q (Q=1010) CaF2 WGM resonator. The oscillations result from the resonantly enhanced four-wave-mixing occurring due to Kerr nonlinearity of the material.

  13. 119Sn-NMR investigations on superconducting Ca3Ir4Sn13: Evidence for multigap superconductivity

    DOE PAGES

    Sarkar, R.; Petrovic, C.; Bruckner, F.; ...

    2015-09-25

    In this study, we report bulk superconductivity (SC) in Ca3Ir4Sn13 by means of 119Sn nuclear magnetic resonance (NMR) experiments. Two classical signatures of BCS superconductivity in spin-lattice relaxation rate (1/T1), namely the Hebel–Slichter coherence peak just below the Tc, and the exponential decay in the superconducting phase, are evident. The noticeable decrease of 119Sn Knight shift below Tc indicates spin-singlet superconductivity. The temperature dependence of the spin-lattice relaxation rate 119(1/T1) is convincingly described by the multigap isotropic superconducting gap. NMR experiments do not witness any sign of enhanced spin fluctuations.

  14. CMOS compatible high-Q photonic crystal nanocavity fabricated with photolithography on silicon photonic platform.

    PubMed

    Ooka, Yuta; Tetsumoto, Tomohiro; Fushimi, Akihiro; Yoshiki, Wataru; Tanabe, Takasumi

    2015-06-18

    Progress on the fabrication of ultrahigh-Q photonic-crystal nanocavities (PhC-NCs) has revealed the prospect for new applications including silicon Raman lasers that require a strong confinement of light. Among various PhC-NCs, the highest Q has been recorded with silicon. On the other hand, microcavity is one of the basic building blocks in silicon photonics. However, the fusion between PhC-NCs and silicon photonics has yet to be exploited, since PhC-NCs are usually fabricated with electron-beam lithography and require an air-bridge structure. Here we show that a 2D-PhC-NC fabricated with deep-UV photolithography on a silica-clad silicon-on-insulator (SOI) structure will exhibit a high-Q of 2.2 × 10(5) with a mode-volume of ~ 1.7(λ/n)(3). This is the highest Q demonstrated with photolithography. We also show that this device exhibits an efficient thermal diffusion and enables high-speed switching. The demonstration of the photolithographic fabrication of high-Q silica-clad PhC-NCs will open possibility for mass-manufacturing and boost the fusion between silicon photonics and CMOS devices.

  15. Silicon on-chip side-coupled high-Q micro-cavities for the multiplexing of high sensitivity photonic crystal integrated sensors array

    NASA Astrophysics Data System (ADS)

    Yang, Daquan; Wang, Chunhong; Yuan, Wei; Wang, Bo; Yang, Yujie; Ji, Yuefeng

    2016-09-01

    A novel two-dimensional (2D) silicon (Si) photonic crystal (PC) α-H0-slot micro-cavity with high Q-factor and high sensitivity (S) is presented. Based on the proposed α-H0-Slot micro-cavities, an optimal design of photonic crystal integrated sensors array (PC-ISA) on monolithic silicon on insulator (SOI) is displayed. By using finite-difference time-domain (FDTD) method, the simulation results demonstrate that both large S of 200 nm/RIU (RIU=refractive index unit) and high Q-factor >104 at telecom wavelength range can be achieved simultaneously. And the sensor figure of merit (FOM)>7000 is featured, an order of magnitude improvement over previous 2D PC sensors array. In addition, for the proposed 2D PC-ISA device, each sensor unit is shown to independently shift its resonance wavelength in response to the changes in refractive index (RI) and does not perturb the others. Thus, it is potentially an ideal platform for realizing ultra-compact lab-on-a-chip applications with dense arrays of functionalized spots for multiplexed sensing, and also can be used as an opto-fluidic architecture for performing highly parallel detection of biochemical interactions in aqueous environments.

  16. Progress in the Development of Superconducting RF

    NASA Astrophysics Data System (ADS)

    Martinello, Martina

    2016-03-01

    The R &D of superconducting radiofrequency (SRF) cavities is focused on lowering the power dissipation, i.e. increasing the Q factor, during their operation in accelerators. Nitrogen doping is the innovative high Q SRF technology currently implemented in the LCLS-II cavity production. Of crucial importance is the understanding on how high Q factors can be maintained from the cavity vertical test to the cryomodule operation. One of the major issue of SRF cavity operation is the remnant magnetic field which will always be present during the cool down through the critical temperature, jeopardizing the cavity performance. Research is ongoing both to reduce the remnant field levels and to avoid magnetic field trapping during the SC transition. In addition, fundamental studies allowed us to define the best nitrogen doping treatment needed to lower the sensitivity to trapped flux. Recent developments on the preparation of Nb3Sn coatings for SRF cavities will be also presented. This alternative technology has been demonstrated to allow high Q operation even at 4.2 K. In addition, the maximum field limit of Nb3Sn is predicted to be twice that of niobium, potentially providing a significant decrease in the required length of an accelerator to reach a given energy.

  17. SUPERCONDUCTING PHOTOINJECTOR

    SciTech Connect

    BEN-ZVI,I.; BURRILL, A.; CALAGA, R.; CHANG, X.; GROVER, R.; GUPTA, R.; HAHN, H.; HAMMONS, L.; KAYRAN, D.; KEWISCH, J.; LAMBIASE, R.; LITVINENKO, V.; MCINTYRE, G.; NAIK, D.; PATE, D.; PHILLIPS, D.; POZDEYEV, E.; RAO, T.; SMEDLEY, J.; THAN, R.; TODD, R.; WEISS, D.; WU, Q.; ZALTSMAN, A.; ET AL.

    2007-08-26

    One of the frontiers in FEL science is that of high power. In order to reach power in the megawatt range, one requires a current of the order of one ampere with a reasonably good emittance. The superconducting laser-photocathode RF gun with a high quantum efficiency photocathode is the most natural candidate to provide this performance. The development of a 1/2 cell superconducting photoinjector designed to operate at up to a current of 0.5 amperes and beam energy of 2 MeV and its photocathode system are the subjects covered in this paper. The main issues are the photocathode and its insertion mechanism, the power coupling and High Order Mode damping. This technology is being developed at BNL for DOE nuclear physics applications such as electron cooling at high energy and electron ion colliders..

  18. Color superconductivity

    SciTech Connect

    Wilczek, F.

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  19. Nonlinear optics and crystalline whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Savchenkov, Anatoliy; Ilchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We report on our recent results concerning fabrication of high-Q whispering gallery mode crystalline resonaors, and discuss some possible applications of lithium niobate WGM resonators in nonlinear optics and photonics.

  20. Superconducting magnet

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

  1. Movable high-Q nanoresonators realized by semiconductor nanowires on a Si photonic crystal platform.

    PubMed

    Birowosuto, Muhammad Danang; Yokoo, Atsushi; Zhang, Guoqiang; Tateno, Kouta; Kuramochi, Eiichi; Taniyama, Hideaki; Takiguchi, Masato; Notomi, Masaya

    2014-03-01

    Subwavelength semiconductor nanowires have recently attracted interest for photonic applications because they possess various unique optical properties and offer great potential for miniaturizing devices. However, realizing tight light confinement or efficient coupling with photonic circuits is not straightforward and remains a challenge. Here we show that a high-Q nanocavity can be created by placing a single III–V semiconductor nanowire with a diameter of under 100 nm in a grooved waveguide in a Si photonic crystal, by means of nanoprobe manipulation. We observe very fast spontaneous emission (91 ps) from nanowires accelerated by the strong Purcell enhancement in nanocavities, which proves that very strong light confinement can be achieved. Furthermore, this system enables us to move the nanocavity anywhere along the waveguide. This configuration provides a significant degree of flexibility in integrated photonics and permits the addition and displacement of various functionalities of III–V nanocavity devices in Si photonic circuits.

  2. Stabilized chip-scale Kerr frequency comb via a high-Q reference photonic microresonator

    NASA Astrophysics Data System (ADS)

    Lim, Jinkang; Huang, Shu-Wei; Vinod, Abhinav K.; Mortazavian, Parastou; Yu, Mingbin; Kwong, Dim-Lee; Savchenkov, Anatoliy A.; Matsko, Andrey B.; Maleki, Lute; Wong, Chee Wei

    2016-08-01

    We stabilize a chip-scale Si3N4 phase-locked Kerr frequency comb via locking the pump laser to an independent stable high-Q reference microresonator and locking the comb spacing to an external microwave oscillator. In this comb, the pump laser shift induces negligible impact on the comb spacing change. This scheme is a step towards miniaturization of the stabilized Kerr comb system as the microresonator reference can potentially be integrated on-chip. Fractional instability of the optical harmonics of the stabilized comb is limited by the microwave oscillator used for comb spacing lock below 1 s averaging time and coincides with the pump laser drift in the long term.

  3. Stabilized chip-scale Kerr frequency comb via a high-Q reference photonic microresonator.

    PubMed

    Lim, Jinkang; Huang, Shu-Wei; Vinod, Abhinav K; Mortazavian, Parastou; Yu, Mingbin; Kwong, Dim-Lee; Savchenkov, Anatoliy A; Matsko, Andrey B; Maleki, Lute; Wong, Chee Wei

    2016-08-15

    We stabilize a chip-scale Si3N4 phase-locked Kerr frequency comb via locking the pump laser to an independent stable high-Q reference microresonator and locking the comb spacing to an external microwave oscillator. In this comb, the pump laser shift induces negligible impact on the comb spacing change. This scheme is a step toward miniaturization of the stabilized Kerr comb system as the microresonator reference can potentially be integrated on-chip. Fractional instability of the optical harmonics of the stabilized comb is limited by the microwave oscillator used for a comb spacing lock below 1 s averaging time and coincides with the pump laser drift in the long term.

  4. Precision Measurement of the Proton Elastic Cross Section at High Q2

    NASA Astrophysics Data System (ADS)

    Ou, Longwu; E12-07-108 Collaboration

    2017-01-01

    The measurement of proton electromagnetic form factors (FF) is a powerful way to understand the internal structure of proton and gain insight into the nature of the strong interaction. Current data of FF at high Q2 have large statistical and systematic uncertainties, which translate into large uncertainties in the extracted cross section in this kinematic range. The GMp experiment in Hall A at Jefferson Lab, starting from 2014, performed precision measurements of elastic ep scattering cross section in the Q2 range from 7 to 14 (GeV / c) 2. These measurements will improve the precision on the cross section in the covered Q2 range to about 2 % . They represent a great complement to the world's cross section data set and will be key inputs for future electromagnetic form factor experiments at similar kinematics. In this talk, the instrumentation and techniques used in the experiment will be described, and the current status of the analysis will be presented.

  5. Vertical integration of high-Q silicon nitride microresonators into silicon-on-insulator platform.

    PubMed

    Li, Qing; Eftekhar, Ali A; Sodagar, Majid; Xia, Zhixuan; Atabaki, Amir H; Adibi, Ali

    2013-07-29

    We demonstrate a vertical integration of high-Q silicon nitride microresonators into the silicon-on-insulator platform for applications at the telecommunication wavelengths. Low-loss silicon nitride films with a thickness of 400 nm are successfully grown, enabling compact silicon nitride microresonators with ultra-high intrinsic Qs (~ 6 × 10(6) for 60 μm radius and ~ 2 × 10(7) for 240 μm radius). The coupling between the silicon nitride microresonator and the underneath silicon waveguide is based on evanescent coupling with silicon dioxide as buffer. Selective coupling to a desired radial mode of the silicon nitride microresonator is also achievable using a pulley coupling scheme. In this work, a 60-μm-radius silicon nitride microresonator has been successfully integrated into the silicon-on-insulator platform, showing a single-mode operation with an intrinsic Q of 2 × 10(6).

  6. On-chip three-dimensional high-Q microcavities fabricated by femtosecond laser direct writing.

    PubMed

    Lin, Jintian; Yu, Shangjie; Ma, Yaoguang; Fang, Wei; He, Fei; Qiao, Lingling; Tong, Limin; Cheng, Ya; Xu, Zhizhan

    2012-04-23

    We report on the fabrication of three-dimensional (3D) high-Q whispering gallery microcavities on a fused silica chip by femtosecond laser microfabriction, enabled by the 3D nature of femtosecond laser direct writing. The processing mainly consists of formation of freestanding microdisks by femtosecond laser direct writing and subsequent wet chemical etching. CO(2) laser annealing is followed to smooth the microcavity surface. Microcavities with arbitrary tilting angle, lateral and vertical positioning are demonstrated, and the quality (Q)-factor of a typical microcavity is measured to be up to 1.07 × 10(6), which is currently limited by the low spatial resolution of the motion stage used during the laser patterning and can be improved with motion stages of higher resolutions.

  7. Harmonic mode locking in a high-Q whispering gallery mode microcavity

    NASA Astrophysics Data System (ADS)

    Tanabe, Takasumi; Kato, Takumi; Kobatake, Tomoya; Suzuki, Ryo; Chen-Jinnai, Akitoshi

    2016-03-01

    We present a numerical and experimental study of the generation of harmonic mode locking in a silica toroid microcavity. We use a generalized mean-field Lugiato-Lefever equation and solve it with the split-step Fourier method. We found that a stable harmonic mode-locking regime can be accessed when we reduce the input power after strong pumping even if we do not carefully adjust the wavelength detuning. This is due to the bistable nature of the nonlinear cavity system. The experiment agrees well with the numerical analysis, where we obtain a low-noise Kerr comb spectrum with a narrow longitudinal mode spacing by gradually reducing the input pump power after strong pumping. This finding clarifies the procedure for generating harmonic mode locking in such high-Q microcavity systems.

  8. Intrinsically High-Q Dynamic AFM Imaging in Liquid with a Significantly Extended Needle Tip

    PubMed Central

    Minary-Jolandan, Majid; Tajik, Arash; Wang, Ning; Yu, Min-Feng

    2012-01-01

    Atomic force microscope (AFM) probe with a long and rigid needle tip was fabricated and studied for high Q factor dynamic (tapping mode) AFM imaging of samples submersed in liquid. The extended needle tip over a regular commercially-available tapping mode AFM cantilever was sufficiently long to keep the AFM cantilever from submersed in liquid, which significantly minimized the hydrodynamic damping involved in dynamic AFM imaging of samples in liquid. Dynamic AFM imaging of samples in liquid at an intrinsic Q factor of over 100 and an operation frequency of over 200 kHz was demonstrated. The method has the potential to be extended to acquire viscoelastic materials properties and provide truly gentle imaging of soft biological samples in physiological environments. PMID:22595833

  9. Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment

    SciTech Connect

    Dhakal, Pashupati; Ciovati, Gianluigi; Kneisel, Peter; Myneni, Ganapati Rao

    2014-07-01

    Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×1010 at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities depth profiles were made on samples heat treated with the cavities.

  10. Polymer microring resonators and their sensor applications

    NASA Astrophysics Data System (ADS)

    Guo, L. Jay; Maxwell, Adam; Chao, Chung-Yen; Ling, Tao; Kim, Jin-Sung; Huang, Sheng-Wen; Ashkenazi, Shai

    2008-02-01

    Photonic microring resonators have great potential in the application of highly sensitive label-free biosensors and detection of high-frequency ultrasound due to high Q-factor resonances. Design consideration, device fabrication techniques, experimental results are report in this paper.

