Quantum dynamics from the Brownian recoil principle
NASA Astrophysics Data System (ADS)
Garbaczewski, Piotr; Vigier, Jean-Pierre
1992-10-01
We formulate a theory of the Brownian motion for particle ensembles, whose diffusive evolution is entirely generated by the surrounding random environment. By demanding the validity of the momentum conservation law on all conceivable scales adopted for the investigation of individual particle scattering (collisions) on the medium constituents, we are forced to incorporate the environmental recoil effects in the formalism. The Brownian recoil principle elevates the individually negligible phenomena to the momentum conservation law on the ensemble average. The resultant dynamics of the statistical ensemble is governed by the Schrödinger equation, once the diffusion constant D is identified with ?/2m.
Quantum dynamics from the Brownian recoil principle
Piotr Garbaczewski; Jean-Pierre Vigier
1992-01-01
We formulate a theory of the Brownian motion for particle ensembles, whose diffusive evolution is entirely generated by the surrounding random environment. By demanding the validity of the momentum conservation law on all conceivable scales adopted for the investigation of individual particle scattering (collisions) on the medium constituents, we are forced to incorporate the environmental recoil effects in the formalism.
FISSION FRAGMENT RECOIL EFFECTS ON ZIRCONIUM OXIDATION
W. C. Yee; G. H. Jenks; E. E. Stansbury
1962-01-01
Fission fragment recoil effects on zirconium oxidation in pure oxygen ; were studied at 1 atm pressure and 250 deg C. Specimens were oxidized under the ; following conditions: reactor radiations including recoils, reactor radiations in ; the absence of recoils, and no radiation. Irradiation experiments were conducted ; in a maximum thermal neutron flux of 8.5 x 10Â¹Â¹ neutrons\\/cmÂ²-sec.
Accounting for Recoil Effects in Geochronometers: A New Model Approach
NASA Astrophysics Data System (ADS)
Lee, V. E.; Huber, C.
2012-12-01
A number of geologically important chronometers are affected by, or owe their utility to, the "recoil effect". This effect describes the physical displacement of a nuclide due to energetic nuclear processes such as radioactive alpha decay (as in the case of various parent-daughter pairs in the uranium-series decay chains, and Sm-Nd), as well as neutron irradiation (in the case of the methodology for the 40Ar/39Ar dating method). The broad range of affected geochronometers means that the recoil effect can impact a wide range of dating method applications in the geosciences, including but not limited to: Earth surface processes, paleoclimate, volcanic processes, and cosmochemistry and planetary evolution. In particular, the recoil effect can have a notable impact on the use of fine grains (silt- and clay-sized particles) for geochronometric dating purposes. This is because recoil-induced loss of a nuclide from the surfaces of a grain can create an isotopically-depleted outer rind, and for small grains, this depleted rind can be volumetrically significant. When this recoil loss is measurable and occurs in a known time-dependent fashion, it can usefully serve as the basis for chronometers (such as the U-series comminution age method); in other cases recoil loss from fine particles creates an unwanted deviation from expected isotope values (such as for the Ar-Ar method). To improve both the accuracy and precision of ages inferred from geochronometric systems that involve the recoil of a key nuclide from small domains, it is necessary to quantify the magnitude of the recoil loss of that particular nuclide. It is also necessary to quantitatively describe the effect of geological processes that can alter the outer surface of grains, and hence the isotopically-depleted rind. Here we present a new mathematical and numerical model that includes two main features that enable enhanced accuracy and precision of ages determined from geochronometers. Since the surface area of the dated grain is a major control on the magnitude of recoil loss, the first feature is the ability to calculate recoil effects on isotopic compositions for realistic, complex grain shapes and surface roughnesses. This is useful because natural grains may have irregular shapes that do not conform to simple geometric descriptions. Perhaps more importantly, the surface area over which recoiled nuclides are lost can be significantly underestimated when grain surface roughness is not accounted for, since the recoil distances can be of similar characteristic lengthscales to surface roughness features. The second key feature is the ability to incorporate dynamical geologic processes affecting grain surfaces in natural settings, such as dissolution and crystallization. We describe the model and its main components, and point out implications for the geologically-relevant chronometers mentioned above.
Effects of gravitational-wave recoil on the dynamics and growth of supermassive black holes
Laura Blecha; Abraham Loeb
2008-08-01
Simulations of binary black hole mergers indicate that asymmetrical gravitational wave (GW) emission can cause black holes to recoil at speeds up to thousands of km/s. These GW recoil events can dramatically affect the coevolution of recoiling supermassive black holes (SMBHs) and their host galaxies. However, theoretical studies of SMBH-galaxy evolution almost always assume a stationary central black hole. In light of the numerical results on GW recoil velocities, we relax that assumption here and consider the consequences of recoil for SMBH evolution. We follow the trajectories of SMBHs ejected in a smooth background potential that includes both a stellar bulge and a multi-component gaseous disk. In addition, we calculate the accretion rate onto the SMBH as a function of time using a hybrid prescription of viscous (alpha-disk) and Bondi accretion. We find that recoil kicks between 100 km/s and the escape speed cause SMBHs to wander through the galaxy and halo for about 1 Myr - 1 Gyr before settling back to the galactic center. However, the mass accreted during this time is roughly constant at about 10% of the initial mass, independent of the recoil velocity. This indicates that while large recoils may disrupt active galactic nuclei feedback processes, recoil itself is an effective means of regulating SMBH growth. Recoiling SMBHs may be observable as spatially or kinematically offset quasars, but finding such systems could be challenging, because the largest offsets correspond to the shortest quasar lifetimes.
Dielectric barrier structure with hollow electrodes and its recoil effect
NASA Astrophysics Data System (ADS)
Yu, Shuang; Chen, Qunzhi; Liu, Jiahui; Wang, Kaile; Jiang, Zhe; Sun, Zhili; Zhang, Jue; Fang, Jing
2015-06-01
A dielectric barrier structure with hollow electrodes (HEDBS), in which gas flow oriented parallel to the electric field, was proposed. Results showed that with this structure, air can be effectively ignited, forming atmospheric low temperature plasma, and the proposed HEDBS could achieve much higher electron density (5 × 1015/cm3). It was also found that the flow condition, including outlet diameter and flow rate, played a key role in the evolution of electron density. Optical emission spectroscopy diagnostic results showed that the concentration of reactive species had the same variation trend as the electron density. The simulated distribution of discharge gas flow indicated that the HEDBS had a strong recoil effect on discharge gas, and could efficiently promote generating electron density as well as reactive species.
Radiation Recoil Effects on the Dynamical Evolution of Asteroids
NASA Astrophysics Data System (ADS)
Cotto-Figueroa, Desiree
The Yarkovsky effect is a radiation recoil force that results in a semimajor axis drift in the orbit that can cause Main Belt asteroids to be delivered to powerful resonances from which they could be transported to Earth-crossing orbits. This force depends on the spin state of the object, which is modified by the YORP effect, a variation of the Yarkovsky effect that results in a torque that changes the spin rate and the obliquity. Extensive analyses of the basic behavior of the YORP effect have been previously conducted in the context of the classical spin state evolution of rigid bodies (YORP cycle). However, the YORP effect has an extreme sensitivity to the topography of the asteroids and a minor change in the shape of an aggregate asteroid can stochastically change the YORP torques. Here we present the results of the first simulations that self-consistently model the YORP effect on the spin states of dynamically evolving aggregates. For these simulations we have developed several algorithms and combined them with two codes, TACO and pkdgrav. TACO is a thermophysical asteroid code that models the surface of an asteroid using a triangular facet representation and which can compute the YORP torques. The code pkdgrav is a cosmological N-body tree code modified to simulate the dynamical evolution of asteroids represented as aggregates of spheres using gravity and collisions. The continuous changes in the shape of an aggregate result in a different evolution of the YORP torques and therefore aggregates do not evolve through the YORP cycle as a rigid body would. Instead of having a spin evolution ruled by long periods of rotational acceleration and deceleration as predicted by the classical YORP cycle, the YORP effect is self-limiting and stochastic on aggregate asteroids. We provide a statistical description of the spin state evolution which lays out the foundation for new simulations of a coupled Yarkovsky/YORP evolution. Both self-limiting YORP and to a lesser degree a stochastic YORP provide a viable means to explain why the Near-Earth Asteroid (NEA) population seems to remember their initial spin states at the time of delivery from the Main Belt. The YORP effect drives the obliquity of most objects that follow the YORP cycle to the values of 0, 90 and 180 degrees. NEAs could complete a YORP cycle on timescales much shorter than their typical dynamical lifetime. Therefore, one should expect the obliquity distribution of the population of NEAs to be concentrated about those values if they follow the YORP cycle. But to obtain a direct measurement of the obliquity distribution will require radar observations or multiple lightcurves at different illumination and orbital phases for each NEA. Instead of obtaining a direct measurement, the obliquity distribution can be inferred if the distribution of semimajor axis drift rates due to the Yarkovsky effect can be measured. From the linear heat diffusion theory for a spherical body, the semimajor axis drift rate varies linearly with cosine obliquity. Previous studies have attempted to infer the obliquity distribution taking advantage of this simple dependence. However, those results should be considered only approximate because of the neglect of the dependence of the semimajor axis drift rate on density, thermal properties, and shape. Here we seek to obtain the obliquity distribution of NEAs using a better approach based on Bayesian inference that takes into account our prior knowledge of the distributions of the physical parameters on which the semimajor axis drift rates depend. A preliminary obliquity distribution of the NEA population has been estimated to be a V-shaped model that lacks a concentration of objects at an obliquity of 90 degrees and which suggests that the most probable value of the fraction of retrograde rotators is 70.0%. Once the obliquity distribution is obtained, it can in turn be used to test YORP predictions and constrain YORP evolution.
Is CHF triggered by the vapor recoil effect?
Nikolayev, Vadim S; Chatain, D
2007-01-01
This paper deals with the triggering mechanism of the boiling crisis, a transition from nucleate to film boiling. We observe the boiling crisis in pool saturated boiling experimentally at nearly critical pressure to take advantage of the slowness of the bubble growth and of the smallness of the Critical Heat Flux (CHF) that defines the transition point. Such experiments require the reduced gravity conditions. Close to the CHF, the slow growth of the individual dry spots and their subsequent fusion on the transparent heater are observed through the latter. As discussed in the paper, these observations are consistent with numerical results obtained with the vapor recoil model of the boiling crisis.
Finite nuclear size corrections to the recoil effect in hydrogenlike ions
NASA Astrophysics Data System (ADS)
Aleksandrov, I. A.; Shchepetnov, A. A.; Glazov, D. A.; Shabaev, V. M.
2015-07-01
The finite nuclear size corrections to the relativistic recoil effect in H-like ions are calculated within the Breit approximation. The calculations are performed for the 1s, 2s, and 2p1/2 states in the range Z = 1–110. The obtained results are compared with previous evaluations of this effect. It is found that for heavy ions the previously neglected corrections amount to about 20% of the total nuclear size contribution to the recoil effect calculated within the Breit approximation.
Searching for universal behaviour in superheated droplet detector with effective recoil nuclei
NASA Astrophysics Data System (ADS)
Das, Mala; Seth, Susnata
2013-06-01
Energy calibration of superheated droplet detector is discussed in terms of the effective recoil nucleus threshold energy and the reduced superheat. This provides a universal energy calibration curve valid for different liquids used in this type of detector. Two widely used liquids, R114 and C4F10, one for neutron detection and the other for WIMPs dark matter search experiment, have been compared. Liquid having recoil nuclei with larger values of LET provides better neutron and gamma discrimination. Gamma response of C4F10 has also been studied and the results are discussed. Behaviour of nucleation parameter with the effective recoil nucleus threshold energy and the reduced superheat have been explored.
Effect of pressure on the radiation annealing of recoil atoms in chromates
M. I. Stamouli
1986-01-01
The effect of pressure on the annealing of recoil atoms by gamma radiation in neutron irradiated potassium chromate, ammonium chromate and ammonium dichromate has been studied. In potassium chromate pressure applied before the gamma-irradiation was found to retard the radiation annealing process. In ammonium chromate and ammonium dichromate the radiation annealing was found to be enhanced in the compressed samples
NASA Astrophysics Data System (ADS)
Trappitsch, Reto; Leya, Ingo
2013-02-01
We present a purely physical model to determine cosmogenic production rates for noble gases and radionuclides in micrometeorites (MMs) and interplanetary dust particles (IDPs) by solar cosmic-rays (SCR) and galactic cosmic-rays (GCR) fully considering recoil loss effects. Our model is based on various nuclear model codes to calculate recoil cross sections, recoil ranges, and finally the percentages of the cosmogenic nuclides that are lost as a function of grain size, chemical composition of the grain, and the spectral distribution of the projectiles. The main advantage of our new model compared with earlier approaches is that we consider the entire SCR particle spectrum up to 240 MeV and not only single energy points. Recoil losses for GCR-produced nuclides are assumed to be equal to recoil losses for SCR-produced nuclides. Combining the model predictions with Poynting-Robertson orbital lifetimes, we calculate cosmic-ray exposure ages for recently studied MMs, cosmic spherules, and IDPs. The ages for MMs and the cosmic-spherule are in the range <2.2-233 Ma, which corresponds, according to the Poynting-Robertson drag, to orbital distances in the range 4.0-34 AU. For two IDPs, we determine exposure ages of longer than 900 Ma, which corresponds to orbital distances larger than 150 AU. The orbital distance in the range 4-6 AU for one MM and the cosmic spherule indicate an origin either in the asteroid belt or release from comets coming either from the Kuiper Belt or the Oort Cloud. Three of the studied MMs have orbital distances in the range 23-34 AU, clearly indicating a cometary origin, either from short-period comets from the Kuiper Belt or from the Oort Cloud. The two IDPs have orbital distances of more than 150 AU, indicating an origin from Oort Cloud comets.
Interference, recoil, and uncontrollable interaction
NASA Astrophysics Data System (ADS)
Ulfbeck, Ole
2014-07-01
When the initial state in a collision involves indeterminate momenta, the conservation law for momentum no longer applies to the individual event with a sharpness beyond the indeterminacy. As a consequence, there are collisions that are recoilless in the sense that the state of one of the quanta is unchanged by the collision while the other quantum emerges in a superposition of momenta. Recoilless collisions that avoid entanglement are basic for experiments studying coherence effects for individual quanta involving interactions of the quantum with reflectors or diaphragms. The idea that in interference experiments there is an inevitable recoil that can be made unobservable by firmly bolting the reflector or diaphragm to a solid support is false since in interference with individual quanta there is no recoil to control. The highly quantal character of the reflector or diaphragm in the interference experiment apparently went unnoticed in the conception of complementarity.
Black hole as a point radiator and recoil effect on the brane world.
Frolov, Valeri; Stojkovi?, Dejan
2002-10-01
A small black hole attached to a brane in a higher-dimensional space emitting quanta into the bulk may leave the brane as a result of a recoil. We construct a field theory model in which such a black hole is described as a massive scalar particle with internal degrees of freedom. In this model, the probability of transition between the different internal levels is identical to the probability of thermal emission calculated for the Schwarzschild black hole. The discussed recoil effect implies that the thermal emission of the black holes, which might be created by interaction of high energy particles in colliders, could be terminated and the energy nonconservation can be observed in the brane experiments. PMID:12365979
Remote recoil: a new wave-mean interaction effect
MICHAEL E. Mc
We present a theoretical study of a fundamentally new wave-mean or wave-vortex interaction effect able to force persistent, cumulative change in mean flows in the absence of wave breaking or other kinds of wave dissipation. It is associated with the refraction of non-dissipating waves by inhomogeneous mean (vortical) flows. The effect is studied in detail in the simplest relevant model,
Quantum effects in electron beam pumped GaAs
NASA Astrophysics Data System (ADS)
Yahia, M. E.; Azzouz, I. M.; Moslem, W. M.
2013-08-01
Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.
Quantum effects in electron beam pumped GaAs
Yahia, M. E. [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt) [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Azzouz, I. M. [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt)] [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)] [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)
2013-08-19
Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.
Quantum radiation reaction effects in multiphoton Compton scattering
A. Di Piazza; K. Z. Hatsagortsyan; C. H. Keitel
2010-11-24
Radiation reaction effects in the interaction of an electron and a strong laser field are investigated in the realm of quantum electrodynamics. We identify quantum radiation reaction with the multiple photon recoils experienced by the laser-driven electron due to consecutive incoherent photon emissions. After determining a quantum radiation dominated regime, we demonstrate how in this regime quantum signatures of radiation reaction strongly affect multiphoton Compton scattering spectra and that they could be measurable in principle with presently available laser technology.
Piszczatowski, Konrad; Komasa, Jacek; Jeziorski, Bogumil; Szalewicz, Krzysztof
2015-01-01
Future metrology standards will be partly based on physical quantities computed from first principles rather than measured. In particular, a new pressure standard can be established if the dynamic polarizability of helium can be determined from theory with an uncertainty smaller than 0.2 ppm. We present calculations of the frequency-dependent part of this quantity including relativistic effects with full account of leading nuclear recoil terms and using highly optimized explicitly correlated basis sets. A particular emphasis is put on uncertainty estimates. At the He-Ne laser wavelength of 632.9908 nm, the computed polarizability value of 1.391 811 41 a.u. has uncertainty of 0.1 ppm that is two orders of magnitude smaller than those of the most accurate polarizability measurements. We also obtained an accurate expansion of the helium refractive index in powers of density.
Piszczatowski, Konrad; Puchalski, Mariusz; Komasa, Jacek; Jeziorski, Bogumi?; Szalewicz, Krzysztof
2015-05-01
Future metrology standards will be partly based on physical quantities computed from first principles rather than measured. In particular, a new pressure standard can be established if the dynamic polarizability of helium can be determined from theory with an uncertainty smaller than 0.2 ppm. We present calculations of the frequency-dependent part of this quantity including relativistic effects with full account of leading nuclear recoil terms and using highly optimized explicitly correlated basis sets. A particular emphasis is put on uncertainty estimates. At the He-Ne laser wavelength of 632.9908 nm, the computed polarizability value of 1.39181141 a.u. has uncertainty of 0.1 ppm that is 2 orders of magnitude smaller than those of the most accurate polarizability measurements. We also obtained an accurate expansion of the helium refractive index in powers of density. PMID:25978230
NASA Astrophysics Data System (ADS)
Piszczatowski, Konrad; Puchalski, Mariusz; Komasa, Jacek; Jeziorski, Bogumi?; Szalewicz, Krzysztof
2015-05-01
Future metrology standards will be partly based on physical quantities computed from first principles rather than measured. In particular, a new pressure standard can be established if the dynamic polarizability of helium can be determined from theory with an uncertainty smaller than 0.2 ppm. We present calculations of the frequency-dependent part of this quantity including relativistic effects with full account of leading nuclear recoil terms and using highly optimized explicitly correlated basis sets. A particular emphasis is put on uncertainty estimates. At the He-Ne laser wavelength of 632.9908 nm, the computed polarizability value of 1.39181141 a.u. has uncertainty of 0.1 ppm that is 2 orders of magnitude smaller than those of the most accurate polarizability measurements. We also obtained an accurate expansion of the helium refractive index in powers of density.
The effect of gravitational-wave recoil on the demography of massive black holes
Piero Madau; Eliot Quataert
2004-03-11
The coalescence of massive black hole (MBH) binaries following galaxy mergers is one of the main sources of low-frequency gravitational radiation. A higher-order relativistic phenomenon, the recoil as a result of the non-zero net linear momentum carried away by gravitational waves, may have interesting consequences for the demography of MBHs at the centers of galaxies. We study the dynamics of recoiling MBHs and its observational consequences. The ``gravitational rocket'' may: i) deplete MBHs from late-type spirals, dwarf galaxies, and stellar clusters; ii) produce off-nuclear quasars, including unusual radio morphologies during the recoil of a radio-loud source; and iii) give rise to a population of interstellar and intergalactic MBHs.
The Effect of Gravitational-Wave Recoil on the Demography of Massive Black Holes
NASA Astrophysics Data System (ADS)
Madau, Piero; Quataert, Eliot
2004-05-01
The coalescence of massive black hole (MBH) binaries following galaxy mergers is one of the main sources of low-frequency gravitational radiation. A higher order relativistic phenomenon, the recoil as a result of the nonzero net linear momentum carried away by gravitational waves, may have interesting consequences for the demography of MBHs at the centers of galaxies. We study the dynamics of recoiling MBHs and its observational consequences. The ``gravitational rocket'' may (1) deplete MBHs from late-type spiral galaxies, dwarf galaxies, and stellar clusters; (2) produce off-nuclear quasars, including unusual radio morphologies during the recoil of a radio-loud source; and (3) give rise to a population of interstellar and intergalactic MBHs.
Molecular modeling of the effects of 40Ar recoil in illite particles on their K-Ar isotope dating
NASA Astrophysics Data System (ADS)
Szczerba, Marek; Derkowski, Arkadiusz; Kalinichev, Andrey G.; ?rodo?, Jan
2015-06-01
The radioactive decay of 40K to 40Ar is the basis of isotope age determination of micaceous clay minerals formed during diagenesis. The difference in K-Ar ages between fine and coarse grained illite particles has been interpreted using detrital-authigenic components system, its crystallization history or post-crystallization diffusion. Yet another mechanism should also be considered: natural 40Ar recoil. Whether this recoil mechanism can result in a significant enough loss of 40Ar to provide observable decrease of K-Ar age of the finest illite crystallites at diagenetic temperatures - is the primary objective of this study which is based on molecular dynamics (MD) computer simulations. All the simulations were performed for the same kinetic energy (initial velocity) of the 40Ar atom, but for varying recoil angles that cover the entire range of their possible values. The results show that 40Ar recoil can lead to various deformations of the illite structure, often accompanied by the displacement of OH groups or breaking of the Si-O bonds. Depending on the recoil angle, there are four possible final positions of the 40Ar atom with respect to the 2:1 layer at the end of the simulation: it can remain in the interlayer space or end up in the closest tetrahedral, octahedral or the opposite tetrahedral sheet. No simulation angles were found for which the 40Ar atom after recoil passes completely through the 2:1 layer. The energy barrier for 40Ar passing through the hexagonal cavity from the tetrahedral sheet into the interlayer was calculated to be 17 kcal/mol. This reaction is strongly exothermic, therefore there is almost no possibility for 40Ar to remain in the tetrahedral sheet of the 2:1 layer over geological time periods. It will either leave the crystal, if close enough to the edge, or return to the interlayer space. On the other hand, if 40Ar ends up in the octahedral sheet after recoil, a substantially higher energy barrier of 55 kcal/mol prevents it from leaving the TOT layer over geological time. Based on the results of MD simulations, the estimates of the potential effect of 40Ar recoil on the K-Ar dating of illite show that some of 40Ar is lost and the loss is substantially dependent on the crystallite dimensions. The 40Ar loss can vary from 10% for the finest crystallites (two 2:1 layers thickness and <0.02 ?m in diameter) to close to zero for the thickest and largest (in the ab plane) ones. Because the decrease of the K-Ar estimated age is approximately proportional to the 40Ar loss, the finer crystallites show lower apparent age than the coarser ones, although the age of crystallization is assumed equal for all the crystallites. From the model it is also clear that the lack of K removal from illite fringes (potentially Ar-free) strongly increases the apparent age differences among crystallites of different size.
NASA Astrophysics Data System (ADS)
Hoffman, Jacek
2015-06-01
Our experiments with the ablation of graphite by a nanosecond laser pulse showed the formation of craters with a depth of upto 60 µm. The creation of such deep craters is hard to explain solely by evaporation. Existing models should be supplemented by an additional mass removal process that ensures penetration of the material. The recoil pressure at the surface of the target generates a compression wave propagating deep into the material. Possible mechanisms of fracture by the longitudinal compression wave are discussed. A phenomenological model of material fragmentation is proposed. Modelling results are in good agreement with the experiment. The model may be used for polycrystalline graphite as well as other brittle materials treated by the nanosecond laser pulse.
Paris-Sud XI, Université de
-321 IRRADIATION DAMAGE CASCADES AND (n, y ) RECOIL EFFECTS IN LOW-TEMPERATURE IRRADIATED a-TIN MONITORED'echantillon utilisB comme absorbant indiquent une transmutation en Btain metallique dans la region descascadesde macroscopic changes by fission neutrons in absorber experiments and low-energy recoil events from (n, y
Fluctuations in recoil numbers
NASA Astrophysics Data System (ADS)
Winterbon, K. B.
The variance of the number of high-energy recoils produced in a cascade is calculated in the power-cross-section approximation. These' recoils have initial energy greater than some specified threshold value, which in turn is greater than a displacement energy. Displacement energy is neglected in this calculation. This distribution of high-energy-recoil number is wider than the Kinchin-Pease distribution but narrower than a Poisson distribution: the variance is (asymptotically) proportional to the number of recoils for all three, and the proportionality constant for the recoil number is greater than the Kinchin-Pease constant but less than unity. Both the asymptotic value of the variance and the energy dependence are obtained. These quantities should be of interest in the study of recoil implantation.
Force optimized recoil control system
NASA Astrophysics Data System (ADS)
Townsend, P. E.; Radkiewicz, R. J.; Gartner, R. F.
1982-05-01
Reduction of the recoil force of high rate of fire automatic guns was proven effective. This system will allow consideration of more powerful guns for use in both helicopter and armored personnel carrier applications. By substituting the large shock loads of firing guns with a nearly constant force, both vibration and fatigue problems that prevent mounting of powerful automatic guns is eliminated.
Force optimized recoil control system
P. E. Townsend; R. J. Radkiewicz; R. F. Gartner
1982-01-01
Reduction of the recoil force of high rate of fire automatic guns was proven effective. This system will allow consideration of more powerful guns for use in both helicopter and armored personnel carrier applications. By substituting the large shock loads of firing guns with a nearly constant force, both vibration and fatigue problems that prevent mounting of powerful automatic guns
Campanelli, Manuela; Lousto, Carlos O; Zlochower, Yosef; Merritt, David
2007-06-01
Recent calculations of gravitational radiation recoil generated during black-hole binary mergers have reopened the possibility that a merged binary can be ejected even from the nucleus of a massive host galaxy. Here we report the first systematic study of gravitational recoil of equal-mass binaries with equal, but counteraligned, spins parallel to the orbital plane. Such an orientation of the spins is expected to maximize the recoil. We find that recoil velocity (which is perpendicular to the orbital plane) varies sinusoidally with the angle that the initial spin directions make with the initial linear momenta of each hole and scales up to a maximum of approximately 4000 km s-1 for maximally rotating holes. Our results show that the amplitude of the recoil velocity can depend sensitively on spin orientations of the black holes prior to merger. PMID:17677894
Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-01-15
The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.
Condition detection and fault diagnosis system for recoil system based on simulation
Lijun Cao; Huibin Hu; Junqi Qin
2009-01-01
Dynamic analysis is carried out for recoil parts in recoil and counter-recoil process to find out the fault effects of liquid and gas leakage of recoil brake and recuperator. In order to detect and simulate the fault occurrence and development process, virtual prototyping is firstly adopted into fault simulation and detection fields in this paper. The basic steps of virtual
The HERMES Recoil Detector Recoil Detector Test Beams
detector versus the of the incoming particle and the position of incidence on the strip. The data was takenThe HERMES Recoil Detector Recoil Detector Test Beams A will be installed to the HERMES experiment of fromprotons recoil detector Deeply Virtual Compton Scattering (DVCS). Recoil proton momentum versus polar
Transport of Radioactive Material by Alpha Recoil
Icenhour, A.S.
2005-05-19
The movement of high-specific-activity radioactive particles (i.e., alpha recoil) has been observed and studied since the early 1900s. These studies have been motivated by concerns about containment of radioactivity and the protection of human health. Additionally, studies have investigated the potential advantage of alpha recoil to effect separations of various isotopes. This report provides a review of the observations and results of a number of the studies.
Boost, recoil, and Wigner rotation effects on no-pair analyses of proton elastic scattering
NASA Astrophysics Data System (ADS)
Tjon, J. A.; Wallace, S. J.
1991-09-01
The relativistic ``no-pair'' potential for elastic proton scattering is shown to reduce to a conventional t? form using optimal factorization of the optical potential and the impulse approximation. The nucleon-nucleon t matrix is needed in the Breit frame and it may be obtained by boosting the NN c.m. frame t matrix. It is shown that the general form of the boost involves a Moller factor, Wigner rotation operators acting on spins, and a Lorentz boost of momentum arguments. The reduction to t? form clarifies how the no-pair analysis differs from conventional Watson or Kerman, McManus, and Thaler (KMT) analyses which usually omit Wigner rotation effects and use a Galilean boost of momentum arguments of the t matrix instead of a Lorentz boost. Recent calculations in momentum space have found rather minor off-shell effects based on the no-pair analysis but other calculations have reported substantial effects based on the KMT formalism. Off-shell effects owing to the momentum dependence of the NN t matrix are found to be considerably smaller than the difference between published no-pair and KMT calculations. It is shown that technical differences, predominantly caused by use of a Galilean boost and inaccurate Coulomb corrections, are capable of explaining the disparate results at least at 200 MeV. Wigner rotations are found to cause negligible differences in proton scattering observables at 200 and 500 MeV. KMT calculations based on a Lorentz boost and accurate Coulomb corrections in momentum space yield rather minor off-shell effects owing to the momentum dependence of the NN t matrix in essential agreement with the no-pair analysis.
High acceptance recoil polarimeter
The HARP Collaboration
1992-12-05
In order to detect neutrons and protons in the 50 to 600 MeV energy range and measure their polarization, an efficient, low-noise, self-calibrating device is being designed. This detector, known as the High Acceptance Recoil Polarimeter (HARP), is based on the recoil principle of proton detection from np[r arrow]n[prime]p[prime] or pp[r arrow]p[prime]p[prime] scattering (detected particles are underlined) which intrinsically yields polarization information on the incoming particle. HARP will be commissioned to carry out experiments in 1994.
NASA Astrophysics Data System (ADS)
Zhang, Shoucheng
2008-12-01
Search for topologically non-trivial states of matter has become a prime goal for condensed matter physics. Recently, a new class of topological insulators has been proposed. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. In two dimensions the edge states give rise to the quantum spin Hall (QSH) effect, in the absence of any external magnetic field. We show that the QSH state can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the electronic state changes at a critical thickness. This is a topological quantum phase transition between a conventional insulating phase and a phase exhibiting the QSH effect with a single pair of helical edge states. This theoretical proposal has been tested in a recent experiment carried out at University of Wuerzburg, and the distinct signatures of the QSH state have been experimentally observed. Note from Publisher: This article contains the abstract only.
Effective Theories of Quantum Cosmology
Xinquan Wu; Yongge Ma
2012-12-24
We introduce two possible ways of defining effective constraints of quantum systems and applied this effective constraint method to models of WDW Quantum Cosmology and Loop Quantum Cosmology. We analyze effective Hamiltonian constraint on both second and third order and calculate Hubble parameter as well as modified Friedmann equation of each model. Then we compare with a special case using coherent state. It shows that this method is reasonable and as before the classical Big Bang singularity is replaced by a quantum bounce in Loop Quantum Cosmology.
Quantum resonant effects in the delta-kicked rotor revisited
NASA Astrophysics Data System (ADS)
Ullah, A.; Ruddell, S. K.; Currivan, J. A.; Hoogerland, M. D.
2012-12-01
We review the theoretical model and experimental realization of the atom optics ?-kicked rotor (AOKR), a paradigm of classical and quantum chaos. We have performed a number of experiments with an all-optical Bose-Einstein condensate (BEC) in a periodic standing wave potential in an AOKR system. We discuss results of the investigation of the phenomena of quantum resonances in the AOKR. An interesting feature of the momentum distribution of the atoms obtained as a result of short pulses of light, is the variance of the momentum distribution or the kinetic energy ? p 2?/2 m in units of the recoil energy E rec = ? ? rec . The energy of the system is examined as a function of pulse period for a range of kicks that allow the observation of quantum resonances. In particular we study the behavior of these resonances for a large number of kicks. Higher order quantum resonant effects corresponding to the fractional Talbot time of (1/4) T T and (1/5) T T for five and ten kicks have been observed. Moreover, we describe the effect of the initial momentum of the atoms on quantum resonances in the AOKR.
Quantum Effects in Biological Systems
NASA Astrophysics Data System (ADS)
Roy, Sisir
2014-07-01
The debates about the trivial and non-trivial effects in biological systems have drawn much attention during the last decade or so. What might these non-trivial sorts of quantum effects be? There is no consensus so far among the physicists and biologists regarding the meaning of "non-trivial quantum effects". However, there is no doubt about the implications of the challenging research into quantum effects relevant to biology such as coherent excitations of biomolecules and photosynthesis, quantum tunneling of protons, van der Waals forces, ultrafast dynamics through conical intersections, and phonon-assisted electron tunneling as the basis for our sense of smell, environment assisted transport of ions and entanglement in ion channels, role of quantum vacuum in consciousness. Several authors have discussed the non-trivial quantum effects and classified them into four broad categories: (a) Quantum life principle; (b) Quantum computing in the brain; (c) Quantum computing in genetics; and (d) Quantum consciousness. First, I will review the above developments. I will then discuss in detail the ion transport in the ion channel and the relevance of quantum theory in brain function. The ion transport in the ion channel plays a key role in information processing by the brain.
Spin-orbit coupling and quantum spin Hall effect for neutral atoms without spin flips.
Kennedy, Colin J; Siviloglou, Georgios A; Miyake, Hirokazu; Burton, William Cody; Ketterle, Wolfgang
2013-11-27
We propose a scheme which realizes spin-orbit coupling and the quantum spin Hall effect for neutral atoms in optical lattices without relying on near resonant laser light to couple different spin states. The spin-orbit coupling is created by modifying the motion of atoms in a spin-dependent way by laser recoil. The spin selectivity is provided by Zeeman shifts created with a magnetic field gradient. Alternatively, a quantum spin Hall Hamiltonian can be created by all-optical means using a period-tripling, spin-dependent superlattice. PMID:24329453
Mikhail Lemeshko; Bretislav Friedrich
2009-03-26
We present the physics of the quantum Zeno effect, whose gist is often expressed by invoking the adage "a watched pot never boils". We review aspects of the theoretical and experimental work done on the effect since its inception in 1977, and mention some applications. We dedicate the article - with our very best wishes - to Rudolf Zahradnik at the occasion of his great jubilee. Perhaps Rudolf's lasting youthfulness and freshness are due to that he himself had been frequently observed throughout his life: until the political turn-around in 1989 by those who wished, by their surveillance, to prevent Rudolf from spoiling the youth by his personal culture and his passion for science and things beautiful and useful in general. This attempt had failed. Out of gratitude, the youth has infected Rudolf with its youthfulness. Chronically. Since 1989, Rudolf has been closely watched by the public at large. For the same traits of his as before, but with the opposite goal and for the benefit of all generations. We relish keeping him in sight ...
George Svetlichny
2009-02-27
The quantum teleportation protocol can be used to probabilistically simulate a quantum circuit with backward-in-time connections. This allows us to analyze some conceptual problems of time travel in the context of physically realizable situations, to realize encrypted measurements of future states for which the decryption key becomes available only after the state is created, and to probabilistically realize a multistage quantum state processing within the time needed to complete only one stage. The probabilistic nature of the process resolves any paradox.
Difference between a Photon's Momentum and an Atom's Recoil
Gibble, Kurt [Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
2006-08-18
When an atom absorbs a photon from a laser beam that is not an infinite plane wave, the atom's recoil is less than ({Dirac_h}/2{pi})k in the propagation direction. We show that the recoils in the transverse directions produce a lensing of the atomic wave functions, which leads to a frequency shift that is not discrete but varies linearly with the field amplitude and strongly depends on the atomic state detection. The same lensing effect is also important for microwave atomic clocks. The frequency shifts are of the order of the naive recoil shift for the transverse wave vector of the photons.
Effective equations for the quantum pendulum from momentous quantum mechanics
Hernandez, Hector H.; Chacon-Acosta, Guillermo [Universidad Autonoma de Chihuahua, Facultad de Ingenieria, Nuevo Campus Universitario, Chihuahua 31125 (Mexico); Departamento de Matematicas Aplicadas y Sistemas, Universidad Autonoma Metropolitana-Cuajimalpa, Artificios 40, Mexico D. F. 01120 (Mexico)
2012-08-24
In this work we study the quantum pendulum within the framework of momentous quantum mechanics. This description replaces the Schroedinger equation for the quantum evolution of the system with an infinite set of classical equations for expectation values of configuration variables, and quantum dispersions. We solve numerically the effective equations up to the second order, and describe its evolution.
Quantum effects in linguistic endeavors
F. Tito Arecchi
2015-05-21
Classifying the information content of neural spike trains in a linguistic endeavor, an uncertainty relation emerges between the bit size of a word and its duration. This uncertainty is associated with the task of synchronizing the spike trains of different duration representing different words. The uncertainty involves peculiar quantum features, so that word comparison amounts to measurement-based-quantum computation. Such a quantum behavior explains the onset and decay of the memory window connecting successive pieces of a linguistic text. The behavior here discussed is applicable to other reported evidences of quantum effects in human linguistic processes, so far lacking a plausible framework, since either no efforts to assign an appropriate quantum constant had been associated or speculating on microscopic processes dependent on Planck's constant resulted in unrealistic decoherence times.
Further insight into gravitational recoil
Lousto, Carlos O.; Zlochower, Yosef [Center for Computational Relativity and Gravitation, School of Mathematical Sciences, Rochester Institute of Technology, 78 Lomb Memorial Drive, Rochester, New York 14623 (United States)
2008-02-15
We test the accuracy of our recently proposed empirical formula to model the recoil velocity imparted to the merger remnant of spinning, unequal-mass black-hole binaries. We study three families of black-hole binary configurations, all with mass ratio q=3/8 (to nearly maximize the unequal-mass contribution to the kick) and spins aligned (or counter-aligned) with the orbital angular momentum, two with spin configurations chosen to minimize the spin-induced tangential and radial accelerations of the trajectories, respectively, and a third family where the trajectories are significantly altered by spin-orbit coupling. We find good agreement between the measured and predicted recoil velocities for the first two families, and reasonable agreement for the third. We also reexamine our original generic binary configuration that led to the discovery of extremely large spin-driven recoil velocities and inspired our empirical formula, and find rough agreement between the predicted and measured recoil speeds.
Quantum Chaos and Effective Thermalization
NASA Astrophysics Data System (ADS)
Altland, Alexander; Haake, Fritz
2012-02-01
We demonstrate effective equilibration for unitary quantum dynamics under conditions of classical chaos. Focusing on the paradigmatic example of the Dicke model, we show how a constructive description of the thermalization process is facilitated by the Glauber Q or Husimi function, for which the evolution equation turns out to be of Fokker-Planck type. The equation describes a competition of classical drift and quantum diffusion in contractive and expansive directions. By this mechanism the system follows a “quantum smoothened” approach to equilibrium, which avoids the notorious singularities inherent to classical chaotic flows.
Quantum Zeno effect and quantum Zeno paradox in atomic physics
Ellen Block; P. R. Berman
1991-01-01
Itano and co-workers [Wayne M. Itano, D. J. Heinzen, J. J. Bollinger, and D. J. Wineland, Phys. Rev. A 41, 2295 (1990)] have recently reported the experimental verification of the quantum Zeno effect, which is the inhibition of a quantum transition by frequent measurements. In this article, we offer an alternative interpretation of the quantum Zeno effect. We show that
Effective theory for quantum gravity
Calmet, Xavier
2013-01-01
In this paper, we discuss an effective theory for quantum gravity and discuss the bounds on the parameters of this effective action. In particular we show that measurement in pulsars binary systems are unlikely to improve the bounds on the coefficients of the $R^2$ and $R_{\\mu\
Toshiaki Fujino; Takashi Fuse; Eisuke Tazou; Toshiaki Nakano; Katsuhiko Inudzuka; Koji Goto; Yujin Yamazaki; Mitsuhiro Katayama; Kenjiro Oura
2000-01-01
To clarify the mechanism of the hydrogen (H)-surfactant effect, we have performed in situ monitoring of the H-surfactant-mediated growth of Ge on Si(001), using coaxial impact-collision ion scattering spectroscopy (CAICISS) and time-of-flight elastic recoil detection analysis (TOF-ERDA). It has been revealed that: (1) at a growth temperature of 350°C, the Ge overlayer of the best quality could be achieved with
Quantum Parrondo game based on a quantum ratchet effect
NASA Astrophysics Data System (ADS)
Chen, Lei; Li, Chuan-Feng; Gong, Ming; Guo, Guang-Can
2010-10-01
A Parrondo game is a counterintuitive game where two losing games can be combined to form a winning game. We construct a quantum version of a Parrondo game based on a quantum ratchet effect for a delta-kicked model, which can be realized in optical lattices. A game set is presented and a quantum anti-Parrondo game is also investigated.
? -decay chains of recoiled superheavy nuclei: A theoretical study
NASA Astrophysics Data System (ADS)
Niyti, Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.
2015-05-01
A systematic theoretical study of ? -decay half-lives in the superheavy mass region of the periodic table of elements is carried out by extending the quantum-mechanical fragmentation theory based on the preformed cluster model (PCM) to include temperature (T ) dependence in its built-in preformation and penetration probabilities of decay fragments. Earlier, the ? -decay chains of the isotopes of Z =115 were investigated by using the standard PCM for spontaneous decays, with"hot-optimum" orientation effects included, which required a constant scaling factor of 104 to approach the available experimental data. In the present approach of the PCM (T ?0 ), the temperature effects are included via the recoil energy of the residual superheavy nucleus (SHN) left after x -neutron emission from the superheavy compound nucleus. The important result is that the ? -decay half-lives calculated by the PCM (T ?0 ) match the experimental data nearly exactly, without using any scaling factor of the type used in the PCM. Note that the PCM (T ?0 ) is an equivalent of the dynamical cluster-decay model for heavy-ion collisions at angular momentum ? =0 . The only parameter of model is the neck-length parameter ? R , which for the calculated half-lives of ? -decay chains of various isotopes of Z =113 to 118 nuclei formed in "hot-fusion" reactions is found to be nearly constant, i.e., ? R ?0.95 ±0.05 fm for all the ? -decay chains studied. The use of recoiled residue nucleus as a secondary heavy-ion beam for nuclear reactions has also been suggested in the past.
Quantum mechanical effects from deformation theory
Much, A. [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)] [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)
2014-02-15
We consider deformations of quantum mechanical operators by using the novel construction tool of warped convolutions. The deformation enables us to obtain several quantum mechanical effects where electromagnetic and gravitomagnetic fields play a role. Furthermore, a quantum plane can be defined by using the deformation techniques. This in turn gives an experimentally verifiable effect.
Nuclear Quantum Effects in Water
NASA Astrophysics Data System (ADS)
Morrone, Joseph A.; Car, Roberto
2008-07-01
A path-integral Car-Parrinello molecular dynamics simulation of liquid water and ice is performed. It is found that the inclusion of nuclear quantum effects systematically improves the agreement of first-principles simulations of liquid water with experiment. In addition, the proton momentum distribution is computed utilizing a recently developed open path-integral molecular dynamics methodology. It is shown that these results are in good agreement with experimental data.
Hyperbolic supersymmetric quantum Hall effect
NASA Astrophysics Data System (ADS)
Hasebe, Kazuki
2008-12-01
Developing a noncompact version of the supersymmetric Hopf map, we formulate the quantum Hall effect on a superhyperboloid. Based on OSp(1|2) group theoretical methods, we first analyze the one-particle Landau problem, and successively explore the many-body problem where the Laughlin wave function, hard-core pseudopotential Hamiltonian, and topological excitations are derived. It is also shown that the fuzzy superhyperboloid emerges at the lowest Landau level.
Quantum effects in beam-plasma instabilities
Bret, A
2015-01-01
Among the numerous works on quantum effects that have been published in recent years, streaming instabilities in plasma have also been revisited. Both the fluid quantum and the kinetic Wigner-Maxwell models have been used to explore quantum effects on the Weibel, Filamentation and Two-Stream instabilities. While quantum effects usually tend to reduce the instabilities, they can also spur new unstable branches. A number of theoretical results will be reviewed together with the implications to one physical setting, namely the electron driven fast ignition scenario.
Nonlinear effects in quantum dissipation
NASA Astrophysics Data System (ADS)
Vitali, David; Grigolini, Paolo
1990-12-01
We study a two-level system linearly interacting with a set of quantum-mechanical oscillators, referred to as the ``bath.'' This system is formally equivalent to a magnetic dipole, with spin 1/2, precessing with the Larmor frequency ?0 around a fixed magnetic field along the z axis and undergoing the influence of a fluctuating field along the x axis. These bath fluctuations are not independent of the state of the spin, and the crucial problem to be studied in this paper is precisely how to take the reaction field, i.e., the influence of the bath on the system, into account. We find a general result based on neglecting a contribution to the reaction field proportional to ?x(t)-, where the angle brackets denote averaging on both the spin and the bath space, with a density matrix corresponding to the spin polarized along the x axis. We show that under the special condition that the spin does not significantly depart from its initial state, our general result turns out to coincide with the noninteracting-blip approximation (NBA) of Leggett and co-workers [Rev. Mod. Phys. 59, 1 (1987)]. When we make the assumption that both quantum and thermal fluctuations of the bath can be neglected and that the time scale of the bath is virtually zero (adiabatic assumption), our general result turns out to coincide with the prediction of the discrete nonlinear Schrödinger equation (DNSE) of Davydov and Kislukha [Phys. Status Solidi B 59, 465 (1973)] and Davydov $[-Biology and Quantum Mechanics (Pergamon, Oxford, 1982)] in the two-sites case. This means that the nonlinear effects proven by Kenkre and co-workers [Phys. Rev. B 34, 4959 (1986); 35, 1473 (1987)] to accompany a significant departure of the spin from the initial state are lost by the NBA. On the other hand, our approach provides a rigorous evaluation of the effects of the oscillator fluctuations on the predictions of the DNSE. It is shown that the quantum fluctuations might have a significant role also in the region of high temperature to which the nonadiabatic corrections of Kenkre and co-workers apply. Finally, it is shown that a still more accurate approximation would be that of neglecting a reaction field proportional to ?x(t)-s, where s denotes an average carried out only on the spin space. This approximation leads our approach to coincide with the exact result in the special case where both the spin and its bath are replaced by their classical counterparts. Under this approximation, the detrapping would be equivalent to an Arrhenius-like thermal-activation process. When the coupling strength between the system and its bath is decreased, the spin is expected to depart from the initial trapped state. The dynamics of this process is expected to be influenced by the joint action of the bath fluctuations (both thermal and quantum mechanical) and of the nonlinearity stemming from the reaction field, and ignored by the NBA. This intriguing problem should be the subject of further investigations.