  11. Plasmon Resonators for Quantum Computing

    DTIC Science & Technology

    2007-06-01

    quantum dot. For free atoms this strong coupling is achieved using high Q optical resonators, such as ultra-low-loss bulk Fabry - Perot cavities or...TR-07-0487 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Unlimited UL 13. ABSTRACT (Maximum 200 words) The

  12. Integrated system modeling analysis of a cryogenic multi-cell deflecting-mode cavity resonator

    NASA Astrophysics Data System (ADS)

    Shin, Young-Min; Church, Michael

    2013-09-01

    A deflecting mode cavity is the integral element for six-dimensional phase-space beam control in bunch compressors and emittance transformers at high energy beam test facilities. RF performance of a high-Q device is, however, highly sensitive to operational conditions, in particular in a cryo-cooling environment. Using analytic calculations and RF simulations, we examined cavity parameters and deflecting characteristics of TM110,π mode of a 5 cell resonator in a liquid nitrogen cryostat, which has long been used at the Fermilab A0 Photoinjector (A0PI). The sensitivity analysis indicated that the cavity could lose 30%-40% of deflecting force due to defective input power coupling accompanying non-uniform field distribution across the cells with 40 ˜ 50 MeV electron beam and 70-80 kW klystron power. Vacuum-cryomodules of the 5 cell cavity are planned to be installed at the Fermilab Advanced Superconducting Test Accelerator facility. Comprehensive modeling analysis integrated with multi-physics simulation tools showed that RF loading of 1 ms can cause a ˜5 K maximum temperature increase, corresponding to a ˜4.3 μm/ms deformation and a 1.32 MHz/K maximum frequency shift. The integrated system modeling analysis will improve design process of a high-Q cavity with more accurate prediction of cryogenic RF performance under a high power pulse operation.

  13. The Cornell Main Linac Cryomodule: A Full Scale, High Q Accelerator Module for cw Application

    NASA Astrophysics Data System (ADS)

    Eichhorn, R.; Bullock, B.; Elmore, B.; Clasby, B.; Furuta, F.; He, Y.; Hoffstaetter, G.; Liepe, M.; O'Connell, T.; Conway, J.; Quigley, P.; Sabol, D.; Sears, J.; Smith, E.; Veshcherevich, V.

    Cornell University is in the process of building a 10 m long superconducting accelerator module as a prototype of the main linac of a proposed ERL facility. This module houses 6 superconducting cavities- operated at 1.8 K in continuous wave (CW) mode - with individual HOM absorbers and one magnet/BPM section. In pushing the limits, a high quality factor of the cavities (2•1010) and high beam currents (100 mA accelerated plus 100 mA decelerated) were targeted. We will review the design shortly and present the results of the components tested before the assembly. This includes data of the quality-factors of all 6 cavities that we produced and treated in-house, the HOM absorber performance measured with beam on a test set-up as well as testing of the couplers and the tuners.

  14. Fabrication and characterization of aluminum airbridges for superconducting microwave circuits

    NASA Astrophysics Data System (ADS)

    Chen, Zijun; Megrant, A.; Kelly, J.; Barends, R.; Bochmann, J.; Chen, Yu; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Mutus, J. Y.; O'Malley, P. J. J.; Neill, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Cleland, A. N.; Martinis, John M.

    2014-02-01

    Superconducting microwave circuits based on coplanar waveguides (CPW) are susceptible to parasitic slotline modes which can lead to loss and decoherence. We motivate the use of superconducting airbridges as a reliable method for preventing the propagation of these modes. We describe the fabrication of these airbridges on superconducting resonators, which we use to measure the loss due to placing airbridges over CPW lines. We find that the additional loss at single photon levels is small, and decreases at higher drive powers.

  15. Driven superconducting quantum circuits

    NASA Astrophysics Data System (ADS)

    Nakamura, Yasunobu

    2014-03-01

    Driven nonlinear quantum systems show rich phenomena in various fields of physics. Among them, superconducting quantum circuits have very attractive features such as well-controlled quantum states with design flexibility, strong nonlinearity of Josephson junctions, strong coupling to electromagnetic driving fields, little internal dissipation, and tailored coupling to the electromagnetic environment. We have investigated properties and functionalities of driven superconducting quantum circuits. A transmon qubit coupled to a transmission line shows nearly perfect spatial mode matching between the incident and scattered microwave field in the 1D mode. Dressed states under a driving field are studied there and also in a semi-infinite 1D mode terminated by a resonator containing a flux qubit. An effective Λ-type three-level system is realized under an appropriate driving condition. It allows ``impedance-matched'' perfect absorption of incident probe photons and down conversion into another frequency mode. Finally, the weak signal from the qubit is read out using a Josephson parametric amplifier/oscillator which is another nonlinear circuit driven by a strong pump field. This work was partly supported by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST), Project for Developing Innovation Systems of MEXT, MEXT KAKENHI ``Quantum Cybernetics,'' and the NICT Commissioned Research.

  16. Antiferromagnetic spin fluctuations and unconventional nodeless superconductivity in an iron-based new superconductor (Ca4Al2O(6-y))(Fe2As2): 75As nuclear quadrupole resonance study.

    PubMed

    Kinouchi, H; Mukuda, H; Yashima, M; Kitaoka, Y; Shirage, P M; Eisaki, H; Iyo, A

    2011-07-22

    We report 75As nuclear quadrupole resonance studies on (Ca4Al2O(6-y))(Fe2As2) with T(c) = 27  K. Measurement of nuclear-spin-relaxation rate 1/T1 has revealed a significant development of two-dimensional antiferromagnetic spin fluctuations down to T(c) in association with the smallest As-Fe-As bond angle. Below T(c), the temperature dependence of 1/T1 without any trace of the coherence peak is well accounted for by a nodeless s(±)-wave multiple-gaps model. From the fact that its T(c) is comparable to T(c) = 28  K in the optimally doped LaFeAsO(1-y) in which antiferromagnetic spin fluctuations are not dominant, we remark that antiferromagnetic spin fluctuations are not a unique factor for enhancing T(c) among Fe-based superconductors, but a condition for optimizing superconductivity should be addressed from the lattice structure point of view.

  17. Optimization of the detection coil of high-Tc superconducting quantum interference device-based nuclear magnetic resonance for discriminating a minimum amount of liver tumor of rats in microtesla fields

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Hsien; Huang, Kai-Wen; Yang, Hong-Chang; Horng, Herng-Er; Liao, Shu-Hsien

    2013-08-01

    This study presents an optimization of the detection coil of high-Tc superconducting quantum interference device (SQUID)-based nuclear magnetic resonance (NMR) in microtesla fields for discriminating a minimum amount of liver tumor in rats by characterizing the longitudinal relaxation rate, T1-1, of tested samples. The detection coil, which was coupled to the SQUID through a flux transformer, was optimized by varying the copper wires' winding turns and diameters. When comparing the measured NMR signals, we found that the simulated NMR signal agrees with simulated signals. When discriminating liver tumors in rats, the averaged longitudinal relaxation rate was observed to be T1-1 = 3.3 s-1 for cancerous liver tissue and T1-1 = 6.6 s-1 for normal liver tissue. The results suggest that it can be used to successfully discriminate cancerous liver tissue from normal liver tissues in rats. The minimum amount of samples that can be detected is 0.2 g for liver tumor and 0.4 g for normal liver tissue in 100 μT fields. The specimen was not damaged; it can be used for other pathological analyses. The proposed method provides more possibilities for examining undersized specimens.

  18. Coexistence of ferromagnetism and superconductivity in YBCO nanoparticles.

    PubMed

    Zhu, Zhonghua; Gao, Daqiang; Dong, Chunhui; Yang, Guijin; Zhang, Jing; Zhang, Jinlin; Shi, Zhenhua; Gao, Hua; Luo, Honggang; Xue, Desheng

    2012-03-21

    Nanoparticles of superconducting YBa(2)Cu(3)O(7-δ) were synthesized via a citrate pyrolysis technique. Room temperature ferromagnetism was revealed in the samples by a vibrating sample magnetometer. Electron spin resonance spectra at selected temperatures indicated that there is a transition from the normal to the superconducting state at temperatures below 100 K. The M-T curves with various applied magnetic fields showed that the superconducting transition temperatures are 92 K and 55 K for the air-annealed and the post-annealed samples, respectively. Compared to the air-annealed sample, the saturation magnetization of the sample by reheating the air-annealed one in argon atmosphere is enhanced but its superconductivity is weakened, which implies that the ferromagnetism maybe originates from the surface oxygen defects. By superconducting quantum interference device measurements, we further confirmed the ferromagnetic behavior at high temperatures and interesting upturns in field cooling magnetization curves within the superconducting region are found. We attributed the upturn phenomena to the coexistence of ferromagnetism and superconductivity at low temperatures. Room temperature ferromagnetism of superconducting YBa(2)Cu(3)O(7-δ) nanoparticles has been observed in some previous related studies, but the issue of the coexistence of ferromagnetism and superconductivity within the superconducting region is still unclear. In the present work, it will be addressed in detail. The cooperation phenomena found in the spin-singlet superconductors will help us to understand the nature of superconductivity and ferromagnetism in more depth.

  19. Effect of source tuning parameters on the plasma potential of heavy ions in the 18 GHz high temperature superconducting electron cyclotron resonance ion source

    SciTech Connect

    Rodrigues, G.; Mathur, Y.; Kumar, Sarvesh; Mandal, A.; Kanjilal, D.; Roy, A.; Baskaran, R.; Kukrety, S.

    2012-03-15

    Plasma potentials for various heavy ions have been measured using the retarding field technique in the 18 GHz high temperature superconducting ECR ion source, PKDELIS [C. Bieth, S. Kantas, P. Sortais, D. Kanjilal, G. Rodrigues, S. Milward, S. Harrison, and R. McMahon, Nucl. Instrum. Methods B 235, 498 (2005); D. Kanjilal, G. Rodrigues, P. Kumar, A. Mandal, A. Roy, C. Bieth, S. Kantas, and P. Sortais, Rev. Sci. Instrum. 77, 03A317 (2006)]. The ion beam extracted from the source is decelerated close to the location of a mesh which is polarized to the source potential and beams having different plasma potentials are measured on a Faraday cup located downstream of the mesh. The influence of various source parameters, viz., RF power, gas pressure, magnetic field, negative dc bias, and gas mixing on the plasma potential is studied. The study helped to find an upper limit of the energy spread of the heavy ions, which can influence the design of the longitudinal optics of the high current injector being developed at the Inter University Accelerator Centre. It is observed that the plasma potentials are decreasing for increasing charge states and a mass effect is clearly observed for the ions with similar operating gas pressures. In the case of gas mixing, it is observed that the plasma potential minimizes at an optimum value of the gas pressure of the mixing gas and the mean charge state maximizes at this value. Details of the measurements carried out as a function of various source parameters and its impact on the longitudinal optics are presented.

  20. Effect of source tuning parameters on the plasma potential of heavy ions in the 18 GHz high temperature superconducting electron cyclotron resonance ion source.

    PubMed

    Rodrigues, G; Baskaran, R; Kukrety, S; Mathur, Y; Kumar, Sarvesh; Mandal, A; Kanjilal, D; Roy, A

    2012-03-01

    Plasma potentials for various heavy ions have been measured using the retarding field technique in the 18 GHz high temperature superconducting ECR ion source, PKDELIS [C. Bieth, S. Kantas, P. Sortais, D. Kanjilal, G. Rodrigues, S. Milward, S. Harrison, and R. McMahon, Nucl. Instrum. Methods B 235, 498 (2005); D. Kanjilal, G. Rodrigues, P. Kumar, A. Mandal, A. Roy, C. Bieth, S. Kantas, and P. Sortais, Rev. Sci. Instrum. 77, 03A317 (2006)]. The ion beam extracted from the source is decelerated close to the location of a mesh which is polarized to the source potential and beams having different plasma potentials are measured on a Faraday cup located downstream of the mesh. The influence of various source parameters, viz., RF power, gas pressure, magnetic field, negative dc bias, and gas mixing on the plasma potential is studied. The study helped to find an upper limit of the energy spread of the heavy ions, which can influence the design of the longitudinal optics of the high current injector being developed at the Inter University Accelerator Centre. It is observed that the plasma potentials are decreasing for increasing charge states and a mass effect is clearly observed for the ions with similar operating gas pressures. In the case of gas mixing, it is observed that the plasma potential minimizes at an optimum value of the gas pressure of the mixing gas and the mean charge state maximizes at this value. Details of the measurements carried out as a function of various source parameters and its impact on the longitudinal optics are presented.

  1. Effect of source tuning parameters on the plasma potential of heavy ions in the 18 GHz high temperature superconducting electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Rodrigues, G.; Baskaran, R.; Kukrety, S.; Mathur, Y.; Kumar, Sarvesh; Mandal, A.; Kanjilal, D.; Roy, A.

    2012-03-01

    Plasma potentials for various heavy ions have been measured using the retarding field technique in the 18 GHz high temperature superconducting ECR ion source, PKDELIS [C. Bieth, S. Kantas, P. Sortais, D. Kanjilal, G. Rodrigues, S. Milward, S. Harrison, and R. McMahon, Nucl. Instrum. Methods B 235, 498 (2005), 10.1016/j.nimb.2005.03.232; D. Kanjilal, G. Rodrigues, P. Kumar, A. Mandal, A. Roy, C. Bieth, S. Kantas, and P. Sortais, Rev. Sci. Instrum. 77, 03A317 (2006), 10.1063/1.2164887]. The ion beam extracted from the source is decelerated close to the location of a mesh which is polarized to the source potential and beams having different plasma potentials are measured on a Faraday cup located downstream of the mesh. The influence of various source parameters, viz., RF power, gas pressure, magnetic field, negative dc bias, and gas mixing on the plasma potential is studied. The study helped to find an upper limit of the energy spread of the heavy ions, which can influence the design of the longitudinal optics of the high current injector being developed at the Inter University Accelerator Centre. It is observed that the plasma potentials are decreasing for increasing charge states and a mass effect is clearly observed for the ions with similar operating gas pressures. In the case of gas mixing, it is observed that the plasma potential minimizes at an optimum value of the gas pressure of the mixing gas and the mean charge state maximizes at this value. Details of the measurements carried out as a function of various source parameters and its impact on the longitudinal optics are presented.

  2. Superconducting quantum circuits theory and application

    NASA Astrophysics Data System (ADS)

    Deng, Xiuhao

    Superconducting quantum circuit models are widely used to understand superconducting devices. This thesis consists of four studies wherein the superconducting quantum circuit is used to illustrate challenges related to quantum information encoding and processing, quantum simulation, quantum signal detection and amplification. The existence of scalar Aharanov-Bohm phase has been a controversial topic for decades. Scalar AB phase, defined as time integral of electric potential, gives rises to an extra phase factor in wavefunction. We proposed a superconducting quantum Faraday cage to detect temporal interference effect as a consequence of scalar AB phase. Using the superconducting quantum circuit model, the physical system is solved and resulting AB effect is predicted. Further discussion in this chapter shows that treating the experimental apparatus quantum mechanically, spatial scalar AB effect, proposed by Aharanov-Bohm, can't be observed. Either a decoherent interference apparatus is used to observe spatial scalar AB effect, or a quantum Faraday cage is used to observe temporal scalar AB effect. The second study involves protecting a quantum system from losing coherence, which is crucial to any practical quantum computation scheme. We present a theory to encode any qubit, especially superconducting qubits, into a universal quantum degeneracy point (UQDP) where low frequency noise is suppressed significantly. Numerical simulations for superconducting charge qubit using experimental parameters show that its coherence time is prolong by two orders of magnitude using our universal degeneracy point approach. With this improvement, a set of universal quantum gates can be performed at high fidelity without losing too much quantum coherence. Starting in 2004, the use of circuit QED has enabled the manipulation of superconducting qubits with photons. We applied quantum optical approach to model coupled resonators and obtained a four-wave mixing toolbox to operate photons

  3. Superconducting inductive displacement detection of a microcantilever

    SciTech Connect

    Vinante, A.

    2014-07-21

    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 μT, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at 4.2 K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  4. Low loss and magnetic field-tunable superconducting terahertz metamaterial.

    PubMed

    Jin, Biaobing; Zhang, Caihong; Engelbrecht, Sebastian; Pimenov, Andrei; Wu, Jingbo; Xu, Qinyin; Cao, Chunhai; Chen, Jian; Xu, Weiwei; Kang, Lin; Wu, Peiheng

    2010-08-02

    Superconducting terahertz (THz) metamaterial (MM) made from niobium (Nb) film has been investigated using a continuous-wave THz spectroscopy. The quality factors of the resonance modes at 0.132 THz and 0.418 THz can be remarkably increased when the working temperature is below the superconducting transition temperature of Nb, indicating that the use of superconducting Nb is a possible way to achieve low loss performance of a THz MM. In addition, the tuning of superconducting THz MM by a magnetic field is also demonstrated, which offers an alternative tuning method apart from the existing electric, optical and thermal tuning methods.

  5. The NASA high temperature superconductivity program

    NASA Technical Reports Server (NTRS)

    Sokoloski, Martin M.; Romanofsky, Robert R.

    1990-01-01

    It has been recognized from the onset that high temperature superconductivity held great promise for major advances across a broad range of NASA interests. The current effort is organized around four key areas: communications and data, sensors and cryogenics, propulsion and power, and space materials technology. Recently, laser ablated YBa2Cu3O(7-x) films on LaAIO produced far superior RF characteristics when compared to metallic films on the same substrate. This achievement has enabled a number of unique microwave device applications, such as low insertion loss phase shifters and high Q filters. Melt texturing and melt quenched techniques are being used to produce bulk materials with optimized magnetic properties. These yttrium enriched materials possess enhanced flux pinning characteristics and will lead to prototype cryocooler bearings. Significant progress has also occurred in bolometer and current lead technology. Studies are being conducted to evaluate the effect of high temperature superconducting materials on the performance and life of high power magneto-plasma-dynamic thrusters. Extended studies were also performed to evaluate the benefit of superconducting magnetic energy storage for LEO space station, lunar and Mars mission applications. The project direction and level of effort of the program are also described.

  6. The NASA high temperature superconductivity program

    NASA Astrophysics Data System (ADS)

    Sokoloski, Martin M.; Romanofsky, Robert R.

    1990-04-01

    It has been recognized from the onset that high temperature superconductivity held great promise for major advances across a broad range of NASA interests. The current effort is organized around four key areas: communications and data, sensors and cryogenics, propulsion and power, and space materials technology. Recently, laser ablated YBa2Cu3O(7-x) films on LaAIO produced far superior RF characteristics when compared to metallic films on the same substrate. This achievement has enabled a number of unique microwave device applications, such as low insertion loss phase shifters and high Q filters. Melt texturing and melt quenched techniques are being used to produce bulk materials with optimized magnetic properties. These yttrium enriched materials possess enhanced flux pinning characteristics and will lead to prototype cryocooler bearings. Significant progress has also occurred in bolometer and current lead technology. Studies are being conducted to evaluate the effect of high temperature superconducting materials on the performance and life of high power magneto-plasma-dynamic thrusters. Extended studies were also performed to evaluate the benefit of superconducting magnetic energy storage for LEO space station, lunar and Mars mission applications. The project direction and level of effort of the program are also described.

  7. High field superconducting magnets

    NASA Technical Reports Server (NTRS)

    Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)

    2011-01-01

    A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.

  8. Superconducting magnet

    DOEpatents

    Satti, John A.

    1980-01-01

    A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.

  9. Superconductivity devices: Commercial use of space

    NASA Technical Reports Server (NTRS)

    Haertling, Gene; Hsi, Chi-Shiung; Mcintyre, Ladawn; Li, Guang

    1992-01-01

    The high T(sub c) superconducting ceramic materials, developed in 1987, are now being extensively investigated for a variety of engineering applications. These applications include such devices as conducting links, rotating and linear bearings, sensors, filters, switches, high Q cavities, magnets, and motors. Some of these devices take advantage of the material's ability to lose all electrical resistance at a critical temperature, T(sub c), while others make use of the repulsion forces generated between the magnetic field of a permanent magnet and a superconductor which is cooled below its T(sub c), Meissner effect. This report describes the work accomplished to date by: (1) reviewing the present state of the art in actuator technology, (2) evaluating processing and fabrication of high strain electrostrictive materials, and (3) testing these electrostrictive materials.

  10. (1) Majorana fermions in pinned vortices; (2) Manipulating and probing Majorana fermions using superconducting circuits; and (3) Controlling a nanowire spin-orbit qubit via electric-dipole spin resonance

    NASA Astrophysics Data System (ADS)

    Nori, Franco

    2014-03-01

    We study a heterostructure which consists of a topological insulator and a superconductor with a hole. This system supports a robust Majorana fermion state bound to the vortex core. We study the possibility of using scanning tunneling spectroscopy (i) to detect the Majorana fermion in this setup and (ii) to study excited states bound to the vortex core. The Majorana fermion manifests itself as an H-dependent zero-bias anomaly of the tunneling conductance. The excited states spectrum differs from the spectrum of a typical Abrikosov vortex, providing additional indirect confirmation of the Majorana state observation. We also study how to manipulate and probe Majorana fermions using super-conducting circuits. In we consider a semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC), which can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, i.e., electric-dipole spin resonance. We develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength ηopt = √ 2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. FN is partly supported by the RIKEN CEMS, iTHES Project, MURI Center for Dynamic Magneto-Optics, JSPS-RFBR Contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program.

  11. Simple Superconducting "Permanent" Electromagnet

    NASA Technical Reports Server (NTRS)

    Israelson, Ulf E.; Strayer, Donald M.

    1992-01-01

    Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

  12. High- Q surface modes in photonic crystal/iron garnet film heterostructures for sensor applications

    NASA Astrophysics Data System (ADS)

    Ignatyeva, D. O.; Kapralov, P. O.; Knyazev, G. A.; Sekatskii, S. K.; Dietler, G.; Nur-E-Alam, M.; Vasiliev, M.; Alameh, K.; Belotelov, V. I.

    2016-11-01

    A novel type of a plasmonic sensor based on a magnetophotonic plasmonic heterostructure with an ultrahigh- Q resonance is considered. A magnetoplasmonic resonance with an angular width of 0.06°, which corresponds to a Q factor of 700 and is a record value for magnetoplasmonic sensors, is experimentally demonstrated. It is shown that, owing to the excitation of long-propagation-range plasmons, the transverse magneto-optical Kerr effect is considerably enhanced and, thus, the sensitivity of the magnetoplasmonic sensor to variations in the refractive index increases to 18 RIU-1, where RIU is the refractive index unit. Numerical calculations indicate that the parameters of the magnetoplasmonic structure can be further optimized to attain sensitivities up to 5 × 103 RIU-1.

  13. Resistive cooling circuits for charged particle traps using crystal resonators.

    PubMed

    Kaltenbacher, T; Caspers, F; Doser, M; Kellerbauer, A; Pribyl, W

    2011-11-01

    The paper addresses a novel method to couple a signal from charged particles in a Penning trap to a high Q resonant circuit using a crystal resonator. Traditionally, the trap capacity is converted into a resonator by means of an inductance. The tuned circuit's Q factor is directly linked to the input impedance "seen" by the trapped particles at resonance frequency. This parallel resonance impedance is a measure of the efficiency of resistive cooling and thus it should be optimized. We propose here a commercially available crystal resonator since it exhibits a very high Q value and a parallel resonance impedance of several MΩ. The possibility to tune the parallel resonance frequency of the quartz results in filter behavior that allows covering a range of some tens of its 3dB bandwidth by means of tuning.

  14. Heterogeneous Superconducting Low-Noise Sensing Coils

    NASA Technical Reports Server (NTRS)

    Hahn, Inseob; Penanen, Konstantin I.; Ho Eom, Byeong

    2008-01-01

    A heterogeneous material construction has been devised for sensing coils of superconducting quantum interference device (SQUID) magnetometers that are subject to a combination of requirements peculiar to some advanced applications, notably including low-field magnetic resonance imaging for medical diagnosis. The requirements in question are the following: The sensing coils must be large enough (in some cases having dimensions of as much as tens of centimeters) to afford adequate sensitivity; The sensing coils must be made electrically superconductive to eliminate Johnson noise (thermally induced noise proportional to electrical resistance); and Although the sensing coils must be cooled to below their superconducting- transition temperatures with sufficient cooling power to overcome moderate ambient radiative heat leakage, they must not be immersed in cryogenic liquid baths. For a given superconducting sensing coil, this combination of requirements can be satisfied by providing a sufficiently thermally conductive link between the coil and a cold source. However, the superconducting coil material is not suitable as such a link because electrically superconductive materials are typically poor thermal conductors. The heterogeneous material construction makes it possible to solve both the electrical- and thermal-conductivity problems. The basic idea is to construct the coil as a skeleton made of a highly thermally conductive material (typically, annealed copper), then coat the skeleton with an electrically superconductive alloy (typically, a lead-tin solder) [see figure]. In operation, the copper skeleton provides the required thermally conductive connection to the cold source, while the electrically superconductive coating material shields against Johnson noise that originates in the copper skeleton.

  15. Apparatus for characterizing conductivity of superconducting materials

    DOEpatents

    Doss, James D.

    1993-01-01

    Apparatus and method for noncontact, radio-frequency shielding current characterization of materials. Self- or mutual inductance changes in one or more inductive elements, respectively, occur when materials capable of supporting shielding currents are placed in proximity thereto, or undergo change in resistivity while in place. Such changes can be observed by incorporating the inductor(s) in a resonant circuit and determining the frequency of oscillation or by measuring the voltage induced on a coupled inductive element. The present invention is useful for determining the critical temperature and superconducting transition width for superconducting samples.

  16. Apparatus for characterizing conductivity of superconducting materials

    DOEpatents

    Doss, J.D.

    1993-12-07

    Apparatus and method for noncontact, radio-frequency shielding current characterization of materials. Self- or mutual inductance changes in one or more inductive elements, respectively, occur when materials capable of supporting shielding currents are placed in proximity thereto, or undergo change in resistivity while in place. Such changes can be observed by incorporating the inductor(s) in a resonant circuit and determining the frequency of oscillation or by measuring the voltage induced on a coupled inductive element. The present invention is useful for determining the critical temperature and superconducting transition width for superconducting samples. 10 figures.

  17. Protective link for superconducting coil

    DOEpatents

    Umans, Stephen D.

    2009-12-08

    A superconducting coil system includes a superconducting coil and a protective link of superconducting material coupled to the superconducting coil. A rotating machine includes first and second coils and a protective link of superconducting material. The second coil is operable to rotate with respect to the first coil. One of the first and second coils is a superconducting coil. The protective link is coupled to the superconducting coil.

  18. Nonlinear optics and crystalline whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey B.; Savchenkov, Anatoliy A.; Ilchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We report on our recent results concerning fabrication of high-Q whispering gallery mode (WGM) crystalline resonators, and discuss some possible applications of lithium niobate WGM resonators in nonlinear optics and photonics. In particular, we demonstrate experimentally a tunable third-order optical filter fabricated from the three metalized resonators; and report observation of parametric frequency dobuling in a WGM resonator made of periodically poled lithium niobate (PPLN).

  19. Superconductivity in transition metals.

    PubMed

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified.

  20. Wave Phenomena in an Acoustic Resonant Chamber

    ERIC Educational Resources Information Center

    Smith, Mary E.; And Others

    1974-01-01

    Discusses the design and operation of a high Q acoustical resonant chamber which can be used to demonstrate wave phenomena such as three-dimensional normal modes, Q values, densities of states, changes in the speed of sound, Fourier decomposition, damped harmonic oscillations, sound-absorbing properties, and perturbation and scattering problems.…

  1. Measurement of Microwave Parameters of a Superconducting Niobium Cavity

    NASA Astrophysics Data System (ADS)

    Azaryan, N. S.; Baturitskii, M. A.; Budagov, Yu. A.; Demin, D. L.; Dem‧yanov, S. E.; Karpovich, V. A.; Kniga, V. V.; Krivosheev, R. M.; Lyubetskii, N. V.; Maksimov, S. I.; Pobol‧, I. L.; Rodionova, V. N.; Shirkov, G. D.; Shumeiko, N. M.; Yurevich, S. V.

    2017-01-01

    This paper describes a method for direct measurement of the amplitude-frequency characteristics and the Q factor of empty superconducting niobium radio frequency Tesla-type cavities. An automated measuring complex that permits recording the superconductivity effect and measuring high Q values has been developed. Measurements have been made of the Q factors of the investigated objects (the first domestic 1.3-GHz niobium cavities) at a level no lower than 0.1·109 (with a maximum value of 1.2·1010) and a level of relative losses lower than 130 dB (with a minimum factor of 139.7 dB) at liquid nitrogen temperature.

  2. Exploration of multi-fold symmetry element-loaded superconducting radio frequency structure for reliable acceleration of low- & medium-beta ion species

    SciTech Connect

    Huang, Shichun; Geng, Rongli

    2015-09-01

    Reliable acceleration of low- to medium-beta proton or heavy ion species is needed for future high-current superconducting radio frequency (SRF) accelerators. Due to the high-Q nature of an SRF resonator, it is sensitive to many factors such as electron loading (from either the accelerated beam or from parasitic field emitted electrons), mechanical vibration, and liquid helium bath pressure fluctuation etc. To increase the stability against those factors, a mechanically strong and stable RF structure is desirable. Guided by this consideration, multi-fold symmetry element-loaded SRF structures (MFSEL), cylindrical tanks with multiple (n>=3) rod-shaped radial elements, are being explored. The top goal of its optimization is to improve mechanical stability. A natural consequence of this structure is a lowered ratio of the peak surface electromagnetic field to the acceleration gradient as compared to the traditional spoke cavity. A disadvantage of this new structure is an increased size for a fixed resonant frequency and optimal beta. This paper describes the optimization of the electro-magnetic (EM) design and preliminary mechanical analysis for such structures.

  3. Superconducting multiturn flux transformers for radio frequency superconducting quantum interference devices

    NASA Astrophysics Data System (ADS)

    Yi, H. R.; Zhang, Y.; Schubert, J.; Zander, W.; Zeng, X. H.; Klein, N.

    2000-11-01

    This article describes three planar layouts of superconducting multiturn flux transformers integrated with a coplanar resonator for radio frequency (rf) superconducting quantum interference device (SQUID) magnetometers. The best magnetic field noise values of 22 and 11.5 fT/Hz1/2 in the white noise regime were obtained for the layout with two input coils and the layout with the labyrinth resonator, respectively. Excess low-frequency noise (about 200 fT/Hz1/2 at 10 Hz) was present. Computer simulation showed that the loss in this trilayer system was dominated by the high loss tangent of the dielectric film used for the separation of the upper and lower superconducting films. The rf coupling coefficient krf between the resonator and the flip-chip-coupled SQUID was also estimated. The values krf2≈14×10-3 obtained for the layout with two input coils, and krf2≈45×10-3 for the layout with the labyrinth resonator were considerably higher than the typical value of krf2≈7×10-3 for the single-layer coplanar resonator. These high coupling coefficients have compensated the somewhat degraded unloaded quality factor of the resonator, thus securing the optimum operation of the rf SQUID.

  4. Applications and Methods of Operating a Three-dimensional Nano-electro-mechanical Resonator and Related Devices

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor); Epp, Larry W. (Inventor); Bagge, Leif (Inventor)

    2013-01-01

    Carbon nanofiber resonator devices, methods for use, and applications of said devices are disclosed. Carbon nanofiber resonator devices can be utilized in or as high Q resonators. Resonant frequency of these devices is a function of configuration of various conducting components within these devices. Such devices can find use, for example, in filtering and chemical detection.

  5. Damping in high-temperature superconducting levitation systems

    DOEpatents

    Hull, John R.