"Exotic" quantum effects in the laboratory?
Ralf Schützhold
2010-04-15
This Article provides a brief (non-exhaustive) review of some recent developments regarding the theoretical and possibly experimental study of "exotic" quantum effects in the laboratory with special emphasis on cosmological particle creation, Hawking radiation, and the Unruh effect.
The quantum Hall effect helicity
NASA Astrophysics Data System (ADS)
Shrivastava, Keshav N.
2015-04-01
The quantum Hall effect in semiconductor heterostructures is explained by two signs in the angular momentum j=l±s and g=(2j+1)/(2l+1) along with the Landau factor (n+1/2). These modifications in the existing theories explain all of the fractional charges. The helicity which is the sign of the product of the linear momentum with the spin p.s plays an important role for the understanding of the data at high magnetic fields. In particular it is found that particles with positive sign in the spin move in one direction and those with negative sign move in another direction which explains the up and down stream motion of the particles.
Quantum pigeonhole effect, Cheshire cat and contextuality
Sixia Yu; C. H. Oh
2014-08-23
A kind of paradoxical effects has been demonstrated that the pigeonhole principle, i.e., if three pigeons are put in two pigeonholes then at least two pigeons must stay in the same hole, fails in certain quantum mechanical scenario. Here we shall show how to associate a proof of Kochen-Specker theorem with a quantum pigeonhole effect and vise versa, e.g., from state-independent proofs of Kochen-Specker theorem some kind of state-independent quantum pigeonhole effects can be demonstrated. In particular, a state-independent version of the quantum Cheshire cat, which can be rendered as a kind of quantum pigeonhole effect about the trouble of putting two pigeons in two or more pigeonholes, arises from Peres-Mermin's magic square proof of contextuality.
Quantum effects in the understanding of consciousness.
Hameroff, Stuart R; Craddock, Travis J A; Tuszynski, Jack A
2014-06-01
This paper presents a historical perspective on the development and application of quantum physics methodology beyond physics, especially in biology and in the area of consciousness studies. Quantum physics provides a conceptual framework for the structural aspects of biological systems and processes via quantum chemistry. In recent years individual biological phenomena such as photosynthesis and bird navigation have been experimentally and theoretically analyzed using quantum methods building conceptual foundations for quantum biology. Since consciousness is attributed to human (and possibly animal) mind, quantum underpinnings of cognitive processes are a logical extension. Several proposals, especially the Orch OR hypothesis, have been put forth in an effort to introduce a scientific basis to the theory of consciousness. At the center of these approaches are microtubules as the substrate on which conscious processes in terms of quantum coherence and entanglement can be built. Additionally, Quantum Metabolism, quantum processes in ion channels and quantum effects in sensory stimulation are discussed in this connection. We discuss the challenges and merits related to quantum consciousness approaches as well as their potential extensions. PMID:25012711
Quantum optical effects in semiconductor microcavities
Elisabeth Giacobino; Jean-Philippe Karr; Gaëtan Messin; Hichem Eleuch; Augustin Baas
2002-01-01
Investigations of quantum effects in semiconductor quantum-well microcavities interacting with laser light in the strong-coupling regime are presented. Modifications of quantum fluctuations of the outgoing light are expected due to the non-linearity originating from coherent exciton–exciton scattering. In the strong-coupling regime, this scattering translates into a four-wave mixing interaction between the mixed exciton–photon states, the polaritons. Squeezing and giant amplification
Interpreting Recoil Motion for Undergraduate Students
King Fahd
The phenomenon of recoil is usually explained to students in the context of Newton's Third Law. When an object is launched from a larger one, the recoil of the large object is interpreted as a reaction to the ejection of the smaller one since \\
Alexander Muck RECOIL-INDUCED RESONANCES FOR
Raizen, Mark G.
the experiment and for the interesting discussions about physics and life in general. Daniel Steck supportedCopyright by Alexander M¨uck 1999 #12;RECOIL-INDUCED RESONANCES FOR VELOCIMETRY OF COLD CESIUM THE UNIVERSITY OF TEXAS AT AUSTIN August 1999 #12;RECOIL-INDUCED RESONANCES FOR VELOCIMETRY OF COLD CESIUM ATOMS
Nuclear recoil correction to the g factor of boron-like argon
NASA Astrophysics Data System (ADS)
Shchepetnov, A. A.; Glazov, D. A.; Volotka, A. V.; Shabaev, V. M.; Tupitsyn, I. I.; Plunien, G.
2015-01-01
The nuclear recoil effect to the g factor of boron-like ions is investigated. The one-photon-exchange correction to the nuclear recoil effect is calculated in the nonrelativistic approximation for the nuclear recoil operator and in the Breit approximation for the interelectronic-interaction operator. The screening potential is employed to estimate the higher-order contributions. The updated g-factor values are presented for the ground 2P1/2 and first excited 2P3/2 states of B-like argon 40Ar13+, which are presently being measured by the ARTEMIS group at GSI.
Planck's quantum-driven integer quantum Hall effect in chaos
Yu Chen; Chushun Tian
2014-09-18
The integer quantum Hall effect (IQHE) and chaos are commonly conceived as being unrelated. Contrary to common wisdoms, we find in a canonical chaotic system, the kicked spin-$1/2$ rotor, a Planck's quantum($h_e$)-driven phenomenon bearing a firm analogy to IQHE but of chaos origin. Specifically, the rotor's energy growth is unbounded ('metallic' phase) for a discrete set of critical $h_e$-values, but otherwise bounded ('insulating' phase). The latter phase is topological in nature and characterized by a quantum number ('quantized Hall conductance'). The number jumps by unity whenever $h_e$ decreases passing through each critical value. Our findings, within the reach of cold-atom experiments, indicate that rich topological quantum phenomena may emerge from chaos.
Quantum effects on propagation of bulk and surface waves in a thin quantum plasma film
NASA Astrophysics Data System (ADS)
Moradi, Afshin
2015-06-01
The propagation of bulk and surface plasma waves in a thin quantum plasma film is investigated, taking into account the quantum effects. The generalized bulk and surface plasma dispersion relation due to quantum effects is derived, using the quantum hydrodynamic dielectric function and applying appropriate additional boundary conditions. The quantum mechanical and film geometric effects on the bulk and surface modes are discussed. It is found that quantum effects become important for a thin film of small thickness.
Quantum effects in multidimensional homogeneous cosmological models
NASA Astrophysics Data System (ADS)
Szydlowski, Marek; Biesiada, Marek; Szczesny, Jerzy
1987-11-01
Finite-temperature quantum effects in multidimensional homogeneous cosmological models are investigated, and results are based on the full classification of such models. These calculations concern the generalized Bianchi I model. However, they are of universal character. The back-reaction of metric to quantum effects leads to dimensional reduction at low temperatures. The problem of the stability of the solutions is also discussed. The influence of macrospace topology upon the effective action originating from gravitational and massless scalar fields is illustrated.
Band mixing effects on quantum well gain
Sel Colak; R. Eppenga; Martin F. H. Schuurmans
1987-01-01
The band structure and the optical matrix elements of a quantum well are studied by the kp perturbation method within the envelope function approximation. The quantum well gain spectra calculated by the kp method and the k-selection rules clearly show the effects of band mixing both in shape and in peak magnitude. The results differ considerably from those based on
The Compton effect: Transition to quantum mechanics
R. H. Stuewer
2000-01-01
The discovery of the Compton effect at the end of 1922 was a decisive event in the transition to the new quantum mechanics of 1925-1926 because it stimulated physicists to examine anew the fundamental problem of the interaction between radiation and matter. I first discuss Albert Einstein's light-quantum hypothesis of 1905 and why physicists greeted it with extreme skepticism, despite
Nuclear quantum effects in water
NASA Astrophysics Data System (ADS)
Morrone, Joseph; Car, Roberto
2008-03-01
In this work, a path integral Car-Parrinello molecular dynamicsootnotetextCPMD V3.11 Copyright IBM Corp 1990-2006, Copyright MPI fuer Festkoerperforschung Stuttgart 1997-2001. simulation of liquid water is performed. It is found that the inclusion of nuclear quantum effects systematically improves the agreement of first-principles simulations of liquid water with experiment. In addition, the proton momentum distribution is computed utilizing a recently developed ``open'' path integral molecular dynamics methodologyootnotetextJ.A. Morrone, V. Srinivasan, D. Sebastiani, R. Car J. Chem. Phys. 126 234504 (2007).. It is shown that these results, which are consistent with our computations of the liquid structure, are in good agreement with neutron Compton scattering dataootnotetextG.F. Reiter, J.C. Li, J. Mayers, T. Abdul-Redah, P. Platzman Braz. J. Phys. 34 142 (2004).. The remaining discrepancies between experiment and the present results are indicative of some degree of over-binding in the hydrogen bond network, likely engendered by the use of semi-local approximations to density functional theory in order to describe the electronic structure.
Retention studies of recoiling daughter nuclides of 225Ac in polymer vesicles.
Wang, G; de Kruijff, R M; Rol, A; Thijssen, L; Mendes, E; Morgenstern, A; Bruchertseifer, F; Stuart, M C A; Wolterbeek, H T; Denkova, A G
2014-02-01
Alpha radionuclide therapy is steadily gaining importance and a large number of pre-clinical and clinical studies have been carried out. However, due to the recoil effects the daughter recoil atoms, most of which are alpha emitters as well, receive energies that are much higher than the energies of chemical bonds resulting in decoupling of the radionuclide from common targeting agents. Here, we demonstrate that polymer vesicles (i.e. polymersomes) can retain recoiling daughter nuclei based on an experimental study examining the retention of (221)Fr and (213)Bi when encapsulating (225)Ac. PMID:24374072
Gas powered fluid gun with recoil mitigation
Grubelich, Mark C; Yonas, Gerold
2013-11-12
A gas powered fluid gun for propelling a stream or slug of a fluid at high velocity toward a target. Recoil mitigation is provided that reduces or eliminates the associated recoil forces, with minimal or no backwash. By launching a quantity of water in the opposite direction, net momentum forces are reduced or eliminated. Examples of recoil mitigation devices include a cone for making a conical fluid sheet, a device forming multiple impinging streams of fluid, a cavitating venturi, one or more spinning vanes, or an annular tangential entry/exit.
Quantum interference effect and electric field domain formation in quantum well infrared April 1995 An observation of quantum interference effect in photocurrent spectra of a weakly coupled, we report on a new observation of a quantum interference effect in the pho- tocurrent spectra
Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils
E. Aprile; K. L. Giboni; P. Majewski; K. Ni; M. Yamashita; R. Hasty; A. Manzur; D. N. McKinsey
2005-03-29
Liquid Xenon (LXe) is expected to be an excellent target and detector medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Knowledge of LXe ionization and scintillation response to low energy nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important for determining the sensitivity of LXe direct detection experiments. Here we report on new measurements of the scintillation yield of Xe recoils with kinetic energy as low as 10 keV. The dependence of the scintillation yield on applied electric field was also measured in the range of 0 to 4 kV/cm. Results are in good agreement with recent theoretical predictions that take into account the effect of biexcitonic collisions in addition to the nuclear quenching effect.
Quantum confinement effects in strained silicon-germanium alloy quantum wells
Quantum confinement effects in strained silicon-germanium alloy quantum wells X. Xiao, C. W. Liu/strained Si, _ ,Ge,/Si single quantum wells. A quantum confinement energy of up to 45 meV has been observed for quantum wells as small as 33 A in width. The experimental results are in good agreement with a calculation
Polarized neutron beta-decay: proton asymmetry and recoil-order currents
Sky Sjue
2006-01-01
We present an analytic calculation of the proton asymmetry from polarized neutron beta-decay, including recoil-order effects. The differential decay rate in terms of electron energy and proton direction follows, parametrized in terms of the most general Lorentz-invariant hadron current coupled to a left-handed lepton current. Implications for experimental efforts to measure recoil-order currents are discussed.
Ramsey type Sub-Recoil Cooling
Sander, F; Esslinger, T; Hänsch, T W; Sander, Frank; Devolder, Thibaut; Esslinger, Tilman; Hansch, Theodor W.
1996-01-01
We experimentally study the motion of atoms interacting with a periodically pulsed near resonant standing wave. For discrete pulse frequencies we observe a comb-like momentum distribution. The peaks have widths of 0.3 recoil momenta and a spacing which is an integer multiple of the recoil momentum. The atomic population is trapped in ground states which periodically evolve to dark states each time the standing wave is switched on.
Locality and universality of quantum memory effects
NASA Astrophysics Data System (ADS)
Liu, B.-H.; Wißmann, S.; Hu, X.-M.; Zhang, C.; Huang, Y.-F.; Li, C.-F.; Guo, G.-C.; Karlsson, A.; Piilo, J.; Breuer, H.-P.
2014-09-01
The modeling and analysis of the dynamics of complex systems often requires to employ non-Markovian stochastic processes. While there is a clear and well-established mathematical definition for non-Markovianity in the case of classical systems, the extension to the quantum regime recently caused a vivid debate, leading to many different proposals for the characterization and quantification of memory effects in the dynamics of open quantum systems. Here, we derive a mathematical representation for the non-Markovianity measure based on the exchange of information between the open system and its environment, which reveals the locality and universality of non-Markovianity in the quantum state space and substantially simplifies its numerical and experimental determination. We further illustrate the application of this representation by means of an all-optical experiment which allows the measurement of the degree of memory effects in a photonic quantum process with high accuracy.
Locality and universality of quantum memory effects.
Liu, B-H; Wißmann, S; Hu, X-M; Zhang, C; Huang, Y-F; Li, C-F; Guo, G-C; Karlsson, A; Piilo, J; Breuer, H-P
2014-01-01
The modeling and analysis of the dynamics of complex systems often requires to employ non-Markovian stochastic processes. While there is a clear and well-established mathematical definition for non-Markovianity in the case of classical systems, the extension to the quantum regime recently caused a vivid debate, leading to many different proposals for the characterization and quantification of memory effects in the dynamics of open quantum systems. Here, we derive a mathematical representation for the non-Markovianity measure based on the exchange of information between the open system and its environment, which reveals the locality and universality of non-Markovianity in the quantum state space and substantially simplifies its numerical and experimental determination. We further illustrate the application of this representation by means of an all-optical experiment which allows the measurement of the degree of memory effects in a photonic quantum process with high accuracy. PMID:25209643
Locality and universality of quantum memory effects
Liu, B.-H.; Wißmann, S.; Hu, X.-M.; Zhang, C.; Huang, Y.-F.; Li, C.-F.; Guo, G.-C.; Karlsson, A.; Piilo, J.; Breuer, H.-P.
2014-01-01
The modeling and analysis of the dynamics of complex systems often requires to employ non-Markovian stochastic processes. While there is a clear and well-established mathematical definition for non-Markovianity in the case of classical systems, the extension to the quantum regime recently caused a vivid debate, leading to many different proposals for the characterization and quantification of memory effects in the dynamics of open quantum systems. Here, we derive a mathematical representation for the non-Markovianity measure based on the exchange of information between the open system and its environment, which reveals the locality and universality of non-Markovianity in the quantum state space and substantially simplifies its numerical and experimental determination. We further illustrate the application of this representation by means of an all-optical experiment which allows the measurement of the degree of memory effects in a photonic quantum process with high accuracy. PMID:25209643
Some boundary effects in quantum field theory
Bezerra, V.B.; Rego-Monteiro, M.A. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, PB (Brazil); Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil)
2004-09-15
We have constructed a quantum field theory in a finite box, with periodic boundary conditions, using the hypothesis that particles living in a finite box are created and/or annihilated by the creation and/or annihilation operators, respectively, of a quantum harmonic oscillator on a circle. An expression for the effective coupling constant is obtained, showing explicitly its dependence on the dimension of the box.
Coherent quantum effects through dispersive bosonic media
Ye Saiyun [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Department of Physics, Fuzhou University, Fuzhou 350002 (China); Yang Zhenbiao; Zheng Shibiao [Department of Physics, Fuzhou University, Fuzhou 350002 (China); Serafini, Alessio [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2010-07-15
The coherent evolution of two qubits mediated by a set of bosonic field modes is investigated. By assuming a specific asymmetric encoding of the quantum states in the internal levels of the qubits, we show that entangling quantum gates can be realized, with high fidelity, even when a large number of mediating modes is involved. The effect of losses and imperfections on the gates' operation is also considered in detail.
A recoil resilient lumen support, design, fabrication and mechanical evaluation
NASA Astrophysics Data System (ADS)
Mehdizadeh, Arash; Ali, Mohamed Sultan Mohamed; Takahata, Kenichi; Al-Sarawi, Said; Abbott, Derek
2013-06-01
Stents are artificial implants that provide scaffolding to a cavity inside the body. This paper presents a new luminal device for reducing the mechanical failure of stents due to recoil, which is one of the most important issues in stenting. This device, which we call a recoil-resilient ring (RRR), is utilized standalone or potentially integrated with existing stents to address the problem of recoil. The proposed structure aims to minimize the need for high-pressure overexpansion that can induce intra-luminal trauma and excess growth of vascular tissue causing later restenosis. The RRR is an overlapped open ring with asymmetrical sawtooth structures that are intermeshed. These teeth can slide on top of each other, while the ring is radially expanded, but interlock step-by-step so as to keep the final expanded state against compressional forces that normally cause recoil. The RRRs thus deliver balloon expandability and, when integrated with a stent, bring both radial rigidity and longitudinal flexibility to the stent. The design of the RRR is investigated through finite element analysis (FEA), and then the devices are fabricated using micro-electro-discharge machining of 200-µm-thick Nitinol sheet. The standalone RRR is balloon expandable in vitro by 5-7 Atm in pressure, which is well within the recommended in vivo pressure ranges for stenting procedures. FEA compression tests indicate 13× less reduction of the cross-sectional area of the RRR compared with a typical stainless steel stent. These results also show perfect elastic recovery of the RRR after removal of the pressure compared to the remaining plastic deformations of the stainless steel stent. On the other hand, experimental loading tests show that the fabricated RRRs have 2.8× radial stiffness compared to a two-column section of a commercial stent while exhibiting comparable elastic recovery. Furthermore, testing of in vitro expansion in a mock artery tube shows around 2.9% recoil, approximately 5-11× smaller than the recoil reported for commercial stents. These experimental results demonstrate the effectiveness of the device design for the targeted luminal support and stenting applications.
Berkeley Experiments on Superfluid Macroscopic Quantum Effects
Packard, Richard [Physics Department, University of California, Berkeley, CA 94720 (United States)
2006-09-07
This paper provides a brief history of the evolution of the Berkeley experiments on macroscopic quantum effects in superfluid helium. The narrative follows the evolution of the experiments proceeding from the detection of single vortex lines to vortex photography to quantized circulation in 3He to Josephson effects and superfluid gyroscopes in both 4He and 3He.
Anatomy of the binary black hole recoil: A multipolar analysis
Schnittman, Jeremy D.; Buonanno, Alessandra [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Meter, James R. van [Gravitational Astrophysics Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771 (United States); Center for Space Science and Technology, University of Maryland Baltimore County, Physics Department, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Baker, John G.; Centrella, Joan; Kelly, Bernard J. [Gravitational Astrophysics Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771 (United States); Boggs, William D.; McWilliams, Sean T. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)
2008-02-15
We present a multipolar analysis of the gravitational recoil computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and nonzero, nonprecessing spins. We show that multipole moments up to and including l=4 are sufficient to accurately reproduce the final recoil velocity (within {approx_equal}2%) and that only a few dominant modes contribute significantly to it (within {approx_equal}5%). We describe how the relative amplitudes, and more importantly, the relative phases, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ringdown phases. We also find that the numerical results can be reproduced by an 'effective Newtonian' formula for the multipole moments obtained by replacing the radial separation in the Newtonian formulas with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasinormal modes. Analytic formulas, obtained by expressing the multipole moments in terms of the fundamental quasinormal modes of a Kerr black hole, are able to explain the onset and amount of 'antikick' for each of the simulations. Lastly, we apply this multipolar analysis to help explain the remarkable difference between the amplitudes of planar and nonplanar kicks for equal-mass spinning black holes.
Anatomy of the Binary Black Hole Recoil: A Multipolar Analysis
NASA Technical Reports Server (NTRS)
Schnittman, Jeremy; Buonanno, Alessandra; vanMeter, James R.; Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.
2007-01-01
We present a multipolar analysis of the recoil velocity computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including 1 = 4 are sufficient to accurately reproduce the final recoil velocity (= 98%) and that only a few dominant modes contribute significantly to it (2 95%). We describe how the relative amplitude, and more importantly, the relative phase, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ring-down phases. We also find that the numerical results can be reproduced, to a high level of accuracy, by an effective Newtonian formula for the multipole moments obtained by replacing in the Newtonian formula the radial separation with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes. Analytic formulae, obtained by expressing the multipole moments in terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and amount of '.anti-kick" for each of the simulations. Lastly, we apply this multipolar analysis to understand the remarkable difference between the amplitudes of planar and non-planar kicks for equal-mass spinning black holes.
Investigation on modeling and controability of a magnetorheological gun recoil damper
NASA Astrophysics Data System (ADS)
Hu, Hongsheng; Wang, Juan; Wang, Jiong; Qian, Suxiang; Li, Yancheng
2009-07-01
Magnetorheological (MR) fluid as a new smart material has done well in the vibration and impact control engineering fields because of its good electromechanical coupling characteristics, preferable dynamic performance and higher sensitivity. And success of MRF has been apparent in many engineering applied fields, such as semi-active suspension, civil engineering, etc. So far, little research has been done about MR damper applied into the weapon system. Its primary purpose of this study is to identify its dynamic performance and controability of the artillery recoil mechanism equipped with MR damper. Firstly, based on the traditional artillery recoil mechanism, a recoil dynamic model is developed in order to obtain an ideal rule between recoil force and its stroke. Then, its effects of recoil resistance on the stability and firing accuracy of artillery are explored. Because MR gun recoil damper under high impact load shows a typical nonlinear character and there exists a shear-thinning phenomenon, to establish an accurate dynamic model has been a seeking aim of its design and application for MR damper under high impact load. Secondly, in this paper, considering its actual bearing load, an inertia factor was introduced to Herschel-Bulkley model, and some factor's effect on damping force are simulated and analyzed by using numerical simulation, including its dynamic performance under different flow coefficients and input currents. Finally, both of tests with the fixed current and different On-Off control algorithms have been done to confirm its controability of MR gun recoil damper under high impact load. Experimental results show its dynamic performances of the large-scale single-ended MR gun recoil damper can be changed by altering the applied currents and it has a good controllability.
Effective Pure States for Bulk Quantum Computation
Emanuel Knill; Isaac Chuang; Raymond Laflamme
1997-06-24
In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each computer in the ensemble is known but not pure. Methods for obtaining effective pure input states by a series of manipulations have been described by Gershenfeld and Chuang (logical labeling) and Cory et al. (spatial averaging) for the case of quantum computation with nuclear magnetic resonance. We give a different technique called temporal averaging. This method is based on classical randomization, requires no ancilla qubits and can be implemented in nuclear magnetic resonance without using gradient fields. We introduce several temporal averaging algorithms suitable for both high temperature and low temperature bulk quantum computing and analyze the signal to noise behavior of each.
Effective pure states for bulk quantum computation
Knill, E.; Chuang, I.; Laflamme, R.
1997-11-01
In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each computer in the ensemble is known but not pure. Methods for obtaining effective pure input states by a series of manipulations have been described by Gershenfeld and Chuang (logical labeling) and Corey et al. (spatial averaging) for the case of quantum computation with nuclear magnetic resonance. We give a different technique called temporal averaging. This method is based on classical randomization, requires no ancilla qubits and can be implemented in nuclear magnetic resonance without using gradient fields. We introduce several temporal averaging algorithms suitable for both high temperature and low temperature bulk quantum computing and analyze the signal to noise behavior of each.
Nonlinear effect on quantum control for two-level systems
W. Wang; J. Shen; X. X. Yi
2009-06-05
The traditional quantum control theory focuses on linear quantum system. Here we show the effect of nonlinearity on quantum control of a two-level system, we find that the nonlinearity can change the controllability of quantum system. Furthermore, we demonstrate that the Lyapunov control can be used to overcome this uncontrollability induced by the nonlinear effect.
Quantum metrology and detection of Unruh effect
Jieci Wang; Zehua Tian; Jiliang Jing; Heng Fan
2014-10-19
We study the quantum metrology for a pair of entangled Unruh-Dewitt detectors when one of them is accelerated and coupled to a massless scalar field. Comparing with previous schemes, our model requires only local interaction and avoids the use of cavities in the probe state preparation process. We show that the probe state preparation and the interaction between the accelerated detector and the external field have significant effects on the value of quantum Fisher information, correspondingly pose variable ultimate limit of precision in the estimation of Unruh effect. We find that the precision of the estimation can be improved by a larger effective coupling strength and a longer interaction time. Alternatively, the energy gap of the detector has a range that can provide us a better precision. Thus we may adjust those parameters and attain a higher precision in the estimation. We also find that an extremely high acceleration is not required in the quantum metrology process.
Quantum metrology and estimation of Unruh effect
Wang, Jieci; Tian, Zehua; Jing, Jiliang; Fan, Heng
2014-01-01
We study the quantum metrology for a pair of entangled Unruh-Dewitt detectors when one of them is accelerated and coupled to a massless scalar field. Comparing with previous schemes, our model requires only local interaction and avoids the use of cavities in the probe state preparation process. We show that the probe state preparation and the interaction between the accelerated detector and the external field have significant effects on the value of quantum Fisher information, correspondingly pose variable ultimate limit of precision in the estimation of Unruh effect. We find that the precision of the estimation can be improved by a larger effective coupling strength and a longer interaction time. Alternatively, the energy gap of the detector has a range that can provide us a better precision. Thus we may adjust those parameters and attain a higher precision in the estimation. We also find that an extremely high acceleration is not required in the quantum metrology process. PMID:25424772
Effective mass in quantum effects of radiation pressure
M. Pinard; Y. Hadjar; A. Heidmann
1999-09-02
We study the quantum effects of radiation pressure in a high-finesse cavity with a mirror coated on a mechanical resonator. We show that the optomechanical coupling can be described by an effective susceptibility which takes into account every acoustic modes of the resonator and their coupling to the light. At low frequency this effective response is similar to a harmonic response with an effective mass smaller than the total mass of the mirror. For a plano-convex resonator the effective mass is related to the light spot size and becomes very small for small optical waists, thus enhancing the quantum effects of optomechanical coupling.
A Double Scattering Analytical Model For Elastic Recoil Detection Analysis
Barradas, N. P.; Lorenz, K.; Alves, E. [Instituto Tecnologico e Nuclear, E.N. 10, Sacavem 2686-953 (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Darakchieva, V. [Instituto Tecnologico e Nuclear, E.N. 10, Sacavem 2686-953 (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IFM, Linkoeping University, SE-581 83 Linkoeping (Sweden)
2011-06-01
We present an analytical model for calculation of double scattering in elastic recoil detection measurements. Only events involving the beam particle and the recoil are considered, i.e. 1) an ion scatters off a target element and then produces a recoil, and 2) an ion produces a recoil which then scatters off a target element. Events involving intermediate recoils are not considered, i.e. when the primary ion produces a recoil which then produces a second recoil. If the recoil element is also present in the stopping foil, recoil events in the stopping foil are also calculated. We included the model in the standard code for IBA data analysis NDF, and applied it to the measurement of hydrogen in Si.
Observation of quantum Zeno effect in a superconducting flux qubit
NASA Astrophysics Data System (ADS)
Kakuyanagi, K.; Baba, T.; Matsuzaki, Y.; Nakano, H.; Saito, S.; Semba, K.
2015-06-01
When a quantum state is subjected to frequent measurements, the time evolution of the quantum state is frozen. This is called the quantum Zeno effect. Here, we observe such an effect by performing frequent discrete measurements in a macroscopic quantum system, a superconducting quantum bit. The quantum Zeno effect induced by discrete measurements is similar to the original idea of the quantum Zeno effect. By using a Josephson bifurcation amplifier pulse readout, we have experimentally suppressed the time evolution of Rabi oscillation using projective measurements, and also observed the enhancement of the quantum state holding time by shortening the measurement period time. This is a crucial step to realize quantum information processing using the quantum Zeno effect.
Quantum plasma effects in the classical regime
G. Brodin; M. Marklund; G. Manfredi
2008-02-01
For quantum effects to be significant in plasmas it is often assumed that the temperature over density ratio must be small. In this paper we challenge this assumption by considering the contribution to the dynamics from the electron spin properties. As a starting point we consider a multicomponent plasma model, where electrons with spin up and spin down are regarded as different fluids. By studying the propagation of Alfv\\'{e}n wave solitons we demonstrate that quantum effects can survive in a relatively high-temperature plasma. The consequences of our results are discussed.
The Compton effect: Transition to quantum mechanics
NASA Astrophysics Data System (ADS)
Stuewer, R. H.
2000-11-01
The discovery of the Compton effect at the end of 1922 was a decisive event in the transition to the new quantum mechanics of 1925-1926 because it stimulated physicists to examine anew the fundamental problem of the interaction between radiation and matter. I first discuss Albert Einstein's light-quantum hypothesis of 1905 and why physicists greeted it with extreme skepticism, despite Robert A. Millikan's confirmation of Einstein's equation of the photoelectric effect in 1915. I then follow in some detail the experimental and theoretical research program that Arthur Holly Compton pursued between 1916 and 1922 at the University of Minnesota, the Westinghouse Lamp Company, the Cavendish Laboratory, and Washington University that culminated in his discovery of the Compton effect. Surprisingly, Compton was not influenced directly by Einstein's light-quantum hypothesis, in contrast to Peter Debye and H.A. Kramers, who discovered the quantum theory of scattering independently. I close by discussing the most significant response to that discovery, the Bohr-Kramers-Slater theory of 1924, its experimental refutation, and its influence on the emerging new quantum mechanics.
Casimir effect in a quantum space-time
Rodolfo Gambini; Javier Olmedo; Jorge Pullin
2014-10-16
We apply quantum field theory in quantum space-time techniques to study the Casimir effect for large spherical shells. As background we use the recently constructed exact quantum solution for spherically symmetric vacuum space-time in loop quantum gravity. All calculations are finite and one recovers the usual results without the need of regularization or renormalization. This is an example of how loop quantum gravity provides a natural resolution to the infinities of quantum field theories.
Casimir effect in a quantum space–time
NASA Astrophysics Data System (ADS)
Gambini, Rodolfo; Olmedo, Javier; Pullin, Jorge
2015-06-01
We apply quantum field theory in quantum space–time techniques to study the Casimir effect for large spherical shells. As background we use the recently constructed exact quantum solution for spherically symmetric vacuum space–time in loop quantum gravity. All calculations are finite and one recovers the usual results without the need for regularization or renormalization. This is an example of how loop quantum gravity provides a natural resolution to the infinities of quantum field theories.
Spectral effects in quantum teleportation
Humble, Travis S.; Grice, Warren P. [Center for Engineering Science Advanced Research, Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6016 (United States)
2007-02-15
We use a multimode description of polarization-encoded qubits to analyze the quantum teleportation protocol. Specifically, we investigate how the teleportation fidelity depends on the spectral correlations inherent to polarization-entangled photons generated by type-II spontaneous parametric down conversion. We find that the maximal obtainable fidelity depends on the spectral entanglement carried by the joint probability amplitude, a result which we quantify for the case of a joint spectrum approximated by a correlated Gaussian function. We contrast these results with a similar analysis of the visibility obtained in a polarization-correlation experiment.
Quantum Coherence Effects in Novel Quantum Optical Systems
Sete, Eyob Alebachew
2012-10-19
separated and uncoupled qubits via interaction with correlated photons in a cavity quantum electrodynamics setup. Finally, we analyze how quantum coherence can be used to generate continuous-variable entanglement in quantum-beat lasers in steady state...
Stochasticity Effects in Quantum Radiation Reaction
NASA Astrophysics Data System (ADS)
Neitz, N.; Di Piazza, A.
2013-08-01
When an ultrarelativistic electron beam collides with a sufficiently intense laser pulse, radiation-reaction effects can strongly alter the beam dynamics. In the realm of classical electrodynamics, radiation reaction has a beneficial effect on the electron beam as it tends to reduce its energy spread. Here we show that when quantum effects become important, radiation reaction induces the opposite effect; i.e., the energy distribution of the electron beam spreads out after interacting with the laser pulse. We identify the physical origin of this opposite tendency in the intrinsic stochasticity of photon emission, which becomes substantial in the quantum regime. Our numerical simulations indicate that the predicted effects of the stochasticity can be measured already with presently available lasers and electron accelerators.
Demir, Hilmi Volkan
Blue quantum electroabsorption modulators based on reversed quantum confined Stark effect of blue quantum electroabsorption modulators that incorporate 5 nm thick In0.35Ga0.65N/GaN quantum cm-1 for 6 V bias swing around 424 nm, holding promise for blue optical clock generation
Significant Quantum Effects in Hydrogen Activation
2014-01-01
Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature reveal completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H2 up to ?190 K and for D2 up to ?140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation. PMID:24684530
Significant quantum effects in hydrogen activation.
Kyriakou, Georgios; Davidson, Erlend R M; Peng, Guowen; Roling, Luke T; Singh, Suyash; Boucher, Matthew B; Marcinkowski, Matthew D; Mavrikakis, Manos; Michaelides, Angelos; Sykes, E Charles H
2014-05-27
Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature reveal completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H2 up to ?190 K and for D2 up to ?140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation. PMID:24684530
Effective Evolution Equations from Quantum Dynamics
Niels Benedikter; Marcello Porta; Benjamin Schlein
2015-02-09
In these notes we review the material presented at the summer school on "Mathematical Physics, Analysis and Stochastics" held at the University of Heidelberg in July 2014. We consider the time-evolution of quantum systems and in particular the rigorous derivation of effective equations approximating the many-body Schr\\"odinger dynamics in certain physically interesting regimes.
The Quantum Hall Effect in Graphene
Paolo Cea
2012-04-24
We investigate the quantum Hall effect in graphene. We argue that in graphene in presence of an external magnetic field there is dynamical generation of mass by a rearrangement of the Dirac sea. We show that the mechanism breaks the lattice valley degeneracy only for the $n=0$ Landau levels and leads to the new observed $\
Unconventional Integer Quantum Hall Effect in Graphene
V. P. Gusynin; S. G. Sharapov
2005-01-01
Monolayer graphite films, or graphene, have quasiparticle excitations that\\u000acan be described by 2+1 dimensional Dirac theory. We demonstrate that this\\u000aproduces an unconventional form of the quantized Hall conductivity $\\\\sigma_{xy}\\u000a= - (2 e^2\\/h)(2n+1)$ with $n=0,1,...$, that notably distinguishes graphene from\\u000aother materials where the integer quantum Hall effect was observed. This\\u000aunconventional quantization is caused by the quantum
Room-Temperature Quantum Hall Effect in Graphene
K. S. Novoselov; Philip Kim; Zhigang Jiang; Horst Stormer; Yuanbo Zhang; Sergey Morozov; G. S. Boebinger; P. Kim; A. K. Geim
2007-01-01
The quantum Hall effect (QHE), one example of a quantum phenomenon that occurs on a truly macroscopic scale, has attracted intense interest since its discovery in 1980 and has helped elucidate many important aspects of quantum physics. It has also led to the establishment of a new metrological standard, the resistance quantum. Disappointingly, however, the QHE has been observed only
Quantum-effect and single-electron devices
Stephen M. Goodnick; Jonathan Bird
2003-01-01
In this paper, we review the current status of nanoelectronic devices based on quantum effects such as quantization of motion and interference, and those based on single electron charging phenomena in ultrasmall structures. In the first part, we discuss wave-behavior in quantum semiconductor structures, and several device structures based on quantum waveguide behavior such as stub tuners, Y-branches, and quantum
Zeeman Effect in Parabolic Quantum Dots
R. Rinaldi; P. V. Giugno; R. Cingolani; H. Lipsanen; M. Sopanen; J. Tulkki; J. Ahopelto
1996-01-01
An unprecedentedly well resolved Zeeman effect has been observed when confined carriers moving along a closed mesoscopic path experience an external magnetic field orthogonal to the orbit plane. Large Zeeman splitting of excited higher angular momentum states is observed in the magnetoluminescence spectrum of quantum dots induced by self-organized InP islands on InGaAs\\/GaAs. The measured effect is quantitatively reproduced by
Quantum Mechanical Effects in Gravitational Collapse
Eric Greenwood
2010-01-12
In this thesis we investigate quantum mechanical effects to various aspects of gravitational collapse. These quantum mechanical effects are implemented in the context of the Functional Schr\\"odinger formalism. The Functional Schr\\"odinger formalism allows us to investigate the time-dependent evolutions of the quantum mechanical effects, which is beyond the scope of the usual methods used to investigate the quantum mechanical corrections of gravitational collapse. Utilizing the time-dependent nature of the Functional Schr\\"odinger formalism, we study the quantization of a spherically symmetric domain wall from the view point of an asymptotic and infalling observer, in the absence of radiation. To build a more realistic picture, we then study the time-dependent nature of the induced radiation during the collapse using a semi-classical approach. Using the domain wall and the induced radiation, we then study the time-dependent evolution of the entropy of the domain wall. Finally we make some remarks about the possible inclusion of backreaction into the system.
Atypical quantum confinement effect in silicon nanowires.
Sorokin, Pavel B; Avramov, Pavel V; Chernozatonskii, Leonid A; Fedorov, Dmitri G; Ovchinnikov, Sergey G
2008-10-01
The quantum confinement effect (QCE) of linear junctions of silicon icosahedral quantum dots (IQD) and pentagonal nanowires (PNW) was studied using DFT and semiempirical AM1 methods. The formation of complex IQD/PNW structures leads to the localization of the HOMO and LUMO on different parts of the system and to a pronounced blue shift of the band gap; the typical QCE with a monotonic decrease of the band gap upon the system size breaks down. A simple one-electron one-dimensional Schrodinger equation model is proposed for the description and explanation of the unconventional quantum confinement behavior of silicon IQD/PNW systems. On the basis of the theoretical models, the experimentally discovered deviations from the typical QCE for nanocrystalline silicon are explained. PMID:18785695
Quantum effects in homogeneous multidimensional cosmologies
NASA Astrophysics Data System (ADS)
Szydlowski, M.; Szczesny, J.
1988-12-01
In the present paper we determine quantum distribution functions for a wide class of multidimensional cosmological models. The exact formulas for quantum distribution functions are given and their universal character at high and low temperatures shown. The obtained formulas provide us with the possibility to investigate the metric back reaction and to discuss the dimensional reduction problem. The assumption of the low-temperature approximation gives us the possibility to discuss the dynamics by using the methods of dynamical systems. Stable solutions, within the class FRW×S3×S3 models, where FRW denotes Friedmann, Robertson and Walker, are discussed, and it is shown that only a zero-measure set of trajectories in the phase space leads to a solution with a static microspace. This analysis shows that, insofar as quantum effects lead to solutions with a static microspace, these solutions are unstable.
The Quantum-Classical and Mind-Brain Linkages: The Quantum Zeno Effect in Binocular Rivalry
Henry P. Stapp
2007-11-05
A quantum mechanical theory of the relationship between perceptions and brain dynamics based on von Neumann's theory of measurments is applied to a recent quantum theoretical treatment of binocular rivaly that makes essential use of the quantum Zeno effect to give good fits to the complex available empirical data. The often-made claim that decoherence effects in the warm, wet, noisy brain must eliminate quantum effects at the macroscopic scale pertaining to perceptions is examined, and it is argued, on the basis of fundamental principles. that the usual decoherence effects will not upset the quantum Zeno effect that is being exploited in the cited work.
Effective theories of the fractional quantum Hall effect: Hierarchy construction
Blok, B.; Wen, X.G. (School of Natural Sciences, Institute of Advanced Study, Princeton, NJ (USA))
1990-11-01
The effective theories for the hierarchical fractional quantum Hall effect (FQHE) are proposed. We obtain the quantum numbers of the quasiparticles and the structure of the edge excitations for the general hierarchical FQHE state. It is shown that at the filling fractions {nu}={ital k}/(2{ital km}{plus minus}1) the Jain states and the hierarchical FQHE states give rise to the same quasiparticles and edge excitations and have the same effective theories (in the dual form). This suggests that these FQHE states are equivalent despite having been obtained from two different schemes.
A gun recoil system employing a magnetorheological fluid damper
Z C Li; J Wang
2012-01-01
This research aims to design and control a full scale gun recoil buffering system which works under real firing impact loading conditions. A conventional gun recoil absorber is replaced with a controllable magnetorheological (MR) fluid damper. Through dynamic analysis of the gun recoil system, a theoretical model for optimal design and control of the MR fluid damper for impact loadings
RecoilUtils A ROOT based Analysis Framework for the
RecoilUtils A ROOT based Analysis Framework for the HERMES Recoil Detector Andreas Mussgiller DESY finished in February 2006 Â Silicon detector finished in September 2006 Understand the detectors: Noise IT Seminar, 26/11/07 II. Physikalisches Institut #12;2 Outline The HERMES Recoil Detector General Idea
A Silicon Recoil Detector for the HERMES Experiment
A Silicon Recoil Detector for the HERMES Experiment A. Vandenbroucke University Gent INW inside. Recoil Detector 4. Silicon Recoil Detector Âª Sensors, Frame, Hybrid, Foils, Tests 5. Summary INW Inside 0 1 2 3 4 5 6 7 8 9 10 RICH SILICON 270 mrad 270 mrad MUON HODOSCOPE WIDE ANGLE FRONT MUON HODO
Effects of lasing in a one-dimensional quantum metamaterial
NASA Astrophysics Data System (ADS)
Asai, Hidehiro; Savel'ev, Sergey; Kawabata, Shiro; Zagoskin, Alexandre M.
2015-04-01
Electromagnetic pulse propagation in a quantum metamaterial, an artificial, globally quantum coherent optical medium, is numerically simulated. We show that a one-dimensional quantum metamaterial based on superconducting quantum bits, initialized in an easily reachable factorized excited state, demonstrates lasing in the microwave range, accompanied by the chaotization of qubit states and generation of higher harmonics. These effects may provide a tool for characterization and optimization of quantum metamaterial prototypes.
Quantum Anomalous Hall Effect in Hg_1-yMn_yTe Quantum Wells
Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Dai, Xi; Fang, Zhong; /Beijing, Inst. Phys.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19
The quantum Hall effect is usually observed when the two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall effect, can be realized in Hg{sub 1-y}Mn{sub y}Te quantum wells, without the external magnetic field and the associated Landau levels. This effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This effect enables dissipationless charge current in spintronics devices.
The effect of quantum nuclear motion on hydrogen bonding
Shyamasundar, R.K.
Most of chemistry can be understood by treating the atoms in molecules as classical particles. Quantum, proton sponges, organic acids, enzymes. Quantum nuclear effects are revealed by isotope substitution bonding, including water, proton sponges, organic acids, Quantum nuclear effects are revealed by isotope
Quantum gravity effects in the Kerr spacetime
Reuter, M. [Institute of Physics, University of Mainz, Staudingerweg 7, D-55099 Mainz (Germany); Tuiran, E. [Departamento de Fisica, Universidad del Norte, Km 5 via a Puerto Colombia, AA-1569 Barranquilla (Colombia)
2011-02-15
We analyze the impact of the leading quantum gravity effects on the properties of black holes with nonzero angular momentum by performing a suitable renormalization group improvement of the classical Kerr metric within quantum Einstein gravity. In particular, we explore the structure of the horizons, the ergosphere, and the static limit surfaces as well as the phase space available for the Penrose process. The positivity properties of the effective vacuum energy-momentum tensor are also discussed and the 'dressing' of the black hole's mass and angular momentum are investigated by computing the corresponding Komar integrals. The pertinent Smarr formula turns out to retain its classical form. As for their thermodynamical properties, a modified first law of black-hole thermodynamics is found to be satisfied by the improved black holes (to second order in the angular momentum); the corresponding Bekenstein-Hawking temperature is not proportional to the surface gravity.
Recoiling Ion-Channeling in Direct DM Detectors
NASA Astrophysics Data System (ADS)
Gelmini, Graciela B.
2012-09-01
The channeling of the recoiling nucleus in crystalline detectors after a WIMP collision would produce a larger scintillation or ionization signal in direct detection experiments than otherwise expected. I present estimates of channeling fractions obtained using analytic models developed from the 1960's onwards to describe channeling and blocking effects. We find the fractions to be too small to affect the fits to potential WIMP candidates. I also examine the possibility of detecting a daily modulation of the dark matter signal due to channeling.
Projectile focusing near the recoil-ion threshold
NASA Astrophysics Data System (ADS)
Rodríguez, V. D.; Macri, P. A.; Barrachina, R. O.
2007-03-01
The post-collisional interactions in ion-atom ionization collisions are studied around the electron capture to the continuum (ECC) process. For this purpose, a suitable double differential cross section is introduced, involving the longitudinal recoil-ion momentum and the projectile transverse momentum transfer. Using the fact that the ECC process is closely related to the threshold in the longitudinal momentum distribution, we study this distribution as a function of the projectile scattering angle. Using the CDW-EIS approximation we theoretically find a focusing (defocusing) effect as we get closer to the distribution threshold for proton (antiproton) impact on He atoms.