    2009-12-15

    Methods and apparatuses for improved damping in high-temperature superconducting levitation systems are disclosed. A superconducting element (e.g., a stator) generating a magnetic field and a magnet (e.g. a rotor) supported by the magnetic field are provided such that the superconducting element is supported relative to a ground state with damped motion substantially perpendicular to the support of the magnetic field on the magnet. Applying this, a cryostat housing the superconducting bearing may be coupled to the ground state with high damping but low radial stiffness, such that its resonant frequency is less than that of the superconducting bearing. The damping of the cryostat may be substantially transferred to the levitated magnetic rotor, thus, providing damping without affecting the rotational loss, as can be derived applying coupled harmonic oscillator theory in rotor dynamics. Thus, damping can be provided to a levitated object, without substantially affecting the rotational loss.

  6. Two distinct superconducting phases in LiFeAs

    PubMed Central

    Nag, P. K.; Schlegel, R.; Baumann, D.; Grafe, H.-J.; Beck, R.; Wurmehl, S.; Büchner, B.; Hess, C.

    2016-01-01

    A non-trivial temperature evolution of superconductivity including a temperature-induced phase transition between two superconducting phases or even a time-reversal symmetry breaking order parameter is in principle expected in multiband superconductors such as iron-pnictides. Here we present scanning tunnelling spectroscopy data of LiFeAs which reveal two distinct superconducting phases: at = 18 K a partial superconducting gap opens, evidenced by subtle, yet clear features in the tunnelling spectra, i.e. particle-hole symmetric coherence peak and dip-hump structures. At Tc = 16 K, these features substantiate dramatically and become characteristic of full superconductivity. Remarkably, the distance between the dip-hump structures and the coherence peaks remains practically constant in the whole temperature regimeT ≤ . This rules out the connection of the dip-hump structures to an antiferromagnetic spin resonance. PMID:27297474

  7. Fundamental analysis of dynamic stability in superconductive power systems

    SciTech Connect

    Mitani, Y.; Tsuji, K.; Murakami, Y. . Faculty of Engineering)

    1991-03-01

    This paper reports on applications of superconductivity to power systems which have possible advantages in economy, reliability and stability. On the other side, superconductive power systems have risks of including insufficient damping due to the effect of inductance-capacitance (LC) resonance. This may cause subsynchronous resonance oscillations (SSR) represented by self-excited oscillation and torsional oscillation of rotor-turbine shafts. The main subject of this paper is to analyze numerically SSR and electro-mechanical power swing in a model power system with superconductive power apparatus. A stabilizing control scheme which uses the stored energy in the field winding circuit of superconductive generator, is applied to some instabilities and its effectiveness is confirmed in a digital simulation study.

  8. Fluid phase thermodynamics : I) nucleate pool boiling of oxygen under magnetically enhanced gravity and II) superconducting cavity resonators for high-stability frequency references and precision density measurements of helium-4 gas

    NASA Astrophysics Data System (ADS)

    Corcovilos, Theodore Allen

    Although fluids are typically the first systems studied in undergraduate thermodynamics classes, we still have only a rudimentary phenomenological understanding of these systems outside of the classical and equilibrium regimes. Two experiments will be presented. First, we present progress on precise measurements of helium-4 gas at low temperatures (1 K-5 K). We study helium because at low densities it is an approximately ideal gas but at high densities the thermodynamic properties can be predicted by numerical solutions of Schroedinger's equation. By utilizing the high resolution and stability in frequency of a superconducting microwave cavity resonator we can measure the dielectric constant of helium-4 to parts in 109, corresponding to an equivalent resolution in density. These data will be used to calculate the virial coefficients of the helium gas so that we may compare with numerical predictions from the literature. Additionally, our data may allow us to measure Boltzmann's constant to parts in 108, a factor of 100 improvement over previous measurements. This work contains a description of the nearly-completed apparatus and the methods of operation and data analysis for this experiment. Data will be taken by future researchers.The second experiment discussed is a study of nucleate pool boiling. To date, no adequate quantitative model exists of this everyday phenomenon. In our experiment, we vary one parameter inaccessible to most researchers, gravity, by applying a magnetic force to our test fluid, oxygen. Using this technique, we may apply effective gravities of 0-80 times Earth's gravitational acceleration (g). In this work we present heat transfer data for the boiling of oxygen at one atmosphere ambient pressure for effective gravity values between 1g and 16g . Our data describe two relationships between applied heat flux and temperature differential: at low heat flux the system obeys a power law and at high heat flux the behavior is linear. We find that the

  9. High-Q silicon photonic crystal cavity for enhanced optical nonlinearities

    SciTech Connect

    Dharanipathy, Ulagalandha Perumal; Tonin, Mario; Houdré, Romuald; Minkov, Momchil Savona, Vincenzo

    2014-09-08

    We fabricate and experimentally characterize an H0 photonic crystal slab nanocavity with a design optimized for maximal quality factor, Q = 1.7 × 10{sup 6}. The cavity, fabricated from a silicon slab, has a resonant mode at λ = 1.59 μm and a measured Q-factor of 400 000. It displays nonlinear effects, including high-contrast optical bistability, at a threshold power among the lowest ever reported for a silicon device. With a theoretical modal volume as small as V = 0.34(λ/n){sup 3}, this cavity ranks among those with the highest Q/V ratios ever demonstrated, while having a small footprint suited for integration in photonic circuits.

  10. Superconductive radiofrequency window assembly

    DOEpatents

    Phillips, H.L.; Elliott, T.S.

    1998-05-19

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The SRF window assembly has a superconducting metal-ceramic design. The SRF window assembly comprises a superconducting frame, a ceramic plate having a superconducting metallized area, and a superconducting eyelet for sealing plate into frame. The plate is brazed to eyelet which is then electron beam welded to frame. A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the SRF window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator. 11 figs.

  11. Superconducting radiofrequency window assembly

    DOEpatents

    Phillips, H.L.; Elliott, T.S.

    1997-03-11

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly has a superconducting metal-ceramic design. The srf window assembly comprises a superconducting frame, a ceramic plate having a superconducting metallized area, and a superconducting eyelet for sealing plate into frame. The plate is brazed to eyelet which is then electron beam welded to frame. A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator. 11 figs.

  12. High Temperature Superconducting Materials Database

    National Institute of Standards and Technology Data Gateway

    SRD 149 NIST High Temperature Superconducting Materials Database (Web, free access)   The NIST High Temperature Superconducting Materials Database (WebHTS) provides evaluated thermal, mechanical, and superconducting property data for oxides and other nonconventional superconductors.

  13. Superconducting energy recovery linacs

    NASA Astrophysics Data System (ADS)

    Ben-Zvi, Ilan

    2016-10-01

    High-average-power and high-brightness electron beams from a combination of laser photocathode electron guns and a superconducting energy recovery linac (ERL) is an emerging accelerator science with applications in ERL light sources, high repetition rate free electron lasers , electron cooling, electron ion colliders and more. This paper reviews the accelerator physics issues of superconducting ERLs, discusses major subsystems and provides a few examples of superconducting ERLs.

  14. Microwave properties of high transition temperature superconducting thin films

    NASA Technical Reports Server (NTRS)

    Gordon, W. L.

    1991-01-01

    Extensive studies of the interaction of microwaves with YBa2Cu3O(7-delta), Bi-based, and Tl-based superconducting thin films deposited in several microwave substrates were performed. The data were obtained by measuring the microwave power transmitted through the film in the normal and the superconducting state and by resonant cavity techniques. The main motives were to qualify and understand the physical parameters such as the magnetic penetration depth, the complex conductivity, and the surface impedance, of high temperature superconducting (HTS) materials at microwave frequencies. Based on these parameters, the suitability of these HTS thin films is discussed for microwave applications.

  15. Fabrication and Characterization of Aluminum Airbridges for Superconducting Qubit Circuits

    NASA Astrophysics Data System (ADS)

    Chen, Zijun; Megrant, Anthony; Kelly, Julian; Barends, Rami; Bochmann, Joerg; Chen, Yu; Chiaro, Benjamin; Dunsworth, Andrew; Jeffrey, Evan; Mutus, Joshua; O'Malley, Peter; Neill, Charles; Roushan, Pedram; Sank, Daniel; Vainsencher, Amit; Wenner, James; White, Theodore; Cleland, Andrew; Martinis, John

    2014-03-01

    Superconducting circuits based on coplanar waveguides (CPWs) are susceptible to parasitic slotline modes which can lead to loss and decoherence. We motivate the use of superconducting airbridges as a reliable method for preventing the propagation of these modes. We describe the fabrication of these airbridges on superconducting resonators, which we use to measure the loss due to placing airbridges over CPW lines. We find that the additional loss at single photon levels is small, and decreases at higher drive powers. These results pave the way for building airbridge crossovers on more complex qubit circuits.

  16. RIA Superconducting Drift Tube Linac R & D

    SciTech Connect

    J. Popielarski; J. Bierwagen; S. Bricker; C. Compton; J. DeLauter; P. Glennon; T. Grimm; W. Hartung; D. Harvell; M. Hodek; M. Johnson; F. Marti; P. Miller; A. Moblo; D. Norton; L. Popielarski; J. Wlodarczak; R. C. York; A. Zeller

    2009-05-22

    Cavity and cryomodule development work for a superconducting ion linac has been underway for several years at the National Superconducting Cyclotron Laboratory. The original application of the work was the proposed Rare Isotope Accelerator. At present, the work is being continued for use with the Facility for Rare Isotope Beams (FRIB). The baseline linac for FRIB requires 4 types of superconducting cavities to cover the velocity range needed to accelerate an ion beam to 200 MeV/u: 2 types of quarter-wave resonator (QWR) and 2 types of half-wave resonator (HWR). Superconducting solenoids are used for focussing. Active and passive shielding is required to ensure that the solenoids’ field does not degrade the cavity performance. First prototypes of both QWR types and one HWR type have been fabricated and tested. A prototype solenoid has been procured and tested. A test cryomodule has been fabricated and tested. The test cryomodule contains one QWR, one HWR, one solenoid, and one super-ferric quadrupole. This report covers the design, fabrication, and testing of this cryomodule

  17. Superconductive imaging surface magnetometer

    DOEpatents

    Overton, Jr., William C.; van Hulsteyn, David B.; Flynn, Edward R.

    1991-01-01

    An improved pick-up coil system for use with Superconducting Quantum Interference Device gradiometers and magnetometers involving the use of superconducting plates near conventional pick-up coil arrangements to provide imaging of nearby dipole sources and to deflect environmental magnetic noise away from the pick-up coils. This allows the practice of gradiometry and magnetometry in magnetically unshielded environments. One embodiment uses a hemispherically shaped superconducting plate with interior pick-up coils, allowing brain wave measurements to be made on human patients. another embodiment using flat superconducting plates could be used in non-destructive evaluation of materials.

  18. Superconducting optical modulator

    NASA Astrophysics Data System (ADS)

    Bunt, Patricia S.; Ference, Thomas G.; Puzey, Kenneth A.; Tanner, David B.; Tache, Nacira; Varhue, Walter J.

    2000-12-01

    An optical modulator based on the physical properties of high temperature superconductors has been fabricated and tested. The modulator was constructed form a film of Yttrium Barium Copper Oxide (YBCO) grown on undoped silicon with a buffer layer of Yttria Stabilized Zirconia. Standard lithographic procedures were used to pattern the superconducting film into a micro bridge. Optical modulation was achieved by passing IR light through the composite structure normal to the micro bridge and switching the superconducting film in the bridge region between the superconducting and non-superconducting states. In the superconducting state, IR light reflects from the superconducting film surface. When a critical current is passed through the micro bridge, it causes the film in this region to switch to the non-superconducting state allowing IR light to pass through it. Superconducting materials have the potential to switch between these two states at speeds up to 1 picosecond using electrical current. Presently, fiber optic transmission capacity is limited by the rate at which optical data can be modulated. The superconducting modulator, when combined with other components, may have the potential to increase the transmission capacity of fiber optic lines.

  19. Superconducting transport in single and parallel double InAs quantum dot Josephson junctions with Nb-based superconducting electrodes

    SciTech Connect

    Baba, Shoji Sailer, Juergen; Deacon, Russell S.; Oiwa, Akira; Shibata, Kenji; Hirakawa, Kazuhiko; Tarucha, Seigo

    2015-11-30

    We report conductance and supercurrent measurements for InAs single and parallel double quantum dot Josephson junctions contacted with Nb or NbTiN superconducting electrodes. Large superconducting gap energy, high critical field, and large switching current are observed, all reflecting the features of Nb-based electrodes. For the parallel double dots, we observe an enhanced supercurrent when both dots are on resonance, which may reflect split Cooper pair tunneling.

  20. Multiple-Rayleigh-scatterer-induced mode splitting in a high-Q whispering-gallery-mode microresonator

    SciTech Connect

    Yi Xu; Xiao Yunfeng; Liu Yongchun; Li Beibei; Chen Youling; Li Yan; Gong Qihuang

    2011-02-15

    We theoretically investigate the mode-splitting phenomenon in a high-Q whispering-gallery-mode (WGM) microresonator coupled to multiple subwavelength Rayleigh scatterers. It is shown that the phase factors of the WGMs play the central role in such a system. Unlike the single-scatterer case, these phase factors in a multiscatterer system significantly influence both the modal coupling strength and the scattering-induced loss of a pair of counterpropagating WGMs. We scrutinize the condition for observing the splitting of transmission spectra. The mechanism can be used for highly sensitive biosensing, and the size of nanoparticles that can be detected is extended down to tens of nanometers.

  1. Hyperuniform photonic slabs for high-Q cavities and low-loss waveguides

    NASA Astrophysics Data System (ADS)

    Amoah, Timothy; Florescu, Marian

    2015-08-01

    Hyperuniform disordered photonic structures/solids (HUDS) are a new class of photonic solids, which display large, isotropic photonic band gaps (PBG) comparable in size to the ones found in photonic crystals (PC). The existence of large band gaps in HUDS contradicts the long-standing intuition that Bragg scattering and long- range translational order is required in PBG formation, and demonstrates that interactions between Mie-like local resonances and multiple scattering can induce on their own PBGs. HUDS combine advantages of both isotropy due to disorder (absence of long range two-point correlations) and controlled scattering properties from uniform local topology due to hyperuniformity (constrained disorder). In this paper we review the photonic properties of HUDS including the origin of PBGs and potential applications. We address technologically realisable designs of HUDS including localisation of light in point-defect-like optical cavities and the guiding of light in free-form PC waveguide analogues. We show that HUDS are a promising general-purpose design platform for integrated optical micro-circuitry, including active devices such as optical microcavity lasers and modulators.

  2. Superconductivity in aromatic hydrocarbons

    NASA Astrophysics Data System (ADS)

    Kubozono, Yoshihiro; Goto, Hidenori; Jabuchi, Taihei; Yokoya, Takayoshi; Kambe, Takashi; Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L. T.; Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya

    2015-07-01

    'Aromatic hydrocarbon' implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (Kxpicene, five benzene rings). Its superconducting transition temperatures (Tc's) were 7 and 18 K. Recently, we found a new superconducting Kxpicene phase with a Tc as high as 14 K, so we now know that Kxpicene possesses multiple superconducting phases. Besides Kxpicene, we discovered new superconductors such as Rbxpicene and Caxpicene. A most serious problem is that the shielding fraction is ⩽15% for Kxpicene and Rbxpicene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of Tc that is clearly observed in some phases of aromatic hydrocarbon superconductors, suggesting behavior not explained by the standard BCS picture of superconductivity. In this article, we describe the present status of this research field, and discuss its future prospects.

  3. Applied Superconductivity Conference, Santa Fe, N. Mex., September 29-October 2, 1980, Proceedings

    NASA Astrophysics Data System (ADS)

    Lorant, S. J. S.