Estimating Noncommutative Effects From the Quantum Hall Effect
Gamboa-Rios, J; Méndez, F; Rojas, J C
2001-01-01
For the lowest Landau level, noncommutative quantum mechanics and the Landau Hamiltonian are equivalent theories. Using this fact, we find that the parameter that measures the noncommutative effects is given by $\\theta = \\frac{4\\hbar^2 c^2}{eH_0}$. From this formula we can infer a numerical estimate for $\\theta$ using the data for the magnetic field used in the quantum Hall effect ($H_0 \\sim 12T$) and we getting that the $\\theta = 0.6 nb$. Note that this value corresponds to a typical cros section in neutrino interactions.
The pinning effect in quantum dots
Monisha, P. J., E-mail: pjmonisha@gmail.com [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Mukhopadhyay, Soma [Department of Physics, D V R College of Engineering and Technology, Hyderabad-502285 (India)
2014-04-24
The pinning effect is studied in a Gaussian quantum dot using the improved Wigner-Brillouin perturbation theory (IWBPT) in the presence of electron-phonon interaction. The electron ground state plus one phonon state is degenerate with the electron in the first excited state. The electron-phonon interaction lifts the degeneracy and the first excited states get pinned to the ground state plus one phonon state as we increase the confinement frequency.
Quantum Spin Hall Effect in Graphene
C. L. Kane; E. J. Mele
2005-01-01
We study the effects of spin orbit interactions on the low energy electronic\\u000astructure of a single plane of graphene. We find that in an experimentally\\u000aaccessible low temperature regime the symmetry allowed spin orbit potential\\u000aconverts graphene from an ideal two dimensional semimetallic state to a quantum\\u000aspin Hall insulator. This novel electronic state of matter is gapped in
Quantum Hall Effect on the Hyperbolic Plane
A. L. Carey; K. C. Hannabuss; V. Mathai; P. McCann
1998-01-01
: In this paper, we study both the continuous model and the discrete model of the Quantum Hall Effect (QHE) on the hyperbolic\\u000a plane. The Hall conductivity is identified as a geometric invariant associated to an imprimitivity algebra of observables.\\u000a We define a twisted analogue of the Kasparov map, which enables us to use the pairing between K-theory and cyclic cohomology
The MSW Effect in Quantum Field Theory
Christian Y. Cardall; Daniel J. H. Chung
1999-04-12
We show in detail the general relationship between the Schr\\"{o}dinger equation approach to calculating the MSW effect and the quantum field theoretical S-matrix approach. We show the precise form a generic neutrino propagator must have to allow a physically meaningful ``oscillation probability'' to be decoupled from neutrino production fluxes and detection cross-sections, and explicitly list the conditions---not realized in cases of current experimental interest---in which the field theory approach would be useful.
Quantum effects in ion implanted devices
NASA Astrophysics Data System (ADS)
Jamieson, D. N.; Chan, V.; Hudson, F. E.; Andresen, S. E.; Yang, C.; Hopf, T.; Hearne, S. M.; Pakes, C. I.; Prawer, S.; Gauja, E.; Dzurak, A. S.; Clark, R. G.
2006-08-01
Fabrication of nanoscale devices that exploit the rules of quantum mechanics to process information presents formidable technical challenges because of the need to control quantum states at the level of individual atoms, electrons or photons. We have used ion implantation to fabricate devices on the scale of 10 nm that have allowed the development and test of nanocircuitry for the control of charge transport at the level of single electrons. This fabrication method is compatible with the construction of devices that employ counted P dopants in Si by employing the technique of ion beam induced charge (IBIC) in which single 14 keV P ions can be implanted into ultra-pure silicon substrates by monitoring on-substrate detector electrodes. We have used IBIC with a MeV nuclear microprobe to map and measure the charge collection efficiency in the development of the electrode structure and show that 100% charge collection efficiency can be achieved. Prototype devices fabricated by this method have been used to investigate quantum effects in the control and transport of single electrons with potential applications to solid state quantum information processing devices.
Quantum theory of the inverse Faraday effect
NASA Astrophysics Data System (ADS)
Battiato, M.; Barbalinardo, G.; Oppeneer, P. M.
2014-01-01
We provide a quantum theoretical description of the magnetic polarization induced by intense circularly polarized light in a material. Such effect—commonly referred to as the inverse Faraday effect—is treated using beyond-linear response theory, considering the applied electromagnetic field as external perturbation. An analytical time-dependent solution of the Liouville-von Neumann equation to second order is obtained for the density matrix and used to derive expressions for the optomagnetic polarization. Two distinct cases are treated, the long-time adiabatic limit of polarization imparted by continuous wave irradiation, and the full temporal shape of the transient magnetic polarization induced by a short laser pulse. We further derive expressions for the Verdet constants for the inverse, optomagnetic Faraday effect and for the conventional, magneto-optical Faraday effect and show that they are in general different. Additionally, we derive expressions for the Faraday and inverse Faraday effects within the Drude-Lorentz theory and demonstrate that their equality does not hold in general, but only for dissipationless media. As an example, we perform initial quantum mechanical calculations of the two Verdet constants for a hydrogenlike atom and we extract the trends. We observe that one reason for a large inverse Faraday effect in heavy atoms is the spatial extension of the wave functions rather than the spin-orbit interaction, which nonetheless contributes positively.
Jiang, X.; Arrington, J.; Benmokhtar, F.; Camsonne, A.; Chen, J. P.; Holt, R. J.; Qattan, I. A.; Reimer, P. E.; Schulte, E. C.; Wijesooriya, K.; Physics; Rutgers Univ.; Univ. Blaise Pascal; Thomas Jefferson National Accelerator Facility
2007-05-01
We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.
Jiang, X.; Benmokhtar, F.; Glashauser, C.; McCormick, K.; Ransome, R. D. [Rutgers, State University of New Jersey, Piscataway, New Jersey 08854 (United States); Arrington, J.; Holt, R. J.; Reimer, P. E.; Schulte, E. C.; Wijesooriya, K. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Camsonne, A. [Universite Blaise Pascal/IN2P3, F-63177 Aubiere (France); Chen, J. P.; Chudakov, E.; Gaskell, D.; Hansen, O.; Higinbotham, D. W.; Jager, C. W. de; Jones, M. K.; Lerose, J.; Michaels, R. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)] (and others)
2007-05-04
We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.
Angular dependence of recoil proton polarization in high-energy ?d \\to p n
X. Jiang; J. Arrington; F. Benmokhtar; A. Camsonne; J. P. Chen; S. Choi; E. Chudakov; F. Cusanno; A. Deur; D. Dutta; F. Garibaldi; D. Gaskell; O. Gayou; R. Gilman; C. Glashauser; D. Hamilton; O. Hansen; D. W. Higinbotham; R. J. Holt; C. W. de Jager; M. K. Jones; L. J. Kaufman; E. R. Kinney; K. Kramer; L. Lagamba; R. de Leo; J. Lerose; D. Lhuillier; R. Lindgren; N. Liyanage; K. McCormick; Z. -E. Meziani; R. Michaels; B. Moffit; P. Monaghan; S. Nanda; K. D. Paschke; C. F. Perdrisat; V. Punjabi; I. A. Qattan; R. D. Ransome; P. E. Reimer; B. Reitz; A. Saha; E. C. Schulte; R. Sheyor; K. Slifer; P. Solvignon; V. Sulkosky; G. M. Urciuoli; E. Voutier; K. Wang; K. Wijesooriya; B. Wojtsekhowski; L. Zhu
2007-02-02
We measured the angular dependence of the three recoil proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily.. Transverse polarizations are not well described, but suggest isovector dominance.
Integer Quantum Hall Effect in Graphene
Jellal, Ahmed
2015-01-01
We study the quantum Hall effect in a monolayer graphene by using an approach based on thermodynamical properties. This can be done by considering a system of Dirac particles in an electromagnetic field and taking into account of the edges effect as a pseudo-potential varying continuously along the $x$ direction. At low temperature and in the weak electric field limit, we explicitly determine the thermodynamical potential. With this, we derive the particle numbers in terms of the quantized flux and therefore the Hall conductivity immediately follows.
Integer Quantum Hall Effect in Graphene
Ahmed Jellal
2015-04-24
We study the quantum Hall effect in a monolayer graphene by using an approach based on thermodynamical properties. This can be done by considering a system of Dirac particles in an electromagnetic field and taking into account of the edges effect as a pseudo-potential varying continuously along the $x$ direction. At low temperature and in the weak electric field limit, we explicitly determine the thermodynamical potential. With this, we derive the particle numbers in terms of the quantized flux and therefore the Hall conductivity immediately follows.
A programmable quantum current standard from the Josephson and the quantum Hall effects
Poirier, W., E-mail: wilfrid.poirier@lne.fr; Lafont, F.; Djordjevic, S.; Schopfer, F.; Devoille, L. [Quantum metrology group, Laboratoire National de métrologie et d'Essais, 29 avenue Roger Hennequin, 78197 Trappes (France)
2014-01-28
We propose a way to realize a programmable quantum current standard (PQCS) from the Josephson voltage standard and the quantum Hall resistance standard (QHR) exploiting the multiple connection technique provided by the quantum Hall effect (QHE) and the exactness of the cryogenic current comparator. The PQCS could lead to breakthroughs in electrical metrology like the realization of a programmable quantum current source, a quantum ampere-meter, and a simplified closure of the quantum metrological triangle. Moreover, very accurate universality tests of the QHE could be performed by comparing PQCS based on different QHRs.
Macroscopic effects of the quantum trace anomaly
Mottola, Emil; Vaulin, Ruslan [Theoretical Division, T-8 Los Alamos National Laboratory M.S. B285 Los Alamos, New Mexico 87545 (United States); Department of Physics Florida Atlantic University 777 Glades Road, Boca Raton, Florida 33431 (United States)
2006-09-15
The low energy effective action of gravity in any even dimension generally acquires nonlocal terms associated with the trace anomaly, generated by the quantum fluctuations of massless fields. The local auxiliary field description of this effective action in four dimensions requires two additional scalar fields, not contained in classical general relativity, which remain relevant at macroscopic distance scales. The auxiliary scalar fields depend upon boundary conditions for their complete specification, and therefore carry global information about the geometry and macroscopic quantum state of the gravitational field. The scalar potentials also provide coordinate invariant order parameters describing the conformal behavior and divergences of the stress tensor on event horizons. We compute the stress tensor due to the anomaly in terms of its auxiliary scalar potentials in a number of concrete examples, including the Rindler wedge, the Schwarzschild geometry, and de Sitter spacetime. In all of these cases, a small number of classical order parameters completely determine the divergent behaviors allowed on the horizon, and yield qualitatively correct global approximations to the renormalized expectation value of the quantum stress tensor.
Quantum confined Stark effect in Gaussian quantum wells: A tight-binding study
Ramírez-Morales, A.; Martínez-Orozco, J. C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)
2014-05-15
The main characteristics of the quantum confined Stark effect (QCSE) are studied theoretically in quantum wells of Gaussian profile. The semi-empirical tight-binding model and the Green function formalism are applied in the numerical calculations. A comparison of the QCSE in quantum wells with different kinds of confining potential is presented.
OPTICS. Quantum spin Hall effect of light.
Bliokh, Konstantin Y; Smirnova, Daria; Nori, Franco
2015-06-26
Maxwell's equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell's theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces. PMID:26113717
Memory Effects in Quantum Channel Discrimination Giulio Chiribella,1
D'Ariano, Giacomo Mauro
Memory Effects in Quantum Channel Discrimination Giulio Chiribella,1 Giacomo M. D'Ariano,1 quantum-memory assisted protocols for discriminating quantum channels. We show that for optimal discrimination of memory channels, memory assisted protocols are needed. This leads to a new notion of distance
The spin Hall effect in quantum wires
NASA Astrophysics Data System (ADS)
Cummings, Aron William
Numerical simulations are used to study the nature of the spin Hall effect in semiconductor quantum wires. The strength of the spin Hall effect is first examined as a function of spin-orbit coupling strength, electron density, and wire width, and is found to exhibit a non-monotonic dependence on these parameters. This behavior is explained by a dispersion relation characterized by the anticrossing of adjacent subbands. The anticrossings are related to phase transitions in momentum space, and are accompanied by an enhancement of the Berry curvature and subsequently of the spin Hall effect. These results lead to an estimate of the optimal wire width for transport experiments, and simulations indicate that this width is independent of disorder. Next, a means of generating spin-polarized currents in quantum wires is discussed. This is accomplished with a Y-shaped junction that uses the spin Hall effect to generate oppositely polarized currents in the output leads. It is shown that the analysis of the spin Hall effect in straight wires can serve to maximize the spin polarization at the output of the Y-junction. A two-stage cascade of Y-junctions is also examined, where the first stage serves as a spin polarizer and the second stage as a spin detector. Simulations show that, when only the lowest subband is occupied, a conductance imbalance can indicate the presence of spin polarization. It is also shown that an in-plane magnetic field can distinguish conductance imbalances due to structural asymmetry from those due to the spin Hall effect. Next, Dresselhaus spin-orbit coupling and its influence on the spin Hall effect is discussed. It is found that the spin Hall effect is maximized for transport along one of two principal axes, depending on the various system parameters. Finally, simulations are used to explain experimental measurements of a cascaded spin filter structure fabricated and measured by Jan Jacob at the University of Hamburg. The simulations reveal that the experimental results are dominated by shifted quantum point contact side gates, but that the role of the spin Hall effect can still be examined with an in-plane magnetic field.
Matrix effective theories of the fractional quantum Hall effect
NASA Astrophysics Data System (ADS)
Cappelli, Andrea; Rodriguez, Ivan D.
2009-07-01
The present understanding of nonperturbative ground states in the fractional quantum Hall effect is based on effective theories of the Jain 'composite fermion' excitations. We review the approach based on matrix variables, i.e. D0 branes, originally introduced by Susskind and Polychronakos. We show that the Maxwell-Chern-Simons matrix gauge theory provides a matrix generalization of the quantum Hall effect, where the composite-fermion construction naturally follows from gauge invariance. The matrix ground states obtained by suitable projections of higher Landau levels are found to be in one-to-one correspondence with the Laughlin and Jain hierarchical states. The matrix theory possesses a physical limit for commuting matrices that could be reachable while staying in the same phase.
Pengjun Wang; L. Deng; E. W. Hagley; Zhengkun Fu; Shijie Chai; Jing Zhang
2010-01-01
We demonstrate clear collective atomic recoil motion in a dilute,\\u000amomentum-squeezed, ultra-cold degenerate fermion gas by circumventing the\\u000aeffects of Pauli blocking. Although gain from bosonic stimulation is\\u000anecessarily absent because the quantum gas obeys Fermi-Dirac statistics,\\u000acollective atomic recoil motion from the underlying wave-mixing process is\\u000aclearly visible. With a single pump pulse of the proper polarization, we\\u000aobserve
Berry phase from a quantum Zeno effect
P. Facchi; A. G. Klein; S. Pascazio; L. S. Schulman
1999-03-31
We exhibit a specific implementation of the creation of geometrical phase through the state-space evolution generated by the dynamic quantum Zeno effect. That is, a system is guided through a closed loop in Hilbert space by means a sequence of closely spaced projections leading to a phase difference with respect to the original state. Our goal is the proposal of a specific experimental setup in which this phase could be created and observed. To this end we study the case of neutron spin, examine the practical aspects of realizing the "projections," and estimate the difference between the idealized projections and the experimental implementation.
Quantum spring from the Casimir effect
NASA Astrophysics Data System (ADS)
Feng, Chao-Jun; Li, Xin-Zhou
2010-07-01
The Casimir effect arises not only in the presence of material boundaries but also in space with nontrivial topology. In this Letter, we choose a topology of the flat (D + 1)-dimensional spacetime, which causes the helix boundary condition for a Hermitian massless scalar field. Especially, Casimir effect for a massless scalar field on the helix boundary condition is investigated in two and three dimensions by using the zeta function techniques. The Casimir force parallel to the axis of the helix behaves very much like the force on a spring that obeys the Hooke's law when the ratio r of the pitch to the circumference of the helix is small, but in this case, the force comes from a quantum effect, so we would like to call it quantum spring. When r is large, this force behaves like the Newton's law of universal gravitation in the leading order. On the other hand, the force perpendicular to the axis decreases monotonously with the increasing of the ratio r. Both forces are attractive and their behaviors are the same in two and three dimensions.
Quantum Spring from the Casimir Effect
Chao-Jun Feng; Xin-Zhou Li
2010-07-13
The Casimir effect arises not only in the presence of material boundaries but also in space with nontrivial topology. In this paper, we choose a topology of the flat $(D+1)$-dimensional spacetime, which causes the helix boundary condition for a Hermitian massless scalar field. Especially, Casimir effect for a massless scalar field on the helix boundary condition is investigated in two and three dimensions by using the zeta function techniques. The Casimir force parallel to the axis of the helix behaves very much like the force on a spring that obeys the Hooke's law when the ratio $r$ of the pitch to the circumference of the helix is small, but in this case, the force comes from a quantum effect, so we would like to call it \\textit{quantum spring}. When $r$ is large, this force behaves like the Newton's law of universal gravitation in the leading order. On the other hand, the force perpendicular to the axis decreases monotonously with the increasing of the ratio $r$. Both forces are attractive and their behaviors are the same in two and three dimensions.
Cosmic fluctuations from quantum effective action
C. Wetterich
2015-03-26
Does the observable spectrum of cosmic fluctuations depend on detailed initial conditions? This addresses the question if the general inflationary paradigm is sufficient to predict within a given model the spectrum and amplitude of cosmic fluctuations, or if additional particular assumptions about the initial conditions are needed. The answer depends on the number of e-foldings $N_{in}$ between the beginning of inflation and horizon crossing of the observable fluctuations. We discuss an interacting inflaton field in an arbitrary homogeneous and isotropic geometry, employing the quantum effective action $\\Gamma$. An exact time evolution equation for the correlation function involves the second functional derivative $\\Gamma^{(2)}$. The operator formalism and quantum vacua for interacting fields are not needed. Use of the effective action also allows one to address the change of frames by field transformations (field relativity). For not too large $N_{in}$ we find that memory of the initial conditions is preserved. In this case the cosmic microwave background cannot disentangle between the initial spectrum and its processing at horizon crossing. The inflaton potential cannot be reconstructed without assumptions about the initial state of the universe. We argue that for very large $N_{in}$ a universal scaling form of the correlation functions is reached. This can be due to symmetrization and equilibration effects not yet contained in our approximation, which drive the short distance tail of the correlation function towards the Lorentz invariant propagator in flat space.
Topological Quantum Computation by Manipulating Quantum Tunneling Effect of the Toric Codes
Su-Peng Kou
2008-06-10
Quantum computers are predicted to utilize quantum states to perform memory and to process tasks far faster than those of conventional classical computers. In this paper we show a new road towards building fault tolerance quantum computer by tuning quantum tunneling effect of the degenerate quantum states in topological order, instead of by braiding anyons. Using a designer Hamiltonian - the Wen-Plaquette model as an example, we study its quantum tunneling effect of the toric codes and show how to control the toric code to realize topological quantum computation (TQC). In particular, we give a proposal to the measurement of TQC. In the end the realization of the Wen-Plaquette model in cold atoms is discussed.
Quantum tunneling vs. thermal effects in experiments on adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Silevitch, D. M.; Rosenbaum, T. F.; Aeppli, G.
2015-02-01
Traditional simulated annealing uses thermal fluctuations for convergence in optimization problems. Quantum tunneling provides a different mechanism for moving between states, with the potential for reduced time scales and different outcomes. Thermal and quantum annealing are compared in two concentration regimes of a model disordered magnet, where the effects of quantum mechanics can be tuned both by varying an applied magnetic field and by controlling the strength of thermal coupling between the magnet and an external heat bath. The results indicate that quantum annealing hastens convergence to the final state, and that the quantum character of the final state can be engineered thermodynamically.
A quantum probability account of order effects in inference.
Trueblood, Jennifer S; Busemeyer, Jerome R
2011-01-01
Order of information plays a crucial role in the process of updating beliefs across time. In fact, the presence of order effects makes a classical or Bayesian approach to inference difficult. As a result, the existing models of inference, such as the belief-adjustment model, merely provide an ad hoc explanation for these effects. We postulate a quantum inference model for order effects based on the axiomatic principles of quantum probability theory. The quantum inference model explains order effects by transforming a state vector with different sequences of operators for different orderings of information. We demonstrate this process by fitting the quantum model to data collected in a medical diagnostic task and a jury decision-making task. To further test the quantum inference model, a new jury decision-making experiment is developed. Using the results of this experiment, we compare the quantum inference model with two versions of the belief-adjustment model, the adding model and the averaging model. We show that both the quantum model and the adding model provide good fits to the data. To distinguish the quantum model from the adding model, we develop a new experiment involving extreme evidence. The results from this new experiment suggest that the adding model faces limitations when accounting for tasks involving extreme evidence, whereas the quantum inference model does not. Ultimately, we argue that the quantum model provides a more coherent account for order effects that was not possible before. PMID:21951058
NASA Astrophysics Data System (ADS)
Elyasi, P.; SalmanOgli, A.
2014-05-01
This paper investigates GaAs/AlGaAs modified quantum dot nanocrystal and GaAs/AlGaAs/GaAs/AlGaAs quantum dot-quantum well heteronanocrystal. These quantum dots have been analyzed by the finite element numerical methods. Simulations carried out for state n=1, l=0, and m=0 which are original, orbital, and magnetic state of quantum numbers. The effects of variation in radius layers such as total radius, GaAs core, shell and AlGaAs barriers radius on the wavelength and emission coefficient are studied. For the best time, it has also investigated the effect of mole fraction on emission coefficient. Meanwhile, one of the problems in biological applications is alteration of the emission wavelength of a quantum dot by changing in its dimension. This problem will be resolved by changing in potential profile.
Tunneling effects in a one-dimensional quantum walk
Mostafa Annabestani; Seyed Javad Akhtarshenas; Mohamad Reza Abolhassani
2010-04-25
In this article we investigate the effects of shifting position decoherence, arisen from the tunneling effect in the experimental realization of the quantum walk, on the one-dimensional discreet time quantum walk. We show that in the regime of this type of noise the quantum behavior of the walker does not fade, in contrary to the coin decoherence for which the walker undergos the quantum-to-classical transition even for weak noise. Particularly, we show that the quadratic dependency of the variance on the time and also the coin-position entanglement, i.e. two important quantum aspects of the coherent quantum walk, are preserved in the presence of tunneling decoherence. Furthermore, we present an explicit expression for the probability distribution of decoherent one-dimensional quantum walk in terms of the corresponding coherent probabilities, and show that this type of decoherence smooths the probability distribution.
Covariant effective action for loop quantum cosmology a la Palatini
Olmo, Gonzalo J. [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain)] [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Singh, Parampreet, E-mail: olmo@iem.cfmac.csic.es, E-mail: psingh@perimeterinstitute.ca [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada)] [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada)
2009-01-15
In loop quantum cosmology, non-perturbative quantum gravity effects lead to the resolution of the big bang singularity by a quantum bounce without introducing any new degrees of freedom. Though fundamentally discrete, the theory admits a continuum description in terms of an effective Hamiltonian. Here we provide an algorithm to obtain the corresponding effective action, establishing in this way the covariance of the theory for the first time. This result provides new insights on the continuum properties of the discrete structure of quantum geometry and opens new avenues to extract physical predictions such as those related to gauge invariant cosmological perturbations.
Paris-Sud XI, Université de
, is the The term quantum beats is generally maximum phase shift of the radiation due to motion -+ applied of lines to distinguish it from the absorber used to obtain centered at the frequencies w = w f nS1, n = 0 it is at rest, and n numbers the side- The time-dependence can be seen easily band. If the source is thin
Focus on quantum effects and noise in biomolecules
G. R. Fleming; S. F. Huelga; M. B. Plenio
2011-01-01
The role of quantum mechanics in biological organisms has been a fundamental question of twentieth-century biology. It is only now, however, with modern experimental techniques, that it is possible to observe quantum mechanical effects in bio-molecular complexes directly. Indeed, recent experiments have provided evidence that quantum effects such as wave-like motion of excitonic energy flow, delocalization and entanglement can be
Guiding effect of quantum wells in semiconductor lasers
Aleshkin, V Ya; Dikareva, Natalia V; Dubinov, A A; Zvonkov, B N; Karzanova, Maria V; Kudryavtsev, K E; Nekorkin, S M; Yablonskii, A N
2013-05-31
The guiding effect of InGaAs quantum wells in GaAs- and InP-based semiconductor lasers has been studied theoretically and experimentally. The results demonstrate that such waveguides can be effectively used in laser structures with a large refractive index difference between the quantum well material and semiconductor matrix and a large number of quantum wells (e.g. in InP-based structures). (semiconductor lasers. physics and technology)
Effect of local filtering on freezing phenomena of quantum correlation
NASA Astrophysics Data System (ADS)
Karmakar, Sumana; Sen, Ajoy; Bhar, Amit; Sarkar, Debasis
2015-05-01
General quantum correlation measures such as quantum discord, one-norm geometric quantum discord exhibit freezing, sudden change, and double sudden change behavior in their decay rates under different noisy channels. Therefore, one may attempt to investigate how the freezing behavior and other dynamical features are affected under application of local quantum operations. In this work, we demonstrate the effect of local filtering on the dynamical evolution of quantum correlations. We have found that using local filtering, one may remove freezing depending upon the filtering parameter.
Effect of local filtering on freezing phenomena of quantum correlation
NASA Astrophysics Data System (ADS)
Karmakar, Sumana; Sen, Ajoy; Bhar, Amit; Sarkar, Debasis
2015-07-01
General quantum correlation measures such as quantum discord, one-norm geometric quantum discord exhibit freezing, sudden change, and double sudden change behavior in their decay rates under different noisy channels. Therefore, one may attempt to investigate how the freezing behavior and other dynamical features are affected under application of local quantum operations. In this work, we demonstrate the effect of local filtering on the dynamical evolution of quantum correlations. We have found that using local filtering, one may remove freezing depending upon the filtering parameter.
ESCA studies on recoil implanted aluminum substrates
Mallya, Narayani R.
1980-01-01
for recoil 1mplantation of gold in A120&/Al substrates was done. Implantation is a technique which can be used for introducing impurit1es 1nto a substrate. Impurity doped surfaces are 1mportant model systems 1n several current areas of act1ve research... Sam le Pre aration Aluminum foil, 99. 999f. pure and 0. 25 mm th1ck (Alfa-Uentron) is cut 1nto rectangular pieces of 1. 2 cms X 1. 0 cms so as to fit the sample probe of the HP5950A ESCA spectrometer. Each piece is sputter etched with a I Kev argon...
Neutron electric form factor via recoil polarimetry
Richard Madey; Andrei Semenov; Simon Taylor; Aram Aghalaryan; Erick Crouse; Glen MacLachlan; Bradley Plaster; Shigeyuki Tajima; William Tireman; Chenyu Yan; Abdellah Ahmidouch; Brian Anderson; Razmik Asaturyan; O. Baker; Alan Baldwin; Herbert Breuer; Roger Carlini; Michael Christy; Steve Churchwell; Leon Cole; Samuel Danagoulian; Donal Day; Mostafa Elaasar; Rolf Ent; Manouchehr Farkhondeh; Howard Fenker; John Finn; Liping Gan; Kenneth Garrow; Paul Gueye; Calvin Howell; Bitao Hu; Mark Jones; James Kelly; Cynthia Keppel; Mahbubul Khandaker; Wooyoung Kim; Stanley Kowalski; Allison Lung; David Mack; D. Manley; Pete Markowitz; Joseph Mitchell; Hamlet Mkrtchyan; Allena Opper; Charles Perdrisat; Vina Punjabi; Brian Raue; Tilmann Reichelt; Joerg Reinhold; Julie Roche; Yoshinori Sato; Wonick Seo; Neven Simicevic; Gregory Smith; Samuel Stepanyan; Vardan Tadevosyan; Liguang Tang; Paul Ulmer; William Vulcan; John Watson; Steven Wells; Frank Wesselmann; Stephen Wood; Chen Yan; Seunghoon Yang; Lulin Yuan; Wei-Ming Zhang; Hong Guo Zhu; Xiaofeng Zhu
2003-05-01
The ratio of the electric to the magnetic form factor of the neutron, G_En/G_Mn, was measured via recoil polarimetry from the quasielastic d({pol-e},e'{pol-n)p reaction at three values of Q^2 [viz., 0.45, 1.15 and 1.47 (GeV/c)^2] in Hall C of the Thomas Jefferson National Accelerator Facility. Preliminary data indicate that G_En follows the Galster parameterization up to Q^2 = 1.15 (GeV/c)^2 and appears to rise above the Galster parameterization at Q^2 = 1.47 (GeV/c)^2.
Numerical simulations of spiral galaxy formation and recoiling black holes
NASA Astrophysics Data System (ADS)
Guedes, Javiera M.
This thesis discusses two major topics in regard to the formation and evolution of galaxies and their central massive black holes (MBH). Part 1 explores the detectability of recoiling massive back as kinematically and spatially offset active galactic nuclei (AGN). Chapter 3 is devoted to understanding the effect of an aspherical dark matter potential on the trajectories of the MBHs. This is done through collisionless N-body simulations of kicked black holes in the Via Lactea I halo and through a semi-analytical model that accounts for the evolution of the halo's triaxiality as a function of radius over cosmic time. We find that the return time of MBHs that wander through a differentially triaxial halo is significantly extended in comparison with spherical models. This is because their trajectories are become highly non-radial which prevents them from passing near the halo's center, where dynamical friction is most efficient. Chapter 4 puts recoiling MBHs into context. Here we carry out N-body + SPH simulations of recoiling MBHs in high-resolution galaxy mergers with mass ratios 1:1 (Mayer et al. 2007), 1:4, and 1:10 (Callegari et al. 2009). We study not only the trajectories and return times of these black holes, but also their detectability as spatially/kinematically offset AGN. We find that the probability of detection of these MBHs is extremely low. The detection of large kinematic offsets requires that the MBH have relative offset velocities Deltav > 600km s-1 at the time of observation. This is unlikely due to (1) the low probability of large recoils to occur from a general-relativistic viewpoint, and (2) the short time scale during which the MBH can sustain large velocities even if the initial kick is high. The large amounts of gas funneled to the center of the host potential during mergers also prevents MBHs from reaching large apocenter distances, which hampers their detection as spatially offset AGN, especially at high redshift when recoil events are expected to be common. Part 2 is dedicated to the formation of massive disk galaxies through N-body + SPH simulations. There, I describe the properties of Eris, the highest resolution cosmological simulation to date of the formation of a Milky Way-like galaxy from z = 90 to z = 0. Eris appears to solve the long-standing problems of mass concentration, which traditionally lead to the formation galaxies with large spheroidal components and small disks. A combination of high-resolution and high star formation threshold was the key to the success of Eris, because stars are only allowed to form at the highest density peaks and therefore feedback is more efficient in removing preferentially low angular momentum gas. Previous simulations tended to over-produce stars in low-density regions, where feedback is ineffective. Eris is in agreement with the Tully-Fischer, and M* - Mhalo relations, matches the observed surface brightness breaks in nearby spirals, is consistent with Sigma SFR - SigmaHI observations in spirals, and agrees with constraints on the hot gas mass abundance in the Galaxy. In addition, Eris' baryon fraction is 30% lower than the universal value, due to star formation driven outflows.
Exact quantum description of the Aharonov–Bohm effect
M. Y Choi; Minchul Lee
2004-01-01
The Aharonov–Bohm effect is considered in the fully quantum mechanical description, where the magnet as well as the moving charged particle is treated as a quantum object and interactions between them are mediated by virtual photon exchange. Employing the path integral representation, we not only establish the standard AB effect in an exact fashion but also reveal the origin of
Kinetic Isotope Effects from Hybrid Classical and Quantum
Minnesota, University of
CHAPTER 5 Kinetic Isotope Effects from Hybrid Classical and Quantum Path Integral Computations is by measurements of kinetic isotope effects (KIE),1 which are of quantum-mechanical origin. This is illustrated AND SHUHUA MA Department of Chemistry and Supercomputer Institute, University of Minnesota, 207 Pleasant
On Quantum Effects in a Theory of Biological Evolution
Calude, Cristian S.
, classical evolution turns out to be more favorable. E ver since its development by Darwin1 , the theoryOn Quantum Effects in a Theory of Biological Evolution M. A. Martin-Delgado Departamento de Fi that considers quantum effects on biological evolution starting from Chaitin's classical framework
Anomalous nuclear quantum effects in ice
NASA Astrophysics Data System (ADS)
Pamuk, Betül; Soler, Jose M.; Allen, Philip B.; Fernández-Serra, Marivi
2012-02-01
The lattice parameters of light (H2O) and heavy (D2O) Ih ice at 10 K differ by 0.09%.[1] The larger lattice constant is that of the heavier isotope. This isotope shift with anomalous sign is linked to the zero point point energy of phonons in ice. To determine the origin of this anomaly, we use ab initio density functional theory to compute the free energy of ice within the quasiharmonic approximation. As expected, the frozen lattice constant at T = 0 K is smaller than the quantum lattice constant, independent of the isotopic substitution. We find that, the heavy isotope D gives more zero point expansion than H, whereas the heavy isotope ^18O gives normal zero point expansion, i.e smaller than ^16O. Relative to the the classical result, the net effect of quantum nuclei (H and O) on volume has the conventional (positive) sign at T = 0 but it becomes negative above 70 K, indicating that it may be also relevant for liquid water. These results are not reproduced by state of art polarizable empirical potentials.[2] [1] B. K. R"ottger et. al., Acta Cryst. B 50, 644-648 (1994). [2] C. P. Herrero and R. Ram'irez, J. Chem. Phys. 134, 094510 (2011).
Decoherence, Quantum Zeno Effect, and the Efficacy of Mental Effort
Henry P. Stapp
2000-03-17
Recent theoretical and experimental papers support the prevailing opinion that large warm systems will rapidly lose quantum coherence, and that classical properties will emerge. This rapid loss of coherence would naturally be expected to block any critical role for quantum theory in explaining the interaction between our conscious experiences and the physical activities of our brains. However, there is a quantum theory of mind in which the efficacy of mental effort is not affected by decoherence effects. In this theory the effects of mental action on brain activity is achieved by a Quantum Zeno Effect that is not weakened by decoherence. The theory is based on a relativistic version of von Neumann's quantum theory. It encompasses all the predictions of Copenhagen quantum theory, which include all the validated predictions of classical physical theory. In addition, it forges two-way dynamical links between the physical and experiential aspects of nature. The theory has significant explanatory power.
Noise Effects in Quantum Magic Squares Game
P. Gawron; J. A. Miszczak; J. Sladkowski
2008-01-31
In the article we analyse how noisiness of quantum channels can influence the magic squares quantum pseudo-telepathy game. We show that the probability of success can be used to determine characteristics of quantum channels. Therefore the game deserves more careful study aiming at its implementation.
NOISE EFFECTS IN QUANTUM MAGIC SQUARES GAME
PIOTR GAWRON; JAN S LADKOWSKI; JAN S?ADKOWSKI
2008-01-01
In the article we analyse how noisiness of quantum channels can influence the\\u000amagic squares quantum pseudo-telepathy game. We show that the probability of\\u000asuccess can be used to determine characteristics of quantum channels. Therefore\\u000athe game deserves more careful study aiming at its implementation.
Noise Effects in Quantum Magic Squares Game
Gawron, P; Sladkowski, J
2008-01-01
In the article we analyse how noisiness of quantum channels can influence the magic squares quantum pseudo-telepathy game. We show that the probability of success can be used to determine characteristics of quantum channels. Therefore the game deserves more careful study aiming at its implementation.
Dynamical competition between quantum Hall and quantum spin Hall effects
NASA Astrophysics Data System (ADS)
Quelle, A.; Morais Smith, C.
2014-11-01
In this paper, we investigate the occurrence of quantum phase transitions in topological systems out of equilibrium. More specifically, we consider graphene with a sizable spin-orbit coupling, irradiated by circularly polarized light. In the absence of light, the spin-orbit coupling drives a quantum spin Hall phase where edge currents with opposite spins counterpropagate. On the other hand, the light generates a time-dependent vector potential, which leads to a hopping parameter with staggered time-dependent phases around the benzene ring. The model is a dynamical version of the Haldane model, which considers a static staggered flux with zero total flux through each plaquette. Since the light breaks time-reversal symmetry, a quantum Hall (QH) phase protected by an integer topological invariant arises. An important difference with the static QH phase is the existence of counterpropagating edge states at different momenta, which are made possible by zero- and two-photon resonances. By numerically solving the complete problem, with spin-orbit coupling and light, and investigating different values of the driving frequency ? , we show that the spectrum exhibits nontrivial gaps not only at zero energy but also at ? /2 . This additional gap is created by photon resonances between the valence and conduction band of graphene, and the symmetry of the spectrum forces it to lie at ? /2 . By increasing the intensity of the irradiation, the topological state in the zero energy gap undergoes a dynamical phase transition from a quantum spin Hall to a quantum Hall phase, whereas the gap around ? /2 remains in the quantum Hall regime.
Quantum interference phenomena in the Casimir effect
NASA Astrophysics Data System (ADS)
Allocca, Andrew A.; Wilson, Justin H.; Galitski, Victor M.
2015-06-01
We propose a definitive test of whether plates involved in Casimir experiments should be modeled with ballistic or diffusive electrons—a prominent controversy highlighted by a number of conflicting experiments. The unambiguous test we propose is a measurement of the Casimir force between a disordered quasi-two-dimensional metallic plate and a three-dimensional metallic system at low temperatures, in which disorder-induced weak-localization effects modify the well-known Drude result in an experimentally tunable way. We calculate the weak-localization correction to the Casimir force as a function of magnetic field and temperature and demonstrate that the quantum interference suppression of the Casimir force is a strong, observable effect. The coexistence of weak-localization suppression in electronic transport and Casimir pressure would lend credence to the Drude theory of the Casimir effect, while the lack of such correlation would indicate a fundamental problem with the existing theory. We also study mesoscopic disorder fluctuations in the Casimir effect and estimate the width of the distribution of Casmir energies due to disorder fluctuations.
Peltier effect in strongly driven quantum wires
NASA Astrophysics Data System (ADS)
Mierzejewski, M.; Crivelli, D.; Prelovšek, P.
2014-08-01
We study a microscopic model of a thermocouple device with two connected correlated quantum wires driven by a constant electric field. In such a closed system we follow the time and position dependence of the entropy density using the concept of the reduced density matrix. At weak driving, the initial changes of the entropy at the junctions can be described by the linear Peltier response. At longer times the quasiequilibrium situation is reached with well defined local temperatures which increase due to an overall Joule heating. On the other hand, a strong electric field induces a nontrivial nonlinear thermoelectric response, e.g., the Bloch oscillations of the energy current. Moreover, we show for the doped Mott insulators that strong driving can reverse the Peltier effect.
Macroscopic quantum effects for classical light
NASA Astrophysics Data System (ADS)
Petrov, N. I.
2014-10-01
Optical analogies of macroscopic quantum effects (Schrödinger cat states, squeezing, collapse, and revival) for light beams propagating in an inhomogeneous linear medium are demonstrated theoretically using exact analytical solutions of the wave equation. It is shown that the coherent superposition of macroscopically distinguishable states is generated via mode interference from an initial off-axis single wave packet. Squeezed cat states with a fidelity >99% arise periodically and disappear rapidly within limited intervals of a propagation distance. Collapse and revival of wave packets at long-term nonparaxial evolution due to mode interference is demonstrated. Oscillations of the beam trajectory occur with extremely small amplitude, of the order of 10-19 m, which is typical of the estimated displacement caused by cosmic gravitational waves in gravity-wave detectors.
Stability of Quantum Fluids : Wavy Interface Effect
A. Kwang-Hua Chu
2005-08-31
A numerical investigation for the stability of the incompressible slip flow of normal quantum fluids (above the critical phase transition temperature) inside a microslab where surface acoustic waves propagate along the walls is presented. Governing equations and associated slip velocity and wavy interface boundary conditions for the flow of normal fluids confined between elastic wavy interfaces are obtained. The numerical approach is an extension (with a complex matrix pre-conditioning) of the spectral method. We found that the critical Reynolds number ($Re_{cr}$ or the critical velocity) decreases significantly once the slip velocity and wavy interface effects are present and the latter is dominated ($Re_{cr}$ mainly depends on the wavy interfaces).
Effect of Quantum Point Contact Measurement on Electron Spin State in Quantum Dot
Fei-Yun Zhu; Zhi-Cheng Zhu; Tao Tu; Hua Tu; Guang-Can Guo; Guo-Ping Guo
2009-01-09
We study the time evolution of two electron spin states in a double quantum-dot system, which includes a nearby quantum point contact (QPC) as a measurement device. We obtain that the QPC measurement induced decoherence is in time scales of microsecond. We also find that the enhanced QPC measurement will trap the system in its initial spin states, which is consistent with quantum Zeno effect.
Synchrotron-radiation experiments with recoil ions
Levin, J.C.
1989-01-01
Studies of atoms, ions and molecules with synchrotron radiation have generally focused on measurements of properties of the electrons ejected during, or after, the photoionization process. Much can also be learned, however, about the atomic or molecular relaxation process by studies of the residual ions or molecular fragments following inner-shell photoionization. Measurements are reported of mean kinetic energies of highly charged argon, krypton, and xenon recoil ions produced by vacancy cascades following inner-shell photoionization using white and monochromatic synchrotron x radiation. Energies are much lower than for the same charge-state ions produced by charged-particle impact. The results may be applicable to design of future angle-resolved ion-atom collision experiments. Photoion charge distributions are presented and compared with other measurements and calculations. Related experiments with synchrotron-radiation produced recoil ion, including photoionization of stored ions and measurement of shakeoff in near-threshold excitation, are briefly discussed. 24 refs., 6 figs., 1 tab.
Low energy ion scattering and recoiling
NASA Astrophysics Data System (ADS)
Wayne Rabalais, J.
1994-01-01
Ion scattering spectrometry was developed as a surface elemental analysis technique in the late 1960's. Further developments during the 1970's and 80's revealed the ability to obtain surface structural information. The recent use of time-of-flight (TOF) methods has led to a surface crystallography that is sensitive to all elements, including hydrogen, and the ability to directly detect hydrogen adsorption sites. TOF detection of both neutrals and ions provides the high sensitivity necessary for non-destructive analysis. Detection of atoms scattered and recoiled from surfaces in simple collision sequences, together with calculations of shadowing and blocking cones, can now be used to make direct measurements of interatomic spacings and adsorption sites within an accuracy of ? 0.1 Å. Structures are determined by monitoring the angular anisotropies in the scattered primary and recoiled target atom flux. Applications of such surface structure and adsorption site determinations are in the fields of catalysis, thin film growth, and interfaces. This article provides a short historical account of these developments along with some examples of the most recent capabilities of the technique.
THE NEW HRIBF RECOIL MASS SPECTROMETER | PERFORMANCE AND FIRST RESULTS
than 15 years recoil mass spectrometers have served as an important tool for nuclear structure for 146Tm new proton transitions were identi ed possibly from the population of excited states in 145Er . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii Chapter I. THE ROLE OF RECOIL MASS SPECTROMETERS IN NUCLEAR SPECTROSCOPY 1 Nuclear Structure
A Silicon Recoil Detector for the HERMES Experiment
A Silicon Recoil Detector for the HERMES Experiment A. Vandenbroucke University Gent On behalf Detector 3. Silicon Recoil Detector Âª Sensors, Frame, Hybrid, Foils, Tests 4. Summary DPG Mainz, March 2004 0 1 2 3 4 5 6 7 8 9 10 RICH SILICON 270 mrad 270 mrad MUON HODOSCOPE WIDE ANGLE FRONT MUON HODO
Asymmetry of recoil protons in neutron beta-decay
V. Gudkov
2008-01-31
A complete analysis of proton recoil asymmetry in neutron decay in the first order of radiative and recoil corrections is presented. The possible contributions from new physics are calculated in terms of low energy coupling constants, and the sensitivity of the measured asymmetry to models beyond the Standard model are discussed.
A delta-kicked model for the quantum ratchet effect
NASA Astrophysics Data System (ADS)
Chen, Lei; Xiong, Chao; Yuan, Hong-Chun; Ding, Li-Hua
2014-03-01
We construct a delta-kicked model for the quantum ratchet effect. Two symmetric flashing potentials alternately act on a particle with a symmetric and homogeneous initial state of zero momentum. Ratchet currents emerge when quantum resonances are excited. We give some results and compare our model and a previous model. Our work provides a way to control the quantum transport of cold atoms experimentally.
Closed-form formula on quantum factorization effectiveness
NASA Astrophysics Data System (ADS)
Zawadzki, Piotr
2013-01-01
The quantum factorization effectiveness is limited both by inherent randomness of the quantum measurement and requirement of special selection of parameters controlling behavior of classic algorithms supporting quantum device operation. However, only coarse bounds on probability of successful parameters selection have been published so far. The proof of an exact expression on factorization efficiency constitutes the main contribution of the paper. The proved expression simply relates Shor's algorithm efficiency to properties of the factors forming the composite number.
Quantum statistical effects on fusion dynamics of heavy ions
Ayik, S. [Physics Department, Tennessee Technological University, Cookeville, Tennessee 38505 (United States); Yilmaz, B. [Physics Department, Ankara University, TR-06100 Ankara (Turkey); Physics Department, Middle East Technical University, TR-06531 Ankara (Turkey); Gokalp, A.; Yilmaz, O. [Physics Department, Middle East Technical University, TR-06531 Ankara (Turkey); Takigawa, N. [Department of Physics, Tohoku University, 980-8578 Sendai (Japan)
2005-05-01
To describe the fusion of two very heavy nuclei at near barrier energies, a generalized Langevin approach is proposed. The approach incorporates the quantum statistical fluctuations in accordance with the fluctuation and dissipation theorem. It is illustrated that the quantum statistical effects introduce an enhancement of the formation of a compound nucleus, though the quantum enhancement is somewhat less pronounced as indicated in the previous calculations.