    1981-01-01

    The conference focused on magnets for fusion technology, Ni-Ti conductors and critical current standards, microbridges and arrays, rotating machinery, discontinuous filament A15 superconductors, materials for tunnel junctions, magnets for energy storage and MHD, magnet technology, multifilamentary Nb3Sn conductors, and cavities and resonators. Papers included superconducting magnets for toroidal fusion reactors, the circular form of the linear superconducting machine for marine propulsion, elastic buckling of superconducting Yin-Yang magnets for fusion, and magnetic energy storage.

  4. Superconducting properties of protactinium.

    PubMed

    Smith, J L; Spirlet, J C; Müller, W

    1979-07-13

    The superconducting transition temperature and upper critical magnetic field of protactinium were measured by alternating-current susceptibility techniques. Since the superconducting behavior of protactinium is affected by its 5f electron character, it is clear now that protactinium is a true actinide element.

  5. Superconductivity of magnesium diboride

    DOE PAGES

    Bud’ko, Sergey L.; Canfield, Paul C.

    2015-07-15

    Over the past 14 years MgB2 has gone from a startling discovery to a promising, applied superconductor. In our article we present a brief overview of the synthesis and the basic superconducting properties of this remarkable compound. Specifically, the effect of pressure, substitutions and neutron irradiation on superconducting properties are discussed.

  6. Superconductivity of magnesium diboride

    SciTech Connect

    Bud’ko, Sergey L.; Canfield, Paul C.

    2015-07-15

    Over the past 14 years MgB2 has gone from a startling discovery to a promising, applied superconductor. In our article we present a brief overview of the synthesis and the basic superconducting properties of this remarkable compound. Specifically, the effect of pressure, substitutions and neutron irradiation on superconducting properties are discussed.

  7. Superconducting gyroscope research

    NASA Technical Reports Server (NTRS)

    Hendricks, J. B.; Karr, G. R.

    1985-01-01

    Four basic areas of research and development of superconducting gyroscopes are studied. Chapter 1 studies the analysis of a SQUID readout for a superconducting gyroscope. Chapter 2 studies the dependence of spin-up torque on channel and gas properties. Chapter 3 studies the theory of super fluid plug operation. And chapter 4 studies the gyro rotor and housing manufacture.

  8. Superconductivity in carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Dlugon, Katarzyna

    The purpose of this thesis is to explain the phenomenon of superconductivity in carbon nanomaterials such as graphene, fullerenes and carbon nanotubes. In the introductory chapter, there is a description of superconductivity and how it occurs at critical temperature (Tc) that is characteristic and different to every superconducting material. The discovery of superconductivity in mercury in 1911 by Dutch physicist Heike Kamerlingh Onnes is also mentioned. Different types of superconductors, type I and type II, low and high temperatures superconductors, as well as the BCS theory that was developed in 1957 by Bardeen, Cooper, and Schrieffer, are also described in detail. The BCS theory explains how Cooper's pairs are formed and how they are responsible for the superconducting properties of many materials. The following chapters explain superconductivity in doped fullerenes, graphene and carbon nanotubes, respectively. There is a thorough explanation followed by many examples of different types of carbon nanomaterials in which small changes in chemical structure cause significant changes in superconducting properties. The goal of this research was not only to take into consideration well known carbon based superconductors but also to search for the newest available materials such as the fullerene nanowhiskers discovered quite recently. There is also a presentation of fairly new ideas about inducing superconductivity in a monolayer of graphene which is more challenging than inducing superconductivity in graphite by simply intercalating metal atoms between its graphene sheets. An effort has been taken to look for any available information about carbon nanomaterials that have the potential to superconduct at room temperature, mainly because discovery of such materials would be a real revolution in the modern world, although no such materials have been discovered yet.

  9. Using Superconducting Qubit Circuits to Engineer Exotic Lattice Systems

    NASA Astrophysics Data System (ADS)

    Tsomokos, Dimitris; Ashhab, Sahel; Nori, Franco

    2011-03-01

    We propose an architecture based on superconducting qubits and resonators for the implementation of a variety of exotic lattice systems, such as spin and Hubbard models in higher or fractal dimensions and higher-genus topologies. Spin systems are realized naturally using qubits, while superconducting resonators can be used for the realization of Bose-Hubbard models. Fundamental requirements for these designs, such as controllable interactions between arbitrary qubit pairs, have recently been implemented in the laboratory, rendering our proposals feasible with current technology.

  10. Using superconducting qubit circuits to engineer exotic lattice systems

    NASA Astrophysics Data System (ADS)

    Tsomokos, Dimitris I.; Ashhab, Sahel; Nori, Franco

    2010-11-01

    We propose an architecture based on superconducting qubits and resonators for the implementation of a variety of exotic lattice systems, such as spin and Hubbard models in higher or fractal dimensions and higher-genus topologies. Spin systems are realized naturally using qubits, while superconducting resonators can be used for the realization of Bose-Hubbard models. Fundamental requirements for these designs, such as controllable interactions between arbitrary qubit pairs, have recently been implemented in the laboratory, rendering our proposals feasible with current technology.

  11. Sensing Based on Fano-Type Resonance Response of All-Dielectric Metamaterials

    PubMed Central

    Semouchkina, Elena; Duan, Ran; Semouchkin, George; Pandey, Ravindra

    2015-01-01

    A new sensing approach utilizing Mie resonances in metamaterial arrays composed of dielectric resonators is proposed. These arrays were found to exhibit specific, extremely high-Q factor (up to 15,000) resonances at frequencies corresponding to the lower edge of the array second transmission band. The observed resonances possessed with features typical for Fano resonances (FRs), which were initially revealed in atomic processes and recently detected in macro-structures, where they resulted from interference between local resonances and a continuum of background waves. Our studies demonstrate that frequencies and strength of Fano-type resonances in all-dielectric arrays are defined by interaction between local Mie resonances and Fabry-Perot oscillations of Bloch eigenmodes that makes possible controlling the resonance responses by changing array arrangements. The opportunity for obtaining high-Q responses in compact arrays is investigated and promising designs for sensing the dielectric properties of analytes in the ambient are proposed. PMID:25905701

  12. A prototype superconducting gravity gradiometer

    SciTech Connect

    van Kann, F.J.; Buckingham, M.J.; Edwards, C.; Penny, R.D.

    1985-03-01

    We report the successful laboratory test of a single-axis gradiometer designed to measure a diagonal component of the earth's gravitational gradient tensor. It consists of a pair of accelerometers mounted with their sensitive axes vertical and in line. The difference in displacement of the accelerometers is proportional to the component of the tensor gradient and is sensed via the modulated inductance of a superconducting coil coupled by a superconducting transformer into an RF biased SHE SQUID with energy sensitivity 4 x 10/sup -29/ J/Hz. Rejection of in-line common mode accelerations is achieved by trimming the natural resonant frequency of each accelerometer: the restoring force acting on an accelerometer test mass is partly magnetic and can be trimmed by adjusting the persistent currents in a pair of force coils. A common mode rejection ratio exceeding 95 dB has been achieved in the presence of linear accelerations about 10/sup -3/ ms/sup -2/, and a laboratory generated gradient of 30 Eo rms has been detected with a signal to noise ratio of about 100. The dependence of this signal on the distance between source and detector has the expected Newtonian form. Under quiet conditions the background noise level of the instrument is at present 3 Eo/..sqrt..Hz. (1 Eo = 10/sup -9/ s/sup -2/.) This is close to the practical limit achievable for such a single axis configuration: a three axis instrument for geophysical application is under development.

  13. Realization of quantum information processing in quantum star network constituted by superconducting hybrid systems

    NASA Astrophysics Data System (ADS)

    Li, Wenlin; Li, Chong; Song, Heshan

    2016-12-01

    In the framework of superconducting hybrid systems, we construct a star quantum network in which a superconducting transmission line resonator as a quantum bus and multiple units constituted by transmission line resonator and superconducting qubits as the carriers of quantum information. We further propose and analyze a theoretical scheme to realize quantum information processing in the quantum network. The coupling between the bus and any two superconducting qubits can be selectively implemented based on the dark state resonances of the highly dissipative transmission line resonators, and it can be found that quantum information processing between any two units can be completed in one step. As examples, the transmission of unknown quantum states and the preparation of quantum entanglement in this quantum network are investigated. At last, we exhibit our simulation results and complete the relevant discussions in order to show the advantages of this kind of quantum network.

  14. Industrial Large Scale Applications of Superconductivity -- Current and Future Trends

    NASA Astrophysics Data System (ADS)

    Amm, Kathleen

    2011-03-01

    Since the initial development of NbTi and Nb3Sn superconducting wires in the early 1960's, superconductivity has developed a broad range of industrial applications in research, medicine and energy. Superconductivity has been used extensively in NMR low field and high field spectrometers and MRI systems, and has been demonstrated in many power applications, including power cables, transformers, fault current limiters, and motors and generators. To date, the most commercially successful application for superconductivity has been the high field magnets required for magnetic resonance imaging (MRI), with a global market well in excess of 4 billion excluding the service industry. The unique ability of superconductors to carry large currents with no losses enabled high field MRI and its unique clinical capabilities in imaging soft tissue. The rapid adoption of high field MRI with superconducting magnets was because superconductivity was a key enabler for high field magnets with their high field uniformity and image quality. With over 30 years of developing MRI systems and applications, MRI has become a robust clinical tool that is ever expanding into new and developing markets. Continued innovation in system design is continuing to address these market needs. One of the key questions that innovators in industrial superconducting magnet design must consider today is what application of superconductivity may lead to a market on the scale of MRI? What are the key considerations for where superconductivity can provide a unique solution as it did in the case of MRI? Many companies in the superconducting industry today are investigating possible technologies that may be the next large market like MRI.

  15. Metal optics and superconductivity

    SciTech Connect

    Golovashkin, A.L.

    1989-01-01

    The articles contained in this collection are dedicated to the study of the electron structure of transition metals and superconducting alloys and compounds based on them. The study of the electron structure of materials is one of the central problems of solid-state physics and defines the solution of a number of problems. One of them is the problem of high-temperature superconductivity which has attracted exceptional attention from physicists in connection with the discovery of new classes of ceramic oxides which are superconducting at liquid-nitrogen temperature. The electron structure is one of the three whales on which all of superconductivity rests. It is frequently our ignorance of the electronic properties of a metal, alloy or compound in its normal state which makes it impossible to predict superconductivity in the material, preventing use from calculating the parameters of the superconducting state. There are now a number of effective methods for investigation of the electron structure of the metals and allows. This collection discusses metal optics, tunneling and magnetic measurements in superconductors. These methods are quite informative and allow us to obtain many important electron characteristics and temperature relations. Various characteristics of the superconducting compounds Nb{sub 3}Ge, Nb{sub 3}Al, nb{sub 3}Sn and Nb{sub 3}Ga with A15 structure and NbN with B1 structure, having rather high critical temperatures, are experimentally studied.

  16. Superconductivity in Opal-based superconducting nanocomposites

    NASA Astrophysics Data System (ADS)

    Lee, M. K.; Charnaya, E. V.; Chang, L. J.; Kumzerov, Yu. A.; Lin, M. F.

    2015-03-01

    In this study, we investigate superconducting nanocomposites (SCNCs) to elucidate superconductivity in nanostructured type I superconductor. In, Sn and Hg are loaded into opal matrices by high pressure up to 10kbar, in which introducing superconducting metals into templates preserves their own 3D nanostructures. The opal matrices is adopted because it is a well-developed nanoconfinement and widely used in the studies of photonic crystal due to its periodically-superlatticed nanoporous structure. The SCNCs are then measured by Quantum Design MPMS 3 under different external magnetic fields reveal the field dependences of Tc and irreversibility temperature (Tirr). Next, AC susceptibility measurements of SCNCs determine grain coupling, vortex dynamics and field dependence of activation barrier (Ua) as well as Tc. Additionally, the phase diagrams of these SCNCs are analyzed to study superconductivity for a system with similar nanogeometry. Exotic phase diagrams in the opal SCNC studies reveal an enhanced upper critical field (Hc2 (0)) and curvature crossover of upper critical field line. Additionally, according to the field dependence of Ua(H), curvature crossover of the upper critical field line can occur, owing to vortex phase transition.

  17. HIGH Q0 AT MEDIUM FIELDS IN Nb3Sn SRF CAVITIES AT 4.2 K

    SciTech Connect

    Posen, Sam; Hall, Daniel Leslie; Liepe, Matthias; Proslier, T.

    2015-01-01

    Nb3Sn has proven itself to be a very promising alternative SRF material. With twice the critical temperature of niobium cavities, 1.3 GHz Nb3Sn cavities can achieve quality factors on the order of 1010 even at 4.2 K, significantly reducing cryogenic infrastructure and operational costs. In addition, its large predicted superheating field may allow for maximum accelerating gradients up to twice that of niobium for high energy applications. In this work, we report on new cavity results fromthe CornellNb3Sn SRF program demonstrating a significant improvement in the maximum field achieved with high Q0 in a Nb3Sn cavity. At 4.2 K, accelerating gradients above 16MV/m were obtainedwith Q0 of 8 × 109, showing the potential of this material for future applications. In addition to this result, current limitations are discussed.

  18. Coherent controlization using superconducting qubits

    PubMed Central

    Friis, Nicolai; Melnikov, Alexey A.; Kirchmair, Gerhard; Briegel, Hans J.

    2015-01-01

    Coherent controlization, i.e., coherent conditioning of arbitrary single- or multi-qubit operations on the state of one or more control qubits, is an important ingredient for the flexible implementation of many algorithms in quantum computation. This is of particular significance when certain subroutines are changing over time or when they are frequently modified, such as in decision-making algorithms for learning agents. We propose a scheme to realize coherent controlization for any number of superconducting qubits coupled to a microwave resonator. For two and three qubits, we present an explicit construction that is of high relevance for quantum learning agents. We demonstrate the feasibility of our proposal, taking into account loss, dephasing, and the cavity self-Kerr effect. PMID:26667893

  19. Field errors in superconducting magnets

    SciTech Connect

    Barton, M. Q.

    1982-01-01

    The mission of this workshop is a discussion of the techniques for tracking particles through arbitrary accelerator field configurations to look for dynamical effects that are suggested by various theoretical models but are not amenable to detailed analysis. A major motivation for this type of study is that many of our accelerator projects are based on the use of superconducting magnets which have field imperfections that are larger and of a more complex nature than those of conventional magnets. Questions such as resonances, uncorrectable closed orbit effects, coupling between planes, and diffusion mechanisms all assume new importance. Since, simultaneously, we are trying to do sophisticated beam manipulations such as stacking, high current accelerator, long life storage, and low loss extraction, we clearly need efficient and accurate tracking programs to proceed with confidence.

  20. Structures behind superconductivity

    SciTech Connect

    Rotman, D.

    1988-07-01

    The previously reported preparation and structures of superconducting materials are reviewed. The two systems, Y-Ba-Cu-O and La-Cu-O, previously reported with high transition temperatures are discussed in some detail. The new systems introduced in 1987 that were not based on a rare earth but including Bi-Sr-Cu-O are also reviewed. Superconductive materials including thallium rather than bismuth that have been reported but not thoroughly studied are discussed briefly. It is pointed out that many superconducting materials have been prepared, but good documentation of the structures and properties of these materials need much more study.

  1. Tunneling in superconducting structures

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.

    2010-12-01

    Here we review our results on the breakpoint features in the coupled system of IJJ obtained in the framework of the capacitively coupled Josephson junction model with diffusion current. A correspondence between the features in the current voltage characteristics (CVC) and the character of the charge oscillations in superconducting layers is demonstrated. Investigation of the correlations of superconducting currents in neighboring Josephson junctions and the charge correlations in neighboring superconducting layers reproduces the features in the CVC and gives a powerful method for the analysis of the CVC of coupled Josephson junctions. A new method for determination of the dissipation parameter is suggested.