Effective fault-tolerant quantum computation with slow measurements
David P. DiVincenzo; Panos Aliferis
2006-08-03
How important is fast measurement for fault-tolerant quantum computation? Using a combination of existing and new ideas, we argue that measurement times as long as even 1,000 gate times or more have a very minimal effect on the quantum accuracy threshold. This shows that slow measurement, which appears to be unavoidable in many implementations of quantum computing, poses no essential obstacle to scalability.
On Quantum Effects in a Theory of Biological Evolution
Martin-Delgado, M. A.
2012-01-01
We construct a descriptive toy model that considers quantum effects on biological evolution starting from Chaitin's classical framework. There are smart evolution scenarios in which a quantum world is as favorable as classical worlds for evolution to take place. However, in more natural scenarios, the rate of evolution depends on the degree of entanglement present in quantum organisms with respect to classical organisms. If the entanglement is maximal, classical evolution turns out to be more favorable. PMID:22413059
Effects of depolarizing quantum channels on BB84 and SARG04 quantum cryptography protocols
Youn-Chang Jeong; Yong-Su Kim; Yoon-Ho Kim
2010-02-11
We report experimental studies on the effect of the depolarizing quantum channel on weak-pulse BB84 and SARG04 quantum cryptography. The experimental results show that, in real world conditions in which channel depolarization cannot be ignored, BB84 should perform better than SARG04.
A study of Quantum Correlation for Three Qubit States under the effect of Quantum Noisy Channels
Pratik K. Sarangi; Indranil Chakrabarty
2014-11-27
We study the dynamics of quantum dissension for three qubit states in various dissipative channels such as amplitude damping, dephasing and depolarizing. Our study is solely based on Markovian environments where quantum channels are without memory and each qubit is coupled to its own environment. We start with mixed GHZ, mixed W, mixture of separable states, a mixed biseparable state, as the initial states and mostly observe that the decay of quantum dissension is asymptotic in contrast to sudden death of quantum entanglement in similar environments. This is a clear indication of the fact that quantum correlation in general is more robust against the effect of noise. However, for a given class of initial mixed states we find a temporary leap in quantum dissension for a certain interval of time. More precisely, we observe the revival of quantum correlation to happen for certain time period. This signifies that the measure of quantum correlation such as quantum discord, quantum dissension, defined from the information theoretic perspective is different from the correlation defined from the entanglement-separability paradigm and can increase under the effect of the local noise. We also study the effects of these channels on the monogamy score of each of these initial states. Interestingly, we find that for certain class of states and channels, there is change from negative values to positive values of the monogamy score with classical randomness as well as with time. This gives us an important insight in obtaining states which are freely sharable (polygamous state) from the states which are not freely sharable (monogamous). This is indeed a remarkable feature, as we can create monogamous states from polygamous states Monogamous states are considered to have more signatures of quantum ness and can be used for security purpose.
Phonon bottleneck effects in rectangular graphene quantum dots
Jun Qian; A. S. Michael; Mitra Dutta
2010-01-01
This paper considers dimensionally-confined graphene quantum dots, provides formulations for the electronic states and the optical phonons in these quantum dots. These results are used to calculate scattering rates for the optical deformation potential and phonon bottleneck effects are identified.
Radiation effects in Si-Ge quantum size structure (Review)
Sobolev, N. A., E-mail: sobolev@ua.pt [Universidade de Aveiro, Departamento de Fisica and I3N (Portugal)
2013-02-15
The article is dedicated to the review and analysis of the effects and processes occurring in Si-Ge quantum size semiconductor structures upon particle irradiation including ion implantation. Comparisons to bulk materials are drawn. The reasons of the enhanced radiation hardness of superlattices and quantum dots are elucidated. Some technological applications of the radiation treatment are reviewed.
Unraveling quantum mechanical effects in water using isotopic fractionation
Berne, Bruce J.
Unraveling quantum mechanical effects in water using isotopic fractionation Thomas E. Marklanda that equilibrium fractionation ratios, an entirely quantum mechan- ical property, also provide a sensitive probe- predict the magnitude of isotope fractionation. Models that account for anharmonicity in this coordinate
Room-temperature quantum Hall effect in graphene.
Novoselov, K S; Jiang, Z; Zhang, Y; Morozov, S V; Stormer, H L; Zeitler, U; Maan, J C; Boebinger, G S; Kim, P; Geim, A K
2007-03-01
The quantum Hall effect (QHE), one example of a quantum phenomenon that occurs on a truly macroscopic scale, has attracted intense interest since its discovery in 1980 and has helped elucidate many important aspects of quantum physics. It has also led to the establishment of a new metrological standard, the resistance quantum. Disappointingly, however, the QHE has been observed only at liquid-helium temperatures. We show that in graphene, in a single atomic layer of carbon, the QHE can be measured reliably even at room temperature, which makes possible QHE resistance standards becoming available to a broader community, outside a few national institutions. PMID:17303717
Hussain, Shazia T.; Kutty, Shelby; Steinmetz, Michael; Sohns, Jan M.; Fasshauer, Martin; Staab, Wieland; Unterberg-Buchwald, Christina; Bigalke, Boris; Lotz, Joachim; Hasenfuß, Gerd; Schuster, Andreas
2014-01-01
Objectives Cardiovascular magnetic resonance feature tracking (CMR-FT) offers quantification of myocardial deformation from routine cine images. However, data using CMR-FT to quantify left ventricular (LV) torsion and diastolic recoil are not yet available. We therefore sought to evaluate the feasibility and reproducibility of CMR-FT to quantify LV torsion and peak recoil rate using an optimal anatomical approach. Methods Short-axis cine stacks were acquired at rest and during dobutamine stimulation (10 and 20 µg·kg?1·min?1) in 10 healthy volunteers. Rotational displacement was analysed for all slices. A complete 3D-LV rotational model was developed using linear interpolation between adjacent slices. Torsion was defined as the difference between apical and basal rotation, divided by slice distance. Depending on the distance between the most apical (defined as 0% LV distance) and basal (defined as 100% LV distance) slices, four different models for the calculation of torsion were examined: Model-1 (25–75%), Model-2 (0–100%), Model-3 (25–100%) and Model-4 (0–75%). Analysis included subendocardial, subepicardial and global torsion and recoil rate (mean of subendocardial and subepicardial values). Results Quantification of torsion and recoil rate was feasible in all subjects. There was no significant difference between the different models at rest. However, only Model-1 (25–75%) discriminated between rest and stress (Global Torsion: 2.7±1.5°cm?1, 3.6±2.0°cm?1, 5.1±2.2°cm?1, p<0.01; Global Recoil Rate: ?30.1±11.1°cm?1s?1,?46.9±15.0°cm?1s?1,?68.9±32.3°cm?1s?1, p<0.01; for rest, 10 and 20 µg·kg?1·min?1 of dobutamine, respectively). Reproducibility was sufficient for all parameters as determined by Bland-Altman analysis, intraclass correlation coefficients and coefficient of variation. Conclusions CMR-FT based derivation of myocardial torsion and recoil rate is feasible and reproducible at rest and with dobutamine stress. Using an optimal anatomical approach measuring rotation at 25% and 75% apical and basal LV locations allows effective quantification of torsion and recoil dynamics. Application of these new measures of deformation by CMR-FT should next be explored in disease states. PMID:25285656
Theory of ionizing neutrino-atom collisions: The role of atomic recoil
Konstantin A. Kouzakov; Alexander I. Studenikin
2014-11-09
We consider theoretically ionization of an atom by neutrino impact taking into account electromagnetic interactions predicted for massive neutrinos by theories beyond the Standard Model. The effects of atomic recoil in this process are estimated using the one-electron and semiclassical approximations and are found to be unimportant unless the energy transfer is very close to the ionization threshold. We show that the energy scale where these effects become important is insignificant for current experiments searching for magnetic moments of reactor antineutrinos.
Quantum confinement effects across two-dimensional planes in MoS2 quantum dots
NASA Astrophysics Data System (ADS)
Gan, Z. X.; Liu, L. Z.; Wu, H. Y.; Hao, Y. L.; Shan, Y.; Wu, X. L.; Chu, Paul K.
2015-06-01
The low quantum yield (˜10-5) has restricted practical use of photoluminescence (PL) from MoS2 composed of a few layers, but the quantum confinement effects across two-dimensional planes are believed to be able to boost the PL intensity. In this work, PL from 2 to 9 nm MoS2 quantum dots (QDs) is excluded from the solvent and the absorption and PL spectra are shown to be consistent with the size distribution. PL from MoS2 QDs is also found to be sensitive to aggregation due to the size effect.
Quantum Spin Hall Effect in Inverted Type II Semiconductors
Liu, Chaoxing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Hughes, Taylor L.; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Wang, Kang; /UCLA; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19
The quantum spin Hall (QSH) state is a topologically non-trivial state of quantum matter which preserves time-reversal symmetry; it has an energy gap in the bulk, but topologically robust gapless states at the edge. Recently, this novel effect has been predicted and observed in HgTe quantum wells. In this work we predict a similar effect arising in Type-II semiconductor quantum wells made from InAs/GaSb/AlSb. Because of a rare band alignment the quantum well band structure exhibits an 'inverted' phase similar to CdTe/HgTe quantum wells, which is a QSH state when the Fermi level lies inside the gap. Due to the asymmetric structure of this quantum well, the effects of inversion symmetry breaking and inter-layer charge transfer are essential. By standard self-consistent calculations, we show that the QSH state persists when these corrections are included, and a quantum phase transition between the normal insulator and the QSH phase can be electrically tuned by the gate voltage.
A gun recoil system employing a magnetorheological fluid damper
NASA Astrophysics Data System (ADS)
Li, Z. C.; Wang, J.
2012-10-01
This research aims to design and control a full scale gun recoil buffering system which works under real firing impact loading conditions. A conventional gun recoil absorber is replaced with a controllable magnetorheological (MR) fluid damper. Through dynamic analysis of the gun recoil system, a theoretical model for optimal design and control of the MR fluid damper for impact loadings is derived. The optimal displacement, velocity and optimal design rules are obtained. By applying the optimal design theory to protect against impact loadings, an MR fluid damper for a full scale gun recoil system is designed and manufactured. An experimental study is carried out on a firing test rig which consists of a 30 mm caliber, multi-action automatic gun with an MR damper mounted to the fixed base through a sliding guide. Experimental buffering results under passive control and optimal control are obtained. By comparison, optimal control is better than passive control, because it produces smaller variation in the recoil force while achieving less displacement of the recoil body. The optimal control strategy presented in this paper is open-loop with no feedback system needed. This means that the control process is sensor-free. This is a great benefit for a buffering system under impact loading, especially for a gun recoil system which usually works in a harsh environment.
Quantum corrections in massive bigravity and new effective composite metrics
NASA Astrophysics Data System (ADS)
Heisenberg, Lavinia
2015-05-01
We compute the one-loop quantum corrections to the interactions between the two metrics of the ghost-free massive bigravity. When considering gravitons running in the loops, we show how the structure of the interactions gets destabilized at the quantum level, exactly in the same way as in its massive gravity limit. A priori one might have expected a better quantum behavior, however, the broken diffeomorphism invariance out of the two initial diffeomorphisms in bigravity has similar consequences at the quantum level as the broken diffeomorphism in massive gravity. From lessons of the generated quantum corrections through matter loops we propose yet other types of effective composite metrics to which the matter fields can couple. Among these new effective metrics there might be one or more that could provide interesting phenomenology and important cosmological implications.
Techniques for measuring the atomic recoil frequency using a grating-echo atom interferometer
NASA Astrophysics Data System (ADS)
Barrett, Brynle
I have developed three types of time-domain echo atom interferometer (AIs) that use either two or three standing-wave pulses in different configurations. Experiments approaching the transit time limit are achieved using samples of laser-cooled rubidium atoms with temperatures < 5 ?K contained within a glass vacuum chamber—an environment that is largely free of both magnetic fields and field gradients. The principles of the atom-interferometric measurement of Eq can be understood based on a description of the "two-pulse" AI. This interferometer uses two standing-wave pulses applied at times t = 0 and t = T 21 to create a superposition of atomic momentum states differing by multiples of the two-photon momentum, ?q = 2 ?k where k is the optical wave number, that interfere in the vicinity of t = 2T 21. This interference or "echo" manifests itself as a density grating in the atomic sample, and is probed by applying a near-resonant traveling-wave "read-out" pulse and measuring the intensity of the coherent light Bragg-scattered in the backward direction. The scattered light from the grating is associated with a ?/2-periodic modulation produced by the interference of momentum states differing by ?q. Interfering states that differ by more than ?q—which produce higher-frequency spatial modulation within the sample—cannot be detected due to the nature of the Bragg scattering detection technique employed in the experiment. The intensity of the scattered light varies in a periodic manner as a function of the standing-wave pulse separation, T21. The fundamental frequency of this modulation is the two-photon atomic recoil frequency, ? q = ?q2/2M, where q = 2k and M is the mass of the atom (a rubidium isotope in this case). The recoil frequency, ? q, is related to the recoil energy, Eq = ??q, which is the kinetic energy associated with the recoil of the atom after a coherent two-photon scattering process. By performing the experiment on a suitably long time scale ( T21 >> ?q = ?/? q ˜32 ?s), ?q can be measured precisely. Since ?q contains the ratio of Planck's constant to the mass of the atom, h/M, a precise measurement of ?q can be used as a strict test of quantum theories of the electromagnetic force. This two-pulse technique has a number of disadvantages for a precision measurement of ?q, such as a complicated functional dependence on T21 (due to the nature of Kapitza-Dirac diffraction, the level structure of the atom, and spontaneous emission). However, many of these difficulties can be avoided by using a three-pulse "perturbative" echo technique, where a third standing-wave pulse is applied at t = T21 + ?T , with ?T < T21. The function of the third pulse is to convert the difference between interfering momentum states from n?q (n > 1) to ?q. In this manner, interference between high-order momentum states contributes more significantly to the three-pulse echo than to the two-pulse echo. By fixing T21 and varying ?T between the second standing-wave pulse and the echo time, the signal exhibits a simple shape with narrow fringes that revive periodically at the recoil period, ?q. Using this technique, I have achieved a single measurement of ?q with a relative statistical uncertainty of ˜ 180 parts per 109 (ppb) on a time scale of 2T21 ˜ 72 ms in ˜ 15 minutes of data acquisition. Further improvements are anticipated by extending the experimental time scale and narrowing the signal fringe width. To demonstrate the final statistical uncertainty using the current configuration of the experiment, I acquired 82 individual measurements of ? q under the same experimental conditions. This resulted in a final measurement with a statistical precision of 37 ppb. However, this measurement is currently overwhelmed by systematic errors at the level of ˜ 5.7 parts per 106 (ppm). The first survey of systematic effects on the measurement of ?q with this technique has also been carried out, where individual measurements had relative statistical uncertaintie
Wang, Yunliang, E-mail: ylwang@ustb.edu.cn; Lü, Xiaoxia [Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)] [Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)
2014-02-15
The modulational instability of quantum electrostatic acoustic waves in electron-hole quantum semiconductor plasmas is investigated using the quantum hydrodynamic model, from which a modified nonlinear Schrödinger equation with damping effects is derived using the reductive perturbation method. Here, we consider the combined effects of quantum recoil, quantum degenerate pressures, as well as the exchange-correlation effect standing for the electrons (holes) spin. The modulational instability for different semiconductors (GaAs, GaSb, and InP) is discussed. The collision between electron (hole) and phonon is also investigated. The permitted maximum time for modulational instability and the damping features of quantum envelope solitary wave are all determined by the collision. The approximate solitary solution with damping effects is presented in weak collision limit. The damping properties were discussed by numerical method.
Fractional quantum Hall effect in the absence of Landau levels.
Sheng, D N; Gu, Zheng-Cheng; Sun, Kai; Sheng, L
2011-01-01
It is well known that the topological phenomena with fractional excitations, the fractional quantum Hall effect, will emerge when electrons move in Landau levels. Here we show the theoretical discovery of the fractional quantum Hall effect in the absence of Landau levels in an interacting fermion model. The non-interacting part of our Hamiltonian is the recently proposed topologically non-trivial flat-band model on a checkerboard lattice. In the presence of nearest-neighbouring repulsion, we find that at 1/3 filling, the Fermi-liquid state is unstable towards the fractional quantum Hall effect. At 1/5 filling, however, a next-nearest-neighbouring repulsion is needed for the occurrence of the 1/5 fractional quantum Hall effect when nearest-neighbouring repulsion is not too strong. We demonstrate the characteristic features of these novel states and determine the corresponding phase diagram. PMID:21750543
Quantum effect on the radial distribution function of liquids
F. P. Ricci; Comitato Nazio
1960-01-01
Summary The quantum effect on the radial distribution function of a liquid has been analyzed by means of the corresponding states\\u000a principle. Also the best mode has been discussed for describing liquid Helium.
Two quantum effects in the theory of gravitation
Robinson, Sean Patrick, 1977-
2005-01-01
We will discuss two methods by which the formalism of quantum field theory can be included in calculating the physical effects of gravitation. In the first of these, the consequences of treating general relativity as an ...
Scintillation of Liquid Helium for Low-Energy Nuclear Recoils
Ito, T M
2013-01-01
The scintillation properties of liquid helium upon the recoil of a low energy helium atom are discussed in the context of the possible use of this medium as a detector of dark matter. It is found that the prompt scintillation yield in the range of recoil energies from a few keV to 100 keV is somewhat higher than that obtained by a linear extrapolation from the measured yield for an 5 MeV alpha particle. A comparison is made of both the scintillation yield and the charge separation by an electric field for nuclear recoils and for electrons stopped in helium.
Spacetime effects on satellite-based quantum communications
Bruschi, David Edward; Fuentes, Ivette; Jennewein, Thomas; Razavi, Mohsen
2013-01-01
We investigate the effects of space-time curvature on space-based quantum communication protocols. We analyze tasks that require either the exchange of single photons in a certain entanglement distribution protocol or beams of light in a continuous-variable quantum key distribution scheme. We find that gravity affects the propagation of photons, therefore acting as a noisy channel for the transmission of information. The effects can be measured with current technology.
Anomaly-free cosmological perturbations in effective canonical quantum gravity
NASA Astrophysics Data System (ADS)
Barrau, Aurelien; Bojowald, Martin; Calcagni, Gianluca; Grain, Julien; Kagan, Mikhail
2015-05-01
This article lays out a complete framework for an effective theory of cosmological perturbations with corrections from canonical quantum gravity. Since several examples exist for quantum-gravity effects that change the structure of space-time, the classical perturbative treatment must be rethought carefully. The present discussion provides a unified picture of several previous works, together with new treatments of higher-order perturbations and the specification of initial states.
Quasiparticle effects in quantum-induced transitions in superconductors
Choi, J.; Jose, J.V.
1989-04-17
The effects of quasi-particle tunneling in the long-range properties of an array of ultrasmall Josephson junctions, with a transverse magnetic field, is studied in two dimensions via extensive quantum Monte Carlo simulations. It is found that quasi-particle tunneling suppresses the zero-point quantum-fluctuation effects in the arrays, as well as triggering a discontinuous transition between the low-temperature metastable phase to the stable high-temperature superconducting phase.
NASA Astrophysics Data System (ADS)
Spooner, N. J. C.; Majewski, P.; Muna, D.; Snowden-Ifft, D. P.
2010-12-01
We present the first detailed simulations of the so-called head-tail effect of nuclear recoils in gas, the presence of which is vital to directional WIMP dark matter searches. We include comparison simulations of the range and straggling of carbon, sulphur and fluorine recoils in low pressure gas. However, the prime focus is a detailed investigation of carbon and sulphur recoils in 40 Torr negative ion carbon disulfide, a gas proposed for use in large scale directional detectors. The focus is to determine whether the location of the majority of the ionization charge released and observed from a recoil track in carbon disulfide is at the beginning (tail) of the track, at the end (head) or evenly distributed. We used the SRIM simulation program, together with a purpose-written Monte Carlo generator to model production of ionizing pairs, diffusion and basic readout geometries relevant to potential real detector scenarios, such as under development for the DRIFT experiment. The results indicate the likely existence of a head-tail track asymmetry but with a magnitude critically influenced by several competing factors, notably the W-value assumed, the drift distance and diffusion, and the recoil energy.
Characterization of control noise effects in optimal quantum unitary dynamics
NASA Astrophysics Data System (ADS)
Hocker, David; Brif, Constantin; Grace, Matthew D.; Donovan, Ashley; Ho, Tak-San; Tibbetts, Katharine Moore; Wu, Rebing; Rabitz, Herschel
2014-12-01
This work develops measures for quantifying the effects of field noise upon targeted unitary transformations. Robustness to noise is assessed in the framework of the quantum control landscape, which is the mapping from the control to the unitary transformation performance measure (quantum gate fidelity). Within that framework, a geometric interpretation of stochastic noise effects naturally arises, where more robust optimal controls are associated with regions of small overlap between landscape curvature and the noise correlation function. Numerical simulations of this overlap in the context of quantum information processing reveal distinct noise spectral regimes that better support robust control solutions. This perspective shows the dual importance of both noise statistics and the control form for robustness, thereby opening up new avenues of investigation on how to mitigate noise effects in quantum systems.
Common physical mechanism for integer and fractional quantum Hall effects
Jianhua wang; Kang Li; Shuming Long; Yi Yuan
2012-01-24
Integer and fractional quantum Hall effects were studied with different physics models and explained by different physical mechanisms. In this paper, the common physical mechanism for integer and fractional quantum Hall effects is studied, where a new unified formulation of integer and fractional quantum Hall effect is presented. Firstly, we introduce a 2-dimensional ideal electron gas model in the presence of strong magnetic field with symmetry gauge, and the transverse electric filed $\\varepsilon_2$ is also introduced to balance Lorentz force. Secondly, the Pauli equation is solved where the wave function and energy levels is given explicitly. Thirdly, after the calculation of the degeneracy density for 2-dimensional ideal electron gas system, the Hall resistance of the system is obtained, where the quantum Hall number $\
Quantum Electron-Exchange Effects on the Buneman Instability in Quantum Plasmas
NASA Astrophysics Data System (ADS)
Hong, Woo-Pyo; Jamil, Muhammad; Rasheed, Abdur; Jung, Young-Dae
2015-06-01
The quantum-mechanical electron-exchange effects on the Buneman instability are investigated in quantum plasmas. The growth rate and wave frequency of the Buneman instability for the quantum plasma system composed of the moving electron fluid relative to the ion fluid are obtained as functions of the electron-exchange parameter, de Broglie's wave length, Debye's length, and wave number. The result shows that the electron-exchange effect suppresses the growth rate of the quantum Buneman instability in quantum plasmas. It is also shown that the influence of electron exchange reduces the instability domain of the wave number in quantum plasmas. However, the instability domain enlarges with an increase in the ratio of the Debye length to the de Broglie wave length. In addition, the electron-exchange effect on the growth rate of the Buneman instability increases with an increase in the ratio of the Debye length to the de Broglie wave length. The variation in the growth rate of the Buneman instability due to the change in the electron-exchange effect and plasma parameters is also discussed.
Effect of tunable superlattice on quantum Hall effect in graphene
NASA Astrophysics Data System (ADS)
Dubey, Sudipta; Deshmukh, Mandar
2015-03-01
We have studied quantum Hall effect in tunable superlattice in graphene created using combination of back gate and an array of top-gates pinned to the same potential. In our device we are in the regime when superlattice period is larger than the magnetic length and superlattice amplitude can be tuned to be larger than Landau level spacing. We observe robust plateaus when charge carrier in adjacent region is of the same polarity. However when we have a series of p-n junction, the high superlattice amplitude leads to large local electric field in p-n junction causing collapse of Landau level and hence incomplete equilibration. We have also studied charge transport at low magnetic field where we have higher number of edge states circulating within a strip of back-gated or top-gated region.
Kondo effect in an integer-spin quantum dot
................................................................. Kondo effect in an integer .............................................................................................................................................. The Kondo effectÃa many-body phenomenon in condensed- matter physics involving the interaction between two-electron singlet and triplet states8 , and a tunable Kondo effect in semiconductor quantum dots9
Heavy-to-light B meson form factors at large recoil energy—spectator-scattering corrections
M. Beneke; D. Yang
2006-01-01
We complete the investigation of loop corrections to hard spectator-scattering in exclusive B meson to light meson transitions by computing the short-distance coefficient (jet-function) from the hard-collinear scale. Adding together the two coefficients from matching QCD?SCETI?SCETII, we investigate the size of loop effects on the ratios of heavy-to-light meson form factors at large recoil. We find the corrections from the
Symmetry relations for heavy-to-light meson form factors at large recoil
Richard J. Hill
2006-01-01
The description of large-recoil heavy-to-light meson form factors is reviewed in the framework of soft-collinear effective theory. At leading power in the heavy-quark expansion, three classes of approximate symmetry relations arise. The relations are compared to experimental data for D --> K* and Ds --> phi form factors, and to light-cone QCD sum rule predictions for B --> pi and
Symmetry relations for heavy-to-light meson form factors at large recoil
Richard J. Hill
2004-01-01
The description of large-recoil heavy-to-light meson form factors is reviewed in the framework of soft-collinear effective theory. At leading power in the heavy quark expansion, three classes of approximate symmetry relations arise. The relations are compared to experimental data for $D\\\\to K^*$ and $D_s\\\\to \\\\phi$ form factors, and to light-cone QCD sum rule predictions for $B\\\\to \\\\pi$ and $B\\\\to \\\\rho$
Michele Allegra; Paolo Giorda; Seth Lloyd
2015-03-18
In this paper we address the problem of charaterizing coherence in dissipative (Markovian) quantum evolutions. We base our analysis on the decoherent histories formalism which is the most basic and proper approach to assess coherence properties of quantum evolutions. We introduce and test different quantifiers and we show how these are able to capture the (average) coherence of general quantum evolutions on various time scales and for different levels of environmentally induced decoherence. In order to show the effectiveness of the introduced tools, we thoroughly apply them to a paradigmatic instance of quantum process where the role of coherence is being hotly debated: exciton transport in the FMO photosynthetic complex and its most relevant trimeric subunit. Our analysis illustrates how the high efficiency of environmentally assisted transport can be traced back to the coherence properties of the evolution and the interference between pathways in the decoherent histories formalism. Indeed, we show that the bath essentially implements a quantum recoil avoiding effect on the exciton dynamics: the action of decoherence in the system is set at precisely the right level needed to preserve and sustain the benefits of the fast initial quantum delocalization of the exciton over the network, while preventing the subsequent recoil that would necessarily follow form a purely coherent dynamics. This picture becomes very clear when expressed in terms of pathways leading to the exit site: the action of the bath is seen to selectively kill the negative interference between pathways, while retaining the intial positive one.
Heavy-to-light meson form factors at large recoil
Richard J. Hill
2006-01-01
Heavy-to-light meson form factors at large recoil can be described using the same techniques as for hard exclusive processes involving only light hadrons. Two competing mechanisms appear in the large recoil regime, describing so-called ``soft-overlap'' and ``hard-scattering'' components of the form factors. It is shown how existing experimental data from B and D decays constrain the relative size of these
Heavy-to-light Meson Form Factors at Large Recoil
Richard J. Hill
2005-01-01
Heavy-to-light meson form factors at large recoil can be described using the same techniques as for hard exclusive processes involving only light hadrons. Two competing mechanisms appear in the large-recoil regime, describing so-called ''soft-overlap'' and ''hard-scattering'' components of the form factors. It is shown how existing experimental data from B and D decays constrain the relative size of these components,
Heavy-to-light meson form factors at large recoil
Richard J. Hill; Richard J
2006-01-01
Heavy-to-light meson form factors at large recoil can be described using the same techniques as for hard exclusive processes involving only light hadrons. Two competing mechanisms appear in the large recoil regime, describing so-called 'soft-overlap' and 'hard-scattering' components of the form factors. It is shown how existing experimental data from B and D decays constrain the relative size of these
K. Hagino; T. Takehi; N. Takigawa
2006-06-06
We propose the no-recoil approximation, which is valid for heavy systems, for a double folding nucleus-nucleus potential. With this approximation, the non-local knock-on exchange contribution becomes a local form. We discuss the applicability of this approximation for the elastic scattering of $^6$Li + $^{40}$Ca system. We find that, for this system and heavier, the no-recoil approximation works as good as another widely used local approximation which employs a local plane wave for the relative motion between the colliding nuclei. We also compare the results of the no-recoil calculations with those of the zero-range approximation often used to handle the knock-on exchange effect.
Exerpts from the history of alpha recoils.
Samuelsson, Christer
2011-05-01
Any confined air volume holding radon ((222)Rn) gas bears a memory of past radon concentrations due to (210)Pb (T(1/2) = 22 y) and its progenies entrapped in all solid objects in the volume. The efforts of quantifying past radon exposures by means of the left-behind long-lived radon progenies started in 1987 with this author's unsuccessful trials of removing (214)Po from radon exposed glass objects. In this contribution the history and different techniques of assessing radon exposure to man in retrospect will be overviewed. The main focus will be on the implantation of alpha recoils into glass surfaces, but also potential traps in radon dwellings will be discussed. It is concluded that for a successful retrospective application, three crucial imperatives must be met, i.e. firstly, the object must persistently store a certain fraction of the created (210)Pb atoms, secondly, be resistant over decades towards disturbances from the outside and thirdly, all (210)Pb atoms analysed must originate from airborne radon only. For large-scale radon epidemiological studies, non-destructive and inexpensive measurement techniques are essential. Large-scale studies cannot be based on objects rarely found in dwellings or not available for measurements. PMID:21306801
Effects of Loss and Decoherence on a Simple Quantum Computer
Isaac L. Chuang; Raymond Laflamme; Juan-Pablo Paz
1996-02-27
We investigate the impact of loss (amplitude damping) and decoherence (phase damping) on the performance of a simple quantum computer which solves the one-bit Deutsch problem. The components of this machine are beamsplitters and nonlinear optical Kerr cells, but errors primarily originate from the latter. We develop models to describe the effect of these errors on a quantum optical Fredkin gate. The results are used to analyze possible error correction strategies in a complete quantum computer. We find that errors due to loss can be avoided perfectly by appropriate design techniques, while decoherence can be partially dealt with using projective error correction.
Quantum effects improve the energy efficiency of feedback control
NASA Astrophysics Data System (ADS)
Horowitz, Jordan M.; Jacobs, Kurt
2014-04-01
The laws of thermodynamics apply equally well to quantum systems as to classical systems, and because of this, quantum effects do not change the fundamental thermodynamic efficiency of isothermal refrigerators or engines. We show that, despite this fact, quantum mechanics permits measurement-based feedback control protocols that are more thermodynamically efficient than their classical counterparts. As part of our analysis, we perform a detailed accounting of the thermodynamics of unitary feedback control and elucidate the sources of inefficiency in measurement-based and coherent feedback.
Dissipative Quantum Transport in Macromolecules: An Effective Field Theory Approach
Schneider, E; Faccioli, P
2013-01-01
We introduce an atomistic approach to the dissipative quantum dynamics of charged or neutral excitations propagating through macromolecular systems. Using the Feynman-Vernon path integral formalism, we analytically trace out from the density matrix the atomic coordinates and the heat bath degrees of freedom. This way we obtain an effective field theory which describes the real-time evolution of the quantum excitation and is fully consistent with the fluctuation-dissipation relation. The main advantage of the field-theoretic approach is that it allows to avoid using the Keldysh contour formulation. This simplification makes it straightforward to derive Feynman diagrams to analytically compute the effects of the interaction of the propagating quantum excitation with the heat bath and with the molecular atomic vibrations. For illustration purposes, we apply this formalism to investigate the loss of quantum coherence of holes propagating through a poly(3-alkylthiophene) polymer
Unraveling quantum mechanical effects in water using isotopic fractionation
Markland, Thomas E
2013-01-01
When two phases of water are at equilibrium, the ratio of hydrogen isotopes in each is slightly altered due to their different phase affinities. This isotopic fractionation process can be utilized to analyze water's movement in the world's climate. Here we show that equilibrium fractionation ratios, an entirely quantum mechanical property, also provide a sensitive probe to assess the magnitude of nuclear quantum fluctuations in water. By comparing the predictions of a series of water models, we show that those describing the OH chemical bond as rigid or harmonic greatly over-predict the magnitude of isotope fractionation. Models that account for anharmonicity in this coordinate are shown to provide much more accurate results due to their ability to give partial cancellation between inter and intra-molecular quantum effects. These results give evidence of the existence of competing quantum effects in water and allow us to identify how this cancellation varies across a wide range of temperatures. In addition, t...
Observation of the fractional quantum Hall effect in an oxide
NASA Astrophysics Data System (ADS)
Tsukazaki, A.; Akasaka, S.; Nakahara, K.; Ohno, Y.; Ohno, H.; Maryenko, D.; Ohtomo, A.; Kawasaki, M.
2010-11-01
The quantum Hall effect arises from the cyclotron motion of charge carriers in two-dimensional systems. However, the ground states related to the integer and fractional quantum Hall effect, respectively, are of entirely different origin. The former can be explained within a single-particle picture; the latter arises from electron correlation effects governed by Coulomb interaction. The prerequisite for the observation of these effects is extremely smooth interfaces of the thin film layers to which the charge carriers are confined. So far, experimental observations of such quantum transport phenomena have been limited to a few material systems based on silicon, III-V compounds and graphene. In ionic materials, the correlation between electrons is expected to be more pronounced than in the conventional heterostructures, owing to a large effective mass of charge carriers. Here we report the observation of the fractional quantum Hall effect in MgZnO/ZnO heterostructures grown by molecular-beam epitaxy, in which the electron mobility exceeds 180,000cm2V-1s-1. Fractional states such as ?=4/3, 5/3 and 8/3 clearly emerge, and the appearance of the ?=2/5 state is indicated. The present study represents a technological advance in oxide electronics that provides opportunities to explore strongly correlated phenomena in quantum transport of dilute carriers.
A quantitative account of quantum effects in liquid water
Georgios S. Fanourgakis; Gregory K. Schenter; Sotiris S. Xantheas
2006-01-01
We report converged quantum statistical mechanical simulations of liquid water with the Thole-type Model (version 2.1), Flexible, polarizable (TTM2.1-F) interaction potential for water. Simulations of total length of 600 ps with a 0.05 fs time step for a periodic unit cell of 256 molecules with up to 32 replicas per atom suggest that the quantum effects contribute 1.01+\\/-0.02 kcal\\/mol to
A quantitative account of quantum effects in liquid water
G. S. Fanourgakis; G. K. Schenter; S. S. Xantheas
2006-01-01
We report converged quantum statistical mechanical simulations of liquid water with the Thole-type Model (version 2.1), Flexible, polarizable (TTM2.1-F) interaction potential for water. Simulations of total length of 600 ps with a 0.05 fs time step for a periodic unit cell of 256 molecules with up to 32 replicas per atom suggest that the quantum effects contribute 1.01±0.02 kcal?mol to
Spacetime effects on satellite-based quantum communications
David Edward Bruschi; Tim Ralph; Ivette Fuentes; Thomas Jennewein; Mohsen Razavi
2014-04-26
We investigate the consequences of space-time being curved on space-based quantum communication protocols. We analyze tasks that require either the exchange of single photons in a certain entanglement distribution protocol or beams of light in a continuous-variable quantum key distribution scheme. We find that gravity affects the propagation of photons, therefore adding additional noise to the channel for the transmission of information. The effects could be measured with current technology.
Effective quantum dynamics of interacting systems with inhomogeneous coupling
Lopez, C. E.; Retamal, J. C. [Departamento de Fisica, Universidad de Santiago de Chile, Casilla 307 Correo 2, Santiago (Chile); Christ, H. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Solano, E. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Physics Department, ASC, and CeNS, Ludwig-Maximilians-Universitaet, Theresienstrasse 37, 80333 Munich (Germany); Departamento de Ciencias, Seccion Fisica, Pontificia Universidad Catolica del Peru, Apartado 1761, Lima (Peru)
2007-03-15
We study the quantum dynamics of a single mode (particle) interacting inhomogeneously with a large number of particles and introduce an effective approach to find the accessible Hilbert space, where the dynamics takes place. Two relevant examples are given: the inhomogeneous Tavis-Cummings model (e.g., N atomic qubits coupled to a single cavity mode, or to a motional mode in trapped ions) and the inhomogeneous coupling of an electron spin to N nuclear spins in a quantum dot.
Plasmon modes of spherical nanoparticles: The effects of quantum nonlocality
NASA Astrophysics Data System (ADS)
Moradi, Afshin
2015-07-01
We develop a new method for calculating the electrostatic surface and bulk plasmon modes of a spherical metal nanoparticle, by taking into account the quantum nonlocal effects. To describe these phenomena, we develop analytical theory based on the quantum hydrodynamical model of plasmon excitation. We derive new dispersion relation for the system and investigate its differences with previous treatments based on the standard nonlocal model.
Universality and phase diagram in the quantum Hall effect
Lauren Wai-Wing Wong
1997-01-01
We have designed and conducted detailed experiments to explore the following critical, unsolved issues in regarding to the global behavior of the two-dimensional electron gas (2DEG) in the presence of disorder and many-body interaction in the quantum Hall effect (QHE) regime: (1) nature of the quantum Hall liquid-Hall insulator (QHL-HI) phase transition induced by disorder, (2) topological phase diagram and
An Equation of Motion with Quantum Effect in Spacetime
Jyh-Yang Wu
2009-05-26
In this paper, we shall present a new equation of motion with Quantum effect in spacetime. To do so, we propose a classical-quantum duality. We also generalize the Schordinger equation to the spacetime and obtain a relativistic wave equation. This will lead a generalization of Einstein's formula $E=m_0c^2$ in the spacetime. In general, we have $E=m_0c^2 + \\frac{\\hbar^2}{12m_0}R$ in a spacetime.
Predictive theory for elastic scattering and recoil of protons from 4He
NASA Astrophysics Data System (ADS)
Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr
2014-12-01
Low-energy cross sections for elastic scattering and recoil of protons from 4He nuclei (also known as ? particles) are calculated directly by solving the Schrödinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles of either hydrogen or helium. We compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.
Global effects in quaternionic quantum field theory
S. P. Brumby; G. C. Joshi
1996-10-07
We present some striking global consequences of a model quaternionic quantum field theory which is locally complex. We show how making the quaternionic structure a dynamical quantity naturally leads to the prediction of cosmic strings and non-baryonic hot dark matter candidates.
Global effects in quaternionic quantum field theory
Brumby, S P
1996-01-01
We present some striking global consequences of a model quaternionic quantum field theory which is locally complex. We show how making the quaternionic structure a dynamical quantity naturally leads to the prediction of cosmic strings and non-baryonic hot dark matter candidates.
Effective field theory of relativistic quantum hall systems
NASA Astrophysics Data System (ADS)
Golkar, Siavash; Roberts, Matthew M.; Son, Dam Thanh
2014-12-01
Motivated by the observation of the fractional quantum Hall effect in graphene, we consider the effective field theory of relativistic quantum Hall states. We find that, beside the Chern-Simons term, the effective action also contains a term of topological nature, which couples the electromagnetic field with a topologically conserved current of 2 + 1 dimensional relativistic fluid. In contrast to the Chern-Simons term, the new term involves the spacetime metric in a nontrivial way. We extract the predictions of the effective theory for linear electromagnetic and gravitational responses. For fractional quantum Hall states at the zeroth Landau level, additional holomorphic constraints allow one to express the results in terms of two dimensionless constants of topological nature.
Quantum Stress Tensor Fluctuation Effects in Inflationary Cosmology
Jen-Tsung Hsiang; Chun-Hsien Wu; L. H. Ford; Kin-Wang Ng
2011-08-22
We review several related investigations of the effects of the quantum stress tensor of a conformal field in inflationary cosmology. Particular attention will be paid to the effects of quantum stress tensor fluctuations as a source of density and tensor perturbations in inflationary models. These effects can possibly depend upon the total expansion factor during inflation, and hence be much larger than one might otherwise expect. They have the potential to contribute a non-scale invariant and non-Gaussian component to the primordial spectrum of perturbations, and might be observable.
Kondo Effect in Coupled Quantum Dots A. M. Chang+
Chang, Albert
Kondo Effect in Coupled Quantum Dots A. M. Chang+ , J. C. Chen+ Department of Physics, Duke of Physics, National Tsing-Hua University, Hsinchu, Taiwan 30043 Abstract We discuss Kondo systems in coupled provide clues as to the relevance of the 2-impurity Kondo (2IK) effect, and the 2-channel Kondo (2CK
Ratchet effects in graphene and quantum wells with lateral superlattice
Golub, L. E.; Nalitov, A. V.; Ivchenko, E. L. [Ioffe Physical-Technical Institute of the Russian Academy of Sciences, St. Petersburg (Russian Federation); Olbrich, P.; Kamann, J.; Eroms, J.; Weiss, D.; Ganichev, S. D. [Terahertz Center, University of Regensburg, Regensburg (Germany)
2013-12-04
Theoretical and experimental studies on the ratchet effects in graphene and in quantum wells with a lateral superlattice excited by alternating electric fields of terahertz frequency range are presented. We discuss the Seebeck ratchet effect and helicity driven photocurrents and show that the photocurrent generation is based on the combined action of a spatially periodic in-plane potential and a spatially modulated light.
Non-Resonant Effects in Implementation of Quantum Shor Algorithm
G. P. Berman; G. D. Doolen; G. V. Lopez; V. I. Tsifrinovich
1999-09-09
We simulate Shor's algorithm on an Ising spin quantum computer. The influence of non-resonant effects is analyzed in detail. It is shown that our ``$2\\pi k$''-method successfully suppresses non-resonant effects even for relatively large values of the Rabi frequency.
``Interaction--free'' interaction: entangling evolution via quantum Zeno effect
Pawe? Horodecki
1998-07-11
The effect of entangling evolution induced by frequently repeated quantum measurement is presented. The interesting possibility of conditional freezing the system in maximally entangled state out of Zeno effect regime is also revealed. The illustration of the phenomena in terms of dynamical version of ``interaction free'' measurement is presented. Some general conclusions are provided.
Nernst effect and dimensionality in the quantum limit
Zengwei Zhu; Huan Yang; Benoît Fauqué; Yakov Kopelevich; Kamran Behnia
2010-01-01
The Nernst effect has recently emerged as a very sensitive, yet poorly understood, probe of electron organization in solids. Graphene, a single layer of carbon atoms set in a honeycomb lattice, embeds a two-dimensional gas of massless electrons and hosts a particular version of the quantum Hall effect. Recent experimental investigations of its thermoelectric response are in agreement with the
Detecting Quantum Gravitational Effects of Loop Quantum Cosmology in the Early Universe?
NASA Astrophysics Data System (ADS)
Zhu, Tao; Wang, Anzhong; Cleaver, Gerald; Kirsten, Klaus; Sheng, Qin; Wu, Qiang
2015-07-01
We derive the primordial power spectra and spectral indexes of the density fluctuations and gravitational waves in the framework of loop quantum cosmology (LQC) with holonomy and inverse-volume corrections by using the uniform asymptotic approximation method to its third order, at which the upper error bounds are ? 0.15% and accurate enough for the current and forthcoming cosmological observations. Then, using the Planck, BAO, and supernova data, we obtain the tightest constraints on quantum gravitational effects from LQC corrections and find that such effects could be well within the detection of the current and forthcoming cosmological observations.
Quantum electrodynamical effects in dusty plasmas
Marklund, M.; Stenflo, L.; Shukla, P.K.; Brodin, G. [Department of Physics, Umeaa University, SE-901 87 Umeaa Sweden and Centre for Fundamental Physics, Rutherford Appleton Laboratory, Chilton Didcot, Oxfordshire OX11 0QX (United Kingdom); Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden) and Centre for Fundamental Physics, Rutherford Appleton Laboratory, Chilton Didcot, Oxfordshire OX11 0QX (United Kingdom)
2005-07-15
A new nonlinear electromagnetic wave mode in a magnetized dusty plasma is predicted. Its existence depends on the interaction of an intense circularly polarized electromagnetic wave with a dusty plasma, where quantum electrodynamical photon-photon scattering is taken into account. Specifically, we consider a dusty electron-positron-ion plasma and show that the propagation of the new mode is admitted. It could be of significance for the physics of supernova remnants and in neutron star formation.
Quantum vacuum effects from boundaries of designer potentials
Konopka, Tomasz [ITP, Utrecht University, Utrecht 3584 CE (Netherlands)
2009-04-15
Vacuum energy in quantum field theory, being the sum of zero-point energies of all field modes, is formally infinite but yet, after regularization or renormalization, can give rise to finite observable effects. One way of understanding how these effects arise is to compute the vacuum energy in an idealized system such as a large cavity divided into disjoint regions by pistons. In this paper, this type of calculation is carried out for situations where the potential affecting a field is not the same in all regions of the cavity. It is shown that the observable parts of the vacuum energy in such potentials do not fall off to zero as the region where the potential is nontrivial becomes large. This unusual behavior might be interesting for tests involving quantum vacuum effects and for studies on the relation between vacuum energy in quantum field theory and geometry.
Semina, M. A., E-mail: msemina@gmail.com; Suris, R. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)
2011-07-15
The variational method taking into account the complex valence band structure is used to study the effect of localization in quantum wells and quantum wires on the acceptor binding energy. Trial functions that make possible tracing of the transition from the bulk material to narrow quantum wells and quantum wires of small radius are constructed. The possibility of the appearance of an unsteadily varying dependence of the acceptor binding energy on the characteristic dimension of the system is shown.