  2. Superconducting active impedance converter

    DOEpatents

    Ginley, David S.; Hietala, Vincent M.; Martens, Jon S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductor allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology.

  3. Superconducting active impedance converter

    DOEpatents

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-11-16

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures.

  4. Magnetic and Superconducting Materials at High Pressures

    SciTech Connect

    Struzhkin, Viktor V.

    2015-03-24

    The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

  5. Optical manipulation in optofluidic microbubble resonators

    NASA Astrophysics Data System (ADS)

    Wang, HaoTian; Wu, Xiang

    2015-11-01

    An optical manipulation system based on optofluidic microbubble resonators (MBR) is proposed. As the high- Q whispering gallery modes (WGMs) are excited in an MBR, the buildup of the field intensity inside the resonator is large enough to trap nanoscale particles. The optical gradient forces generated by the WGMs with different radial orders are investigated numerically. The negative effect of the resonance detuning induced by the particles is taken into account to investigate the optical gradient forces exerting on the particles. By the stability analysis, the WGMs with high radial orders show a better trapping stability under Brownian motion since most of the optical fields reside within the water core.

  6. Hybrid superconducting magnetic suspensions

    SciTech Connect

    Tixador, P.; Hiebel, P.; Brunet, Y.

    1996-07-01

    Superconductors, especially high T{sub c} ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO.

  7. Superconducting thermoelectric generator

    DOEpatents

    Metzger, John D.; El-Genk, Mohamed S.

    1998-01-01

    An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

  8. Superconducting thermoelectric generator

    SciTech Connect

    Metzger, J.D.; El-Genk, M.S.

    1998-05-05

    An apparatus and method for producing electricity from heat is disclosed. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device. 4 figs.

  9. Superconducting thermoelectric generator

    SciTech Connect

    Metzger, J.D.; El-Genk, M.S.

    1996-01-01

    An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

  10. Supertubes and Superconducting Membranes

    SciTech Connect

    Cordero, Ruben; Miguel-Pilar, Zelin

    2007-02-09

    We show the equivalence between configurations that arise from string theory of type IIA, called supertubes, and superconducting membranes at the bosonic level. We find equilibrium and oscillating configurations for a tubular membrane carrying a current along its axis.

  11. Robust signatures detection of Majorana fermions in superconducting iron chains

    PubMed Central

    Chen, Hua-Jun; Fang, Xian-Wen; Chen, Chang-Zhao; Li, Yang; Tang, Xu-Dong

    2016-01-01

    We theoretically propose an optical means to detect Majorana fermions in superconducting iron (Fe) chains with a hybrid quantum dot-nanomechanical resonator system driven by two-tone fields, which is very different from the current tunneling spectroscopy experiments with electrical means. Based on the scheme, the phenomenon of Majorana modes induced transparency is demonstrated and a straightforward method to determine the quantum dot-Majorana fermions coupling strength is also presented. We further investigate the role of the nanomechanical resonator, and the resonator behaving as a phonon cavity enhances the exciton resonance spectrum, which is robust for detecting of Majorana fermions. The coherent optical spectrum affords a potential supplement to detecte Majorana fermions and supports Majorana fermions-based topological quantum computation in superconducting iron chains. PMID:27857149

  12. Robust signatures detection of Majorana fermions in superconducting iron chains

    NASA Astrophysics Data System (ADS)

    Chen, Hua-Jun; Fang, Xian-Wen; Chen, Chang-Zhao; Li, Yang; Tang, Xu-Dong

    2016-11-01

    We theoretically propose an optical means to detect Majorana fermions in superconducting iron (Fe) chains with a hybrid quantum dot-nanomechanical resonator system driven by two-tone fields, which is very different from the current tunneling spectroscopy experiments with electrical means. Based on the scheme, the phenomenon of Majorana modes induced transparency is demonstrated and a straightforward method to determine the quantum dot-Majorana fermions coupling strength is also presented. We further investigate the role of the nanomechanical resonator, and the resonator behaving as a phonon cavity enhances the exciton resonance spectrum, which is robust for detecting of Majorana fermions. The coherent optical spectrum affords a potential supplement to detecte Majorana fermions and supports Majorana fermions-based topological quantum computation in superconducting iron chains.

  13. Prospects and progress of high Tc superconductivity for space applications

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.; Sokoloski, Marty M.

    1991-01-01

    Current research in the area of high temperature superconductivity is organized around four key areas: communications and data, sensors and cryogenics, propulsion and power, and space materials technology. Recently, laser ablated YBa2Cu3O(7-x) films on LaAlO3 produced far superior RF characteristics when compared to metallic films on the same substrate. The achievement has enabled a number of unique microwave device applications, such as low insertion loss phase shifters and high-Q filters. Melt texturing and melt-quenched techniques are being used to produce bulk material with optimized magnetic properties. These yttrium-enriched materials possess enhanced flux pinning characteristics and could lead to prototype cryocooler bearings. Significant progress has also occurred in bolometer and current lead technology. Studies were conducted to evaluate the effect of high temperature superconducting materials on the performance and life of high power magnetoplasma-dynamic thrusters. Extended studies were also performed to evaluate the benefit of superconducting magnetic energy storage for LEO space station, lunar, and Mars mission applications.

  14. High Temperature Superconducting Compounds.

    DTIC Science & Technology

    1999-04-02

    addition to superconducting films, non-superconducting mixed-valence manganite perovskites, which exhibit so-called colossal magnetoresistance were grown...The manganites are unique in that their charge carriers are believed to be almost 100% spin polarized. These materials were combined with the...brought about by the injection of spin polarized carriers from the manganite into the curate. This work may make possible new classes of devices based on

  15. Crosstalk in a KID Array Caused by the Thickness Variation of Superconducting Metal

    NASA Astrophysics Data System (ADS)

    Adane, A.; Boucher, C.; Coiffard, G.; Leclercq, S.; Schuster, K. F.; Goupy, J.; Calvo, M.; Hoarau, C.; Monfardini, A.

    2016-07-01

    The work presented in this paper is focused on the improvement of the kinetic detectors used on NIKA2 instrument (New IRAM KID array 2). Based on the simulation and low temperature measurements, it aims at showing how the variations of the superconducting metal corrupt the frequency comb of the kinetic Inductance detectors (KID) in the frequency range (between 1 and 3 GHz), i.e., how the superconducting metal inhomogeneity induces the resonance-to-resonance cross-coupling which deteriorates the homogeneity of the resonance quality factor and the frequency resonance separation. Solutions are then proposed to fight against the effect of these metallic variations when designing the KID array.

  16. Tailored Asymmetry for Enhanced Coupling to WGM Resonators

    NASA Technical Reports Server (NTRS)

    Mohageg, Makan; Maleki, Lute

    2008-01-01

    Coupling of light into and out of whispering- gallery-mode (WGM) optical resonators can be enhanced by designing and fabricating the resonators to have certain non-axisymmetric shapes (see figure). Such WGM resonators also exhibit the same ultrahigh values of the resonance quality factor (Q) as do prior WGM resonators. These WGM resonators are potentially useful as tunable narrow-band optical filters having throughput levels near unity, high-speed optical switches, and low-threshold laser resonators. These WGM resonators could also be used in experiments to investigate coupling between high-Q and chaotic modes within the resonators. For a WGM resonator made of an optically nonlinear material (e.g., lithium niobate) or another material having a high index of refraction, a prism made of a material having a higher index of refraction (e.g., diamond) must be used as part of the coupling optics. For coupling of a beam of light into (or out of) the high-Q resonator modes, the beam must be made to approach (or recede from) the resonator at a critical angle determined by the indices of refraction of the resonator and prism materials. In the case of a lithium niobate/diamond interface, this angle is approximately 22 .

  17. Superconducting transmission line particle detector

    DOEpatents

    Gray, K.E.

    1988-07-28

    A microvertex particle detector for use in a high energy physic collider including a plurality of parallel superconducting thin film strips separated from a superconducting ground plane by an insulating layer to form a plurality of superconducting waveguides. The microvertex particle detector indicates passage of a charged subatomic particle by measuring a voltage pulse measured across a superconducting waveguide caused by the transition of the superconducting thin film strip from a superconducting to a non- superconducting state in response to the passage of a charged particle. A plurality of superconducting thin film strips in two orthogonal planes plus the slow electromagnetic wave propagating in a superconducting transmission line are used to resolve N/sup 2/ ambiguity of charged particle events. 6 figs.

  18. Superconducting transmission line particle detector

    DOEpatents

    Gray, Kenneth E.

    1989-01-01

    A microvertex particle detector for use in a high energy physic collider including a plurality of parallel superconducting thin film strips separated from a superconducting ground plane by an insulating layer to form a plurality of superconducting waveguides. The microvertex particle detector indicates passage of a charged subatomic particle by measuring a voltage pulse measured across a superconducting waveguide caused by the transition of the superconducting thin film strip from a superconducting to a non-superconducting state in response to the passage of a charged particle. A plurality of superconducting thin film strips in two orthogonal planes plus the slow electromagnetic wave propogating in a superconducting transmission line are used to resolve N.sup.2 ambiguity of charged particle events.

  19. Heavy-ion acceleration with a superconducting linac

    SciTech Connect

    Bollinger, L.M.

    1988-01-01

    This year, 1988, is the tenth anniversary of the first use of RF superconductivity to accelerate heavy ions. In June 1978, the first two superconducting resonators of the Argonne Tandem-Linac Accelerator System (ATLAS) were used to boost the energy of a /sup 19/F beam from the tandem, and by September 1978 a 5-resonator linac provided an /sup 16/O beam for a nuclear-physics experiment. Since then, the superconducting linac has grown steadily in size and capability until now there are 42 accelerating structures and 4 bunchers. Throughout this period, the system was used routinely for physics research, and by now the total time with beam on target is 35,000 hours. Lessons learned from this long running experience and some key technical developments that made it possible are reviewed in this paper. 19 refs., 3 figs., 2 tabs.

  20. Superconductive radiofrequency window assembly

    DOEpatents

    Phillips, Harry Lawrence; Elliott, Thomas S.

    1998-01-01

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly (20) has a superconducting metal-ceramic design. The srf window assembly (20) comprises a superconducting frame (30), a ceramic plate (40) having a superconducting metallized area, and a superconducting eyelet (50) for sealing plate (40) into frame (30). The plate (40) is brazed to eyelet (50) which is then electron beam welded to frame (30). A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator.

  1. Superconducting radiofrequency window assembly

    DOEpatents

    Phillips, Harry L.; Elliott, Thomas S.

    1997-01-01

    The present invention is a superconducting radiofrequency window assembly for use in an electron beam accelerator. The srf window assembly (20) has a superconducting metal-ceramic design. The srf window assembly (20) comprises a superconducting frame (30), a ceramic plate (40) having a superconducting metallized area, and a superconducting eyelet (50) for sealing plate (40) into frame (30). The plate (40) is brazed to eyelet (50) which is then electron beam welded to frame (30). A method for providing a ceramic object mounted in a metal member to withstand cryogenic temperatures is also provided. The method involves a new metallization process for coating a selected area of a ceramic object with a thin film of a superconducting material. Finally, a method for assembling an electron beam accelerator cavity utilizing the srf window assembly is provided. The procedure is carried out within an ultra clean room to minimize exposure to particulates which adversely affect the performance of the cavity within the electron beam accelerator.

  2. High temperature interfacial superconductivity

    SciTech Connect

    Bozovic, Ivan; Logvenov, Gennady; Gozar, Adrian Mihai

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  3. Recent developments in rf superconductivity for high-brightness and high-gradient ion beam accelerators

    SciTech Connect

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Nichols, G.L.; Roche, C.T.; Sagalovsky, L.

    1992-02-01

    Recent progress in on-going development program leading to the design of superconducting continuous-wave (cw) linear accelerators for high-brightness ion beams is reviewed. A new spoke-resonator geometry incorporating a half-wavelength resonant line was fabricated and tested. This geometry serves as the basis for the constituent cavities of a superconducting section being designed for high-current testing with a deuterium beam. Considerable progress has been made in the design of this section. A multi-phased program leading to the development of a superconducting radio-frequency quadrupole (SCRFQ) has been initiated. Design considerations and test results from the various activities are presented.

  4. Recent developments in rf superconductivity for high-brightness and high-gradient ion beam accelerators

    SciTech Connect

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Nichols, G.L.; Roche, C.T.; Sagalovsky, L.

    1992-01-01

    Recent progress in on-going development program leading to the design of superconducting continuous-wave (cw) linear accelerators for high-brightness ion beams is reviewed. A new spoke-resonator geometry incorporating a half-wavelength resonant line was fabricated and tested. This geometry serves as the basis for the constituent cavities of a superconducting section being designed for high-current testing with a deuterium beam. Considerable progress has been made in the design of this section. A multi-phased program leading to the development of a superconducting radio-frequency quadrupole (SCRFQ) has been initiated. Design considerations and test results from the various activities are presented.

  5. Measurements of the superconducting proximity effect in Pd/Al NS bilayers at GHz frequencies

    NASA Astrophysics Data System (ADS)

    Nersisyan, Ani; Manenti, Riccardo; Peterer, Michael; Magnusson, Einar; Tancredi, Giovanna; Patterson, Andrew; Leek, Peter

    The superconducting proximity effect, well known since the 1960s, describes superconductivity in the case of a superconductor contacted to a normal metal, and is typically studied experimentally using transport techniques such as tunneling spectroscopy. Here we will present studies of the superconducting proximity effect in thin film palladium/aluminum NS bilayers using microwave frequency lumped element LC resonators. Measurements of the resonance frequency and quality factor as a function of temperature and film thickness reveal properties of the NS bilayers such as the critical temperature and penetration depth. Our results should be useful for understanding losses in superconducting quantum circuits that incorporate thin normal layers, and, in the particular case of Pd, should aid in design of hybrid superconducting quantum devices incorporating carbon nanotubes with high contact transparency

  6. The superconducting spin valve and triplet superconductivity

    NASA Astrophysics Data System (ADS)

    Garifullin, I. A.; Leksin, P. V.; Garif`yanov, N. N.; Kamashev, A. A.; Fominov, Ya. V.; Schumann, J.; Krupskaya, Y.; Kataev, V.; Schmidt, O. G.; Büchner, B.

    2015-01-01

    A review of our recent results on the spin valve effect is presented. We have used a theoretically proposed spin switch design F1/F2/S comprising a ferromagnetic bilayer (F1/F2) as a ferromagnetic component, and an ordinary superconductor (S) as the second interface component. Based on it we have prepared and studied in detail a set of multilayers CoOx/Fe1/Cu/Fe2/S (S=In or Pb). In these heterostructures we have realized for the first time a full spin switch effect for the superconducting current, have observed its sign-changing oscillating behavior as a function of the Fe2-layer thickness and finally have obtained direct evidence for the long-range triplet superconductivity arising due to noncollinearity of the magnetizations of the Fe1 and Fe2 layers.

  7. Superconducting mirror for laser gyroscope

    SciTech Connect

    Wang, X.

    1991-05-14

    This paper describes an apparatus for reflecting a light beam. It comprises: a mirror assembly comprising a substrate and a superconductive mirror formed on such substrate, wherein: the substrate is optically transparent to the light beam and has a thickness of from about 0.5 to about 1.0 millimeter, and the superconductive mirror has a thickness of from about 0.5 to about 1.0 microns; means for cooling the superconductive mirror; means for measuring the temperature of the superconductive mirror; means for determining the reflectivity of the superconductive mirror; and means for varying the reflectivity of the superconductive mirror.

  8. Waveguide-Coupled Superconducting Nanowire Single-Photon Detectors

    NASA Technical Reports Server (NTRS)

    Beyer, Andrew D.; Briggs, Ryan M.; Marsili, Francesco; Cohen, Justin D.; Meenehan, Sean M.; Painter, Oskar J.; Shaw, Matthew D.