D. A. B. Miller; M. D. Feuer; T. Y. Chang; S. C. Shunk; J. E. Henry; D. J. Burrows; D. S. Chemla
1989-01-01
The authors propose and demonstrate the integration of a photodiode, a quantum-confined Stark-effect quantum-well optical modulator, and a metal-semiconductor field-effect transistor (MESFET) to make a field-effect transistor self-electrooptic effect device. This integration allows optical inputs and outputs on the surface of a GaAs-integrated circuit chip, compatible with standard MESFET processing. To provide an illustration of feasibility, the authors demonstrate signal
CHANDRA HIGH-RESOLUTION OBSERVATIONS OF CID-42, A CANDIDATE RECOILING SUPERMASSIVE BLACK HOLE
Civano, F.; Elvis, M.; Lanzuisi, G.; Aldcroft, T.; Trichas, M.; Fruscione, A. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Bongiorno, A.; Brusa, M. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Blecha, L.; Loeb, A. [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States); Comastri, A.; Gilli, R. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, Bologna 40127 (Italy); Salvato, M.; Komossa, S. [Max-Planck-Institute for Plasma Physics, Excellence Cluster, Boltzmannstrass 2, 85748 Garching (Germany); Koekemoer, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Mainieri, V. [ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Piconcelli, E. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, Monteporzio-Catone 00040 (Italy); Vignali, C. [Dipartimento di Astronomia, Universita di Bologna, Via Ranzani 1, Bologna 40127 (Italy)
2012-06-10
We present Chandra High Resolution Camera observations of CID-42, a candidate recoiling supermassive black hole (SMBH) at z = 0.359 in the COSMOS survey. CID-42 shows two optical compact sources resolved in the HST/ACS image embedded in the same galaxy structure and a velocity offset of {approx}1300 km s{sup -1} between the H{beta} broad and narrow emission line, as presented by Civano et al. Two scenarios have been proposed to explain the properties of CID-42: a gravitational wave (GW) recoiling SMBH and a double Type 1/Type 2 active galactic nucleus (AGN) system, where one of the two is recoiling because of slingshot effect. In both scenarios, one of the optical nuclei hosts an unobscured AGN, while the other one, either an obscured AGN or a star-forming compact region. The X-ray Chandra data allow us to unambiguously resolve the X-ray emission and unveil the nature of the two optical sources in CID-42. We find that only one of the optical nuclei is responsible for the whole X-ray unobscured emission observed and a 3{sigma} upper limit on the flux of the second optical nucleus is measured. The upper limit on the X-ray luminosity plus the analysis of the multiwavelength spectral energy distribution indicate the presence of a star-forming region in the second source rather than an obscured SMBH, thus favoring the GW recoil scenario. However, the presence of a very obscured SMBH cannot be fully ruled out. A new X-ray feature, in a SW direction with respect to the main source, is discovered and discussed.
The Benefits of B ---> K* l+ l- Decays at Low Recoil
Christoph Bobeth; Gudrun Hiller; Danny van Dyk
2010-07-08
Using the heavy quark effective theory framework put forward by Grinstein and Pirjol we work out predictions for B -> K* l+ l-, l = (e, mu), decays for a softly recoiling K*, i.e., for large dilepton masses sqrt{q^2} of the order of the b-quark mass m_b. We work to lowest order in Lambda/Q, where Q = (m_b, sqrt{q^2}) and include the next-to-leading order corrections from the charm quark mass m_c and the strong coupling at O(m_c^2/Q^2, alpha_s). The leading Lambda/m_b corrections are parametrically suppressed. The improved Isgur-Wise form factor relations correlate the B -> K* l+ l- transversity amplitudes, which simplifies the description of the various decay observables and provides opportunities for the extraction of the electroweak short distance couplings. We propose new angular observables which have very small hadronic uncertainties. We exploit existing data on B -> K* l+ l- distributions and show that the low recoil region provides powerful additional information to the large recoil one. We find disjoint best-fit solutions, which include the Standard Model, but also beyond-the-Standard Model ones. This ambiguity can be accessed with future precision measurements.
NASA Astrophysics Data System (ADS)
Niu, X. Y.; Huang, X. L.; Shang, Y. F.; Wang, X. Y.
2015-04-01
Superposition principle plays a crucial role in quantum mechanics, thus its effects on thermodynamics is an interesting topic. Here, the effects of superpositions of quantum states on isoenergetic cycle are studied. We find superposition can improve the heat engine efficiency and release the positive work condition in general case. In the finite time process, we find the efficiency at maximum power output in superposition case is lower than the nonsuperposition case. This efficiency depends on one index of the energy spectrum of the working substance. This result does not mean the superposition discourages the heat engine performance. For fixed efficiency or fixed power, the superposition improves the power or efficiency respectively. These results show how quantum mechanical properties affect the thermodynamical cycle.
Observation of the Kondo effect in a quadruple quantum dot
NASA Astrophysics Data System (ADS)
Shang, Runan; Li, Hai-Ou; Cao, Gang; Yu, Guodong; Xiao, Ming; Tu, Tao; Guo, Guang-Can; Jiang, Hongwen; Chang, A. M.; Guo, Guo-Ping
2015-06-01
We investigate the Kondo effect in a quadruple-quantum-dot device of coupled double quantum dots (DQDs), which simultaneously contain intra-DQD and inter-DQD coupling. A variety of novel behaviors are observed. The differential conductance dI/dV is measured in the upper DQDs as a function of source drain bias. It is found to exhibit multiple peaks, including a zero-bias peak, where the number of peaks exceeds five. Alternatively, tuning the lower DQDs yielded regions of four peaks. In addition, a Kondo effect switcher is demonstrated, using the lower DQDs as the controller.
Effects of atomic interactions on quantum accelerator modes
NASA Astrophysics Data System (ADS)
Rebuzzini, Laura; Artuso, Roberto; Fishman, Shmuel; Guarneri, Italo
2007-09-01
We consider the influence of the inclusion of interatomic interactions on the ? -kicked accelerator model. Our analysis concerns in particular quantum accelerator modes, namely quantum ballistic transport near quantal resonances. The atomic interaction is modeled by a Gross-Pitaevskii cubic nonlinearity, and we address both attractive (focusing) and repulsive (defocusing) cases. The most remarkable effect is enhancement or damping of the accelerator modes, depending on the sign of the nonlinear parameter. We provide arguments showing that the effect persists beyond mean-field description, and lies within the experimentally accessible parameter range.
The spin Hall effect in a quantum gas.
Beeler, M C; Williams, R A; Jiménez-García, K; LeBlanc, L J; Perry, A R; Spielman, I B
2013-06-13
Electronic properties such as current flow are generally independent of the electron's spin angular momentum, an internal degree of freedom possessed by quantum particles. The spin Hall effect, first proposed 40 years ago, is an unusual class of phenomena in which flowing particles experience orthogonally directed, spin-dependent forces--analogous to the conventional Lorentz force that gives the Hall effect, but opposite in sign for two spin states. Spin Hall effects have been observed for electrons flowing in spin-orbit-coupled materials such as GaAs and InGaAs (refs 2, 3) and for laser light traversing dielectric junctions. Here we observe the spin Hall effect in a quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz forces to realize a cold-atom spin transistor. By engineering a spatially inhomogeneous spin-orbit coupling field for our quantum gas, we explicitly introduce and measure the requisite spin-dependent Lorentz forces, finding them to be in excellent agreement with our calculations. This 'atomtronic' transistor behaves as a type of velocity-insensitive adiabatic spin selector, with potential application in devices such as magnetic or inertial sensors. In addition, such techniques for creating and measuring the spin Hall effect are clear prerequisites for engineering topological insulators and detecting their associated quantized spin Hall effects in quantum gases. As implemented, our system realizes a laser-actuated analogue to the archetypal semiconductor spintronic device, the Datta-Das spin transistor. PMID:23739329
Submillisecond Elastic Recoil Reveals Molecular Origins of Fibrin Fiber Mechanics
Hudson, Nathan E.; Ding, Feng; Bucay, Igal; O’Brien, E. Timothy; Gorkun, Oleg V.; Superfine, Richard; Lord, Susan T.; Dokholyan, Nikolay V.; Falvo, Michael R.
2013-01-01
Fibrin fibers form the structural scaffold of blood clots. Thus, their mechanical properties are of central importance to understanding hemostasis and thrombotic disease. Recent studies have revealed that fibrin fibers are elastomeric despite their high degree of molecular ordering. These results have inspired a variety of molecular models for fibrin’s elasticity, ranging from reversible protein unfolding to rubber-like elasticity. An important property that has not been explored is the timescale of elastic recoil, a parameter that is critical for fibrin’s mechanical function and places a temporal constraint on molecular models of fiber elasticity. Using high-frame-rate imaging and atomic force microscopy-based nanomanipulation, we measured the recoil dynamics of individual fibrin fibers and found that the recoil was orders of magnitude faster than anticipated from models involving protein refolding. We also performed steered discrete molecular-dynamics simulations to investigate the molecular origins of the observed recoil. Our results point to the unstructured ?C regions of the otherwise structured fibrin molecule as being responsible for the elastic recoil of the fibers. PMID:23790375
Calculation of recoil implantation profiles using known range statistics
NASA Technical Reports Server (NTRS)
Fung, C. D.; Avila, R. E.
1985-01-01
A method has been developed to calculate the depth distribution of recoil atoms that result from ion implantation onto a substrate covered with a thin surface layer. The calculation includes first order recoils considering projected range straggles, and lateral straggles of recoils but neglecting lateral straggles of projectiles. Projectile range distributions at intermediate energies in the surface layer are deduced from look-up tables of known range statistics. A great saving of computing time and human effort is thus attained in comparison with existing procedures. The method is used to calculate recoil profiles of oxygen from implantation of arsenic through SiO2 and of nitrogen from implantation of phosphorus through Si3N4 films on silicon. The calculated recoil profiles are in good agreement with results obtained by other investigators using the Boltzmann transport equation and they also compare very well with available experimental results in the literature. The deviation between calculated and experimental results is discussed in relation to lateral straggles. From this discussion, a range of surface layer thickness for which the method applies is recommended.
Focus on quantum effects and noise in biomolecules
NASA Astrophysics Data System (ADS)
Fleming, G. R.; Huelga, S. F.; Plenio, M. B.
2011-11-01
The role of quantum mechanics in biological organisms has been a fundamental question of twentieth-century biology. It is only now, however, with modern experimental techniques, that it is possible to observe quantum mechanical effects in bio-molecular complexes directly. Indeed, recent experiments have provided evidence that quantum effects such as wave-like motion of excitonic energy flow, delocalization and entanglement can be seen even in complex and noisy biological environments (Engel et al 2007 Nature 446 782; Collini et al 2010 Nature 463 644; Panitchayangkoon et al 2010 Proc. Natl Acad. Sci. USA 107 12766). Motivated by these observations, theoretical work has highlighted the importance of an interplay between environmental noise and quantum coherence in such systems (Mohseni et al 2008 J. Chem. Phys. 129 174106; Plenio and Huelga 2008 New J. Phys. 10 113019; Olaya-Castro et al 2008 Phys. Rev. B 78 085115; Rebentrost et al 2009 New J. Phys. 11 033003; Caruso et al 2009 J. Chem. Phys. 131 105106; Ishizaki and Fleming 2009 J. Chem. Phys. 130 234111). All of this has led to a surge of interest in the exploration of quantum effects in biological systems in order to understand the possible relevance of non-trivial quantum features and to establish a potential link between quantum coherence and biological function. These studies include not only exciton transfer across light harvesting complexes, but also the avian compass (Ritz et al 2000 Biophys. J. 78 707), and the olfactory system (Turin 1996 Chem. Sens. 21 773; Chin et al 2010 New J. Phys. 12 065002). These examples show that the full understanding of the dynamics at bio-molecular length (10 Å) and timescales (sub picosecond) in noisy biological systems can uncover novel phenomena and concepts and hence present a fertile ground for truly multidisciplinary research.
Dynamical quantum Hall effect in the parameter space.
Gritsev, V; Polkovnikov, A
2012-04-24
Geometric phases in quantum mechanics play an extraordinary role in broadening our understanding of fundamental significance of geometry in nature. One of the best known examples is the Berry phase [M.V. Berry (1984), Proc. Royal. Soc. London A, 392:45], which naturally emerges in quantum adiabatic evolution. So far the applicability and measurements of the Berry phase were mostly limited to systems of weakly interacting quasi-particles, where interference experiments are feasible. Here we show how one can go beyond this limitation and observe the Berry curvature, and hence the Berry phase, in generic systems as a nonadiabatic response of physical observables to the rate of change of an external parameter. These results can be interpreted as a dynamical quantum Hall effect in a parameter space. The conventional quantum Hall effect is a particular example of the general relation if one views the electric field as a rate of change of the vector potential. We illustrate our findings by analyzing the response of interacting spin chains to a rotating magnetic field. We observe the quantization of this response, which we term the rotational quantum Hall effect. PMID:22493228
Dynamical quantum Hall effect in the parameter space
Gritsev, V.; Polkovnikov, A.
2012-01-01
Geometric phases in quantum mechanics play an extraordinary role in broadening our understanding of fundamental significance of geometry in nature. One of the best known examples is the Berry phase [M.V. Berry (1984), Proc. Royal. Soc. London A, 392:45], which naturally emerges in quantum adiabatic evolution. So far the applicability and measurements of the Berry phase were mostly limited to systems of weakly interacting quasi-particles, where interference experiments are feasible. Here we show how one can go beyond this limitation and observe the Berry curvature, and hence the Berry phase, in generic systems as a nonadiabatic response of physical observables to the rate of change of an external parameter. These results can be interpreted as a dynamical quantum Hall effect in a parameter space. The conventional quantum Hall effect is a particular example of the general relation if one views the electric field as a rate of change of the vector potential. We illustrate our findings by analyzing the response of interacting spin chains to a rotating magnetic field. We observe the quantization of this response, which we term the rotational quantum Hall effect. PMID:22493228
Phenomenology of effective geometries from quantum gravity
Torromé, Ricardo Gallego; Liberati, Stefano
2015-01-01
In a recent paper (arXiv:1412.6000) a general mechanism for emergence of cosmological space-time geometry from a quantum gravity setting was devised and departure from standard dispersion relations for elementary particle were predicted. We elaborate here on this approach extending the results obtained in that paper and showing that generically such a framework will not lead to higher order modified dispersion relations in the matter sector. Furthermore, we shall discuss possible phenomenological constraints to this scenarios showing that space-time will have to be by nowadays classical to a very high degree in order to be consistent with current observations.
Andreev reflection in the quantum Hall effect
NASA Astrophysics Data System (ADS)
Sandler, Nancy; Chamon, Claudio De C.; Fradkin, Eduardo
1998-03-01
We study the reflection of electrons and quasiparticles on point-contact interfaces between fractional quantum Hall (FQH) states and normal metals (leads), as well as interfaces between two FQH states with mismatched filling fractions. We classify the processes taking place at the interface in the strong coupling limit. In this regime a set of quasiparticles can decay into quasiholes on the FQH side and charge excitations on the other side of the junction. This process is analogous to an Andreev reflection in normal-metal/superconductor (N-S) interfaces. We also discuss the connection between FQH/normal-metal junctions and two-channel Kondo systems.
The Effect of Electric Field on a Quantum Rod Qubit
NASA Astrophysics Data System (ADS)
Xiao, Jing-Lin
The Hamiltonian of a quantum rod with an ellipsoidal boundary is given after a coordinate transformation, which changes the ellipsoidal boundary into a spherical one. We study the electron which is strongly coupled to the LO-phonon eigenenergies and eigenfunctions of the ground and the first-excited states in a quantum rod under an applied electric field by using variational method of Pekar type. This quantum rod system may be used as a two-level qubit. When the electron is in the superposition state of the ground and the first-excited states, we obtain the time evolution of the electron probability density. The probability density of the electron oscillates in the quantum rod with an oscillation period. It is found that due to the presence of the three-dimensional anisotropic harmonic potential in the radius and the length directions of the quantum rod, the electron probability density shows double-peak configuration, whereas there is only peak if the confinement is a two-dimensional symmetric one in the x- and y-directions. The oscillation period is an increasing function of the ellipsoid aspect ratio and the transverse and longitudinal effective confinement lengths of the quantum rod, whereas it is decreasing one of the electron-phonon coupling strength and the electric field.
Advanced theory of multiple exciton generation effect in quantum dots
NASA Astrophysics Data System (ADS)
Oksengendler, B. L.; Turaeva, N. N.; Rashidova, S. S.
2012-06-01
The theoretical aspects of the effect of multiple exciton generation (MEG) in quantum dots (QDs) have been analysed in this work. The statistical theory of MEG in QDs based on Fermi's approach is presented, taking into account the momentum conservation law. According to Fermi this approach should give the ultimate quantum efficiencies of multiple particle generation. The microscopic mechanism of this effect is based on the theory of electronic "shaking". According to this approach, the wave function of "shaking" electrons can be selected as Plato's functions with effective charges depending on the number of generated excitons. From the theory it is known increasing the number of excitons leads to enhancement of the Auger recombination of electrons which results in reduced quantum yields of excitons. The deviation of the averaged multiplicity of the MEG effect from the Poisson law of fluctuations has been investigated on the basis of synergetics approaches. In addition the role of interface electronic states of QDs and ligands has been considered by means of quantum mechanical approaches. The size optimisation of QDs has been performed to maximise the multiplicity of the MEG effect.
Pseudorelativistic effects on solitons in quantum semiconductor plasma.
Wang, Yunliang; Wang, Xiaodan; Jiang, Xiangqian
2015-04-01
A theory for nonlinear excitations in quantum plasmas is presented for narrow-gap semiconductors by considering the combined effects of quantum and pseudorelativity. The system is governed by a coupled Klein-Gordon equation for the collective wave functions of the conduction electrons and Poisson's equation for the electrostatic potential. This gives a closed system, including the effects of charge separation, quantum tunneling, and pseudorelativity. By choosing the typical parameters of semiconductor InSb, the quasistationary soliton solution, which is a multipeaked dark soliton, is obtained numerically and shows depleted electron densities correlated with a localized potential. The dynamical simulation result shows that the dark soliton is stable and has a multipeaked profile, which is consistent with the quasistationary solution. The present model and results may be useful in understanding the nonlinear properties of semiconductor plasma on an ultrafast time scale. PMID:25974603
Composite Fermion Theory of Exotic Fractional Quantum Hall Effect
NASA Astrophysics Data System (ADS)
Jain, Jainendra K.
2015-03-01
The fractional quantum Hall effect (FQHE) arises from strong correlations between electrons when they are confined to two dimensions and exposed to a strong magnetic field. The underlying physics is the formation of topological particles called composite fermions (CFs), electron-vortex bound states whose integer quantum Hall effect explains a large majority of the observed FQHE states. In recent years, the focus has shifted to the more exotic states that originate from a weak residual interaction between composite fermions. These include chiral p-wave paired states of composite fermions at certain even denominator fractions, unconventional FQHE of composite fermions, and a series of CF crystals at low fillings. Aside from these states, we also review the FQHE in multicomponent systems, which has attracted renewed attention because of the observation of well-developed FQHE in several multivalley systems, such as graphene and AlAs quantum wells.
Quantum mechanical effects of topological origin
NASA Astrophysics Data System (ADS)
Duru, I. H.
1993-03-01
Following a brief review of the original Casimir and Aharonov-Bohm effects, some other effects of similar natures are mentioned. A Casimir interaction between AB fluxes is presented. Possible realizations of the Casimir effects for massive charged fields in solid state structures and a new AB effect for photons are suggested.
Quantum mechanical effects of topological origin
I. H. Duru
1993-01-01
Following a brief review of the original Casimir and Aharonov-Bohm effects, some other effects of similar natures are mentioned. A Casimir interaction between AB fluxes is presented. Possible realizations of the Casimir effects for massive charged fields in solid state structures and a new AB effect for photons are suggested.
First detection of tracks of radon progeny recoils by MIMAC
Riffard, Q; Bosson, G; Bourrion, O; Descombes, T; Fourel, C; Guillaudin, O; Muraz, J -F; Colas, P; Ferrer-Ribas, E; Giomataris, I; Busto, J; Fouchez, D; Tao, C; Lebreton, L; Maire, D
2015-01-01
The MIMAC experiment is a $\\mu$-TPC matrix project for directional dark matter search. Directional detection is a strategy based on the measurement of the WIMP flux anisotropy due to the solar system motion with respect to the dark matter halo. The main purpose of MIMAC project is the measurement of the energy and the direction of nuclear recoils in 3D produced by elastic scattering of WIMPs. Since June 2012 a bi-chamber prototype is operating at the Modane underground laboratory. In this paper, we report the first ionization energy and 3D track observations of nuclear recoils produced by the radon progeny. This measurement shows the capability of the MIMAC detector and opens the possibility to explore the low energy recoil directionality signature.
First detection of tracks of radon progeny recoils by MIMAC
Q. Riffard; D. Santos; G. Bosson; O. Bourrion; T. Descombes; C. Fourel; O. Guillaudin; J. -F. Muraz; P. Colas; E. Ferrer-Ribas; I. Giomataris; J. Busto; D. Fouchez; C. Tao; L. Lebreton; D. Maire
2015-04-22
The MIMAC experiment is a $\\mu$-TPC matrix project for directional dark matter search. Directional detection is a strategy based on the measurement of the WIMP flux anisotropy due to the solar system motion with respect to the dark matter halo. The main purpose of MIMAC project is the measurement of the energy and the direction of nuclear recoils in 3D produced by elastic scattering of WIMPs. Since June 2012 a bi-chamber prototype is operating at the Modane underground laboratory. In this paper, we report the first ionization energy and 3D track observations of nuclear recoils produced by the radon progeny. This measurement shows the capability of the MIMAC detector and opens the possibility to explore the low energy recoil directionality signature.
Effects of quantum coherence in metalloprotein electron transfer.
Dorner, Ross; Goold, John; Heaney, Libby; Farrow, Tristan; Vedral, Vlatko
2012-09-01
Many intramolecular electron transfer (ET) reactions in biology are mediated by metal centers in proteins. This process is commonly described by a model of diffusive hopping according to the semiclassical theories of Marcus and Hopfield. However, recent studies have raised the possibility that nontrivial quantum mechanical effects play a functioning role in certain biomolecular processes. Here, we investigate the potential effects of quantum coherence in biological ET by extending the semiclassical model to allow for the possibility of quantum coherent phenomena using a quantum master equation based on the Holstein Hamiltonian. We test the model on the structurally defined chain of seven iron-sulfur clusters in nicotinamide adenine dinucleotide plus hydrogen:ubiquinone oxidoreductase (complex I), a crucial respiratory enzyme and one of the longest chains of metal centers in biology. Using experimental parameters where possible, we find that, in limited circumstances, a small quantum mechanical contribution can provide a marked increase in the ET rate above the semiclassical diffusive-hopping rate. Under typical biological conditions, our model reduces to well-known diffusive behavior. PMID:23030959
Hammes-Schiffer, Sharon
Hybrid approach for including electronic and nuclear quantum effects in molecular dynamics profiles. The dynamical effects are studied with the molecular dynamics with quantum transitions MDQT is the use of classical molecular dynamics simulations with molecular mechanical forcefields.7
Low Energy Theorems of Quantum Gravity from Effective Field Theory
Donoghue, John F
2015-01-01
In this survey, we review some of the low energy quantum predictions of General Relativity which are independent of details of the yet unknown high-energy completion of the gravitational interaction. Such predictions can be extracted using the techniques of effective field theory.
Isotropic cosmological models determined by vacuum quantum effects
Mamaev, S.G.; Mostepanenko, V.M.
1980-01-01
The evolution of cosmological models with scalar or spinor quantized fields is studied. In the class of spatially homogeneous isotropic models, all self-consistent models are found in which the metric is determined by vacuum quantum effects of massless fields. It is shown that the obtained results are also valid for massive fields.
Stopping Power of Au for Ti Using Elastic Recoil Technique
Linares, R.; Freire, J. A.; Ribas, R. V.; Medina, N. H.; Oliveira, J. R. B.; Seale, W. A.; Cybulska, E. W.; Wiedemann, K. T.; Allegro, P. R.; Toufen, D. L. [Instituto de Fisica da Universidade de Sao Paulo, C.P. 66318, 05317-970, S. Paulo, SP (Brazil)
2009-06-03
The slowing down of heavy ions in matter is still not well understood especially at low energies (<0.5 MeV/u). In this contribution we present new experimental data for the stopping power of Au for Ti ions using an elastic recoil technique where a heavy-ion beam at low energies is produced by elastic scattering of an energetic primary beam imping on a thin target. Atoms from the target recoil at low energies. We compare our experimental data with previous data and with semi-empirical and theoretical models.
About empty waves, their effect, and the quantum theory
Sofia Wechsler
2010-08-28
When a quantum object -- a particle as we call it in a non-rigorous way -- is described by a multi-branched wave- function, with the corresponding wave-packets occupying separated regions of the time-space, a frequently asked question is whether the quantum object is actually contained in only one of these wave-packets. If the answer is positive, then the other wave-packets are called in literature empty waves. The wave-packet containing the object is called a full wave, and is the only one that would produce a recording in a detector. A question immediately arising is whether the empty waves may also have an observable effect. Different works were dedicated to the elucidation of this question. None of them proved that the hypothesis of full/empty waves is correct - it may be that the Nature is indeed non-deterministic and the quantum object is not confined to one region of the space-time. All the works that proved that the empty waves have an effect, in fact, proved that if there exist full and empty waves, then the latter may have an observable effect. This is also the purpose and the limitation of the present work. What is shown here is that if the hypothesis is true, the empty waves have an influence. An experiment is indicated which reveals this influence. The analysis of the experiment is according to the quantum formalism. This experiment has the advantage of being more intuitive and practically more feasible than a previous proposal also in agreement with the quantum formalism. However, the presently proposed experiment also shows that the quantum theory is not in favor of the above hypothesis.
Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243
U. Forsberg; D. Rudolph; L. -L. Andersson; A. Di Nitto; Ch. E. Düllmann; J. M. Gates; P. Golubev; K. E. Gregorich; C. J. Gross; R. -D. Herzberg; F. P. Hessberger; J. Khuyagbaatar; J. V. Kratz; K. Rykaczewski; L. G. Sarmiento; M. Schädel; A. Yakushev; S. Åberg; D. Ackermann; M. Block; H. Brand; B. G. Carlsson; D. Cox; X. Derkx; J. Dobaczewski; K. Eberhardt; J. Even; C. Fahlander; J. Gerl; E. Jäger; B. Kindler; J. Krier; I. Kojouharov; N. Kurz; B. Lommel; A. Mistry; C. Mokry; W. Nazarewicz; H. Nitsche; J. P. Omtvedt; P. Papadakis; I. Ragnarsson; J. Runke; H. Schaffner; B. Schausten; Y. Shi; P. Thörle-Pospiech; T. Torres; T. Traut; N. Trautmann; A. Türler; A. Ward; D. E. Ward; N. Wiehl
2015-02-10
Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum f\\"ur Schwerionenforschung. Amongst the detected thirty correlated alpha-decay chains associated with the production of element Z=115, two recoil-alpha-fission and five recoil-alpha-alpha-fission events were observed. The latter are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289.
Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243
Forsberg, U; Andersson, L -L; Di Nitto, A; Düllmann, Ch E; Gates, J M; Golubev, P; Gregorich, K E; Gross, C J; Herzberg, R -D; Hessberger, F P; Khuyagbaatar, J; Kratz, J V; Rykaczewski, K; Sarmiento, L G; Schädel, M; Yakushev, A; Åberg, S; Ackermann, D; Block, M; Brand, H; Carlsson, B G; Cox, D; Derkx, X; Dobaczewski, J; Eberhardt, K; Even, J; Fahlander, C; Gerl, J; Jäger, E; Kindler, B; Krier, J; Kojouharov, I; Kurz, N; Lommel, B; Mistry, A; Mokry, C; Nazarewicz, W; Nitsche, H; Omtvedt, J P; Papadakis, P; Ragnarsson, I; Runke, J; Schaffner, H; Schausten, B; Shi, Y; Thörle-Pospiech, P; Torres, T; Traut, T; Trautmann, N; Türler, A; Ward, A; Ward, D E; Wiehl, N
2015-01-01
Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum f\\"ur Schwerionenforschung. Amongst the detected thirty correlated alpha-decay chains associated with the production of element Z=115, two recoil-alpha-fission and five recoil-alpha-alpha-fission events were observed. The latter are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289.
The Quantum Hall Effect: Novel Excitations And Broken Symmetries
Steven M. Girvin
The Quantum Hall Effect (QHE) is one of the most remarkable condensed-matter phenomena discovered in the second half of the\\u000a 20th century. It rivals superconductivity in its fundamental significance as a manifestation of quantum mechanics on macroscopic\\u000a scales. The basic experimental observation is the nearly vanishing dissipation ?\\u000a xx ? 0 (1.1) and the quantization of the Hall conductance \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a\\u000a\\u000a\\u000a\\u000a\\u000as<\\/font
The Meissner effect puzzle and the quantum force in superconductor
A. V. Nikulov
2012-10-31
The puzzle of the acceleration of the mobile charge carriers and the ions in the superconductor in direction opposite to the electromagnetic force revealed formerly in the Meissner effect is considered in the case of the transition of a narrow ring from normal to superconducting state. It is elucidated that the azimuthal quantum force was deduced eleven years ago from the experimental evidence of this acceleration but it can not solve this puzzle. This quantum force explains other paradoxical phenomena connected with reiterated switching of the ring between normal and superconducting states.
Nuclear Quantum Vibrational Effects in Shock Hugoniot Temperatures
Goldman, N; Reed, E; Fried, L E
2009-07-23
We present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a Grueneisen equation of state and a quasiharmonic approximation to the vibrational energies, we derive a simple, post-processing method for calculation of the quantum corrected Hugoniot temperatures. We have used our novel technique on ab initio simulations of shock compressed water. Our results indicate significantly closer agreement with all available experimental temperature data. Our formalism and technique can be easily applied to a number of different shock compressed molecular liquids or solids.
Yimin Huang; Chenhsin Lien; Tan-Fu Lei
1993-01-01
A tunable asymmetric coupled quantum well far-infrared photodetector is proposed. The basic asymmetric coupled quantum wells are composed of two quantum wells separated by a thin barrier. In this way, the electron in each well interacts strongly with other electrons to achieve a large Stark tuning effect. The eigenenergies and the wave functions of the quantum-well structures are solved by
Yimin Huang; Chenhsin Lien; Tan-Fu Lei
1993-01-01
A tunable asymmetric coupled quantum well far-infrared photodetector is proposed in this paper. The basic asymmetric coupled quantum wells are composed of two quantum wells separated by a thin barrier. In this way, the electron in each well interacts strongly with other electrons to achieve a large Stark tuning effect. The eigenenergies and the wave functions of the quantum-well structures
Martonosi, Margaret
Estimation (GSE) for quantum chemistry, also use QPE. Unfortunately, QPE can be computationally expensiveCharacterizing the Performance Effect of Trials and Rotations in Applications that use Quantum@cs.ucsb.edu Abstract--Quantum Phase Estimation (QPE) is one of the key techniques used in quantum computation to design
Second Activation Energy in the Fractional Quantum Hall Effect
Junichi Wakabayashi; Satoru Sudou; Shinji Kawaji; Kazuhiko Hirakawa; Hiroyuki Sakaki
1987-01-01
The temperature dependence of the resistivity minima of the 2\\/3 effect in the fractional quantum Hall effect has been measured for a GaAs\\/AlGaAs heterostructure with a backside gate. The results at the highest negative gate bias have shown a single activated conduction. The systematic change of the temperature dependence controlled by the gate bias indicates that this activation energy does
NASA Astrophysics Data System (ADS)
Donoghue, John F.; El-Menoufi, Basem Kamal
2014-05-01
We discuss cosmological effects of the quantum loops of massless particles, which lead to temporal nonlocalities in the equations of motion governing the scale factor a(t). For the effects discussed here, loops cause the evolution of a(t) to depend on the memory of the curvature in the past with a weight that scales initially as 1/(t -t'). As one of our primary examples, we discuss the situation with a large number of light particles, such that these effects occur in a region where gravity may still be treated classically. However, we also describe the effect of quantum graviton loops and the full set of Standard Model particles. We show that these effects decrease with time in an expanding phase, leading to classical behavior at late time. In a contracting phase, within our approximations the quantum results can lead to a bouncelike behavior at scales below the Planck mass, avoiding the singularities required classically by the Hawking-Penrose theorems. For conformally invariant fields, such as the Standard Model with a conformally coupled Higgs, this result is purely nonlocal and parameter independent.
The Quantum Spin Hall Effect: Theory and Experiment
Konig, Markus; Buhmann, Hartmut; Molenkamp, Laurens W.; /Wurzburg U.; Hughes, Taylor L.; /Stanford U., Phys. Dept.; Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19
The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Recently, a new class of topological insulators has been proposed. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. In two dimensions the helical edge states give rise to the quantum spin Hall (QSH) effect, in the absence of any external magnetic field. Here we review a recent theory which predicts that the QSH state can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the band structure changes from a normal to an 'inverted' type at a critical thickness d{sub c}. We present an analytical solution of the helical edge states and explicitly demonstrate their topological stability. We also review the recent experimental observation of the QSH state in HgTe/(Hg,Cd)Te quantum wells. We review both the fabrication of the sample and the experimental setup. For thin quantum wells with well width d{sub QW} < 6.3 nm, the insulating regime shows the conventional behavior of vanishingly small conductance at low temperature. However, for thicker quantum wells (d{sub QW} > 6.3 nm), the nominally insulating regime shows a plateau of residual conductance close to 2e{sup 2}/h. The residual conductance is independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance is destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, d{sub c} = 6.3 nm, is also independently determined from the occurrence of a magnetic field induced insulator to metal transition.
Self-action effects in semiconductor quantum dots
NASA Astrophysics Data System (ADS)
Dneprovskii, V. S.; Kanev, A. R.; Kozlova, M. V.; Smirnov, A. M.
2014-05-01
Two-dimensional (2D) dynamic photonic crystal regime has been utilized to investigate self-diffraction effect and nonlinear optical properties of excitons in CdSe/ZnS colloidal quantum dots (QDs). Self-diffraction at 2D photonic crystal arises for three intersecting beams of Nd+3:YAG laser second harmonic in the case of one-photon resonant excitation of the exciton (electron - hole) transition QDs. The relaxation time of excited excitons has been measured by pump and probe technique at induced one-dimensional transient diffraction grating. Two-exponential decay with initial fast and slow parts was discovered. Self-action effect has been discovered in the case of stationary resonant excitation of excitons in CdSe/ZnS QDs by the beam of second harmonic of powerful 12-nanosecond laser pulses. The bleaching of exciton absorption and the creation of transparency channel (this effect provokes self-diffraction of the second harmonic beam) was explained by the dominating coexisting and competing processes of state filling in stationary excited quantum dots and Stark-shift of exciton spectral band. The peculiarities of the influence of these processes at the change of exciton absorption in quantum dots in the case of different detuning from exciton resonance (quantum dots with different size have been used) was analyzed.
Quantum Hall effect in graphene with twisted bilayer stripe defects
NASA Astrophysics Data System (ADS)
Löfwander, Tomas; San-Jose, Pablo; Prada, Elsa
2013-05-01
We analyze the quantum Hall effect in single layer graphene with bilayer stripe defects. Such defects are often encountered at steps in the substrate of graphene grown on silicon carbide. We show that AB or AA stacked bilayer stripes result in large Hall conductivity fluctuations that destroy the quantum Hall plateaux. The fluctuations are a result of the coupling of edge states at opposite edges through currents traversing the stripe. Upon rotation of the second layer with respect to the continuous monolayer (a twisted-bilayer stripe defect), such currents decouple from the extended edge states and develop into long-lived discrete quasibound states circulating around the perimeter of the stripe. Backscattering of edge modes then occurs only at precise resonant energies, and hence the quantum Hall plateaux are recovered as twist angle grows.
Quantum Point Contact Transistor and Ballistic Field-Effect Transistors
NASA Astrophysics Data System (ADS)
Grémion, E.; Niepce, D.; Cavanna, A.; Gennser, U.; Jin, Y.
2012-12-01
We report the experimental results and theoretical understanding of the Quantum Point Contact Transistor - a fully ballistic one-dimensional (1D) Field-Effect Transistor (FET). Experimentally obtained voltage gain greater than 1 in our Quantum-Point-Contact transistors at 4.2 K can be explained with the help of an analytical modeling based on the Landauer-Büttiker approach in mesosopic physics: the lowest 1D subband and the band gap play the key role in increasing its transconductance, especially by reducing its output conductance, and thus achieving a voltage gain higher than 1. This work provides a general basis for devising future ballistic FETs and the quantum limits found in this work may be used to estimate normalized transconductance and channel resistance in future two-dimensional (2D) ballistic FETs.
Effect of Local Channels on Quantum Steering Ellipsoids
Xueyuan Hu; Heng Fan
2014-11-27
The effect of a local trace-preserving single-qubit channel on a two-qubit state is investigated in the picture of the quantum steering ellipsoids (QSE). The phenomenon of locally increased quantum correlation is visualized in this picture. We strictly prove that a $B$-side two-qubit discordant state can be locally prepared from a classical state by a trace-preserving channel on qubit $B$ if and only if its QSE of $B$ is a non-radial line segment. For states with higer-dimensional QSEs, the phenomenon of locally increased quantum correlation generally happens when the shape of the QSE is like a baguette. Based on this observation, we find a class of entangled states whose quantum discord can be increased by the local amplitude damping channel. Further, We find that the local quantum channel does not increase the size of QSEs of either qubit $A$ or qubit $B$, for the needle-shape QSE states, as well as the Bell diagonal states with higher-dimensional QSE.
Quantum plasmon effects in epsilon-near-zero metamaterials
Moaied, M; Ostrikov, K
2014-01-01
Dispersion properties of metals and propagation of quantum bulk plasmon in the high photon energy regime are studied. The nonlocal dielectric permittivity of a metal is determined by the quantum plasma effects and is calculated by applying the Wigner equation in the kinetic theory and taking into account the electron lattice collisions. The properties of epsilon near zero material are investigated in a thin gold film. The spectrum and the damping rate of the quantum bulk plasmon are obtained for a wide range of energies, and the electron wave function is analytically calculated in both classical and quantum limits. It is shown that the quantum bulk plasmons exist with a propagation length of 1 to 10nm, which strongly depends on the electron energy. The propagation length is found to be much larger than the propagation length in the classical regime which is comparable to the atomic radius and the average inter particle distance. It is found that the spatial localization of the electron wave function is extend...
Test modeling and parameter identification of a gun magnetorheological recoil damper
Hu Hongsheng; Wang Jiong; Qian Suxiang; Jiang Xuezheng
2009-01-01
Since its performance requirements of gun recoil mechanism have been continuously increased, this paper was explored and aimed at its dynamic model and parameter identification of a new type of gun magnetorheological recoil damper. Combining with its recoil resistance rule and stroke requirements of the 37mm caliber gun, a long-stroke magnetorheological recoil damper was developed. Using the developed hardware-in-the-loop simulation
Qian, Xiaofeng
Quantum spin Hall (QSH) effect materials feature edge states that are topologically protected from backscattering. However, the small band gap in materials that have been identified as QSH insulators limits applications. ...
Negative muon chemistry: the quantum muon effect and the finite nuclear mass effect.
Posada, Edwin; Moncada, Félix; Reyes, Andrés
2014-10-01
The any-particle molecular orbital method at the full configuration interaction level has been employed to study atoms in which one electron has been replaced by a negative muon. In this approach electrons and muons are described as quantum waves. A scheme has been proposed to discriminate nuclear mass and quantum muon effects on chemical properties of muonic and regular atoms. This study reveals that the differences in the ionization potentials of isoelectronic muonic atoms and regular atoms are of the order of millielectronvolts. For the valence ionizations of muonic helium and muonic lithium the nuclear mass effects are more important. On the other hand, for 1s ionizations of muonic atoms heavier than beryllium, the quantum muon effects are more important. In addition, this study presents an assessment of the nuclear mass and quantum muon effects on the barrier of He? + H2 reaction. PMID:25188920
Photodynamic antibacterial effect of graphene quantum dots.
Ristic, Biljana Z; Milenkovic, Marina M; Dakic, Ivana R; Todorovic-Markovic, Biljana M; Milosavljevic, Momir S; Budimir, Milica D; Paunovic, Verica G; Dramicanin, Miroslav D; Markovic, Zoran M; Trajkovic, Vladimir S
2014-05-01
Synthesis of new antibacterial agents is becoming increasingly important in light of the emerging antibiotic resistance. In the present study we report that electrochemically produced graphene quantum dots (GQD), a new class of carbon nanoparticles, generate reactive oxygen species when photoexcited (470 nm, 1 W), and kill two strains of pathogenic bacteria, methicillin-resistant Staphylococcus aureus and Escherichia coli. Bacterial killing was demonstrated by the reduction in number of bacterial colonies in a standard plate count method, the increase in propidium iodide uptake confirming the cell membrane damage, as well as by morphological defects visualized by atomic force microscopy. The induction of oxidative stress in bacteria exposed to photoexcited GQD was confirmed by staining with a redox-sensitive fluorochrome dihydrorhodamine 123. Neither GQD nor light exposure alone were able to cause oxidative stress and reduce the viability of bacteria. Importantly, mouse spleen cells were markedly less sensitive in the same experimental conditions, thus indicating a fairly selective antibacterial photodynamic action of GQD. PMID:24612819
Memory effects in attenuation and amplification quantum processes
Lupo, Cosmo [School of Science and Technology, University of Camerino, via Madonna delle Carceri 9, I-62032 Camerino (Italy); Giovannetti, Vittorio [NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza dei Cavalieri 7, I-56126 Pisa (Italy); Mancini, Stefano [School of Science and Technology, University of Camerino, via Madonna delle Carceri 9, I-62032 Camerino (Italy); INFN-Sezione di Perugia, I-06123 Perugia (Italy)
2010-09-15
With increasing communication rates via quantum channels, memory effects become unavoidable whenever the use rate of the channel is comparable to the typical relaxation time of the channel environment. We introduce a model of a bosonic memory channel, describing correlated noise effects in quantum-optical processes via attenuating or amplifying media. To study such a channel model, we make use of a proper set of collective field variables, which allows us to unravel the memory effects, mapping the n-fold concatenation of the memory channel to a unitarily equivalent, direct product of n single-mode bosonic channels. We hence estimate the channel capacities by relying on known results for the memoryless setting. Our findings show that the model is characterized by two different regimes, in which the cross correlations induced by the noise among different channel uses are either exponentially enhanced or exponentially reduced.
Evanescent radiation, quantum mechanics and the Casimir effect
NASA Technical Reports Server (NTRS)
Schatten, Kenneth H.
1989-01-01
An attempt to bridge the gap between classical and quantum mechanics and to explain the Casimir effect is presented. The general nature of chaotic motion is discussed from two points of view: the first uses catastrophe theory and strange attractors to describe the deterministic view of this motion; the underlying framework for chaos in these classical dynamic systems is their extreme sensitivity to initial conditions. The second interpretation refers to randomness associated with probabilistic dynamics, as for Brownian motion. The present approach to understanding evanescent radiation and its relation to the Casimir effect corresponds to the first interpretation, whereas stochastic electrodynamics corresponds to the second viewpoint. The nonlinear behavior of the electromagnetic field is also studied. This well-understood behavior is utilized to examine the motions of two orbiting charges and shows a closeness between the classical behavior and the quantum uncertainty principle. The evanescent radiation is used to help explain the Casimir effect.
Experimental superradiance and slow-light effects for quantum memories
Walther, A.; Amari, A.; Kroell, S.; Kalachev, A. [Department of Physics, Lund Institute of Technology, P.O. Box 118, SE-22100 Lund (Sweden); Zavoisky Physical-Technical Institute of the Russian Academy of Sciences, Sibirsky Trakt 10/7, Kazan 420029 (Russian Federation)
2009-07-15
The effects of high optical depth phenomena, such as superradiance, are investigated in potential quantum memory materials. The results may have relevance for several schemes, including controlled reversible inhomogeneous broadening, atomic frequency combs, and quantum memories based on electromagnetically induced transparency, which are based on using ensembles as storage media. It is shown that strong superradiant effects manifested as decay rates larger than 1/T{sub 2}* are present even for moderate values of {alpha}L{<=}5 and increases as a function of {alpha}L. For even higher {alpha}L, effects such as off-resonant slow light is demonstrated and discussed and, finally, the efficiency of time-reversed optimized input pulses is tested. A maximum retrieval efficiency of {approx}20% is reached and agreement with the theoretically expected result is discussed.
Experimental superradiance and slow light effects for quantum memories
Andreas Walther; Atia Amari; Stefan Kröll; Alexey Kalachev
2009-04-29
The effects of high optical depth phenomena, such as superradiance, are investigated in potential quantum memory materials. The results may have relevance for several schemes, including CRIB, AFC and EIT-based quantum memories, which are based on using ensembles as storage media. It is shown that strong superradiant effects, manifested as decay rates larger than 1/T2*, are present even for moderate values of alphaL < 5, and increases as a function of alphaL. For even higher alphaL, effects like off-resonant slow light is demonstrated and discussed, and finally, the efficiency of time-reversed optimized input pulses are tested. A maximum retrieval efficiency of ~20% is reached, and agreement with the theoretically expected result is discussed.
Quantum anti-Zeno effect without rotating wave approximation
Ai Qing; Sun, C. P. [Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li Yong [Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Zheng Hang [Department of Physics, Shanghai Jiao Tong University, Shanghai 200030 (China)
2010-04-15
In this article, we systematically study the spontaneous decay phenomenon of a two-level system under the influences of both its environment and repetitive measurements. In order to clarify some well-established conclusions about the quantum Zeno effect (QZE) and the quantum anti-Zeno effect (QAZE), we do not use the rotating wave approximation (RWA) in obtaining an effective Hamiltonian. We examine various spectral distributions by making use of our present approach in comparison with other approaches. It is found that with respect to a bare excited state even without the RWA, the QAZE can still happen for some cases, for example, the interacting spectra of hydrogen. However, for a physical excited state, which is a renormalized dressed state of the atomic state, the QAZE disappears and only the QZE remains. These discoveries inevitably show a transition from the QZE to the QAZE as the measurement interval changes.
Dynamics of kinematically constrained bimolecular reactions having constant product recoil energy
Zare, Richard N.
Dynamics of kinematically constrained bimolecular reactions having constant product recoil energy reactions in which the product recoil energy is assumed constant (CPR approximation). It is further assumed-shaped, peaking at the vibrational level with an energy equal to the reaction exoergicity minus the product recoil
H + D2 Reaction Dynamics in the Limit of Low Product Recoil Energy J. Aldegunde,
Zare, Richard N.
H + D2 Reaction Dynamics in the Limit of Low Product Recoil Energy J. Aldegunde, D. Herraez increases and the corresponding energy available for product recoil decreases. This behavior was attributed, whose influence becomes more significant as the recoil energy of the products tends to zero, which
Dynamic simulation of the recoil mechanism on artillery weapons
T. Y. Lin; H. C. Ping; T. Y. Yang; C. T. Chan; C. C. Yang
Summary The artillery weapons have been developed from the thirteenth century to the present. Generally, it contains a gun body and a gun mount. The gun body consists of a barrel, a breech, a breechblock, and a muzzle brake. In addition,thegun mount is composed of recoil mechanisms, elevating mechanisms, traversing mechanisms, and supporting parts. Among these parts, the muzzle brake
Distribution of Recoil Nucleus in Pair Production by Photons
R. Jost; J. M. Luttinger; M. Slotnick
1950-01-01
The angular and momentum distribution of the recoil nucleus in pair production by a photon is calculated covariantly by a method which utilizes the unitarity of the S matrix. The results are in disagreement with a recent experiment, particularly for small angles and high momentum transfers. The exact total cross section for pair creation is also given.
Status and Prospects of the HERMES Recoil Detector
/Scintillator sandwich Fiber Detector (SFT) 2 barrels with 4 layers of scintillating fibers 2 parallel and 2 stereo SFT Particle Identification 8HERMES Recoil Detector A. Mussgiller, SPIN 2008, 10/10/08 SSDV /c : SSD & SFT & PDp ~0.6 GeV /c #12; Particle Identification (p > 0
Report on the HERMES Recoil Detector Sergey Yaschenko
Detector 2 layers of double-sided silicon strip sensors located in beam vacuum Strips: pitch=758 m, 300m hydrogen target: 38 Mio DIS (41.000 DVCS) Unpolarized deuterium target: 10 Mio DIS (7.500 DVCS) Two beam hydrogen and deuterium targets #12;S. Yaschenko, Report on the HERMES Recoil Detector 7 Silicon Strip
Loop quantum cosmology of Bianchi IX: Effective dynamics
Alejandro Corichi; Edison Montoya
2015-02-09
We study numerically the solutions to the effective equations of Bianchi IX spacetimes within Loop Quantum Cosmology. We consider Bianchi IX models with and without inverse triad corrections whose matter content is a scalar field without mass. The solutions are classified using the classical observables. We show that both effective theories --with lapse N=V and N=1-- solve the big bang singularity and reproduce the classical dynamics far from the bounce. Moreover, due to the spatial compactness, there is an infinity number of bounces and recollapses. We study the limit of large volume and show that both effective theories reproduce the same dynamics, thus recovering general relativity. We implement a procedure to identify amongst the Bianchi IX solutions, those that behave like k=0,1 FLRW as well as Bianchi I, II, and VII_0 models. The effective solutions exhibit Bianchi I phases with Bianchi II transitions and also Bianchi VII_0 phases, which had not been studied before, at the quantum nor effective level. We comment on the possible implications of these results for a quantum modification to the classical BKL behaviour.
Quantum spin Hall effect in nanostructures based on cadmium fluoride
Bagraev, N. T., E-mail: Bagraev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Guimbitskaya, O. N. [St. Petersburg State Polytechnical University (Russian Federation); Klyachkin, L. E.; Koudryavtsev, A. A.; Malyarenko, A. M. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Romanov, V. V. [St. Petersburg State Polytechnical University (Russian Federation); Ryskin, A. I.; Shcheulin, A. S. [St. Petersburg State University of Information Technologies, Mechanics, and Optics (Russian Federation)
2010-10-15
Tunneling current-voltage (I-V) characteristics and temperature dependences of static magnetic susceptibility and specific heat of the CdB{sub x}F{sub 2-x}/p-CdF{sub 2}-QW/CdB{sub x}F{sub 2-x} planar sandwich structures formed on the surface of an n-CdF{sub 2} crystal have been studied in order to identify superconducting properties of the CdB{sub x}F{sub 2-x} {delta} barriers confining the p-type CdF{sub 2} ultranarrow quantum well. Comparative analysis of current-voltage (I-V) characteristics and conductance-voltage dependences (measured at the temperatures, respectively, below and above the critical temperature of superconducting transition) indicates that there is an interrelation between quantization of supercurrent and dimensional quantization of holes in the p-CdF{sub 2} ultranarrow quantum well. It is noteworthy that detection of the Josephson peak of current in each hole subband is accompanied by the appearance of the spectrum of the multiple Andreev reflection (MAR). A high degree of spin polarization of holes in the edge channels along the perimeter of the p-CdF{sub 2} ultranarrow quantum well appears as a result of MAR and makes it possible to identify the quantum spin Hall effect I-V characteristics; this effect becomes pronounced in the case of detection of nonzero conductance at the zero voltage applied to the vertical gate in the Hall geometry of the experiment. Within the energy range of superconducting gap, the I-V characteristics of the spin transistor and quantum spin Hall effect are controlled by the MAR spectrum appearing as the voltage applied to the vertical gate is varied. Beyond the range of the superconducting gap, the observed I-V characteristic of the quantum spin Hall effect is represented by a quantum conductance staircase with a height of the steps equal to e{sub 2}/h; this height is interrelated with the Aharonov-Casher oscillations of longitudinal and depends on the voltage applied to the vertical gate.
Unraveling quantum mechanical effects in water using isotopic fractionation
Markland, Thomas E.; Berne, B. J.
2012-01-01
When two phases of water are at equilibrium, the ratio of hydrogen isotopes in each is slightly altered because of their different phase affinities. This isotopic fractionation process can be utilized to analyze water’s movement in the world’s climate. Here we show that equilibrium fractionation ratios, an entirely quantum mechanical property, also provide a sensitive probe to assess the magnitude of nuclear quantum fluctuations in water. By comparing the predictions of a series of water models, we show that those describing the OH chemical bond as rigid or harmonic greatly overpredict the magnitude of isotope fractionation. Models that account for anharmonicity in this coordinate are shown to provide much more accurate results because of their ability to give partial cancellation between inter- and intramolecular quantum effects. These results give evidence of the existence of competing quantum effects in water and allow us to identify how this cancellation varies across a wide-range of temperatures. In addition, this work demonstrates that simulation can provide accurate predictions and insights into hydrogen fractionation. PMID:22566650
Effective equations of cosmological models in (loop) quantum gravity
NASA Astrophysics Data System (ADS)
Simpson, David
This dissertation focuses on the properties of several differing models within quantum cosmology. Specifically, by using the method of effective equations, we explore: a linear discrete Schrodinger model, a non-linear discrete Schrodinger model, factor ordering ambiguities in the Hamiltonian constraint (with a focus on large-volume behavior), and the use of the electric vector potential as deparameterized time. In the linear and non-linear Schrodinger models, we arrive at a new possibility for studying inhomogeneous quantum cosmology (where the non-linearities are interpreted as non-local deviations from the spatial average) that allows for a variety of dynamics and raises a number of questions for future research. We then turn our focus to the general effects of factor ordering ambiguities and their possible role in large-volume collapse of a k = 0 isotropic quantum cosmology with a free, massless scalar field. With the additional inclusion of holonomy and inverse-triad corrections, the choice in factor ordering of the Hamiltonian constraint is quite relevant; however, with our assumptions, we do not see any significant departure from classical large-volume behavior. The final model discussed is formulated with the electric vector potential as the global internal time in a Wheeler-DeWitt setting sourced by radiation. While further analysis is required to make a definitive statement on the impact that the choice of deparameterization makes, we find that the specific form of quantum state can affect early-universe dynamics and even lead to new possibilities.
Nonadiabatic effect on the quantum heat flux control.
Uchiyama, Chikako
2014-05-01
We provide a general formula of quantum transfer that includes the nonadiabatic effect under periodic environmental modulation by using full counting statistics in Hilbert-Schmidt space. Applying the formula to an anharmonic junction model that interacts with two bosonic environments within the Markovian approximation, we find that the quantum transfer is divided into the adiabatic (dynamical and geometrical phases) and nonadiabatic contributions. This extension shows the dependence of quantum transfer on the initial condition of the anharmonic junction just before the modulation, as well as the characteristic environmental parameters such as interaction strength and cut-off frequency of spectral density. We show that the nonadiabatic contribution represents the reminiscent effect of past modulation including the transition from the initial condition of the anharmonic junction to a steady state determined by the very beginning of the modulation. This enables us to tune the frequency range of modulation, whereby we can obtain the quantum flux corresponding to the geometrical phase by setting the initial condition of the anharmonic junction. PMID:25353740
Unraveling quantum mechanical effects in water using isotopic fractionation.
Markland, Thomas E; Berne, B J
2012-05-22
When two phases of water are at equilibrium, the ratio of hydrogen isotopes in each is slightly altered because of their different phase affinities. This isotopic fractionation process can be utilized to analyze water's movement in the world's climate. Here we show that equilibrium fractionation ratios, an entirely quantum mechanical property, also provide a sensitive probe to assess the magnitude of nuclear quantum fluctuations in water. By comparing the predictions of a series of water models, we show that those describing the OH chemical bond as rigid or harmonic greatly overpredict the magnitude of isotope fractionation. Models that account for anharmonicity in this coordinate are shown to provide much more accurate results because of their ability to give partial cancellation between inter- and intramolecular quantum effects. These results give evidence of the existence of competing quantum effects in water and allow us to identify how this cancellation varies across a wide-range of temperatures. In addition, this work demonstrates that simulation can provide accurate predictions and insights into hydrogen fractionation. PMID:22566650
New Precise Method for Accurate Modeling of Thermal Recoil Forces
NASA Astrophysics Data System (ADS)
Rievers, Benny; Lämmerzahl, C.
2009-05-01
The exact modeling of external and internal perturbations acting on spacecraft becomes increasingly important as the scientific requirements become more demanding. Disturbance models included in orbit determination and propagation tools need to be improved to account for the needed accuracy. The simulation of perturbations which are caused by thermal effects are particularly challenging because the optical properties of spacecraft surfaces can change during the mission due to exposure to the space environment. At ZARM (Center of Applied Space Technology and Microgravity) algorithms for the simulation and analysis of thermal perturbations have been developed. These codes include the simulation of the thermal recoil force (waste heat dissipation), Earth Albedo influence as well as Solar radiation pressure. The applied methods are based on the inclusion of the actual spacecraft geometry by means of Finite Element (FE) models in the calculation of the disturbance forces. Thus the modeling accuracy is increased considerably and also housekeeping and sensor data can be included in the calculations. As an application for the developed method a test case model of the Pioneer 11 radio isotopic thermal generators is presented. For accurate thermal modeling the knowledge of optical surface properties and their change during the mission of a spacecraft is crucial. Looking at material behaviour in space, in-situ experiments are indispensable because in ground tests space environment can be simulated only partially. At ZARM a dedicated nano satellite concept has been developed which enables the low cost and repeatable observation of material behaviour in space. The concept consists of a bus cube in the center of the satellite and two experiment cubes attached at the sides which include thermal sensors for the direct measurement of the thermo-optical properties of different materials. The design and the mission will be presented and the impact on thermal modeling will be discussed.
Hatef, Ali; Singh, Mahi R. [Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6 A 3K7 (Canada)
2010-06-15
We have studied the effect of plasma energy on the absorption coefficient of metallic photonic crystals doped with an ensemble of three-level quantum dots, which are interacting with each other via dipole-dipole interaction. The quantum dots are also interacting with coupled plasma-photon modes present in the system. A probe laser field is applied in order to study the absorption coefficient. We also consider the effect of quantum interference in our simulations, whereby two absorbed photons interfere with one another. Here the density matrix method has been used to calculate the steady-state and transient behavior of the absorption coefficient for the system. Two different field configurations are considered in our numerical simulations. In the first configuration, a probe field couples the ground state and two closely excited states. Absorption occurs due to transitions from the ground state to the two excited states. It is found that the position of the transparent peak moves when the plasma energy is changed. In other words, changing the plasma energy causes the system to switch between a transparent and an absorbing state. The strong coupling between plasmons and the quantum dots is responsible for this phenomenon. In the second configuration, the probe field couples with only one excited state, while a pump field couples to the other excited state. The transition between excited states is dipole forbidden. We observed that the peak in the absorption profile splits into two and also that the system exhibits gain with inversion due to the change in the plasma frequency, which is caused by quantum interference and coherence. These are interesting results and can be used make nanoscale plasma devices.
The mechanics of elastic loading and recoil in anuran jumping.
Astley, Henry C; Roberts, Thomas J
2014-12-15
Many animals use catapult mechanisms to produce extremely rapid movements for escape or prey capture, resulting in power outputs far beyond the limits of muscle. In these catapults, muscle contraction loads elastic structures, which then recoil to release the stored energy extremely rapidly. Many arthropods employ anatomical 'catch mechanisms' to lock the joint in place during the loading period, which can then be released to allow joint motion via elastic recoil. Jumping vertebrates lack a clear anatomical catch, yet face the same requirement to load the elastic structure prior to movement. There are several potential mechanisms to allow loading of vertebrate elastic structures, including the gravitational load of the body, a variable mechanical advantage, and moments generated by the musculature of proximal joints. To test these hypothesized mechanisms, we collected simultaneous 3D kinematics via X-ray Reconstruction of Moving Morphology (XROMM) and single-foot forces during the jumps of three Rana pipiens. We calculated joint mechanical advantage, moment and power using inverse dynamics at the ankle, knee, hip and ilio-sacral joints. We found that the increasing proximal joint moments early in the jump allowed for high ankle muscle forces and elastic pre-loading, and the subsequent reduction in these moments allowed the ankle to extend using elastic recoil. Mechanical advantage also changed throughout the jump, with the muscle contracting against a poor mechanical advantage early in the jump during loading and a higher mechanical advantage late in the jump during recoil. These 'dynamic catch mechanisms' serve to resist joint motion during elastic loading, then allow it during elastic recoil, functioning as a catch mechanism based on the balance and orientation of forces throughout the limb rather than an anatomical catch. PMID:25520385
Danil Doubochinski; Jonathan Tennenbaum
2007-11-30
Einstein, De Broglie and others hoped that the schism between classical and quantum physics might one day be overcome by a theory taking into account the essential nonlinearity of elementary physical processes. However, neither their attempts, nor subsequent ones were able to supply a unifying principle that could serve as a starting-point for a coherent understanding of both microphysical and macroscopic phenomena. In the late 1960s the phenomenon of amplitude quantization, or Macroscopic Quantum Effect (MQE), was discovered in a class of nonlinear oscillating systems in which two or more subsystems are coupled to each other by interactions having a specific phase-dependent character -- so-called argumental interactions. Experimental and theoretical studies of the MQE, carried out up to the present time, suggest the possibility of a new conceptual framework for physics, which would provide a bridge between classical and quantum physics, replacing the Newtonian notion of "force" by a new conception of physical interaction. The present paper presents a brief introduction to the MQE and some ideas about its possible significance in the search for new approaches to the understanding of quantum phenomena.
InAs/GaSb quantum wells: quantum spin Hall effect and topological superconductivity
NASA Astrophysics Data System (ADS)
Sitte, Matthias; Everschor-Sitte, Karin; MacDonald, Allan
2015-03-01
Topological insulators have attracted a great deal of attention as a new quantum state of matter in the last decade. The first realizations of 2D TIs were HgTe/CdTe quantum well heterostructures, but in recent years another class of semiconductor heterostructures -- namely InAs/GaSb quantum wells -- was shown to yield 2D TIs as well. Compared to the HgTe/CdTe-based systems they have many advantages, most prominently a continuously tunable band structure via external electric fields and stronger proximity coupling to superconductors. We perform empirical tight-binding calculations on these systems to study how topological properties are changed by varying external control parameters such as electric fields or well thicknesses. Since proximity coupling of a 2D TI and an ordinary s-wave superconductor gives rise to 1D topological superconductivity, these systems also support Majorana fermions as non-local excitations. We will present preliminary results on the proximity effects when InAs/GaSb quantum wells are coupled to a superconductor.
8-band k.p modeling of the quantum confined Stark effect in Ge quantum wells on Si substrates
D. J. Paul
2008-01-01
Recent work using compressively strained-Ge quantum wells grown on Si1-yGey virtual substrates has demonstrated efficient modulation on a silicon substrate through the quantum confined Stark effect with performance comparable to many direct band gap III-V materials. The absorption of compressively strained-Ge quantum wells is calculated by using an 8-band k.p solver within the envelope function technique. The calculated absorption spectra
Symmetry relations for heavy-to-light meson form factors at large recoil
Richard J. Hill
2006-01-01
The description of large-recoil heavy-to-light meson form factors is reviewed\\u000ain the framework of soft-collinear effective theory. At leading power in the\\u000aheavy quark expansion, three classes of approximate symmetry relations arise.\\u000aThe relations are compared to experimental data for $D\\\\to K^*$ and $D_s\\\\to\\u000a\\\\phi$ form factors, and to light-cone QCD sum rule predictions for $B\\\\to \\\\pi$\\u000aand $B\\\\to \\\\rho$
Effects of quantum stress tensor fluctuations with compact extra dimensions
Borgman, J.; Ford, L.H. [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States)
2004-12-15
The effects of compact extra dimensions upon quantum stress tensor fluctuations are discussed. It is argued that as the compactification volume decreases, these fluctuations increase in magnitude. In principle, this would have the potential to create observable effects, such as luminosity fluctuations or angular blurring of distant sources, and lead to constraints upon Kaluza-Klein theories. However, the dependence of the four-dimensional Newton's constant upon the compactification volume causes the gravitational effects of the stress tensor fluctuations to be finite in the limit of small volume. Consequently, no observational constraints upon Kaluza-Klein theories are obtained.
SU(4) Kondo Effect in Carbon Nanotube Quantum Dots: Kondo Effect without Charge Quantization
Finkelstein, Gleb
SU(4) Kondo Effect in Carbon Nanotube Quantum Dots: Kondo Effect without Charge Quantization Gleb: NSF DMR-0239748 #12;Electronic band structure, sample Coulomb blockade Kondo effect / Mixed Valence -apparent Kondo behavior without charge quantization -Kondo in magnetic field #12;Samples doped Si SiO2
Quantum field theory: Finiteness and Effectiveness
Jifeng Yang
1998-01-01
A new attempt is demonstrated that QFTs can be UV finite if they are viewed as the low energy effective theories of a fundamental underlying theory (that is complete and well-defined in all respects) according to the modern standard point of view. This approach works for any interaction model and space-time dimension. It is much simpler in principle and in
Casimir effects for classical and quantum liquids in slab geometry: A brief review
NASA Astrophysics Data System (ADS)
Biswas, Shyamal
2015-05-01
We analytically explore Casimir effects for confinement of classical and quantum fluctuations in slab (film) geometry (i) for classical (critical) fluctuations over 4He liquid around the ? point, and (ii) for quantum (phonon) fluctuations of Bogoliubov excitations over an interacting Bose-Einstein condensate. We also briefly review Casimir effects for confinement of quantum vacuum fluctuations confined to two plates of different geometries.
Heat capacity of water: A signature of nuclear quantum effects
NASA Astrophysics Data System (ADS)
Vega, C.; Conde, M. M.; McBride, C.; Abascal, J. L. F.; Noya, E. G.; Ramirez, R.; Sesé, L. M.
2010-01-01
In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 model, as obtained from path-integral simulations. The model does a rather good job of describing both the heat capacity of ice Ih and of liquid water. Classical simulations using the TIP4P/2005, TIP3P, TIP4P, TIP4P-Ew, simple point charge/extended, and TIP5P models are unable to reproduce the heat capacity of water. Given that classical simulations do not satisfy the third law of thermodynamics, one would expect such a failure at low temperatures. However, it seems that for water, nuclear quantum effects influence the heat capacities all the way up to room temperature. The failure of classical simulations to reproduce Cp points to the necessity of incorporating nuclear quantum effects to describe this property accurately.
High speed quantum-well lasers and carrier transport effects
Radhakrishnan Nagarajan; Masayuki Ishikawa; Toru Fukushima; Randall S. Geels; John E. Bowers
1992-01-01
Carrier transport can significantly affect the high-speed properties of quantum-well lasers. The authors have developed a model and derived analytical expressions for the modulation response, resonance frequency, damping rate, and K factor to include these effects. They show theoretically and experimentally that carrier transport can lead to significant low-frequency parasitic-like rolloff that reduces the modulation response by as much as
Probing Quantum-Vacuum Geometrical Effects with Cold Atoms
Dalvit, Diego A. R. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Neto, Paulo A. Maia [Instituto de Fisica, UFRJ, CP 68528, Rio de Janeiro, RJ, 21941-972 (Brazil); Lambrecht, Astrid; Reynaud, Serge [Laboratoire Kastler Brossel, Case 74, CNRS, ENS, UPMC, Campus Jussieu, F-75252 Paris Cedex 05 (France)
2008-02-01
The lateral Casimir-Polder force between an atom and a corrugated surface should allow one to study experimentally nontrivial geometrical effects in the electromagnetic quantum vacuum. Here, we derive the theoretical expression of this force in the scattering approach. We show that large corrections to the 'proximity force approximation' could be measured using present-day technology with a Bose-Einstein condensate used as a vacuum field sensor.
Investigation of Thermal Effects in Quantum-Cascade Lasers
C. A. Evans; V. D. Jovanovic; Dragan Indjin; Zoran Ikonic; Paul Harrison
2006-01-01
The development of a thermal model for quantum cascade lasers (QCLs) is presented. The model is used in conjunc- tion with a self-consistent scattering rate calculation of the electron dynamics of an InGaAs-AlAsSb QCL to calculate the temperature distribution throughout the device which can be a limiting factor for high temperature operation. The model is used to investigate the effects
Radiation effects on strain compensated quantum dot solar cells
Cory D. Cress; Christopher G. Bailey; Seth M. Hubbard; David M. Wilt; Sheila G. Bailey; Ryne P. Raffaelle
2008-01-01
The effects of alpha-particle irradiation on the current-voltage characteristics and spectral responsivity of GaAs-based p-type \\/ intrinsic \\/ n-type solar cell devices containing 5-layers of InAs quantum dots (QD) grown with strain-compensation layers were investigated. The devices were subjected to ?4.2 MeV alpha-particle irradiation and the variation in the air mass zero short circuit current, open circuit voltage, fill factor,
Toward realistic effective models of quantum-Hall edges
U. Zülicke; A. H. MacDonald
1997-01-01
We have investigated the dynamical properties of edge excitations in the (fractional) quantum-Hall regime for a sharp confining potential, emphasizing the effects resulting from the presence of long-range interaction. Our study uses chiral-Luttinger-liquid models that are motivated by the close analogy between the physics of edge excitations and that of plasmons in quasi-one-dimensional electron systems. We find that incorporating realistic
Quantum effects can render w<-1 on cosmological scales
V. K. Onemli; R. P. Woodard
2004-01-01
We report on a revision of our previous computation of the renormalized expectation value of the stress-energy tensor of a massless, minimally coupled scalar with a quartic self-interaction on a locally de Sitter background. This model is important because it demonstrates that quantum effects can lead to violations of the weak energy condition on cosmological scales--on average, not just in
Quantum effects can render w<-1 on cosmological scales
V. K. Onemli; R. P. Woodard
2004-01-01
We report on a revision of our previous computation of the renormalized expectation value of the stress-energy tensor of a massless, minimally coupled scalar with a quartic self-interaction on a locally de Sitter background. This model is important because it demonstrates that quantum effects can lead to violations of the weak energy condition on cosmological scales---on average, not just in
Magneto-optical Kerr effect tomography of an electron spin state in a semiconductor quantum dot
Yoshiaki Rikitake; Hiroshi Imamura; Hideo Kosaka
2009-01-01
We propose an magneto-optical Kerr effect tomography(MOKET) of an electron spin state in a semiconductor quantum dot. This method can measure the quantum spin coherence between spin up and down states.
Robust electron pairing in the integer quantum hall effect regime.
Choi, H K; Sivan, I; Rosenblatt, A; Heiblum, M; Umansky, V; Mahalu, D
2015-01-01
Electron pairing is a rare phenomenon appearing only in a few unique physical systems; for example, superconductors and Kondo-correlated quantum dots. Here, we report on an unexpected electron pairing in the integer quantum Hall effect regime. The pairing takes place within an interfering edge channel in an electronic Fabry-Perot interferometer at a wide range of bulk filling factors, between 2 and 5. We report on three main observations: high-visibility Aharonov-Bohm conductance oscillations with magnetic flux periodicity equal to half the magnetic flux quantum; an interfering quasiparticle charge equal to twice the elementary electron charge as revealed by quantum shot noise measurements, and full dephasing of the pairs' interference by induced dephasing of the adjacent inner edge channel-a manifestation of inter-channel entanglement. Although this pairing phenomenon clearly results from inter-channel interaction, the exact mechanism that leads to electron-electron attraction within a single edge channel is not clear. We believe that substantial efforts are needed in order to clarify these intriguing and unexpected findings. PMID:26096516
Gravitational-wave probe of effective quantum gravity
Alexander, Stephon; Finn, Lee Samuel; Yunes, Nicolas [Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
2008-09-15
All modern routes leading to a quantum theory of gravity - i.e., perturbative quantum gravitational one-loop exact correction to the global chiral current in the standard model, string theory, and loop quantum gravity - require modification of the classical Einstein-Hilbert action for the spacetime metric by the addition of a parity-violating Chern-Simons term. The introduction of such a term leads to spacetimes that manifest an amplitude birefringence in the propagation of gravitational waves. While the degree of birefringence may be intrinsically small, its effects on a gravitational wave accumulate as the wave propagates. Observation of gravitational waves that have propagated over cosmological distances may allow the measurement of even a small birefringence, providing evidence of quantum gravitational effects. The proposed Laser Interferometer Space Antenna (LISA) will be sensitive enough to observe the gravitational waves from sources at cosmological distances great enough that interesting bounds on the Chern-Simons coupling may be found. Here we evaluate the effect of a Chern-Simons induced spacetime birefringence to the propagation of gravitational waves from such systems. Focusing attention on the gravitational waves from coalescing binary black holes systems, which LISA will be capable of observing at redshifts approaching 30, we find that the signature of Chern-Simons gravity is a time-dependent change in the apparent orientation of the binary's orbital angular momentum with respect to the observer line-of-sight, with the magnitude of change reflecting the integrated history of the Chern-Simons coupling over the worldline of the radiation wave front. While spin-orbit coupling in the binary system will also lead to an evolution of the system's orbital angular momentum, the time dependence and other details of this real effect are different than the apparent effect produced by Chern-Simons birefringence, allowing the two effects to be separately identified. In this way gravitational-wave observations with LISA may thus provide our first and only opportunity to probe the quantum structure of spacetime over cosmological distances.
Quantum size effects induced by barrierless confinement
NASA Astrophysics Data System (ADS)
Häberle, Patricio
2005-03-01
We have measured the thickness dependence of Inverse Photoemission (IPS) intensity in the Ag/Al(100) system. Intensity variations show a smooth dependence as a function of coverage which is interpreted as a layer by layer growth. We have used a two step potential to model the effect of the crystal on the valence electrons at the overlayer. Calculated resonaces due to the reflection at the potential step show similar energies as those shown in the experimental data. A refinement of the model, using a corrugated potential for the Ag atoms provides a full description of the experimental coverage dispersion.
Quantum gravitational optics: Effective Raychaudhuri equation
N. Ahmadi; M. Nouri-Zonoz
2006-12-26
Vacuum polarization in QED in a background gravitational field induces interactions which {\\it effectively} modify the classical picture of light rays, as the null geodesics of spacetime. These interactions violate the strong equivalence principle and affect the propagation of light leading to superluminal photon velocities. Taking into account the QED vacuum polarization, we study the propagation of a bundle of rays in a background gravitational field. To do so we consider the perturbative deformation of Raychaudhuri equation through the influence of vacuum polarization on photon propagation. We analyze the contribution of the above interactions to the optical scalars namely, shear, vorticity and expansion using the Newman-Penrose formalism.
8 ? -periodic Josephson effects in a quantum dot/ quantum spin-Hall josephson junction system
NASA Astrophysics Data System (ADS)
Hui, Hoi-Yin; Sau, Jay
2015-03-01
Josephson junctions made of conventional s-wave superconductors display 2 ? periodicity. On the other hand, 4 ? -periodic fractional Josephson effect is known to be a characteristic signature of topological superconductors and Majorana fermions [1]. Zhang and Kane have shown that Josephson junctions made of topological superconductors are 8 ? -periodic if interaction is used to avoid dissipation [2]. Here we present a general argument for how time-reversal symmetry and Z2 non-trivial topology constrains the Josephson periodicity to be 8 ? . We then illustrate this through a microscopic model of a quantum dot in a quantum spin-hall Josephson junction. Work supported by NSF-JQI-PFC, LPS-CMTC and Microsoft Q.
Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve
2011-01-01
Spin-dependent transport through a quantum-dot (QD) ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR) as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively. PACS numbers: PMID:21711779
Indirect recoil implantation following nuclear reactions: Theory and potential applications
NASA Astrophysics Data System (ADS)
Conlon, T. W.
1980-04-01
A general treatment of indirect recoil implantation following nuclear reactions is given for the first time. This method allows implantation into any substrate of a wide range of species produced by nuclear reactions either in a thin sacrificial target or from a solid target. It is demonstrated that this can be done whilst avoiding primary beam damage to the substrate. Two cases are considered, the general one in which non-elastic nuclear reactions produce the recoil species of interest and secondly the special case of elastic recoils. In both cases a number of novel features of the process not previously described are outlined. For example, by controlling the angular acceptance of the substrate for recoil products the method can be tailored to give well controlled implantation profiles very similar to direct implantation (i.e., approximately Gaussian in range) or more extensive depth distributions whose profiles are simply determined by the centre of mass angular distribution of the reaction product. The flux of particles available for implantation is approximately 10 -4 smaller than from direct implantation facilities, but is comparable to the useful implantation dose achieved by the established technique of direct elastic recoil implantation. The radiation damage is little more than that associated with the indirect implant itself in contrast to direct elastic recoil implantation where the potential damage produced often mediates against the use of that technique. The main advantage of this relatively new method over the conventional methods is the wider range of species which can be implanted with minimum damage to the substrate. These include elements which cannot be conveniently produced from ion sources as well as exotic species which cannot be produced other than by nuclear reactions; radioactive species are good examples of both cases. The method could make an impact in a number of areas, for example, for the injection of radioactive isotopes of the substrate in the study of irradiation damage, diffusion and catalysis; thin film technology, device technology, implantation metallurgy and radiotracers are also possible areas of exploitation. A number of applications in the radiotracer area, viz to radiation sensitive materials, specifically for thin layer activation studies, are discussed.
Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils
NASA Astrophysics Data System (ADS)
Bergé, L.; Blümer, J.; Broniatowski, A.; Censier, B.; Chantelauze, A.; Chapellier, M.; Chardin, G.; Collin, S.; Defay, X.; de Jésus, M.; Deschamps, H.; di Stefano, P.; Dolgorouky, Y.; Dumoulin, L.; Eitel, K.; Fesquet, M.; Fiorucci, S.; Gascon, J.; Gerbier, G.; Goldbach, C.; Gros, M.; Horn, M.; Juillard, A.; Lemrani, R.; de Lesquen, A.; Luca, M.; Marnieros, S.; Mosca, L.; Navick, X.-F.; Nollez, G.; Olivieri, E.; Pari, P.; Sanglard, V.; Schoeffel, L.; Schwamm, F.; Stern, M.; EDELWEISS Collaboration
2007-07-01
The heat quenching factor Q (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDELWEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q/Q, where Q is the quenching factor of the ionization yield. To measure Q, a precise EDELWEISS measurement of Q/Q is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q are discussed in detail. For recoil energies between 20 and 100 keV, the resulting heat quenching factor is Q=0.91±0.03±0.04, where the two errors are the contributions from the Q and Q/Q measurements, respectively. The present compilation of Q values and evaluation of Q represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for WIMP dark matter.
Zeno and anti-Zeno effects for quantum Brownian motion
Sabrina Maniscalco; Jyrki Piilo; Kalle-Antti Suominen
2006-10-04
In this paper we investigate the occurrence of the Zeno and anti-Zeno effects for quantum Brownian motion. We single out the parameters of both the system and the reservoir governing the crossover between Zeno and anti-Zeno dynamics. We demonstrate that, for high reservoir temperatures, the short time behaviour of environment induced decoherence is the ultimate responsible for the occurrence of either the Zeno or the anti-Zeno effect. Finally we suggest a way to manipulate the decay rate of the system and to observe a controlled continuous passage from decay suppression to decay acceleration using engineered reservoirs in the trapped ion context .
Ionization of deep quantum wells: Optical trampoline effect
NASA Astrophysics Data System (ADS)
Perlin, E. Yu.; Levitski?, R. S.
2007-02-01
A new mechanism of transitions of an electronic system from the ground state to states with excitation energies exceeding many times the energy of a light photon initiating the transitions has been considered. This mechanism is based on the so-called optical “trampoline” effect: one of the interacting electrons receives energy from another electron and, simultaneously absorbing a photon ??, overcomes the energy gap significantly exceeding ??. Ionization of deep quantum wells by low-frequency light of moderate intensity due to the optical trampoline effect was calculated.
Viscous Dark Cosmology with Account of Quantum Effects
I. Brevik; O. Gorbunova
2008-06-09
The analytic properties of the energy density rho(t) of the cosmic fluid, and the Hubble parameter H(t), are investigated near to the future singularity t=t_s assuming different forms for the equation of state. First, it is shown that the inclusion of quantum effects coming from the conformal anomaly modifies the singularity. Thereafter, we consider the effect coming from a bulk viscosity in the fluid. The viscosity tends to reduce the magnitude of t_s, but does not alter the singularity itself (the exponent). Main emphasis is laid on the simple case when the equation of state is p=w*rho, with w a constant.
Complex scattering dynamics and the integer quantum Hall effect
Trugman, S.A.; Waugh, F.R.
1987-01-01
The effect of a magnetic field on potential scattering is investigated microscopically. A magnetic field renders the scattering of a classical charged particle far more complex than previously suspected. Consequences include possible 1/f noise and an explanation of the observed breakdown of the quantum Hall effect at large currents. A particular scatterer is described by a discontinuous one dimensional Hamiltonian map, a class of maps that has not previously been studied. A renormalization group analysis indicates that singular behavior arises from the interplay of electron orbits that are periodic and orbits that are quasiperiodic.
Gamma-ray free-electron lasers: Quantum fluid model
Silva, H M
2014-01-01
A quantum fluid model is used to describe the interacion of a nondegenerate cold relativistic electron beam with an intense optical wiggler taking into account the beam space-charge potential and photon recoil effect. A nonlinear set of coupled equations are obtained and solved numerically. The numerical results shows that in the limit of plasma wave-breaking an ultra-high power radiation pulse are emitted at the$\\gamma$-ray wavelength range which can reach an output intensity near the Schwinger limit depending of the values of the FEL parameters such as detuning and input signal initial phase at the entrance of the interaction region.
Recoiling black holes: electromagnetic signatures, candidates, and astrophysical implications
Komossa, S
2012-01-01
Supermassive black holes (SMBHs) may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves. Long-lived oscillations of the SMBHs in galaxy cores, and in rare cases even SMBH ejections from their host galaxies, are the consequence. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically off-set from their host galaxies. The presence of the "kicks" has a wide range of astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy assembly at the epoch of structure formation, black hole feeding, and unified models of Active Galactic Nuclei (AGN). Here, we review the observational signatures of recoiling SMBHs and the properties of the first candidates which...
A quantitative account of quantum effects in liquid water
NASA Astrophysics Data System (ADS)
Fanourgakis, G. S.; Schenter, G. K.; Xantheas, S. S.
2006-10-01
We report converged quantum statistical mechanical simulations of liquid water with the Thole-type Model (version 2.1), Flexible, polarizable (TTM2.1-F) interaction potential for water. Simulations of total length of 600ps with a 0.05fs time step for a periodic unit cell of 256 molecules with up to 32 replicas per atom suggest that the quantum effects contribute 1.01±0.02kcal/mol to the liquid enthalpy of formation at 298.15K. They furthermore demonstrate for the first time a quantitative agreement with experiment for the heights and broadening of the intramolecular OH and HH peaks in the radial distribution functions.
Nuclear quantum effects and hydrogen bond fluctuations in water
Ceriotti, Michele; Cuny, Jérôme; Parrinello, Michele; Manolopoulos, David E.
2013-01-01
The hydrogen bond (HB) is central to our understanding of the properties of water. However, despite intense theoretical and experimental study, it continues to hold some surprises. Here, we show from an analysis of ab initio simulations that take proper account of nuclear quantum effects that the hydrogen-bonded protons in liquid water experience significant excursions in the direction of the acceptor oxygen atoms. This generates a small but nonnegligible fraction of transient autoprotolysis events that are not seen in simulations with classical nuclei. These events are associated with major rearrangements of the electronic density, as revealed by an analysis of the computed Wannier centers and 1H chemical shifts. We also show that the quantum fluctuations exhibit significant correlations across neighboring HBs, consistent with an ephemeral shuttling of protons along water wires. We end by suggesting possible implications for our understanding of how perturbations (solvated ions, interfaces, and confinement) might affect the HB network in water. PMID:24014589
Dielectric function of spherical dome shells with quantum size effects.
Kumarasinghe, Chathurangi; Premaratne, Malin; Agrawal, Govind P
2014-05-19
Metallic spherical dome shells have received much attention in recent years because they have proven to possess highly impressive optical properties. The expected distinctive changes occurring owing to quantum confinement of conduction electrons in these nanoparticles as their thickness is reduced, have not been properly investigated. Here we carry out a detailed analytical derivation of the quantum contributions by introducing linearly shifted Associated Legendre Polynomials, which form an approximate orthonormal eigenbasis for the single-electron Hamiltonian of a spherical dome shell. Our analytical results clearly show the contribution of different elements of a spherical dome shell to the effective dielectric function. More specifically, our results provide an accurate, quantitative correction for the dielectric function of metallic spherical dome shells with thickness below 10 nm. PMID:24921317
Understanding boundary effects in quantum state tomography - One qubit case
NASA Astrophysics Data System (ADS)
Sugiyama, Takanori; Turner, Peter S.; Murao, Mio
2014-12-01
For classical and quantum estimation with finite data sets, the estimation error can deviate significantly from its asymptotic (large data set) behavior. In quantum state tomography, a major reason for this is the existence of a boundary in the parameter space imposed by constraints, such as the positive semidefiniteness of density matrices. Intuitively, we should be able to reduce the estimation error by using our knowledge of these constraints. This intuition is correct for maximumlikelihood estimators, but the size of the reduction has not been evaluated quantitatively. In this proceeding, we evaluate the improvement in one qubit state tomography by using mathematical tools in classical statistical estimation theory. In particular, we show that the effect of the reduction decreases exponentially with respect to the number of data sets when the true state is mixed, and it remains at arbitrarily large data set when the true state is pure.
Loop quantum cosmology of Bianchi IX: Effective dynamics
Corichi, Alejandro
2015-01-01
We study numerically the solutions to the effective equations of Bianchi IX spacetimes within Loop Quantum Cosmology. We consider Bianchi IX models with and without inverse triad corrections whose matter content is a scalar field without mass. The solutions are classified using the classical observables. We show that both effective theories --with lapse N=V and N=1-- solve the big bang singularity and reproduce the classical dynamics far from the bounce. Moreover, due to the spatial compactness, there is an infinity number of bounces and recollapses. We study the limit of large volume and show that both effective theories reproduce the same dynamics, thus recovering general relativity. We implement a procedure to identify amongst the Bianchi IX solutions, those that behave like k=0,1 FLRW as well as Bianchi I, II, and VII_0 models. The effective solutions exhibit Bianchi I phases with Bianchi II transitions and also Bianchi VII_0 phases, which had not been studied before, at the quantum nor effective level. W...
Time-of-flight direct recoil ion scattering spectrometer
Krauss, A.R.; Gruen, D.M.; Lamich, G.J.
1994-09-13
A time-of-flight direct recoil and ion scattering spectrometer beam line is disclosed. The beam line includes an ion source which injects ions into pulse deflection regions and separated by a drift space. A final optics stage includes an ion lens and deflection plate assembly. The ion pulse length and pulse interval are determined by computerized adjustment of the timing between the voltage pulses applied to the pulsed deflection regions. 23 figs.
Giovanni Amelino-Camelia; Y. Jack NG; Hendrik Van Dam
2002-04-24
A growing number of studies is being devoted to the identification of plausible quantum properties of spacetime which might give rise to observably large effects. The literature on this subject is now relatively large, including studies in string theory, loop quantum gravity and noncommutative geometry. It is useful to divide the various proposals into proposals involving a systematic quantum-gravity effect (an effect that would shift the main/average prediction for a given observable quantity) and proposals involving a non-systematic quantum-gravity effect (an effect that would introduce new fundamental uncertanties in some observable quantity). The case of quantum-gravity-induced particle-production-threshold anomalies, a much studied example of potentially observable quantum-gravity effect, is here used as an example to illustrate the differences to be expected between systematic and non-systematic effects.
Unsteady combustion of homogeneous energetic solids using the laser-recoil method
Son, S.F.; Brewster, M.Q. (Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering)
1995-01-01
The laser-recoil technique was used to study the unsteady burning of a fine oxidizer AP-HTPB composite propellant (APF series) and a catalyzed double-base propellant (N5) at one atmosphere. Steady burning rate and temperature measurements were performed and quasi-steady, homogeneous, one-dimensional (OSHOD) theory implemented in order to interpret the unsteady results. The frequency response of the fine oxidizer AP-HTPB composite propellant exhibited two peaks that were shown to correspond to the condensed phase thermal layer and the condensed-phase reaction zone of the low- and high-frequency peaks, respectively. Several other factors were considered and eliminated as possible causes of the two peaks. For the fine oxidizer AP-HTPB composite propellant, at these conditions, the assumption of a quasi-steady surface reaction zone was clearly violated at frequencies as low as 60 Hz. The effect of mean radiant flux level on frequency response was also investigated for both APF and N5 propellants. N5 showed a pronounced steady-state burning rate plateau with radiant flux (similar to that for pressure) with corresponding effects exhibited in the frequency response. The results of this work show that detailed information can be obtained using the laser-recoil method that clarifies the structure and dynamics of burning solids. Further, the results suggest that more detailed models that relax the quasi-steady surface reaction zone assumption should be developed.
Recoil correction to the proton finite-size contribution to the Lamb shift in muonic hydrogen
NASA Astrophysics Data System (ADS)
Karshenboim, Savely G.; Korzinin, Evgeny Yu.; Shelyuto, Valery A.; Ivanov, Vladimir G.
2015-04-01
The Lamb shift in muonic hydrogen was measured some time ago to a high accuracy. The theoretical prediction of this value is very sensitive to the proton finite-size effects. The proton radius extracted from muonic hydrogen is in contradiction with the results extracted from elastic electron-proton scattering. That creates a certain problem for the interpretation of the results from the muonic hydrogen Lamb shift. For the latter we need also to take into account the two-photon-exchange contribution with the proton finite size involved. The only way to describe it relies on the data from the scattering, which may produce an internal inconsistency of theory. Recently the leading proton-finite-size contribution to the two-photon exchange was found within the external field approximation. The recoil part of the two-photon-exchange has not been considered. Here we revisit calculation of the external-field part and take the recoil correction to the finite-size effects into account.
Revealing Compressed Stops Using High-Momentum Recoils
Macaluso, Sebastian; Shih, David; Tweedie, Brock
2015-01-01
Searches for supersymmetric top quarks at the LHC have been making great progress in pushing sensitivity out to higher mass, but are famously plagued by gaps in coverage around lower-mass regions where the decay phase space is closing off. Within the common stop-NLSP / neutralino-LSP simplified model, the line in the mass plane where there is just enough phase space to produce an on-shell top quark remains almost completely unconstrained. Here, we show that is possible to define searches capable of probing a large patch of this difficult region, with S/B ~ 1 and significances often well beyond 5 sigma. The basic strategy is to leverage the large energy gain of LHC Run 2, leading to a sizable population of stop pair events recoiling against a hard jet. The recoil not only re-establishes a MET signature, but also leads to a distinctive anti-correlation between the MET and the recoil jet transverse vectors when the stops decay all-hadronically. Accounting for jet combinatorics, backgrounds, and imperfections in ...
Recoil-induced Resonances as All-optical Switches
NASA Astrophysics Data System (ADS)
Narducci, F. A.; Desavage, S. A.; Gordon, K. H.; Duncan, D. L.; Welch, G. R.; Davis, J. P.