    2015-01-01

    We have demonstrated WSi-based superconducting nanowire single-photon detectors coupled to SiNx waveguides with integrated ring resonators. This photonics platform enables the implementation of robust and efficient photon-counting detectors with fine spectral resolution near 1550 nm.

  9. Study of some superconducting and magnetic materials on high T sub c oxide superconductors

    NASA Technical Reports Server (NTRS)

    Wu, M. K.

    1987-01-01

    On the basis of existing data it appears that the high-temperature superconductivity above 77 K reported here, occurs only in compound systems consisting of a phase other than the K2NiF4 phase. A narrow superconducting transition was obtained with T sub c0 = 98 K and T sub c1 = 94 K in Y-Ba-Cu-O (YBCO). Preliminary results indicate that YBCO is rather different from the layered LaBCO, LaSCO, and LaCCO. While electron-photon interaction cannot be absent from this compound system, nonconventional enhanced superconducting interactions due to interfaces, Resonating Valence Bond (RVB) states, or even a superconducting state beyond the BCS framework, may be required to account for the high T sub c in YBCO. It is believed that study of the possible subtle correlation between magnetism and superconductivity will definitely provide important insight into the superconducting mechanism in YBCO and other oxides.

  10. Tuning of superconducting niobium nitride terahertz metamaterials.

    PubMed

    Wu, Jingbo; Jin, Biaobing; Xue, Yuhua; Zhang, Caihong; Dai, Hao; Zhang, Labao; Cao, Chunhai; Kang, Lin; Xu, Weiwei; Chen, Jian; Wu, Peiheng

    2011-06-20

    Superconducting planar terahertz (THz) metamaterials (MMs), with unit cells of different sizes, are fabricated on 200 nm-thick niobium nitride (NbN) films deposited on MgO substrates. They are characterized using THz time domain spectroscopy over a temperature range from 8.1 K to 300 K, crossing the critical temperature of NbN films. As the gap frequency (f(g) = 2Δ0/h, where Δ0 is the energy gap at 0 K and h is the Plank constant) of NbN is 1.18 THz, the experimentally observed THz spectra span a frequency range from below f(g) to above it. We have found that, as the resonance frequency approaches f(g), the relative tuning range of MMs is quite wide (30%). We attribute this observation to the large change of kinetic inductance of superconducting film.

  11. Superconducting heavy-ion linac at Argonne

    SciTech Connect

    Aron, J.; Benaroya, R.; Bollinger, L.M.; Clifft, B.G.; Johnson, K.W.; Nixon, J.M.; Markovich, P.; Pardo, R.C.; Shepard, K.W.

    1981-01-01

    The design, status, and performance of the first operating superconducting heavy-ion accelerator, a linac used to boost the energies of beams from a 9-MV tandem, is summarized. When completed in 1981, the linac will consist of 24 independently-phased split-ring niobium resonators operating at 97 MHz. This linac is designed to provide 29 MV of acceleration. Because of the modular character of the system, the linac has been operable and useful since mid-1978, when a beam was accelerated through 2 units and the first nuclear-physics experiments were preformed. Now, 16 resonators are in use, and a beam has been accelerated for approx. 6000 h. Resonator performance has been remarkably stable, in spite of vacuum accidents, and the linac as a whole operates reliably without operators in attendance during nights and weekends. The ease and speed with which the beam energy can be changed is proving to be unexpectedly valuable to users.

  12. Superconducting Microwave Electronics at Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Warner, Joseph D.; Bhasin, Kul B.; Leonard, Regis F.

    1991-01-01

    Over the last three years, NASA Lewis Research Center has investigated the application of newly discovered high temperature superconductors to microwave electronics. Using thin films of YBa2Cu3O7-delta and Tl2Ca2Ba2Cu3Ox deposited on a variety of substrates, including strontium titanate, lanthanum gallate, lanthanum aluminate and magnesium oxide, a number of microwave circuits have been fabricated and evaluated. These include a cavity resonator at 60 GHz, microstrip resonators at 35 GHz, a superconducting antenna array at 35 GHz, a dielectric resonator at 9 GHz, and a microstrip filter at 5 GHz. Performance of some of these circuits as well as suggestions for other applications are reported.

  13. Linear and nonlinear behavior of crystalline optical whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy A.; Matsko, Andrey B.; Ilchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We demonstrate strong nonlinear behavior of high-Q whispering gallery mode (WGM) resonators made out of various crystals adn devices based on the resonators. The maximum WGM optical Q-fact or achieved at room temperature exceeds 2X10 to the tenth power.

  14. Superconducting nanostructured materials.

    SciTech Connect

    Metlushko, V.

    1998-07-13

    Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical currents without any energy loss--but there are limits to how much current can flow before superconductivity is destroyed. The current at which superconductivity breaks down is called the critical current. The value of the critical current is determined by the balance of Lorentz forces and pinning forces acting on the flux lines in the superconductor. Lorentz forces proportional to the current flow tend to drive the flux lines into motion, which dissipates energy and destroys zero resistance. Pinning forces created by isolated defects in the microstructure oppose flux line motion and increase the critical current. Many kinds of artificial pinning centers have been proposed and developed to increase critical current performance, ranging from dispersal of small non-superconducting second phases to creation of defects by proton, neutron or heavy ion irradiation. In all of these methods, the pinning centers are randomly distributed over the superconducting material, causing them to operate well below their maximum efficiency. We are overcome this drawback by creating pinning centers in aperiodic lattice (see Fig 1) so that each pin site interacts strongly with only one or a few flux lines.

  15. Gap-plasmon nanoantennas and bowtie resonators

    NASA Astrophysics Data System (ADS)

    Gramotnev, Dmitri K.; Pors, Anders; Willatzen, Morten; Bozhevolnyi, Sergey I.

    2012-01-01

    Plasmonic bowtie resonators involving gap surface plasmons (GSPs) in metal-insulator-metal (MIM) structures, in which only the top metal layer is structured, are investigated using numerical simulations. We demonstrate that the considered configuration features two efficiently excitable GSP resonances associated with distinct charge distributions with the domination of the dipole and quadrupole moments resulting in low- and high-Q resonances, respectively. The typical Q factors for the high-Q resonances are shown to achieve ˜25 in the near-infrared, thus potentially exceeding the quasistatic limit. Detailed physical interpretations of the obtained results and consistent dependencies of the resonance characteristics on the geometrical structural parameters are presented. Excellent resonant characteristics, the simplicity of fabrication, and tuning of the resonance wavelength by adjusting the size of the bowtie arms, separation between them, and/or thickness of the insulator (SiO2) layer in the MIM structure appear attractive for a wide variety of applications, ranging from surface sensing to photovoltaics.

  16. Miniaturization and Optimization of Nanoscale Resonant Oscillators

    DTIC Science & Technology

    2013-09-07

    dielectric cavities can be grouped into two main categories: (i) surface bound (that is, surface plasmon polariton (SPP)) resonant modes and (ii...photonic molecule lasing. IEEE J. Sel. Top. Quantum Electron. 12, 78–85 (2006). 7. Min, B. K. et al. High-Q surface-plasmon– polariton whispering-gallery... polaritons on planar metallic waveguides. Opt. Express 12, 4072–4079 (2004). 16. P. Yeh, A. Yariv, and E. Marom, J. Opt. Soc. Am. 68, 1196 (1978). 17. A

  17. Overview of high-Q2 nucleon form factor program with Super BigBite Spectrometer in JLab's Hall A

    NASA Astrophysics Data System (ADS)

    Puckett, Andrew; Jefferson Lab Hall A; Super BigBite Spectrometer Collaboration

    2017-01-01

    The elastic electromagnetic form factors (EMFFs) of the nucleon describe the impact-parameter-space distributions of electric charge and magnetization in the nucleon in the infinite momentum frame. The form factors are among the simplest and most fundamental measurable dynamical quantities describing the nucleon's structure. Precision measurements of the nucleon form factors provide stringent benchmarks testing the most sophisticated theoretical models of the nucleon, as well as ab initio calculations in lattice QCD and continuum non-perturbative QCD calculations based on the Dyson-Schwinger equations. Measurements at momentum transfers Q in the few-GeV range probe the theoretically challenging region of transition between the non-perturbative and perturbative regimes of QCD. The recent upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) to a maximum electron beam energy of 11 GeV will facilitate the measurement of the nucleon helicity-conserving (F1) and helicity-flip (F2) form factors of both proton and neutron to Q2 > 10 GeV2, In this talk, I will present an overview of the Super BigBite Spectrometer, currently under construction in CEBAF's experimental Hall A, and its physics program of high-Q2 nucleon EMFF measurements. Supported by US DOE award DE-SC0014230.

  18. Whispering Gallery Mode Optomechanical Resonator

    NASA Technical Reports Server (NTRS)

    Aveline, David C.; Strekalov, Dmitry V.; Yu, Nan; Yee, Karl Y.

    2012-01-01

    Great progress has been made in both micromechanical resonators and micro-optical resonators over the past decade, and a new field has recently emerged combining these mechanical and optical systems. In such optomechanical systems, the two resonators are strongly coupled with one influencing the other, and their interaction can yield detectable optical signals that are highly sensitive to the mechanical motion. A particularly high-Q optical system is the whispering gallery mode (WGM) resonator, which has many applications ranging from stable oscillators to inertial sensor devices. There is, however, limited coupling between the optical mode and the resonator s external environment. In order to overcome this limitation, a novel type of optomechanical sensor has been developed, offering great potential for measurements of displacement, acceleration, and mass sensitivity. The proposed hybrid device combines the advantages of all-solid optical WGM resonators with high-quality micro-machined cantilevers. For direct access to the WGM inside the resonator, the idea is to radially cut precise gaps into the perimeter, fabricating a mechanical resonator within the WGM. Also, a strategy to reduce losses has been developed with optimized design of the cantilever geometry and positions of gap surfaces.

  19. Resonating feathers produce courtship song.

    PubMed

    Bostwick, Kimberly S; Elias, Damian O; Mason, Andrew; Montealegre-Z, Fernando

    2010-03-22

    Male Club-winged Manakins, Machaeropterus deliciosus (Aves: Pipridae), produce a sustained tonal sound with specialized wing feathers. The fundamental frequency of the sound produced in nature is approximately 1500 Hz and is hypothesized to result from excitation of resonance in the feathers' hypertrophied shafts. We used laser Doppler vibrometry to determine the resonant properties of male Club-winged Manakin's wing feathers, as well as those of two unspecialized manakin species. The modified wing feathers exhibit a response peak near 1500 Hz, and unusually high Q-values (a measure of resonant tuning) for biological objects (Q up to 27). The unmodified wing feathers of the Club-winged Manakin do not exhibit strong resonant properties when measured in isolation. However, when measured still attached to the modified feathers (nine feathers held adjacent by an intact ligament), they resonate together as a unit near 1500 Hz, and the wing produces a second harmonic of similar or greater amplitude than the fundamental. The feathers of the control species also exhibit resonant peaks around 1500 Hz, but these are significantly weaker, the wing does not resonate as a unit and no harmonics are produced. These results lend critical support to the resonant stridulation hypothesis of sound production in M. deliciosus.

  20. Microwave study of superconducting Sn films above and below percolation

    NASA Astrophysics Data System (ADS)

    Beutel, Manfred H.; Ebensperger, Nikolaj G.; Thiemann, Markus; Untereiner, Gabriele; Fritz, Vincent; Javaheri, Mojtaba; Nägele, Jonathan; Rösslhuber, Roland; Dressel, Martin; Scheffler, Marc

    2016-08-01

    The electronic properties of superconducting Sn films ({T}{{c}}≈ 3.8 {{K}}) change significantly when reducing the film thickness down to a few {nm}, in particular close to the percolation threshold. The low-energy electrodynamics of such Sn samples can be probed via microwave spectroscopy, e.g. with superconducting stripline resonators. Here we study Sn thin films, deposited via thermal evaporation—ranging in thickness between 38 and 842 {nm}—which encompasses the percolation transition. We use superconducting Pb stripline resonators to probe the microwave response of these Sn films in a frequency range between 4 and 20 {GHz} at temperatures from 7.2 down to 1.5 {{K}}. The measured quality factor of the resonators decreases with rising temperature due to enhanced losses. As a function of the sample thickness we observe three regimes with significantly different properties: samples below percolation, i.e. ensembles of disconnected superconducting islands, exhibit dielectric properties with negligible losses, demonstrating that macroscopic current paths are required for appreciable dynamical conductivity of Sn at GHz frequencies. Thick Sn films, as the other limit, lead to low-loss resonances both above and below T c of Sn, as expected for bulk conductors. But in an intermediate thickness regime, just above percolation and with labyrinth-like morphology of the Sn, we observe a quite different behavior: the superconducting state has a microwave response similar to the thicker, completely covering films with low microwave losses; but the metallic state of these Sn films is so lossy that resonator operation is suppressed completely.

  1. Cryogenic Systems and Superconductive Power

    DTIC Science & Technology

    subsystem suitable for providing reliable long-lived cryogenic refrigeration for a superconductive ship propulsion system; and, Provide a sound...technical basis for subsequent applications of superconductive power in the area of ship propulsion .

  2. Superconductivity in diamond.

    PubMed

    Ekimov, E A; Sidorov, V A; Bauer, E D; Mel'nik, N N; Curro, N J; Thompson, J D; Stishov, S M

    2004-04-01

    Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature T(c) approximately 4 K; superconductivity survives in a magnetic field up to Hc2(0) > or = 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.

  3. Adaptive high temperature superconducting filters for interference rejection

    SciTech Connect

    Raihn, K.F.; Fenzi, N.O.; Hey-Shipton, G.L.; Saito, E.R.; Loung, P.V.; Aidnik, D.L.

    1996-07-01

    An optically switched high temperature superconducting (HTS) band-reject filter bank is presented. Fast low loss switching of high quality (Q) factor HTS filter elements enables digital selection of arbitrary pass-bands and stop-bands. Patterned pieces of GaAs and silicon are used in the manufacture of the photosensitive switches. Fiber optic cabling is used to transfer the optical energy from an LED to the switch. The fiber optic cable minimizes the thermal loading of the filter package and de-couples the switch`s power source from the RF circuit. This paper will discuss the development of a computer-controlled HTS bank of optically switchable, narrow band, high Q bandstop filters which incorporates a cryocooler to maintain the 77 K operating temperature of the HTS microwave circuit.

  4. High-Q energy trapping of temperature-stable shear waves with Lamé cross-sectional polarization in a single crystal silicon waveguide

    NASA Astrophysics Data System (ADS)

    Tabrizian, R.; Daruwalla, A.; Ayazi, F.

    2016-03-01

    A multi-port electrostatically driven silicon acoustic cavity is implemented that efficiently traps the energy of a temperature-stable eigen-mode with Lamé cross-sectional polarization. Dispersive behavior of propagating and evanescent guided waves in a ⟨100⟩-aligned single crystal silicon waveguide is used to engineer the acoustic energy distribution of a specific shear eigen-mode that is well known for its low temperature sensitivity when implemented in doped single crystal silicon. Such an acoustic energy trapping in the central region of the acoustic cavity geometry and far from substrate obviates the need for narrow tethers that are conventionally used for non-destructive and high quality factor (Q) energy suspension in MEMS resonators; therefore, the acoustically engineered waveguide can simultaneously serve as in-situ self-oven by passing large uniformly distributed DC currents through its body and without any concern about perturbing the mode shape or deforming narrow supports. Such a stable thermo-structural performance besides large turnover temperatures than can be realized in Lamé eigen-modes make this device suitable for implementation of ultra-stable oven-controlled oscillators. 78 MHz prototypes implemented in arsenic-doped single crystal silicon substrates with different resistivity are transduced by in- and out-of-plane narrow-gap capacitive ports, showing high Q of ˜43k. The low resistivity device shows an overall temperature-induced frequency drift of 200 ppm over the range of -20 °C to 80 °C, which is ˜15× smaller compared to overall frequency drift measured for the similar yet high resistivity device in the same temperature range. Furthermore, a frequency tuning of ˜2100 ppm is achieved in high resistivity device by passing 45 mA DC current through its body. Continuous operation of the device under such a self-ovenizing current over 10 days did not induce frequency instability or degradation in Q.

  5. Relationship between magnetic fluctuations and superconductivity in Na x(H 3O) zCoO 2 · yH 2O revealed by a Co nuclear quadrupole resonance

    NASA Astrophysics Data System (ADS)

    Ishida, K.; Ihara, Y.; Takeya, H.; Michioka, C.; Yoshimura, K.; Takada, K.; Sasaki, T.; Sakurai, H.; Takayama-Muromachi, E.

    2007-09-01

    Nuclear quadrupole frequency (νQ) and spin-lattice relaxation rate 1/T1 of Co were measured on various bilayered hydrate (BLH) NaxCoO2 · yH2O (y ∼ 1.3) with different values of superconducting (SC) and magnetic-transition temperatures, Tc and TM, together with non-SC monolayered hydrate (MLH) NaxCoO2 · yH2O (y ∼ 0.7). In the temperature range above 70 K, 1/T1T in all samples follows the similar temperature dependence as each other. In the BLH compounds, 1/T1T is enhanced with decreasing temperature below 70 K, and the values of 1/T1T at Tc are larger in the higher-ν3 sample, where ν3 is the peak frequency of the NQR spectrum arising from ±5/2 ↔ ±7/2 transitions. The magnetic ordering is indicated from the prominent divergence of 1/T1T at TM and the presence of the internal field at the Co nuclear site in the samples with ν3 higher than 12.5 MHz. We analyze the temperature dependence of 1/T1T in all samples on the basis of identical formula, and discuss the relationship between magnetic fluctuations and superconductivity in the BLH cobaltate.

  6. Interface high-temperature superconductivity

    NASA Astrophysics Data System (ADS)

    Wang, Lili; Ma, Xucun; Xue, Qi-Kun

    2016-12-01

    Cuprate high-temperature superconductors consist of two quasi-two-dimensional (2D) substructures: CuO2 superconducting layers and charge reservoir layers. The superconductivity is realized by charge transfer from the charge reservoir layers into the superconducting layers without chemical dopants and defects being introduced into the latter, similar to modulation-doping in the semiconductor superlattices of AlGaAs/GaAs. Inspired by this scheme, we have been searching for high-temperature superconductivity in ultra-thin films of superconductors epitaxially grown on semiconductor/oxide substrates since 2008. We have observed interface-enhanced superconductivity in both conventional and unconventional superconducting films, including single atomic layer films of Pb and In on Si substrates and single unit cell (UC) films of FeSe on SrTiO3 (STO) substrates. The discovery of high-temperature superconductivity with a superconducting gap of ∼20 meV in 1UC-FeSe/STO has stimulated tremendous interest in the superconductivity community, for it opens a new avenue for both raising superconducting transition temperature and understanding the pairing mechanism of unconventional high-temperature superconductivity. Here, we review mainly the experimental progress on interface-enhanced superconductivity in the three systems mentioned above with emphasis on 1UC-FeSe/STO, studied by scanning tunneling microscopy/spectroscopy, angle-resolved photoemission spectroscopy and transport experiments. We discuss the roles of interfaces and a possible pairing mechanism inferred from these studies.

  7. Superconducting tensor gravity gradiometer

    NASA Technical Reports Server (NTRS)

    Paik, H. J.

    1981-01-01

    The employment of superconductivity and other material properties at cryogenic temperatures to fabricate sensitive, low-drift, gravity gradiometer is described. The device yields a reduction of noise of four orders of magnitude over room temperature gradiometers, and direct summation and subtraction of signals from accelerometers in varying orientations are possible with superconducting circuitry. Additional circuits permit determination of the linear and angular acceleration vectors independent of the measurement of the gravity gradient tensor. A dewar flask capable of maintaining helium in a liquid state for a year's duration is under development by NASA, and a superconducting tensor gravity gradiometer for the NASA Geodynamics Program is intended for a LEO polar trajectory to measure the harmonic expansion coefficients of the earth's gravity field up to order 300.

  8. Nonlinear terahertz superconducting plasmonics

    NASA Astrophysics Data System (ADS)

    Wu, Jingbo; Zhang, Caihong; Liang, Lanju; Jin, Biaobing; Kawayama, Iwao; Murakami, Hironaru; Kang, Lin; Xu, Weiwei; Wang, Huabing; Chen, Jian; Tonouchi, Masayoshi; Wu, Peiheng

    2014-10-01

    Nonlinear terahertz (THz) transmission through subwavelength hole array in superconducting niobium nitride (NbN) film is experimentally investigated using intense THz pulses. The good agreement between the measurement and numerical simulations indicates that the field strength dependent transmission mainly arises from the nonlinear properties of the superconducting film. Under weak THz pulses, the transmission peak can be tuned over a frequency range of 145 GHz which is attributed to the high kinetic inductance of 50 nm-thick NbN film. Utilizing the THz pump-THz probe spectroscopy, we study the dynamic process of transmission spectra and demonstrate that the transition time of such superconducting plasmonic device is within 5 ps.

  9. Encoding quantum information in a stabilized manifold of a superconducting cavity

    NASA Astrophysics Data System (ADS)

    Touzard, S.; Leghtas, Z.; Mundhada, S. O.; Axline, C.; Reagor, M.; Chou, K.; Blumoff, J.; Sliwa, K. M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Mirrahimi, M.; Devoret, M. H.

    In a superconducting Josephson circuit architecture, we activate a multi-photon process between two modes by applying microwave drives at specific frequencies. This creates a pairwise exchange of photons between a high-Q cavity and the environment. The resulting open dynamical system develops a two-dimensional quasi-energy ground state manifold. Can we encode, protect and manipulate quantum information in this manifold? We experimentally investigate the convergence and escape rates in and out of this confined subspace. Finally, using quantum Zeno dynamics, we aim to perform gates which maintain the state in the protected manifold at all times. Work supported by: ARO, ONR, AFOSR and YINQE.

  10. 119Sn-NMR investigations on superconducting Ca3Ir4Sn13: Evidence for multigap superconductivity

    SciTech Connect

    Sarkar, R.; Petrovic, C.; Bruckner, F.; Gunther, M.; Wang, Kefeng; Biswas, P. K.; Luetkens, H.; Morenzoni, E.; Amato, A.; Klauss, H. -H.

    2015-09-25

    In this study, we report bulk superconductivity (SC) in Ca3Ir4Sn13 by means of 119Sn nuclear magnetic resonance (NMR) experiments. Two classical signatures of BCS superconductivity in spin-lattice relaxation rate (1/T1), namely the Hebel–Slichter coherence peak just below the Tc, and the exponential decay in the superconducting phase, are evident. The noticeable decrease of 119Sn Knight shift below Tc indicates spin-singlet superconductivity. The temperature dependence of the spin-lattice relaxation rate 119(1/T1) is convincingly described by the multigap isotropic superconducting gap. NMR experiments do not witness any sign of enhanced spin fluctuations.

  11. Superconducting magnetic quadrupole

    SciTech Connect

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-08-01

    A design was developed for a 350 T/m, 2.6-cm clear aperture superconducting quadrupole focussing element for use in a very low q/m superconducting linac as discussed below. The quadrupole incorporates holmium pole tips, and a rectangular-section winding using standard commercially-available Nb-Ti wire. The magnet was modeled numerically using both 2D and 3D codes, as a basis for numerical ray tracing using the quadrupole as a linac element. Components for a prototype singlet are being procured during FY 1995.

  12. Technology of RF superconductivity

    SciTech Connect

    1995-08-01

    This work has several parts, two of which are collaborative development projects with the majority of the work being performed at Argonne. The first is the development of a superconducting RFQ structure in collaboration with AccSys Technology Inc. of Pleasanton, California, funded as a Phase II SBIR grant. Another is a collaborative project with the Nuclear Science Centre, New Delhi, India (who are funding the work) to develop new superconducting ion accelerating structures. Other initiatives are developing various aspects of the technology required to utilize ATLAS as a secondary beam linac for radioactive beams.

  13. Superconducting Metastable Compounds.

    PubMed

    Luo, H L; Merriam, M F; Hamilton, D C

    1964-08-07

    A number of metastable phases, germanides and tellurides of gold and silver, have been prepared, analyzed by x-ray diffraction, and investigated for superconductivity. The new superconductors and their transition temperatures are AgTe(3) (2.6 degrees K), Ag(4)Ge (0.85 degrees K), Au(3)Te(5) (1.62 degrees K), and Au(1-x)Ge(x) (0.99 degrees K-1.63 degrees K) where (0.27 superconduct above 0.32 degrees K.

  14. Ceramic superconducting components

    NASA Technical Reports Server (NTRS)

    Haertling, G. H.

    1991-01-01

    An approach to the application of high-Tc ceramic superconductors to practical circuit elements was developed and demonstrated. This method, known as the rigid conductor process (RCP), involves the mounting of a preformed, sintered, and tested superconductor material onto an appropriate, rigid substrate with an epoxy adhesive which also serves to encapsulate the element from the ambient environment. Circuit elements such as straight conductors, coils and connectors were fabricated from YBa2Cu3O(7-x) superconducting material. Performance results are included for a low-noise low-thermal-conductivity superconducting grounding link for NASA.

  15. Quantization of inductively shunted superconducting circuits

    NASA Astrophysics Data System (ADS)

    Smith, W. C.; Kou, A.; Vool, U.; Pop, I. M.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.

    2016-10-01

    We present a method for calculating the energy levels of superconducting circuits that contain highly anharmonic, inductively shunted modes with arbitrarily strong coupling. Our method starts by calculating the normal modes of the linearized circuit and proceeds with numerical diagonalization in this basis. As an example, we analyze the Hamiltonian of a fluxonium qubit inductively coupled to a readout resonator. While elementary, this simple example is nontrivial because it cannot be efficiently treated by the method known as "black-box quantization," numerical diagonalization in the bare harmonic oscillator basis, or perturbation theory. Calculated spectra are compared to measured spectroscopy data, demonstrating excellent quantitative agreement between theory and experiment.

  16. Interplay between magnetism and superconductivity in iron-chalcogenide superconductors: crystal growth and characterizations

    NASA Astrophysics Data System (ADS)

    Wen, Jinsheng; Xu, Guangyong; Gu, Genda; Tranquada, J. M.; Birgeneau, R. J.

    2011-12-01

    In this review, we present a summary of results on single crystal growth of two types of iron-chalcogenide superconductors, Fe1+yTe1-xSex (11), and AxFe2-ySe2 (A = K, Rb, Cs, Tl, Tl/K, Tl/Rb), using Bridgman, zone-melting, vapor self-transport and flux techniques. The superconducting and magnetic properties (the latter gained mainly from neutron scattering measurements) of these materials are reviewed to demonstrate the connection between magnetism and superconductivity. It will be shown that for the 11 system, while static magnetic order around the reciprocal lattice position (0.5, 0) competes with superconductivity, spin excitations centered around (0.5, 0.5) are closely coupled to the materials' superconductivity; this is made evident by the strong correlation between the spectral weight around (0.5, 0.5) and the superconducting volume fraction. The observation of a spin resonance below the superconducting temperature, Tc, and the magnetic-field dependence of the resonance emphasize the close interplay between spin excitations and superconductivity, similar to cuprate superconductors. In AxFe2-ySe2, superconductivity with Tc ~ 30 K borders an antiferromagnetic insulating phase; this is closer to the behavior observed in the cuprates but differs from that in other iron-based superconductors.

  17. High-Q ultrasonic determination of the critical nanoaggregate concentration of asphaltenes and the critical micelle concentration of standard surfactants.

    PubMed

    Andreatta, Gaëlle; Bostrom, Neil; Mullins, Oliver C

    2005-03-29

    Asphaltenes are known to be interfacially active in many circumstances such as at toluene-water interfaces. Furthermore, the term micelle has been used to describe the primary aggregation of asphaltenes in good solvents such as toluene. Nevertheless, there has been significant uncertainty regarding the critical micelle concentration (CMC) of asphaltenes and even whether the micelle concept is appropriate for asphaltenes. To avoid semantic debates we introduce the terminology critical nanoaggregate concentration (CNAC) for asphaltenes. In this report, we investigate asphaltenes and standard surfactants using high-Q, ultrasonic spectroscopy in both aqueous and organic solvents. As expected, standard surfactants are shown to exhibit a sharp break in sonic velocity versus concentration at known CMCs. To prove our methods, we measured known surfactants with CMCs in the range from 0.010 g/L to 2.3 g/L in agreement with the literature. Using density determinations, we obtain micelle compressibilities consistent with previous literature reports. Asphaltenes are also shown to exhibit behavior similar to that of ultrasonic velocity versus concentration as standard surfactants; asphaltene CNACs in toluene occur at roughly 0.1 g/L, although the exact concentration depends on the specific (crude oil) asphaltene. Furthermore, using asphaltene solution densities, we show that asphaltene nanoaggregate compressibilities are similar to micellar compressibilities obtained with standard nonionic surfactants in toluene. These results strongly support the contention that asphaltenes in toluene can be treated roughly within the micelle framework, although asphaltenes may exhibit small levels of aggregation (dimers, etc.) below their CNAC. Furthermore, our extensive results on known surfactants agree with the literature while the asphaltene CNACs reported here are one to two orders of magnitude lower than most previously published results. (Previous work utilized the terminology "micelle

  18. Local Magnetic Order vs Superconductivity in a Layered Cuprate

    NASA Astrophysics Data System (ADS)

    Ichikawa, N.; Uchida, S.; Tranquada, J. M.; Niemöller, T.; Gehring, P. M.; Lee, S.-H.; Schneider, J. R.

    2000-08-01

    We report on the phase diagram for charge-stripe order in La1.6-xNd0.4SrxCuO4, determined by neutron and x-ray scattering studies and resistivity measurements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition temperature for local charge ordering decreases monotonically with x, and hence that local antiferromagnetic order is uniquely correlated with the anomalous depression of superconductivity at x~18. This result is consistent with theories in which superconductivity depends on the existence of charge-stripe correlations.

  19. Unusual nature of ferromagnetism coexisting with superconductivity in UGe2.

    PubMed

    Nishioka, T; Motoyama, G; Nakamura, S; Kadoya, H; Sato, N K

    2002-06-10

    We report the discovery of a jump in the magnetization of a macroscopic single crystalline sample of UGe2 that shows coexistence of ferromagnetism and superconductivity. In particular, we observe that the jump occurs at regular intervals of field and only at very low temperatures. This novel feature implies that the magnetic field induces a sudden change of the direction of the magnetization between two equivalent easy axes of magnetization even in a macroscopic sample. We ascribe it to a field-tuned resonant tunneling between quantum spin states, and we propose that the size of a magnetic domain is smaller than a superconducting coherence length.

  20. Superconducting travelling wave ring with high gradient accelerating section

    SciTech Connect

    Avrakhov, P.; Solyak, N.; /Fermilab

    2007-06-01

    Use of a superconducting traveling wave accelerating (STWA) structure instead of a standing wave cavity has major advantages in increasing the accelerating gradient in the ILC. In contrast with standing wave cavity STWA requires feedback loop, which sends wave from the structure output to input, making a superconducting traveling wave ring (STWR). One or few input couplers need to excite STWR and compensate power dissipations due to beam loading. To control traveling wave regime in the structure two independent knobs can be used for tuning both resonant ring frequency and backward wave. We discuss two variants of the STWR with one and two feed couplers.