2010-03-01
We have measured recoil-induced resonances (RIR) [1,2] in our system of laser-cooled 85Rb atoms. Although this technique has been demonstrated to be useful for the purpose of extracting the cloud temperature [3], our aim was to demonstrate an all optical switch based on recoil-induced resonances. In addition to a very narrow ``free-space'' recoil-induced resonance of approximately 15 kHz, we also discovered a much broader resonance (˜30 MHz), caused by standing waves established by our trapping fields. We compare and contrast the switching dynamics of these two resonances and demonstrate optical switching using both resonances. Finally, we consider the applicability of the narrow, free-space resonance to the slowing of a weak probe field. [1] J. Guo, P.R. Berman, B. Dubetsky and G. Grynberg PRA, 46, 1426 (1992). [2] (a) P. Verkerk, B. Loumis, C. Salomon, C. Cohen-Tannoudji, J. Courtois PRL, 68, 3861 (1992). (b) G. Grynberg, J-Y Courtois, B. Lounis, P. Verkerk PRL, 72, 3017 (1994). [3] (a) T. Brzozowski, M. Brzozowska, J. Zachorowski, M. Zawada, W. Gawlik PRA, 71, 013401 (2005). (b) M. Brzozowska, T. Brzozowski J. Zachorowski, W. Gawlik PRA, 72, 061401(R), (2005).
Recoiling black holes: electromagnetic signatures, candidates, and astrophysical implications
S. Komossa
2012-02-09
Supermassive black holes (SMBHs) may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves. Long-lived oscillations of the SMBHs in galaxy cores, and in rare cases even SMBH ejections from their host galaxies, are the consequence. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically off-set from their host galaxies. The presence of the "kicks" has a wide range of astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy assembly at the epoch of structure formation, black hole feeding, and unified models of Active Galactic Nuclei (AGN). Here, we review the observational signatures of recoiling SMBHs and the properties of the first candidates which have emerged, including follow-up studies of the candidate recoiling SMBH of SDSSJ092712.65+294344.0.
Effect of carrier dynamics and temperature on two-state lasing in semiconductor quantum dot lasers
Korenev, V. V., E-mail: korenev@spbau.ru; Savelyev, A. V.; Zhukov, A. E.; Omelchenko, A. V.; Maximov, M. V. [Saint Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation)] [Saint Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation)
2013-10-15
It is analytically shown that the both the charge carrier dynamics in quantum dots and their capture into the quantum dots from the matrix material have a significant effect on two-state lasing phenomenon in quantum dot lasers. In particular, the consideration of desynchronization in electron and hole capture into quantum dots allows one to describe the quenching of ground-state lasing observed at high injection currents both qualitatevely and quantitatively. At the same time, an analysis of the charge carrier dynamics in a single quantum dot allowed us to describe the temperature dependences of the emission power via the ground- and excited-state optical transitions of quantum dots.
Quantum Interference Effects in Slowly Rotating NUT Space-time
V. S. Morozova; B. J. Ahmedov
2008-04-20
General relativistic quantum interference effects in the slowly rotating NUT space-time as the Sagnac effect and the phase shift effect of interfering particle in neutron interferometer are considered. It was found that in the case of the Sagnac effect the influence of NUT parameter is becoming important due to the fact that the angular velocity of the locally non rotating observer must be larger than one in the Kerr space-time. In the case of neutron interferometry it is found that due to the presence of NUT-parameter an additional term in the phase shift of interfering particle emerges. This term can be, in principle, detected by sensitive interferometer and derived results can be further used in experiments to detect the gravitomagnetic charge. Finally, as an example, we apply the obtained results to the calculation of the UCN (ultra-cold neutrons) energy level modification in the slowly rotating NUT space-time.
Effect of quantum nuclear motion on hydrogen bonding.
McKenzie, Ross H; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G
2014-05-01
This work considers how the properties of hydrogen bonded complexes, X-H?Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H?O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4-3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends. PMID:24811647
Decoherence due to thermal effects in two quintessential quantum systems
S. Nussinov; T. Madziwa-Nussinov; Z. Nussinov
2014-07-01
Decoherence effects at finite temperature (T) are examined for two manifestly quantum systems: (i) Casimir forces between parallel plates that conduct along different directions, and (ii) a topological Aharonov-Bohm (AB) type force between fluxons in a superconductor. As we illustrate, standard path integral calculations suggest that thermal effects may remove the angular dependence of the Casimir force in case (i) with a decoherence time set by h/(k_{B} T) where h is Plank's constant and k_{B} is the Boltzmann constant. This prediction may be tested. The effect in case (ii) is due a phase shift picked by unpaired electrons upon encircling an odd number of fluxons. In principle, this effect may lead to small modifications in Abrikosov lattices. While the AB forces exist at extremely low temperatures, we find that thermal decoherence may strongly suppress the topological force at experimentally pertinent finite temperatures. It is suggested that both cases (i) and (ii) (as well as other examples briefly sketched) are related to a quantum version of the fluctuation-dissipation theorem.
Effect of phonon confinement on the thermoelectric figure of merit of quantum wells
Effect of phonon confinement on the thermoelectric figure of merit of quantum wells Alexander in quantum wells and superlattices due to two-dimensional carrier confinement. We predict that the figure of merit can increase even further in quantum well structures with free-surface or rigid boundaries
Quantum decoherence and the isotope effect in condensed phase nonadiabatic molecular dynamics of this isotope dependence of the nonadiabatic transition rate on changes in the quantum decoherence time to simulate the physics and chemistry of interest by treating a few select degrees of freedom quantum mechani
Faller; Sven
2008-01-01
In this paper we consider general relativity and its combination with scalar quantum electrodynamics (QED) as an effective quantum field theory at energies well below the Planck scale. This enables us to compute the one-loop quantum corrections to the Newton and Coulomb potentials induced by the combination of graviton and photon fluctuations. We derive the relevant Feynman rules and compute
NASA Astrophysics Data System (ADS)
Hong, Ran; Bagdasarova, Yelena; Garcia, Alejandro; Storm, Derek; Sternberg, Matthew; Swanson, Erik; Wauters, Frederik; Zumwalt, David; Bailey, Kevin; Leredde, Arnaud; Mueller, Peter; O'Connor, Thomas; Fléchard, Xavier; Liennard, Etienne; Knecht, Andreas; Naviliat-Cuncic, Oscar
2014-09-01
In order to measure the ? - ? angular correlation coefficient a and put more stringent limits on exotic tensor type weak currents, we constructed a system which detects ? particles in coincidence with recoil ions from the ?-decay of laser trapped 6He atoms. The ? particles are detected by a scintillator and a multi-wire proportional chamber (MWPC) with a capacitive charge division anode. The recoil ions are detected by a microchannel plate (MCP) with delay-line anodes. The coefficient a is extracted by fitting the coincidence data to GEANT4 based Monte Carlo simulations, which are also used to study systematic uncertainties related to the detector system. A new method of calibrating the MWPC using a cathode focusing effect will be presented. This work is supported by DOE, Office of Nuclear Physics, under contract nos. DE-AC02-06CH11357 and DE-FG02-97ER41020.
Quantum confinement in Si and Ge nanostructures: effect of crystallinity
NASA Astrophysics Data System (ADS)
Barbagiovanni, Eric G.; Lockwood, David J.; Costa Filho, Raimundo N.; Goncharova, Lyudmila V.; Simpson, Peter J.
2013-10-01
We look at the relationship between the preparation method of Si and Ge nanostructures (NSs) and the structural, electronic, and optical properties in terms of quantum confinement (QC). QC in NSs causes a blue shift of the gap energy with decreasing NS dimension. Directly measuring the effect of QC is complicated by additional parameters, such as stress, interface and defect states. In addition, differences in NS preparation lead to differences in the relevant parameter set. A relatively simple model of QC, using a `particle-in-a-box'-type perturbation to the effective mass theory, was applied to Si and Ge quantum wells, wires and dots across a variety of preparation methods. The choice of the model was made in order to distinguish contributions that are solely due to the effects of QC, where the only varied experimental parameter was the crystallinity. It was found that the hole becomes de-localized in the case of amorphous materials, which leads to stronger confinement effects. The origin of this result was partly attributed to differences in the effective mass between the amorphous and crystalline NS as well as between the electron and hole. Corrections to our QC model take into account a position dependent effective mass. This term includes an inverse length scale dependent on the displacement from the origin. Thus, when the deBroglie wavelength or the Bohr radius of the carriers is on the order of the dimension of the NS the carriers `feel' the confinement potential altering their effective mass. Furthermore, it was found that certain interface states (Si-O-Si) act to pin the hole state, thus reducing the oscillator strength.
A time-asymmetric delta-kicked model for the quantum ratchet effect
NASA Astrophysics Data System (ADS)
Chen, Lei; Xiong, Chao; Xiao, Jin; Yuan, Hong-Chun
2014-12-01
We investigate a time-asymmetric delta-kicked model for the quantum ratchet effect, in which a flashing potential acts on a particle at unequal time intervals. Ratchet currents emerge when quantum resonances are excited. The currents in time-asymmetric models may be stronger than those found in the previous time-symmetric model. Our work expands upon the quantum delta-kicked model and may contribute to experimental investigation of the quantum transport of cold atoms.
Quantum anomalous Hall effect in topological insulator memory
NASA Astrophysics Data System (ADS)
Jalil, Mansoor B. A.; Tan, S. G.; Siu, Z. B.
2015-05-01
We theoretically investigate the quantum anomalous Hall effect (QAHE) in a magnetically coupled three-dimensional-topological insulator (3D-TI) system. We apply the generalized spin-orbit coupling Hamiltonian to obtain the Hall conductivity ?xy of the system. The underlying topology of the QAHE phenomenon is then analyzed to show the quantization of ?xy and its relation to the Berry phase of the system. Finally, we analyze the feasibility of utilizing ?xy as a memory read-out in a 3D-TI based memory at finite temperatures, with comparison to known magnetically doped 3D-TIs.
Quantum Hall Effect (QHE) in ABA stacked trilayer graphene
NASA Astrophysics Data System (ADS)
Stepanov, Petr; Barlas, Yafis; Gillgren, Nathaniel; Taniguchi, Takashi; Lau, Jeanie
2015-03-01
Since its experimental discovery in 2004 graphene was under extensive research as a promising counterpart of silicon for the future electronics application as well as an excellent model of 2 dimensional electron gas. Here we investigate quantum Hall effect in ABA trilayer graphene - hexagonal boron nitride heterostructures. Landau Levels (LL) crossings at low filling factors were observed and explored at different external electric fields. The formation of the QH states as an interaction of monlayer-like and bilayer-like branches will be discussed. We will present the most recent experimental results.
Vector Theory of Gravity: quantum and classical effects, renormalization
V. N. Borodikhin
2012-10-26
In this work, we make quantization of gravitation interaction within the framework of a vector theory of gravitation for the first time. The work demonstrates that this theory meets the requirement of renormalizability. Here we consider some quantum effects, particularly graviton scattering on fermion and corrections to the Newton's. Gravitational energy sign changing mechanism and classical transition on small scale is discussed. It is shown that within this theory black holes of Schwarzschield hole type can exist. Problem of dark energy structure and acceleration of Universe expansion is investigated. We also consider the behavior of binary pulsars in the vector theory of gravitation.
Non-linear quantum noise effects in scale invariant junctions
NASA Astrophysics Data System (ADS)
Mintchev, Mihail; Santoni, Luca; Sorba, Paul
2015-07-01
We study non-equilibrium steady state transport in scale invariant quantum junctions with focus on the particle and heat fluctuations captured by the two-point current correlation functions. We show that the nonlinear behavior of the particle current affects both the particle and heat noise. The existence of domains of enhancement and reduction of the noise power with respect to the linear regime are observed. The impact of the statistics is explored. We demonstrate that the bosonic particle noise exceeds the fermionic one in the common domain of heat bath parameters. Multi-lead configurations are also investigated and the effect of probe terminals on the noise is discussed.
Computational Investigation of Quantum Size Effects in Gold Nanoparticles
None
2010-01-01
Electron density perturbation from carbon monoxide adsorption on a multi-hundred atom gold nanoparticle. The perturbation causes significant quantum size effects in CO catalysis on gold particles. Science: Jeff Greeley and Nick Romero, Argonne National Laboratory; Jesper Kleis, Karsten Jacobsen, Jens Nørskov, Technical University of Denmark? Visualization: Joseph Insley, Argonne National Laboratory This research used resources of the Argonne Leadership Computing Facility at Argonne National Laboratory, which is supported by the Office of Science of the U.S. Dept. of Energy under contract DE-AC02-06CH11357.
Fractional quantum Hall effect at Landau level filling ? =4 /11
NASA Astrophysics Data System (ADS)
Pan, W.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.; Tsui, D. C.
2015-01-01
We report low-temperature electronic transport results on the fractional quantum Hall effect of composite fermions at Landau level filling ? =4 /11 in a very high mobility and low density sample. Measurements were carried out at temperatures down to 15 mK , where an activated magnetoresistance Rx x and a quantized Hall resistance Rx y, within 1 % of the expected value of h /(4 /11 ) e2 , were observed. The temperature dependence of the Rx x minimum at 4 /11 yields an activation energy gap of ˜7 mK . Developing Hall plateaus were also observed at the neighboring states at ? =3 /8 and 5 /13 .
Configuration interaction matrix elements for the quantum Hall effect
NASA Astrophysics Data System (ADS)
Wooten, Rachel; Macek, Joseph
2015-03-01
In the spherical model of the quantum Hall system, the two-body matrix elements and pseudopotentials can be found analytically in terms of a general scalar pair interaction potential by expressing the pair interaction as a weighted sum over Legendre polynomials. For non-infinite systems, only a finite set of terms in the potential expansion contribute to the interactions; the contributing terms define an effective spatial potential for the system. The connection between the effective spatial potential and the pseudopotential is one-to-one for finite systems, and any completely defined model pseudopotential can be analytically inverted to give a unique corresponding spatial potential. This technique of inverting the pseudopotential to derive effective spatial potentials may be of use for developing accurate model spatial potentials for quantum Monte Carlo simulations. We demonstrate the technique and the corresponding spatial potentials for a few example model pseudopotentials. Supported by Office of Basic Energy Sciences, U.S. DOE, Grant DE-FG02-02ER15283 to the University of Tennessee.
Graphene nanomesh photodetector with effective charge tunnelling from quantum dots.
Liu, Xiang; Liu, Nianze; Liu, Mingju; Tao, Zhi; Kuang, Wenjian; Ji, Xiangbing; Chen, Jing; Lei, Wei; Dai, Qing; Li, Chi; Li, Xuehua; Nathan, Arokia
2015-03-01
Graphene nanomesh (GNM)-based optoelectronics integrated with quantum dots (QDs) are investigated in this article. The charge transfer mechanism in the QDs/GNM interface is probed in four terminal gated FET-type photodetectors. The insulating ligand is used to make the GNM/ligand/QDs vertically behave like a metal/insulate/semiconductor (MIS) structure to facilitate the charge tunnelling. With the current constraint effect of the GNM and the effective charge tunnelling, a high-performance photodetector is fabricated with higher responsivity, higher on/off ratio and shorter response time. The results of our analysis and experimental approach can be extended to future graphene-based photodetectors, as long as suitable ligands and an effective architecture are chosen for this type of device. PMID:25673220
More Benefits of Semileptonic Rare B Decays at Low Recoil: CP Violation
Christoph Bobeth; Gudrun Hiller; Danny van Dyk
2011-12-08
We present a systematic analysis of the angular distribution of Bbar -> Kbar^\\ast (-> Kbar pi) l^+ l^- decays with l = e, mu in the low recoil region (i.e. at high dilepton invariant masses of the order of the mass of the b-quark) to account model-independently for CP violation beyond the Standard Model, working to next-to-leading order QCD. From the employed heavy quark effective theory framework we identify the key CP observables with reduced hadronic uncertainties. Since some of the CP asymmetries are CP-odd they can be measured without B-flavour tagging. This is particularly beneficial for Bbar_s,B_s -> phi(-> K^+ K^-) l^+ l^- decays, which are not self-tagging, and we work out the corresponding time-integrated CP asymmetries. Presently available experimental constraints allow the proposed CP asymmetries to be sizeable, up to values of the order ~ 0.2, while the corresponding Standard Model values receive a strong parametric suppression at the level of O(10^-4). Furthermore, we work out the allowed ranges of the short-distance (Wilson) coefficients C_9,C_10 in the presence of CP violation beyond the Standard Model but no further Dirac structures. We find the Bbar_s -> mu^+ mu^- branching ratio to be below 9*10^-9 (at 95% CL). Possibilities to check the performance of the theoretical low recoil framework are pointed out.
Graphene nanomesh photodetector with effective charge tunnelling from quantum dots
NASA Astrophysics Data System (ADS)
Liu, Xiang; Liu, Nianze; Liu, Mingju; Tao, Zhi; Kuang, Wenjian; Ji, Xiangbing; Chen, Jing; Lei, Wei; Dai, Qing; Li, Chi; Li, Xuehua; Nathan, Arokia
2015-02-01
Graphene nanomesh (GNM)-based optoelectronics integrated with quantum dots (QDs) are investigated in this article. The charge transfer mechanism in the QDs/GNM interface is probed in four terminal gated FET-type photodetectors. The insulating ligand is used to make the GNM/ligand/QDs vertically behave like a metal/insulate/semiconductor (MIS) structure to facilitate the charge tunnelling. With the current constraint effect of the GNM and the effective charge tunnelling, a high-performance photodetector is fabricated with higher responsivity, higher on/off ratio and shorter response time. The results of our analysis and experimental approach can be extended to future graphene-based photodetectors, as long as suitable ligands and an effective architecture are chosen for this type of device.Graphene nanomesh (GNM)-based optoelectronics integrated with quantum dots (QDs) are investigated in this article. The charge transfer mechanism in the QDs/GNM interface is probed in four terminal gated FET-type photodetectors. The insulating ligand is used to make the GNM/ligand/QDs vertically behave like a metal/insulate/semiconductor (MIS) structure to facilitate the charge tunnelling. With the current constraint effect of the GNM and the effective charge tunnelling, a high-performance photodetector is fabricated with higher responsivity, higher on/off ratio and shorter response time. The results of our analysis and experimental approach can be extended to future graphene-based photodetectors, as long as suitable ligands and an effective architecture are chosen for this type of device. Electronic supplementary information (ESI) available: The TEM image of all the four QDs with different ligands, the PL and UV-vis spectra of QDs and the GNM/QDs with different ligands and the testing device on the probe station under the LED light. See DOI: 10.1039/c4nr06883a
Kondo Effect in a Many-Electron Quantum Ring A. Fuhrer,1
Ihn, Thomas
Kondo Effect in a Many-Electron Quantum Ring A. Fuhrer,1 T. Ihn,1 K. Ensslin,1 W. Wegscheider,2 October 2004) The Kondo effect is investigated in a many-electron quantum ring as a function of the magnetic field. For fields applied perpendicular to the plane of the ring a modulation of the Kondo effect
Framing Anomaly in the Effective Theory of Fractional Quantum Hall Effect
NASA Astrophysics Data System (ADS)
Gromov, Andrey; Abanov, Alexander; Cho, Gil Young; You, Yizhi; Fradkin, Eduardo
2015-03-01
While the classical Chern-Simons theory is topological, it's quantum version is not as it depends on the metric of the base manifold through the path integral measure. This phenomenon is known as the framing anomaly. It is shown that accounting for the framing anomaly of the quantum Chern-Simons theory is essential to obtain the correct gravitational linear response functions of fractional quantum Hall systems (FQH). In the lowest order in gradients the effective action includes Chern-Simons, Wen-Zee and gravitational Chern-Simons terms. The latter term has a contribution from the framing anomaly which fixes the value of thermal Hall conductivity and generates a ``finite size correction'' to the Hall viscosity of the FQH states on a sphere. We also discuss the effects of the framing anomaly on linear responses of non-Abelian FQH states.
Quantum noise effects with Kerr-nonlinearity enhancement in coupled gain-loss waveguides
NASA Astrophysics Data System (ADS)
He, Bing; Yan, Shu-Bin; Wang, Jing; Xiao, Min
2015-05-01
It is generally difficult to study the dynamical properties of a quantum system with both inherent quantum noises and nonperturbative nonlinearity. Due to the possibly drastic intensity increase of an input coherent light in gain-loss waveguide couplers with parity-time (PT ) symmetry, the Kerr effect from a nonlinearity added into the system can be greatly enhanced and is expected to create macroscopic entangled states of the output light fields with huge photon numbers. Meanwhile, quantum noises also coexist with the amplification and dissipation of the light fields. Under the interplay between the quantum noises and nonlinearity, the quantum dynamical behaviors of the systems become rather complicated. However, the important quantum noise effects have been mostly neglected in previous studies about nonlinear PT -symmetric systems. Here we present a solution to this nonperturbative quantum nonlinear problem, showing the real-time evolution of the system observables. The enhanced Kerr nonlinearity is found to give rise to a previously unknown decoherence effect that is irrelevant to the quantum noises and imposes a limit on the emergence of macroscopic nonclassicality. In contrast to what happens in linear systems, the quantum noises exert significant impact on the system dynamics and can create nonclassical light field states in conjunction with the enhanced Kerr nonlinearity. This study on the noise involved in quantum nonlinear dynamics of coupled gain-loss waveguides can help to better understand the quantum noise effects in many nonlinear systems.
The effectiveness of quantum operations for eavesdropping on sealed messages
Paul A Lopata; Thomas B Bahder
2007-04-04
A quantum protocol is described which enables a user to send sealed messages and that allows for the detection of active eavesdroppers. We examine a class of eavesdropping strategies, those that make use of quantum operations, and we determine the information gain versus disturbance caused by these strategies. We demonstrate this tradeoff with an example and we compare this protocol to quantum key distribution, quantum direct communication, and quantum seal protocols.
Recoil ion charge state distribution following the beta(sup +) decay of {sup 21}Na
Scielzo, Nicholas D.; Freedman, Stuart J.; Fujikawa, Brian K.; Vetter, Paul A.
2003-01-03
The charge state distribution following the positron decay of 21Na has been measured, with a larger than expected fraction of the daughter 21Ne in positive charge states. No dependence on either the positron or recoil nucleus energy is observed. The data is compared to a simple model based on the sudden approximation. Calculations suggest a small but important contribution from recoil ionization has important consequences for precision beta decay correlation experiments detecting recoil ions.
Nuclear recoil detection in liquid argon using a two-phase CRAD and DD neutron generator
NASA Astrophysics Data System (ADS)
Bondar, A.; Buzulutskov, A.; Dolgov, A.; Grishnyaev, E.; Polosatkin, S.; Shemyakina, E.; Sokolov, A.
2014-08-01
The detection of nuclear recoils in noble liquids using neutron elastic scattering off nuclei is relevant in the field of calibration of rare-event detectors for dark matter search and coherent neutrino-nucleus scattering experiments. We present here the first results on nuclear recoil detection in liquid Ar, using a two-phase Cryogenic Avalanche Detector (CRAD) and DD neutron generator. The technique to select the nuclear recoils for backward neutron scattering has been demonstrated.
NASA Astrophysics Data System (ADS)
Rowe, M. A.; Gansen, E. J.; Greene, M.; Hadfield, R. H.; Harvey, T. E.; Su, M. Y.; Nam, S. W.; Mirin, R. P.; Rosenberg, D.
2006-12-01
We investigate the operation of a quantum dot, optically gated, field-effect transistor as a photon detector. The detector exhibits time-gated, single-shot, single-photon sensitivity, a linear response, and an internal quantum efficiency of up to (68±18)% at 4K. Given the noise of the detector system, they find that a particular discriminator level can be chosen so the device operates with an internal quantum efficiency of (53±11)% and dark counts of 0.003 counts per shot.
NASA Astrophysics Data System (ADS)
Ludwig, Andreas W. W.
1996-03-01
We review recent exact results (Work done in collaboration with Paul Fendley and Hubert Saleur, Physics Dept., University of Southern California, Los Angeles, CA 90089-0484.) for transport properties through a local impurity in a Luttinger liquid. These represent ``spectroscopic probes'' of the Luttinger non-Fermi-liquid state. Edge modes occuring in the fractional quantum Hall effect provide realizations of Luttinger liquids, insensitive to disorder. The linear-response conductance through a point contact in the ? =1/3 quantum Hall state has been predicted to be a universal function of temperature and point-contact interaction strength, independent of sample-specific details of the device. Our exact result for this scaling function is in quantitative agreement with experimental measurements (F.P. Milliken, C.P. Umbach and R.A. Webb, preprint.). The theoretical advance made in this work(P. Fendley, A.W.W. Ludwig and H. Saleur, Phys. Rev. Lett. 74) (1995) 3005; 75 (1995) 2196; Phys. Rev. B 52 (1995) 8934. is the computation of exact transport properties from the Bethe ansatz; in the past, the Bethe ansatz was useful mainly for thermodynamic quantities. We utilize an exact kinetic transport equation in a particular quasiparticle basis of the Luttinger liquid dictated by the integrability of the point-contact interaction. Since this equation is also valid out of equilibrium, we obtain also non-equilibrium quantum transport properties in this fully interacting system. In particular, we also present universal exact results for the I(V) characteristics and the DC shot noise of the point contact. The differential conductance develops a peak beyond a critical value e V/kB T >7.18868 of driving.
Landau damping and the onset of particle trapping in quantum plasmas
Daligault, Jérôme [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-04-15
Using analytical theory and simulations, we assess the impact of quantum effects on non-linear wave-particle interactions in quantum plasmas. We more specifically focus on the resonant interaction between Langmuir waves and electrons, which, in classical plasmas, lead to particle trapping. Two regimes are identified depending on the difference between the time scale of oscillation t{sub B}(k)=?(m/eEk) of a trapped electron and the quantum time scale t{sub q}(k)=2m/?k{sup 2} related to recoil effect, where E and k are the wave amplitude and wave vector. In the classical-like regime, t{sub B}(k)?quantum regime, t{sub B}(k)?>?t{sub q}(k), particle trapping is hampered by the finite recoil imparted to resonant electrons in their interactions with plasmons.
Igor Romanovsky; Constantine Yannouleas; Uzi Landman
2009-01-01
We investigate the way that the degenerate manifold of midgap edge states in quasicircular graphene quantum dots with zigzag boundaries supports, under free-magnetic-field conditions, strongly correlated many-body behavior analogous to the fractional quantum Hall effect (FQHE), familiar from the case of semiconductor heterostructures in high-magnetic fields. Systematic exact-diagonalization (EXD) numerical studies are presented for 5<=N<=8 fully spin-polarized electrons and for
Richards, Christopher T; Sawicki, Gregory S
2012-11-21
Frog jumps exceed muscle power limits. To achieve this, a muscle may store elastic energy in tendon before it is released rapidly, producing 'power amplification' as tendon recoil assists the muscle to accelerate the load. Do the musculoskeletal modifications conferring power amplification help or hinder frog swimming? We used a Hill-type mathematical model of a muscle-tendon (MT) with contractile element (CE) and series elastic element (SEE) properties of frogs. We varied limb masses from 0.3 to 30 g, foot-fin areas from 0.005 to 50 cm(2) and effective mechanical advantage (EMA=in-lever/out-lever) from 0.025 to 0.1. 'Optimal' conditions produced power amplification of ~19% greater than the CE limit. Yet, other conditions caused ~80% reduction of MT power (power attenuation) due to SEE recoil absorbing power from (rather than adding to) the CE. The tendency for elastic recoil to cause power amplification vs. attenuation was load dependent: low fluid drag loads, high limb mass and EMA=0.1 caused power amplification whereas high drag, low mass and low EMA (=0.025) caused attenuation. Power amplification emerged when: (1) CE shortening velocity is 1/3V(max), (2) elastic energy storage is neither too high nor too low, and (3). peak inertial-drag force ratio ? ~1.5. Excessive elastic energy storage delayed the timing of recoil, causing power attenuation. Thus our model predicts that for fluid loads, the benefit from a compliant tendon is modest, and when the system is 'poorly tuned' (i.e., inappropriate EMA), MT power attenuation can be severe. PMID:22898554
Quantum Anomalous Hall Effect in Graphene-based Heterostructure
Zhang, Jiayong; Zhao, Bao; Yao, Yugui; Yang, Zhongqin
2015-01-01
Quantum anomalous Hall (QAH) effect, with potential applications in low-power-consumption electronics, is predicted in the heterostructure of graphene on the (001) surface of a real antiferromagnetic insulator RbMnCl3, based on density-functional theory and Wannier function methods. Due to the interactions from the substrate, a much large exchange field (about 280?meV) and an enhanced Rashba spin-orbit coupling are induced in graphene, leading to a topologically nontrivial QAH gap opened in the system. The avenues of enhancing the nontrivial gap are also proposed, from which nearly a gap one order large is achieved. Our work demonstrates that this graphene-based heterostructure is an appropriate candidate to be employed to experimentally observe the QAH effect and explore the promising applications. PMID:26024508
Kondo effect in coupled quantum dots under magnetic fields
Aono, Tomosuke; Eto, Mikio
2001-08-15
The Kondo effect in coupled quantum dots is investigated theoretically under magnetic fields. We show that the magnetoconductance (MC) illustrates the peak structures of Kondo resonant spectra. When the dot-dot tunneling coupling V{sub C} is smaller than the dot-lead coupling {Delta} (level broadening), Kondo resonant levels appear at the Fermi level (E{sub F}). The Zeeman splitting of the levels weakens the Kondo effect, which results in a negative MC. When V{sub C} is larger than {Delta}, the Kondo resonances form bonding and antibonding levels, located below and above E{sub F}, respectively. We observe a positive MC since the Zeeman splitting increases the overlap between the levels at E{sub F}. In the presence of antiferromagnetic spin coupling between the dots, the sign of the MC can change as a function of the gate voltage.
Anisotropic charge Kondo effect in a triple quantum dot.
Yoo, Gwangsu; Park, Jinhong; Lee, S-S B; Sim, H-S
2014-12-01
We predict that an anisotropic charge Kondo effect appears in a triple quantum dot, when the system has twofold degenerate ground states of (1,1,0) and (0,0,1) charge configurations. Using bosonization and refermionization methods, we find that at low temperature the system has the two different phases of massive charge fluctuations between the two charge configurations and vanishing fluctuations, which are equivalent with the Kondo-screened and ferromagnetic phases of the anisotropic Kondo model, respectively. The phase transition is identifiable by electron conductance measurement, offering the possibility of experimentally exploring the anisotropic Kondo model. Our charge Kondo effect has a similar origin to that in a negative-U Anderson impurity. PMID:25526143
Quantum Anomalous Hall Effect in Graphene-based Heterostructure.
Zhang, Jiayong; Zhao, Bao; Yao, Yugui; Yang, Zhongqin
2015-01-01
Quantum anomalous Hall (QAH) effect, with potential applications in low-power-consumption electronics, is predicted in the heterostructure of graphene on the (001) surface of a real antiferromagnetic insulator RbMnCl3, based on density-functional theory and Wannier function methods. Due to the interactions from the substrate, a much large exchange field (about 280?meV) and an enhanced Rashba spin-orbit coupling are induced in graphene, leading to a topologically nontrivial QAH gap opened in the system. The avenues of enhancing the nontrivial gap are also proposed, from which nearly a gap one order large is achieved. Our work demonstrates that this graphene-based heterostructure is an appropriate candidate to be employed to experimentally observe the QAH effect and explore the promising applications. PMID:26024508
Quantum effects can render w<-1 on cosmological scales
Onemli, V.K. [LPT, Universite Paris Sud, Batiment 210, 91405 Orsay (France); Woodard, R.P. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)
2004-11-15
We report on a revision of our previous computation of the renormalized expectation value of the stress-energy tensor of a massless, minimally coupled scalar with a quartic self-interaction on a locally de Sitter background. This model is important because it demonstrates that quantum effects can lead to violations of the weak energy condition on cosmological scales--on average, not just in fluctuations--although the effect in this particular model is far too small to be observed. The revision consists of modifying the propagator so that dimensional regularization can be used when the dimension of the renormalized theory is not four. Although the finite part of the stress-energy tensor does not change (in D=4) from our previous result, the counterterms do. We also speculate that a certain, finite and separately conserved part of the stress tensor can be subsumed into a natural correction of the initial state from free Bunch-Davies vacuum.
Quantum effects can render w<-1 on cosmological scales
NASA Astrophysics Data System (ADS)
Onemli, V. K.; Woodard, R. P.
2004-11-01
We report on a revision of our previous computation of the renormalized expectation value of the stress-energy tensor of a massless, minimally coupled scalar with a quartic self-interaction on a locally de Sitter background. This model is important because it demonstrates that quantum effects can lead to violations of the weak energy condition on cosmological scales—on average, not just in fluctuations—although the effect in this particular model is far too small to be observed. The revision consists of modifying the propagator so that dimensional regularization can be used when the dimension of the renormalized theory is not four. Although the finite part of the stress-energy tensor does not change (in D=4) from our previous result, the counterterms do. We also speculate that a certain, finite and separately conserved part of the stress tensor can be subsumed into a natural correction of the initial state from free Bunch-Davies vacuum.
Thermoelectric effects in quantum Hall systems beyond linear response
NASA Astrophysics Data System (ADS)
López, Rosa; Hwang, Sun-Yong; Sánchez, David
2014-12-01
We consider a quantum Hall system with an antidot acting as a energy dependent scatterer. In the purely charge case, we find deviations from the Wiedemann-Franz law that take place in the nonlinear regime of transport. We also discuss Peltier effects beyond linear response and describe both effects using magnetic-field asymmetric transport coefficients. For the spin case such as that arising along the helical edge states of a two-dimensional topological insulator, we investigate the generation of spin currents as a result of applied voltage and temperature differences in samples attached to ferromagnetic leads. We find that in the parallel configuration the spin current can be tuned with the leads' polarization even in the linear regime of transport. In contrast, for antiparallel magnetizations the spin currents has a strict nonlinear dependence on the the applied fields.
Quantum Hall Effect near the charge neutrality point in graphene
NASA Astrophysics Data System (ADS)
Leon, Jorge; Gusev, Guennadii; Plentz, Flavio
2013-03-01
The Quantum Hall effect (QHE) of a two-dimensional (2D) electron gas in a strong magnetic field is one of the most fascinating quantum phenomena discovered in condensed matter physics. In this work we propose to study the transport properties of the single layer and bilayer of graphene at the charge neutrality point (CNP) and compare it with random magnetic model developed in theoretical papers in which we argue that at CNP graphene layer is still inhomogeneous, very likely due to random potential of impurities. The random potential fluctuations induce smooth fluctuations in the local filling factor around ? = 0. In this case the transport is determined by special class of trajectories, ``the snake states'', propagating along contour ? = 0. The situation is very similar to the transport of a two-dimensional particles moving in a spatially modulated random magnetic field with zero mean value. We especially emphasize that our results may be equally relevant to the composite fermions description of the half-filled Landau level. The Quantum Hall effect (QHE) of a two-dimensional (2D) electron gas in a strong magnetic field is one of the most fascinating quantum phenomena discovered in condensed matter physics. In this work we propose to study the transport properties of the single layer and bilayer of graphene at the charge neutrality point (CNP) and compare it with random magnetic model developed in theoretical papers in which we argue that at CNP graphene layer is still inhomogeneous, very likely due to random potential of impurities. The random potential fluctuations induce smooth fluctuations in the local filling factor around ? = 0. In this case the transport is determined by special class of trajectories, ``the snake states'', propagating along contour ? = 0. The situation is very similar to the transport of a two-dimensional particles moving in a spatially modulated random magnetic field with zero mean value. We especially emphasize that our results may be equally relevant to the composite fermions description of the half-filled Landau level. The authors thank to CNPq and FAPESP for financial support for this work.
Towards Quantum Spin Hall Effect in InAs/GaSb Quantum Wells
NASA Astrophysics Data System (ADS)
Knez, Ivan; Du, Rui-Rui; Sullivan, Gerrard
2011-03-01
Recently, it has been proposed that inverted InAs/GaSb composite quantum wells (CQWs) should exhibit the Quantum Spin Hall Effect (QSHE), characterized by the energy gap in the bulk and gapless edge modes which are protected from backscattering by time reversal symmetry. We have successfully fabricated a double-gated device on high-quality MBE-grown InAs/GaAs CQWs in the inverted regime, in which we were able to vary the band structure via an electrical field, and tune the Fermi level into mini-gap regime. We observed clear evidence for an energy gap in the inverted regime, with values of the gap consistent with those theoretically predicted; however, the mini-gap exhibits residual conductivity of non-trivial origin, which complicates transport investigation of proposed edge channels. We note that the InAs surface states around the sample edges may play a role in the observed resistivity features. In ongoing work, we pursue Cooper pair injection experiments by proximity to an s-wave superconductor, which should provide a novel probe of the proposed helical edge modes. We will discuss our progress towards observing QSHE in this unique material system. The work at Rice was supported by grants from NSF, Keck Foundation, and Hackerman Advanced Research Program.
Phase diagram of the two-component fractional quantum Hall effect.
Archer, Alexander C; Jain, Jainendra K
2013-06-14
We calculate the phase diagram of the two component fractional quantum Hall effect as a function of the spin or valley Zeeman energy and the filling factor, which reveals new phase transitions and phase boundaries spanning many fractional plateaus. This phase diagram is relevant to the fractional quantum Hall effect in graphene and in GaAs and AlAs quantum wells, when either the spin or valley degree of freedom is active. PMID:25165951
B -> D* l nu at zero recoil: an update
Bailey, Jon A.; Bazavov, A.; Bernard, C.; Bouchard, C.M.; DeTar, C.; El-Khadra, A.X.; Freeland, E.D.; Gamiz, E.; Gottlieb, Steven; Heller, U.M.; Hetrick, J.E.
2010-11-01
We present an update of our calculation of the form factor for {bar B} {yields} D*{ell}{bar {nu}} at zero recoil, with higher statistics and finer lattices. As before, we use the Fermilab action for b and c quarks, the asqtad staggered action for light valence quarks, and the MILC ensembles for gluons and light quarks (Luescher-Weisz married to 2+1 rooted staggered sea quarks). In this update, we have reduced the total uncertainty on F(1) from 2.6% to 1.7%.
A Proton Recoil Telescope Detector for Neutron Spectroscopy
Bocci, F. [INFN and Dipartimento di Fisica Nucleare e Teorica dell'Universita di Pavia (Italy); Dipartimento di Meccanica dell'Universita di Brescia and INFN Sezione di Pavia (Italy); Cinausero, M.; Rizzi, V.; Barbui, M.; Prete, G.; Andrighetto, A.; Lunardon, M.; Pesente, S. [INFN Laboratori Nazionali di Legnaro (Italy); Fontana, A.; Gemignian, G. [INFN and Dipartimento di Fisica Nucleare e Teorica dell'Universita di Pavia (Italy); Bonomi, G.; Donzella, A.; Zenoni, A. [Dipartimento di Meccanica dell'Universita di Brescia and INFN Sezione di Pavia (Italy); Fabris, D.; Morando, M.; Moretto, S.; Nebbia, G.; Viesti, G. [INFN and Dipartimento di Fisica dell'Universita di Padova (Italy)
2007-10-26
A compact and versatile Proton Recoil Telescope (PRT) detector has been realized to measure neutron energy spectra in the range from few to hundred MeV. The PRT is a position sensitive detector made by: an active multilayer segmented plastic scintillator as neutron to proton converter, two silicon strip detectors for proton energy and position measurement and a final thick CsI(T1) scintillator to measure the residual proton energy. The detector has been tested with the {sup 13}C(d,n) reaction at Laboratori Nazionali del Sud using a 40 MeV deuteron beam.
Cavity-Controlled Collective Scattering at the Recoil Limit
Bux, Simone; Gnahm, Christine; Maier, Reinhardt A. W.; Zimmermann, Claus [Physikalisches Institut, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Courteille, Philippe W. [Physikalisches Institut, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, 13560-970 Sao Carlos, SP (Brazil)
2011-05-20
We study collective scattering with Bose-Einstein condensates interacting with a high-finesse ring cavity. The condensate scatters the light of a transverse pump beam superradiantly into modes which, in contrast to previous experiments, are not determined by the geometrical shape of the condensate, but specified by a resonant cavity mode. Moreover, since the recoil-shifted frequency of the scattered light depends on the initial momentum of the scattered fraction of the condensate, we show that it is possible to employ the good resolution of the cavity as a filter selecting particular quantized momentum states.
Scanning Capacitance Microscopy of the Quantum Hall Effect
NASA Astrophysics Data System (ADS)
Ashoori, Ray
1997-03-01
Since the discovery of the quantum Hall effect in 1980, physicists have drawn schematic pictures to illustrate hypothetical structure of the two-dimensional electron gas (2DEG) in the presence of a quantizing magnetic field. Quantum Hall plateaus are thought to occur as a result of localization of electrons in the 2DEG. Distinct areas of the electron gas may consist of ``localized'' or ``delocalized'' electrons. We recently developed a technique which permits direct imaging of this structure with ~400 Angstrom resolution. We constructed a scanning tunneling microscope that works both in the usual tunneling mode and in a novel capacitance mode. The microscope operates in a liquid helium-3 cryostat at 300 mK equipped with a magnet permitting application of fields of up to 12 Tesla. An insulating AlGaAs layer separates the 2DEG from the sample surface. The initial approach to the sample is achieved in tunneling mode with a sufficiently large applied bias between the tip and the 2DEG to permit electron tunneling through the AlGaAs layer. With the surface found, the microscope is switched into capacitance mode. The tip is scanned at fixed height (typically 50 Angstroms) above the sample surface. We tune two different parameters: tip bias and magnetic field strength. The capacitance signal is measured with a 1 mV amplitude 100 KHz excitation on the 2DEG. Regions of the 2DEG which are near integer Landau level filling fraction appear black (low capacitance) in the capacitance images. This arises because charge cannot readily flow into or out of these ``incompressible'' regions. Other, ``compressible'', areas display varying brightness according to their conductivities. The positions and shapes of the boundaries between these regions vary substantially as the magnetic field strength is changed, in a fashion significantly different than simple models would suggest. This new direct imaging of a quantum fluid reveals a fascinatingly complex sea of distinct phases.
Quantum Zero Point Effects in Water and Ice
NASA Astrophysics Data System (ADS)
Pamuk, Betül; Fernández-Serra, Marivi
2013-03-01
Nuclear zero point effects have recently been shown to have an interesting quantum anomaly in ice. In particular, In hexagonal ice Ih, the lattice volume increases when H is replaced by D. This anomalous isotope shift of the lattice parameter increases with temperature, contrary to normal expectations. Free energy calculations within the quasiharmonic approximation, with ab initio density functional theory, explain the origin of his anomaly. In this study, we extend our study to show that the anomalous isotope effect persists in amorphous ices, inherent structures of liquid water. This indicates that the anomalous isotope effect on the density of liquid water might be intrinsically related to the one observed in ice, even if their structures are radically different. In addition, we show that clathrate hydrides, also have this anomaly. We make a detailed analysis of the origin of the anomaly and study how the Hbond interaction and the vdW bond in liquid water are modified by these nuclear zero point effects. Nuclear zero point effects have recently been shown to have an interesting quantum anomaly in ice. In particular, In hexagonal ice Ih, the lattice volume increases when H is replaced by D. This anomalous isotope shift of the lattice parameter increases with temperature, contrary to normal expectations. Free energy calculations within the quasiharmonic approximation, with ab initio density functional theory, explain the origin of his anomaly. In this study, we extend our study to show that the anomalous isotope effect persists in amorphous ices, inherent structures of liquid water. This indicates that the anomalous isotope effect on the density of liquid water might be intrinsically related to the one observed in ice, even if their structures are radically different. In addition, we show that clathrate hydrides, also have this anomaly. We make a detailed analysis of the origin of the anomaly and study how the Hbond interaction and the vdW bond in liquid water are modified by these nuclear zero point effects. This work is supported by DOE Grant No. DE-SC0003871
Observation of an even-denominator quantum number in the fractional quantum Hall effect
NASA Astrophysics Data System (ADS)
Willett, R.; Eisenstein, J. P.; Stormer, H. L.; Gossard, A. C.; Tsui, D. C.
1987-10-01
The fractional quantum Hall effect (FQHE) in a two-dimensional electron system is investigated experimentally. Transport measurements on MBE-grown GaAs/AlGaAs heterostructures of mobility 1.3 x 10 to the 6th sq cm/V sec and areal density 3.0 x 10 to the 11th/sq cm are performed in magnetic fields up to 30 T and at temperatures down to 20 mK, taking precautions to maintain thermal equilibrium between the two-dimensional electrons and the lattice. The results are presented graphically and characterized in detail. Firm evidence of FQHE to an even-denominator fraction, nu = 5/2, is obtained in the first excited Landau level but not in the lowest Landau level. The theoretical implications of these observations are discussed.
Unconventional quantum Hall effect and Berry's phase of 2pi in bilayer graphene
K. S. Novoselov; E. McCann; S. V. Morozov; V. I. Fal'Ko; M. I. Katsnelson; U. Zeitler; D. Jiang; F. Schedin; A. K. Geim
2006-01-01
There are two known distinct types of the integer quantum Hall effect. One is the conventional quantum Hall effect, characteristic of two-dimensional semiconductor systems, and the other is its relativistic counterpart observed in graphene, where charge carriers mimic Dirac fermions characterized by Berry's phase pi, which results in shifted positions of the Hall plateaus. Here we report a third type
SÃ¡nchez, David
Kondo Effect in a Quantum Dot Coupled to Ferromagnetic Leads: A Numerical Renormalization Group-polarized leads on the Kondo physics of a quantum dot using the numerical renormalization group method. Our study demonstrates in an unambiguous way that the Kondo effect is not necessarily suppressed by the lead polarization
Many-body and quantum effects in the radial distribution function of liquid neon and argon
Elena Ermakova; Jan Solca; Hanspeter Huber; Dominik Marx
1995-01-01
Most simulations of liquids are performed in the framework of classical mechanics and the approximation of additivity of pair potentials. Besides errors due to the approximate pair potential, this leads to errors due to quantum effects and the neglect of many-body interactions. By calculating the radial distribution function from pure theory for liquid neon and argon with a quantum effective
MAS 335 Cryptography Notes 12: Quantum effects and bibliography Spring 2006
Banaji,. Murad
MAS 335 Cryptography Notes 12: Quantum effects and bibliography Spring 2006 Quantum effects systems, and how this behaviour is relevant to cryptography. There are two aspects which we treat in turn solve the hard problems on which modern public-key cryptography depends (factorisation and dis- crete
Hall effect of triplons in a dimerized quantum magnet
NASA Astrophysics Data System (ADS)
Romhányi, Judit; Penc, Karlo; Ganesh, R.
2015-04-01
SrCu2(BO3)2 is the archetypal quantum magnet with a gapped dimer-singlet ground state and triplon excitations. It serves as an excellent realization of the Shastry-Sutherland model, up to small anisotropies arising from Dzyaloshinskii-Moriya interactions. Here we demonstrate that these anisotropies, in fact, give rise to topological character in the triplon band structure. The triplons form a new kind of Dirac cone with three bands touching at a single point, a spin-1 generalization of graphene. An applied magnetic field opens band gaps resulting in topological bands with Chern numbers +/-2. SrCu2(BO3)2 thus provides a magnetic analogue of the integer quantum Hall effect and supports topologically protected edge modes. At a threshold value of the magnetic field set by the Dzyaloshinskii-Moriya interactions, the three triplon bands touch once again in a spin-1 Dirac cone, and lose their topological character. We predict a strong thermal Hall signature in the topological regime.
Magnetic topological insulators and quantum anomalous hall effect
NASA Astrophysics Data System (ADS)
Kou, Xufeng; Fan, Yabin; Lang, Murong; Upadhyaya, Pramey; Wang, Kang L.
2015-07-01
When the magnetic order is introduced into topological insulators (TIs), the time-reversal symmetry (TRS) is broken, and the non-trivial topological surface is driven into a new massive Dirac fermions state. The study of such TRS-breaking systems is one of the most emerging frontiers in condensed-matter physics. In this review, we outline the methods to break the TRS of the topological surface states. With robust out-of-plane magnetic order formed, we describe the intrinsic magnetisms in the magnetically doped 3D TI materials and the approach to manipulate each contribution. Most importantly, we summarize the theoretical developments and experimental observations of the scale-invariant quantum anomalous Hall effect (QAHE) in both the 2D and 3D Cr-doped (BiSb)2Te3 systems; at the same time, we also discuss the correlations between QAHE and other quantum transport phenomena. Finally, we highlight the use of TI/Cr-doped TI heterostructures to both manipulate the surface-related ferromagnetism and realize electrical manipulation of magnetization through the giant spin-orbit torques.
Single Electron Charging Effects in Quantum Dot Nanostructures.
NASA Astrophysics Data System (ADS)
Kumar, Arvind
This thesis focuses on the study of GaAs quantum dot devices, in which an electron gas is electrostatically confined to a small conducting island. The device dimensions are sufficiently small that striking effects due to the capacitive charging of the island by a single electron can be observed in the transistor characteristics, leading to a periodic dependence of the current on gate voltage. In particular, we study a quantum dot structure in which a novel gate geometry allows the island to be contacted by three electron reservoirs. When the dot charge is well -confined, periodic conductance oscillations due to Coulomb charging are observed in-phase with each other at two of the leads in response to a small excitation voltage at the third. As the tunnel barriers are made softer by changing the gate voltage, a strikingly different phenomenon is observed: conductance peaks at the two output leads evolve from perfect correlation to perfect anti-correlation with each other. Two simple models of transport in the weakly blockaded regime are presented as possible explanations. (Cpies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.).
Quantum effects in a simple ring with hydrogen bonds.
Kariev, Alisher M; Green, Michael E
2015-05-14
Complexes containing multiple arginines are common in proteins. The arginines are typically salt-bridged or hydrogen-bonded, so that their charges do not repel. Here we present a quantum calculation of a ring in which the components of a salt bridge composed of a guanidinium, the arginine side chain, and a carboxylic acid are separated by water molecules. When one water molecule is displaced from the ring, atomic charges of the other water molecule, as well as other properties, are significantly affected. The exchange and correlation energy differences between optimized and displaced rings are larger than thermal energy at room temperature, and larger than the sum of other energy differences. This suggests that calculations on proteins and other systems where such a ring may occur must take quantum effects into account; charges on certain atoms shift as substituents are added to the system: another water molecule, an -OH, or -CN bonded to either moiety. Also, charge shifts accompany proton shifts from the acid to guanidinium to ionize the salt bridge. The consequences of moving one water out of the ring give evidence for electron delocalization. Bond order and atomic charges are determined using natural bond orbital calculations. The geometry of the complex changes with ionization as well as the -OH and -CN additions but not in a simple manner. These results help in understanding the role of groups of arginines in salt-bridged clusters in proteins. PMID:25906287
Quantum Hall effect in polycrystalline CVD graphene: grain boundaries impact
NASA Astrophysics Data System (ADS)
Ribeiro-Palau, Rebeca; Lafont, Fabien; Schopfer, Felicien; Poirier, Wilfrid; Bouchiat, Vincent; Han, Zhen; Cresti, Alessandro; Cummings, Aron; Roche, Stephan
2014-03-01
It was demonstrated by Janssen et al. (New J. Phys. 2011) that graphene could surpass GaAs for quantum Hall resistance standards with an accuracy better than 10-10. Graphene should render possible the realization of a standard operating at T > 4 K and B < 4 T, easing its dissemination towards industry. To materialize this goal scalable graphene with outstanding electronic transport properties is required. We present measurements performed in large area Hall bars made of polycrystalline CVD graphene on Si/SiO2, with a carrier mobility of 0.6 T-1. Even at 20.2 T and 300 mK, the Hall resistance plateaus are insufficiently quantized at ? = +/- 2 and +/- 6 . This is due to a high dissipation manifested by a longitudinal resistance which does not drop to zero. We pointed out unusual power-law temperature dependencies of Rxx and an exponential magnetic field dependence. We do not observe the common thermally activated or VRH behaviors. This can be attributed to the grain boundaries in the sample that short-circuit the edge states, as supported by our numerical simulations. This reveals new and peculiar aspects of the quantum Hall effect in polycrystalline systems. Another unexpected feature is the observation of the ? = 0 and 1 states in such low mobility systems.
Ridolfo, A; Di Stefano, O; Fina, N; Saija, R; Savasta, S
2010-12-31
We study theoretically the quantum optical properties of hybrid molecules composed of an individual quantum dot and a metallic nanoparticle. We calculate the resonance fluorescence of this composite system. Its incoherent part, arising from nonlinear quantum processes, is enhanced by more than 2 orders of magnitude as compared to that of the dot alone. The coupling between the two systems gives rise to a Fano interference effect which strongly influences the quantum statistical properties of the scattered photons: a small frequency shift of the incident light field may cause changes in the intensity correlation function of the scattered field of orders of magnitude. The system opens a good perspective for applications in active metamaterials and ultracompact single-photon devices. PMID:21231659
William C. Daniel; Mark J. Pirwitz; John E. Willard; Richard A. Lange; L. David Hillis; Charles Landau
1996-01-01
This study was performed (1) to assess the incidence and magnitude of elastic recoil occurring within 15 minutes of successful coronary angioplasty, and (2) to determine the effect of subsequent additional balloon inflations on coronary luminal diameter in patients displaying substantial recoil. The coronary angiograms of 50 consecutive patients who underwent a successful percutaneous transluminal coronary angioplasty were analyzed using
Framing Anomaly in the Effective Theory of the Fractional Quantum Hall Effect
NASA Astrophysics Data System (ADS)
Gromov, Andrey; Cho, Gil Young; You, Yizhi; Abanov, Alexander G.; Fradkin, Eduardo
2015-01-01
We consider the geometric part of the effective action for the fractional quantum Hall effect (FQHE). It is shown that accounting for the framing anomaly of the quantum Chern-Simons theory is essential to obtain the correct gravitational linear response functions. In the lowest order in gradients, the linear response generating functional includes Chern-Simons, Wen-Zee, and gravitational Chern-Simons terms. The latter term has a contribution from the framing anomaly which fixes the value of thermal Hall conductivity and contributes to the Hall viscosity of the FQH states on a sphere. We also discuss the effects of the framing anomaly on linear responses for non-Abelian FQH states.
The WITCH experiment: Acquiring the first recoil ion spectrum
V. Yu. Kozlov; M. Beck; S. Coeck; P. Delahaye; P. Friedag; M. Herbane; A. Herlert; I. S. Kraev; M. Tandecki; S. Van Gorp; F. Wauters; Ch. Weinheimer; F. Wenander; D. Zakoucky; N. Severijns
2008-07-22
The standard model of the electroweak interaction describes beta-decay in the well-known V-A form. Nevertheless, the most general Hamiltonian of a beta-decay includes also other possible interaction types, e.g. scalar (S) and tensor (T) contributions, which are not fully ruled out yet experimentally. The WITCH experiment aims to study a possible admixture of these exotic interaction types in nuclear beta-decay by a precise measurement of the shape of the recoil ion energy spectrum. The experimental set-up couples a double Penning trap system and a retardation spectrometer. The set-up is installed in ISOLDE/CERN and was recently shown to be fully operational. The current status of the experiment is presented together with the data acquired during the 2006 campaign, showing the first recoil ion energy spectrum obtained. The data taking procedure and corresponding data acquisition system are described in more detail. Several further technical improvements are briefly reviewed.
Thermal/quantum effects and induced superstring cosmologies
NASA Astrophysics Data System (ADS)
Catelin-Jullien, Tristan; Kounnas, Costas; Partouche, Hervé; Toumbas, Nicolaos
2008-07-01
We consider classical superstring theories on flat four-dimensional space times, and where N=4 or N=2 supersymmetry is spontaneously broken. We obtain the thermal and quantum corrections at the string one-loop level and show that the back-reaction on the space time metric induces a cosmological evolution. We concentrate on heterotic string models obtained by compactification on a T torus and on T/Z orbifolds. The temperature T and the supersymmetry breaking scale M are generated via the Scherk Schwarz mechanism on the Euclidean time cycle and on an internal spatial cycle respectively. The effective field theory corresponds to a no-scale supergravity, where the corresponding no-scale modulus controls the SUSY-breaking scale. The classical flatness of this modulus is lifted by an effective thermal potential, given by the free energy. The gravitational field equations admit solutions where M, T and the inverse scale factor 1/a of the universe remain proportional. In particular the ratio M/T is fixed during time evolution. The induced cosmology is governed by a Friedmann Hubble equation involving an effective radiation term ˜1/a and an effective curvature term ˜1/a, whose coefficients are functions of the complex structure ratio M/T.
QUANTUM AND COULOMB EFFECTS IN NANODEVICES D. VASILESKA, H.R. KHAN, S.S. AHMED
Ringhofer, Christian
. Keywords: nanodevice modeling; quantum effects; discrete impurity effects. 1. Introduction Semiconductor in 1960. By 1968, both complementary metalÂoxideÂsemiconductor devices (CMOS) and polysilicon Work Kroemer's contributions to heterostructures--from heterostructure bipolar tran- sistors to lasers
Ferromagnetic Kondo effect in a triple quantum dot system.
Baruselli, P P; Requist, R; Fabrizio, M; Tosatti, E
2013-07-26
A simple device of three laterally coupled quantum dots, the central one contacted by metal leads, provides a realization of the ferromagnetic Kondo model, which is characterized by interesting properties like a nonanalytic inverted zero-bias anomaly and an extreme sensitivity to a magnetic field. Tuning the gate voltages of the lateral dots allows us to study the transition from a ferromagnetic to antiferromagnetic Kondo effect, a simple case of a Berezinskii-Kosterlitz-Thouless transition. We model the device by three coupled Anderson impurities that we study by numerical renormalization group. We calculate the single-particle spectral function of the central dot, which at zero frequency is proportional to the zero-bias conductance, across the transition, both in the absence and in the presence of a magnetic field. PMID:23931401
Evolution of Quantum Confinement Effects in Lead Iodide Semiconductor Clusters
NASA Astrophysics Data System (ADS)
Sawamura, Makoto
1990-01-01
Molecular orbital theory is used in the context of ab initio Hartree-Fock calculations to study the origin of quantum confinement effects in layered Pb_7 I_{14} clusters. As the cluster geometry is energy optimized in several steps, the structure distends into two quasi-hemispherical iodine layers sandwiching a hexagonal lead layer. At the equilibrium geometry for the lowest electronic state, Pb-Pb in-plane interatomic distances are contracted by 11.3% compared to the experimental bulk PbI_2 values. Optical spectra are observed to be blue-shifted by 0.3 to 2.1 eV relative to the energy band gap of crystalline PbI _2.
Magnetoelectric transport and quantum interference effect in ultrathin manganite films
Wang, Cong; Jin, Kui-juan, E-mail: kjjin@iphy.ac.cn; Gu, Lin; Lu, Hui-bin; Li, Shan-ming; Zhou, Wen-jia; Zhao, Rui-qiang; Guo, Hai-zhong; He, Meng; Yang, Guo-zhen [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2014-04-21
The magnetoelectric transport behavior with respect to the thicknesses of ultrathin La{sub 0.9}Sr{sub 0.1}MnO{sub 3} films is investigated in detail. The metal-insulator phase transition, which has never been observed in bulk La{sub 0.9}Sr{sub 0.1}MnO{sub 3}, is found in ultrathin films with thicknesses larger than 6 unit cells. Low-temperature resistivity minima appeared in films with thicknesses less than 10 unit cells. This is attributed to the presence of quantum interference effects. These data suggest that the influence of the weak localization becomes much pronounced as the film thickness decreases from 16 to 8 unit cells.
Fractional quantum Hall effect in a dilute magnetic semiconductor
NASA Astrophysics Data System (ADS)
Betthausen, C.; Giudici, P.; Iankilevitch, A.; Preis, C.; Kolkovsky, V.; Wiater, M.; Karczewski, G.; Piot, B. A.; Kunc, J.; Potemski, M.; Wojtowicz, T.; Weiss, D.
2014-09-01
We report the observation of the fractional quantum Hall effect in the lowest Landau level of a two-dimensional electron system (2DES), residing in the diluted magnetic semiconductor Cd1-xMnxTe. The presence of magnetic impurities results in a giant Zeeman splitting leading to an unusual ordering of composite fermion Landau levels. In experiment, this results in an unconventional opening and closing of fractional gaps around the filling factor ? =3/2 as a function of an in-plane magnetic field, i.e., of the Zeeman energy. By including the s-d exchange energy into the composite Landau level spectrum the opening and closing of the gap at filling factor 5/3 can be modeled quantitatively. The widely tunable spin-splitting in a diluted magnetic 2DES provides a means to manipulate fractional states.
Spin quantum Hall effects in featureless nonfractionalized spin-1 magnets
NASA Astrophysics Data System (ADS)
Lu, Yuan-Ming; Lee, Dung-Hai
2014-05-01
The Affleck-Kennedy-Lieb-Tasaki state (or Haldane phase) in a spin-1 chain represents a large class of gapped topological paramagnets that host symmetry-protected gapless excitations on the boundary. In this work, we show how to realize this type of featureless spin-1 state on a generic two-dimensional lattice. These states have a gapped spectrum in the bulk, but they support gapless edge states protected by spin rotational symmetry along a certain direction, and they exhibit the spin quantum Hall effect. Using a fermion representation of integer spins, we show a concrete example of such spin-1 topological paramagnets on a kagome lattice, and we suggest a microscopic spin-1 Hamiltonian that may realize it.
Casimir effect between Topological Insulators: a proposal for quantum levitation
NASA Astrophysics Data System (ADS)
Rodriguez-Lopez, Pablo; Grushin, Adolfo; Cortijo, Alberto
2013-03-01
In this talk I will study the Casimir interaction between Topological Insulators (TIs). I will start with a brief description of the TIs, to explain what a TI is, and why they are interesting from a Casimir effect point of view. In particular, a three dimensional Topological Insulator is characterized by its topological magnetoelectric coupling ? ? 0. We will discuss the electromagnetic response of the TIs, how a magnetoelectric coupling between TE and TM modes appears in this material and its consequences. We will show how, by tuning the parameter ? of the TI, we will be able to change the behavior of the Casimir energy between Tis from attraction to repulsion for all distances, and even the appearance of an equilibrium distance in the system. Then TIs can be potentially used to obtain ``quantum levitation'' and to avoid the sticking phenomena in NEMS.
Magnetic quantum coherence effect in Ni4 molecular transistors.
González, Gabriel; Leuenberger, Michael N
2014-07-01
We present a theoretical study of electron transport in Ni4 molecular transistors in the presence of Zeeman spin splitting and magnetic quantum coherence (MQC). The Zeeman interaction is extended along the leads which produces gaps in the energy spectrum which allow electron transport with spin polarized along a certain direction. We show that the coherent states in resonance with the spin up or down states in the leads induces an effective coupling between localized spin states and continuum spin states in the single molecule magnet and leads, respectively. We investigate the conductance at zero temperature as a function of the applied bias and magnetic field by means of the Landauer formula, and show that the MQC is responsible for the appearence of resonances. Accordingly, we name them MQC resonances. PMID:24918902
Quantum spin Hall effect and topological insulators for light
Bliokh, Konstantin Y
2015-01-01
We show that free-space light has intrinsic quantum spin-Hall effect (QSHE) properties. These are characterized by a non-zero topological spin Chern number, and manifest themselves as evanescent modes of Maxwell equations. The recently discovered transverse spin of evanescent modes demonstrates spin-momentum locking stemming from the intrinsic spin-orbit coupling in Maxwell equations. As a result, any interface between free space and a medium supporting surface modes exhibits QSHE of light with opposite transverse spins propagating in opposite directions. In particular, we find that usual isotropic metals with surface plasmon-polariton modes represent natural 3D topological insulators for light. Several recent experiments have demonstrated transverse spin-momentum locking and spin-controlled unidirectional propagation of light at various interfaces with evanescent waves. Our results show that all these experiments can be interpreted as observations of the QSHE of light.
Non-linear quantum noise effects in scale invariant junctions
Mihail Mintchev; Luca Santoni; Paul Sorba
2015-02-18
We study non-equilibrium steady state transport in scale invariant quantum junctions with focus on the particle and heat fluctuations captured by the two-point current correlation functions. We show that the non-linear behavior of the particle current affects both the particle and heat noise. The existence of domains of enhancement and reduction of the noise power with respect to the linear regime are observed. The impact of the statistics is explored. We demonstrate that in the scale invariant case the bosonic particle noise exceeds the fermionic one in the common domain of heat bath parameters. Multi-lead configurations are also investigated and the effect of probe terminals on the noise is discussed.
The effect of dust size distribution on quantum dust acoustic wave
El-Labany, S. K.; El-Taibany, W. F.; Behery, E. E. [Department of Physics, Faculty of Science, Mansoura University, Damietta Branch, Damietta El-Gedida, P.O. 34517 (Egypt); El-Siragy, N. M. [Department of Physics, Faculty of Science, Tanta University, Tanta, P.O. 31527 (Egypt)
2009-09-15
Based on the quantum hydrodynamics theory, a proposed model for quantum dust acoustic waves (QDAWs) is presented including the dust size distribution (DSD) effect. A quantum version of Zakharov-Kuznetsov equation is derived adequate for describing QDAWs. Two different DSD functions are applied. The relevance of the wave velocity, amplitude, and width to the DSD is investigated numerically. The quantum effect changes only the soliton width. A brief conclusion is presented to the current findings and their relevance to astrophysics data is also discussed.
Sodium multiple quantum spectroscopy of articular cartilage: effects of mechanical compression.
Duvvuri, U; Kaufman, J H; Patel, S D; Bolinger, L; Kneeland, J B; Leigh, J S; Reddy, R
1998-09-01
The effects of mechanical compression on the multiple quantum coherences generated from sodium ions in articular cartilage were investigated. Cartilage samples obtained from bovine patellae were studied during compression at 0.7 MPa (100 psi) for 1 hour. The double quantum filtered spectra showed marked lineshape changes in the compressed samples. Compression did not seem to influence the lineshapes of the single quantum and triple quantum filtered spectra significantly. We found that the residual quadrupolar interaction was reduced in the compressed samples. Changes in the ordering of collagen fibers may be responsible for the observed effect. PMID:9727939
On the empirical adequacy of quantum-like models of judgment for question order effect
Thomas Boyer-Kassem; Sébastien Duchêne; Éric Guerci
2015-05-12
Lately, so-called "quantum" models, based on parts of the mathematics of quantum mechanics, have been developed in decision theory and cognitive sciences to account for seemingly irrational or paradoxical human judgments. In this paper, we limit ourselves to such quantum-like models that address question order effects, i. e. cases in which given answers depend on the order of presentation of the questions. From the quantum law of reciprocity, we derive new empirical predictions that we call the Grand Reciprocity equations, that must be satisfied by many existing quantum-like models, on the condition that they are non-degenerate. Using only existing data sets, we show that most models on which these equations apply fail the test. We take it to suggest that degenerate quantum-like models should be the focus of forthcoming research in the area, and that more research should be done on the empirical adequacy of quantum-like models more generally.
J. D. Lewin; P. F. Smith
1996-01-01
We present a systematic derivation and discussion of the practical formulae needed to design and interpret direct searches for nuclear recoil events caused by hypothetical weakly interacting dark matter particles. Modifications to the differential energy spectrum arise from the Earth's motion, recoil detection efficiency, instrumental resolution and threshold, multiple target elements, spin-dependent and coherent factors, and nuclear form factor. We
New Technique for the Measurement of the Scintillation Efficiency of Nuclear Recoils
Jelena Ninkovic; Peter Christ; Godehard Angloher; Dieter Hauff; Partick Huff; Emilija Pantic; Federica Petricca; Franz Proebst; Wolfgang Seidel
2006-04-05
We present a new technique developed for the measurement of the scintillation efficiency of nuclear recoils in solid scintillators. Using this technique we measured the quenching of the scintillation efficiency for the various recoiling nuclei in CaWO4 crystals which are used in direct Dark Matter searches.
at OMEGA and the NIF D. T. Casey, J. A. Frenje, M. Gatu Johnson, F. H. SÃ©guin, C. K. Li et al. Citation the magnetic recoil spectrometer at OMEGA and the NIFa) D. T. Casey,1,b) J. A. Frenje,1 M. Gatu Johnson,1 F. H 2012) A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA
Beam suppression of the DRAGON recoil separator for 3He(?,?)7Be
NASA Astrophysics Data System (ADS)
Sjue, S. K. L.; Nara Singh, B. S.; Adsley, P.; Buchmann, L.; Carmona-Gallardo, M.; Davids, B.; Fallis, J.; Fulton, B. R.; Galinski, N.; Hager, U.; Hass, M.; Howell, D.; Hutcheon, D. A.; Laird, A. M.; Martin, L.; Ottewell, D.; Reeve, S.; Ruiz, C.; Ruprecht, G.; Triambak, S.
2013-02-01
Preliminary studies in preparation for an absolute cross-section measurement of the radiative capture reaction 3He(?,?)7Be with the DRAGON recoil separator have demonstrated beam suppression >1014 at the 90% confidence level. A measurement of this cross section by observation of 7Be recoils at the focal plane of the separator should be virtually background free.
Polarized Neutron $?$-Decay: the Proton Asymmetry and Recoil-Order Currents
S. K. L. Sjue
2010-10-01
We present an analytic, recoil-order calculation of the proton asymmetry from polarized neutron $\\beta$-decay. The differential decay rate in terms of electron energy and proton direction follows, parametrized in terms of the most general Lorentz-invariant hadron current coupled to a left-handed lepton current. Implications for experimental efforts to measure recoil-order currents are discussed.
Serial intravascular ultrasound studies fail to show evidence of chronic Palmaz-Schatz stent recoil
Jack A. Painter; Gary S. Mintz; S. Chiu Wong; Jeffrey J. Popma; Augusto D. Pichard; Kenneth M. Kent; Lowell F. Satler; Martin B. Leon
1995-01-01
Serial IVUS analysis after intervention and at follow-up showed that late recoil of the Palmaz-Schatz stent rarely occurred, and when it did occur, late stent recoil was minimal. The dominant mechanism of late lumen loss in this setting was neointimal hyperplasia.
Polarized neutron beta-decay: Proton asymmetry and recoil-order currents
S. K. Sjue
2005-01-01
We present an analytic, recoil-order calculation of the proton asymmetry from polarized neutron beta-decay. The differential decay rate in terms of electron energy and proton direction follows, parametrized in terms of the most general Lorentz-invariant hadron current coupled to a left-handed lepton current. Implications for experimental efforts to measure recoil-order currents are discussed.
Analysis of $B\\to K^* \\ell^+ \\ell^-$ decays at large recoil
Chuan-Hung Chen; C. Q. Geng
2002-05-31
We study the exclusive decays of $B\\to K^{*}\\ell^+ \\ell^-$ within the framework of the perturbative QCD (PQCD). We obtain the form factors for the $B\\to K^{*}$ transition in the large recoil region, where the PQCD for heavy $B$ meson decays is reliable. We find that our results for the form factors at $q^2=0$ are consistent with those from most of the other QCD models in the literature. Via the decay chain of $B\\to K^* (K\\pi) \\ell^+ \\ell^-$, we obtain many physical observables related to the different helicity combinations of $B\\to K^* \\ell^+ \\ell^-$. In particular, we point out that the T violating effect suppressed in the standard model can be up to $O(10%)$ in some CP violating models with new physics.
Stochastic Liouville equation approach for the effect of noise in quantum computations
Cheng, Y.C.; Silbey, R.J. [Department of Chemistry and Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2004-05-01
We propose a model based on a generalized effective Hamiltonian for studying the effect of noise in quantum computations. The system-environment interactions are taken into account by including stochastic fluctuating terms in the system Hamiltonian. Treating these fluctuations as Gaussian Markov processes with zero mean and {delta}-function correlation times, we derive an exact equation of motion describing the dissipative dynamics for a system of n qubits. We then apply this model to study the effect of noise on the quantum teleportation and a generic quantum controlled-NOT (CNOT) gate. For quantum teleportation, the effect of noise in the quantum channels is found to be additive, and the teleportation fidelity depends on the state of the teleported qubit. The effect of collective decoherence is also studied for the two-qubit entangled states. For the quantum CNOT gate, we study the effect of noise on a set of one- and two-qubit quantum gates, and show that the results can be assembled together to investigate the quality of a quantum CNOT gate operation. We compute the averaged gate fidelity and gate purity for the quantum CNOT gate and investigate phase, bit-flip, and flip-flop errors during the CNOT gate operation. The effects of direct interqubit coupling and fluctuations on the control fields are also studied. We find that the quality of the CNOT gate operation is sensitive to the strengths of the control fields and the strengths of the noise, and the effect of noise is additive regardless of its origin. We discuss the limitations and possible extensions of this model. In sum, we demonstrate a simple model that enables us to investigate the effect of noise in arbitrary quantum circuits under realistic device conditions.
Performance of a two-state quantum engine improved by the superposition effect
NASA Astrophysics Data System (ADS)
Ou, CongJie; Huang, ZhiFu; Lin, BiHong; Chen, JinCan
2013-10-01
The performance of a two-state quantum engine under different conditions is analyzed. It is shown that the efficiency of the quantum engine can be enhanced by superposing the eigenstates at the beginning of the cycle. By employing the finite-time movement of the potential wall, the power output of the quantum engine as well as the efficiency at the maximum power output (EMP) can be obtained. A generalized potential is adopted to describe a class of two-level quantum engines in a unified way. The results obtained show clearly that the performances of these engines depend on the external potential, the geometric configuration of the quantum engines, and the superposition effect. Moreover, it is found that the superposition effect will enlarge the optimally operating region of quantum engines.
Kondo effect in a topological insulator quantum dot
NASA Astrophysics Data System (ADS)
Xin, Xianhao; Zhou, Di
2015-04-01
We investigate theoretically the nonequilibrium transport properties of a topological insulator quantum dot (TIQD) in the Coulomb blockade and Kondo regime. An Anderson impurity model is applied to a TIQD system coupled to two external leads, and we show that the model realizes the spin-orbital Kondo effect at the Dirac point where the edge states are not split by a finite-size effect, leading to an additional S U (4 ) symmetry because of the presence of strong mixture among four internal degrees of freedom. In a more realistic situation where the degeneracy is lifted due to the finite-size effect, we demonstrate that there is a richer structure in transport measurements. We illustrate a continuous crossover from four (spin and orbital) Coulomb peaks with large interpair spacing and small intrapair spacing to a double-peak structure in the local density of states (LDOS) as increasing the hybridization strength ? within the Coulomb blockade regime. When temperature falls below the Kondo temperature TK, four Kondo peaks show up in the nonequilibrium LDOS. Two of them are located at the chemical potential of each lead, and the other two are shifted away from the chemical potential by an amount proportional to the TIQD's bare energy level, leading to a triple-peak structure in the differential conductance when a bias voltage is applied.
Quantum Interference Effects in Horava-Lifshitz Gravity
Abdullo Hakimov; Bobur Turimov; Ahmadjon Abdujabbarov; Bobomurot Ahmedov
2010-08-26
The relativistic quantum interference effects in the spacetime of slowly rotating object in the Ho\\v{r}ava-Lifshitz gravity as the Sagnac effect and phase shift of interfering particle in neutron interferometer are derived. We consider the extension of Kehagias-Sfetsos (KS) solution~\\cite{ks09} in the Ho\\v{r}ava-Lifshitz gravity for the slowly rotating gravitating object. Using the covariant Klein-Gordon equation in the nonrelativistic approximation, it is shown that the phase shift in the interference of particles includes the gravitational potential term with the KS parameter $\\omega$. It is found that in the case of the Sagnac effect, the influence of the KS parameter $\\omega$ is becoming important due to the fact that the angular velocity of the locally non rotating observer is increased in Ho\\v{r}ava gravity. From the results of the recent experiments~\\cite{holgeretal} we have obtained lower limit for the coupling KS constant as $\\omega \\simeq 1.25 \\cdot 10^{-25} \\rm{cm}^{2}$. Finally, as an example, we apply the obtained results to the calculation of the UCN (ultra-cold neutrons) energy level modification in the gravitational field of slowly rotating gravitating object in the Ho\\v{r}ava-Lifshitz gravity.
Effective theories of the fractional quantum Hall effect at generic filling fractions
Blok, B.; Wen, X.G. (Institute for Advanced Study, Princeton, NJ (USA))
1990-11-01
We propose effective theories that describe the fractional quantum Hall effect (FQHE) states for the generic filling fractions {nu}=1/ {summation}{sub {ital I}} (1/{ital m}{sub {ital I}}) where {ital m}{sub {ital I}} are integers. The theories describe the microscopic FQHE states proposed by Jain. We calculate charges and statistics of quasiparticles in these states. The structure of the edge states is derived directly from the underlying effective theory in the bulk. Our results are shown to be consistent with those obtained from the microscopic theory.
A RUNAWAY BLACK HOLE IN COSMOS: GRAVITATIONAL WAVE OR SLINGSHOT RECOIL?
Civano, F.; Elvis, M.; Lanzuisi, G.; Hao, H.; Aldcroft, T. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Jahnke, K. [Max Planck Institut fuer Astronomie, Koenigstuhl 17, Heidelberg, D-69117 (Germany); Zamorani, G.; Comastri, A.; Bolzonella, M. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Blecha, L.; Loeb, A. [Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States); Bongiorno, A.; Brusa, M. [Max Planck Institut fuer Extraterrestrische Physik Giessenbachstrasse 1, D-85748 Garching (Germany); Leauthaud, A. [LBNL and BCCP, University of California, Berkeley, CA 94720 (United States); Mainieri, V. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany); Piconcelli, E. [INAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio Catone (Italy); Salvato, M.; Scoville, N. [California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Trump, J. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Vignali, C. [Dipartimento di Astronomia, Universita degli Studi di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
2010-07-01
We present a detailed study of a peculiar source detected in the COSMOS survey at z = 0.359. Source CXOC J100043.1+020637, also known as CID-42, has two compact optical sources embedded in the same galaxy. The distance between the two, measured in the HST/ACS image, is 0.''495 {+-} 0.''005 that, at the redshift of the source, corresponds to a projected separation of 2.46 {+-} 0.02 kpc. A large ({approx}1200 km s{sup -1}) velocity offset between the narrow and broad components of H{beta} has been measured in three different optical spectra from the VLT/VIMOS and Magellan/IMACS instruments. CID-42 is also the only X-ray source in COSMOS, having in its X-ray spectra a strong redshifted broad absorption iron line and an iron emission line, drawing an inverted P-Cygni profile. The Chandra and XMM-Newton data show that the absorption line is variable in energy by {Delta}E = 500 eV over four years and that the absorber has to be highly ionized in order not to leave a signature in the soft X-ray spectrum. That these features-the morphology, the velocity offset, and the inverted P-Cygni profile-occur in the same source is unlikely to be a coincidence. We envisage two possible explanations, both exceptional, for this system: (1) a gravitational wave (GW) recoiling black hole (BH), caught 1-10 Myr after merging; or (2) a Type 1/Type 2 system in the same galaxy where the Type 1 is recoiling due to the slingshot effect produced by a triple BH system. The first possibility gives us a candidate GW recoiling BH with both spectroscopic and imaging signatures. In the second case, the X-ray absorption line can be explained as a BAL-like outflow from the foreground nucleus (a Type 2 AGN) at the rearer one (a Type 1 AGN), which illuminates the otherwise undetectable wind, giving us the first opportunity to show that fast winds are present in obscured active galactic nuclei (AGNs), and possibly universal in AGNs.
Exponential speed-up with a single bit of quantum information: Testing the quantum butterfly effect
David Poulin; Robin Blume-Kohout; Raymond Laflamme; Harold Ollivier
2003-10-06
We present an efficient quantum algorithm to measure the average fidelity decay of a quantum map under perturbation using a single bit of quantum information. Our algorithm scales only as the complexity of the map under investigation, so for those maps admitting an efficient gate decomposition, it provides an exponential speed up over known classical procedures. Fidelity decay is important in the study of complex dynamical systems, where it is conjectured to be a signature of quantum chaos. Our result also illustrates the role of chaos in the process of decoherence.
Experimental observation of the quantum Hall effect and Berry's phase in graphene
Yuanbo Zhang; Yan-Wen Tan; Horst L. Stormer; Philip Kim
2005-01-01
When electrons are confined in two-dimensional materials, quantum-mechanically enhanced transport phenomena such as the quantum Hall effect can be observed. Graphene, consisting of an isolated single atomic layer of graphite, is an ideal realization of such a two-dimensional system. However, its behaviour is expected to differ markedly from the well-studied case of quantum wells in conventional semiconductor interfaces. This difference
Effects of disorder in three-dimensional Z2 quantum spin Hall systems
Ryuichi Shindou; Shuichi Murakami
2009-01-01
In this paper, we address ourselves to the nonmagnetic disorder effects onto the quantum critical point, which intervenes the three-dimensional Z2 quantum spin Hall insulator (topological insulator) and an ordinary insulator. The minimal model describing this type of the quantum critical point is the single copy of the 3+1 Dirac fermion, whose topological mass m induces the phase transition between
Disorder and the transition to the quantum Hall effect in quasi-one-dimensional channels
K. Shepard
1991-01-01
The transition to the integral-quantum-Hall-effect regime through the suppression of backscattering is studied theoretically on a model system by calculating the two-terminal conductance of a quasi-one-dimensional quantum wire as a magnetic field is applied in the presence of disorder. The quantum Hall regime is entered when there is negligible overlap between electron edge states localized at opposite sides of the
Fragment recoil anisotropies in the photoinitiated decomposition of HNCO
NASA Astrophysics Data System (ADS)
Zyrianov, M.; Droz-Georget, Th.; Reisler, H.
1999-01-01
The photofragment ion imaging technique is used to determine product recoil anisotropy parameters, ?, and correlated state distributions in the S1(1A?)?S0(1A') photoinitiated decomposition of HNCO into three competing channels: (1) 3NH+CO, (2) H+NCO, and (3) 1NH+CO [where 3NH and 1NH denote NH(X 3?-) and NH(a 1?), respectively]. In particular, the region in the vicinity of the 1NH+CO threshold is investigated. The measured recoil anisotropies fall into two distinct groups corresponding to time scales of <1 ps (?<-0.6), and >5-10 ps (??0.0). With 230.1 nm photolysis, CO(J=0-14) originating in channel (3) is produced with ?=-0.8±0.05 via direct dissociation on S1 above a barrier of 470±60 cm-1. CO at low J-states appears with most of the available energy in the translational degree of freedom and is correlated with 1NH in its lowest rotational states. A small contribution to channel (3) from S0 dissociation (observed mainly for J=14,15) gives rise to an isotropic recoil distribution, and a hotter correlated 1NH rotational distribution. At the same wavelength, CO correlated with 3NH is identified by its high translational energy and exhibits an isotropic angular distribution. We propose that the pathway leading to its formation is S1?S0?T1. H-atom signals from channel (2) have isotropic angular distributions at photolysis wavelengths 243-215 nm; this places a lower limit of 8140 cm-1 on the barrier to direct dissociation on S1 to channel (2). The >5 ps time scale for the appearance of channel (2) implies dissociation on S0 following internal conversion. The mechanism described here for the one-photon decomposition of HNCO in the wavelength region 260-230 nm is in accord with other available experimental and theoretical findings.
Effective-field-theory model for the fractional quantum Hall effect
NASA Technical Reports Server (NTRS)
Zhang, S. C.; Hansson, T. H.; Kivelson, S.
1989-01-01
Starting directly from the microscopic Hamiltonian, a field-theory model is derived for the fractional quantum Hall effect. By considering an approximate coarse-grained version of the same model, a Landau-Ginzburg theory similar to that of Girvin (1986) is constructed. The partition function of the model exhibits cusps as a function of density. It is shown that the collective density fluctuations are massive.
Choi, Mahn-Soo
Kondo effect of quantum dots in the quantum Hall regime Mahn-Soo Choi, N. Y. Hwang, and S.-R. Eric December 2002; revised manuscript received 3 March 2003; published 26 June 2003 We report on the Kondo to a Kondo effect, which can be mapped into an ordinary Kondo effect in a fictitious magnetic field. We
Single Electron Charging and Quantum Effects in Semiconductor Nanostructures
NASA Astrophysics Data System (ADS)
Foxman, Ethan Bradley
1993-01-01
We present an experimental study of a small region (~0.3 times 0.3 mum^2) of two-dimensional electron gas in a GaAs/rm Al_{x}Ga_{1-x}As heterostructure. The small electron gas is coupled to electrical leads through tunnel barriers formed by negatively biased Schottky gates on the surface of the heterostructure. Electron transport is studied as a function of gate voltage, magnetic field, temperature, bias voltage and tunneling barrier height. We observe a rich interplay between single electron charging and quantum effects. The conductance of such systems was known to consist of a series of nearly periodic conductance peaks.^{1,2} We further investigate this behavior and show that our observations are consistent with a model that synthesizes classical single electron charging and a discrete tunneling density of states.^{3,4}. We investigate the nature and origin of this tunneling density of states. The spectrum of states is determined through current-voltage measurements and low-bias conductance measurements. The tunneling density of states is mapped as a function of gate voltage and magnetic field. In the latter case, we show that our observations can be understood through a self-consistent model of single electron charging in the quantum Hall regime.^5. Lastly, we report conductance measurements in the regime where the conductance across the tunnel barriers separating the small electron gas from its leads becomes of order e^2/h. We observe that in this regime single electron charging effects are quenched. This effect is shown to arise from an increased capacitance across one of the barriers and from the increased lifetime broadening of states in the small electron gas. ^6 (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.) ftn^1J. H. F. Scott -Thomas, S. B. Field, M. A. Kastner, H. I. Smith, and D. A. Antoniadis, Phys. Rev. Lett. 62, 583 (1989). ^2U. Meirav, M. A. Kastner, and S. J. Wind, Phys. Rev. Lett. 65, 771 (1990). ^3Yigal Meir, Ned S. Wingreen, P. A. Lee, Phys. Rev. Lett. 66, 3048 (1991). ^4 C. W. J. Beenakker, Phys. Rev. B 44, 1646 (1991). ^5P. L. McEuen, E. B. Foxman, Jari Kinaret, U. Meirav, M. A. Kastner, Ned S. Wingreen, and S. J. Wind, Phys. Rev. B 45, 11419 (1992). ^6E. B. Foxman, P. L. McEuen, U. Meirav, Ned S. Wingreen, Yigal Meir, Paul A. Belk, N. R. Belk, M. A. Kastner and S. J. Wind, Phys. Rev. B 47, 10020 (1993).
Chaos and the quantum: how nonlinear effects can explain certain quantum paradoxes
Wm C. McHarris
2011-01-01
In recent years we have suggested that many of the so-called paradoxes resulting from the Copenhagen interpretation of quantum mechanics could well have more logical parallels based in nonlinear dynamics and chaos theory. Perhaps quantum mechanics might not be strictly linear as has been commonly postulated, and indeed, during the past year experimentalists have discovered signatures of chaos in a
Orbital Kondo effect in a parallel double quantum dot.
Bao, Zhi-qiang; Guo, Ai-Min; Sun, Qing-feng
2014-10-29
We construct a theoretical model to study the orbital Kondo effect in a parallel double quantum dot (DQD). Recently, pseudospin-resolved transport spectroscopy of the orbital Kondo effect in a DQD has been experimentally reported. The experiment revealed that when interdot tunneling is ignored, two and one Kondo peaks exist in the conductance-bias curve for pseudospin-non-resolved and pseudospin-resolved cases, respectively. Our theoretical studies reproduce this experimental result. We also investigate the case of all lead voltages being non-equal (the complete pseudospin-resolved case) and found that there are at most four Kondo peaks in the curve of the conductance versus the pseudospin splitting energy. When interdot tunneling is introduced, some new Kondo peaks and dips can emerge. Furthermore, the pseudospin transport and the pseudospin flipping current are also studied in the DQD system. Since the pseudospin transport is much easier to control and measure than the real spin transport, it can be used to study the physical phenomenon related to the spin transport. PMID:25299453
Many-Body Effects in Quantum-Well Intersubband Transitions
NASA Technical Reports Server (NTRS)
Li, Jian-Zhong; Ning, Cun-Zheng
2003-01-01
Intersubband polarization couples to collective excitations of the interacting electron gas confined in a semiconductor quantum well (Qw) structure. Such excitations include correlated pair excitations (repellons) and intersubband plasmons (ISPs). The oscillator strength of intersubband transitions (ISBTs) strongly varies with QW parameters and electron density because of this coupling. We have developed a set of kinetic equations, termed the intersubband semiconductor Bloch equations (ISBEs), from density matrix theory with the Hartree-Fock approximation, that enables a consistent description of these many-body effects. Using the ISBEs for a two-conduction-subband model, various many-body effects in intersubband transitions are studied in this work. We find interesting spectral changes of intersubband absorption coefficient due to interplay of the Fermi-edge singularity, subband renormalization, intersubband plasmon oscillation, and nonparabolicity of bandstructure. Our results uncover a new perspective for ISBTs and indicate the necessity of proper many-body theoretical treatment in order for modeling and prediction of ISBT line shape.
Quantum fluctuations and isotope effects in ab initio descriptions of water
Wang, Lu; Markland, Thomas E., E-mail: tmarkland@stanford.edu [Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, California 94305 (United States); Ceriotti, Michele, E-mail: michele.ceriotti@epfl.ch [Laboratory of Computational Science and Modeling, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland)
2014-09-14
Isotope substitution is extensively used to investigate the microscopic behavior of hydrogen bonded systems such as liquid water. The changes in structure and stability of these systems upon isotope substitution arise entirely from the quantum mechanical nature of the nuclei. Here, we provide a fully ab initio determination of the isotope exchange free energy and fractionation ratio of hydrogen and deuterium in water treating exactly nuclear quantum effects and explicitly modeling the quantum nature of the electrons. This allows us to assess how quantum effects in water manifest as isotope effects, and unravel how the interplay between electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water.
Neutron absorbed dose determination by calculations of recoil energy.
Wrobel, F; Benabdesselam, M; Iacconi, P; Lapraz, D
2004-01-01
The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy. PMID:15353750
Proton recoil spectroscopy 400 meters from a fission neutron source
Stanka, M.B. [STECS-NE, Aberdeen Proving Ground, MD (United States)
1994-12-31
Neutron kerma and spectrum measurements have been made at the US Army Pulse Radiation Facility (APRF) to 400m in an air-over-ground geometry from a fission neutron source and have been compared to Monte Carlo transport calculations. The neutron spectra measurements were made using a rotating neutron spectrometer. This spectrometer consists of four spherical proton-recoil detectors mounted on a common rotating base. Detector radius, gas composition, and pressure have been varied to allow sensitivity over a neutron range of 50 keV to 4.5 MeV. Neutron kerma was determined by using the Kerr soft-tissue kerma factors. Measured neutron kerma agreed with the calculated neutron kerma to within 5%. Comparisons with other neutron spectrometers such as NE213 and Bonner Spheres are presented and agreement between the different spectrometers is better than 20%.
Time of flight elastic recoil detection for thin film analysis
Rabalais, M. S.; Peterson, D. L. Jr.; Wang, Y. Q.; Sheu, W. J.; Glass, G. A. [Eric Jonsson School of Engineering, University of Texas at Dallas, Dallas, Texas 75080 (United States); Center for Interfacial Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Acadiana Research Laboratory, University of Southwestern Louisiana, Lafayette, Louisiana 70504 (United States)
1999-06-10
Time-of-flight elastic recoil detection (TOF-ERD) is a powerful and complimentary technique to Rutherford Backscattering Spectrometry (RBS) for elemental analysis in surfaces and thin films. Its main advantages lie in its capability of not only simultaneously depth profiling light elements (3
Time of flight elastic recoil detection for thin film analysis
Rabalais, M.S.; Peterson, D.L. Jr. [Eric Jonsson School of Engineering, University of Texas at Dallas, Dallas, Texas 75080 (United States); Wang, Y.Q. [Center for Interfacial Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Sheu, W.J.; Glass, G.A. [Acadiana Research Laboratory, University of Southwestern Louisiana, Lafayette, Louisiana 70504 (United States)
1999-06-01
Time-of-flight elastic recoil detection (TOF-ERD) is a powerful and complimentary technique to Rutherford Backscattering Spectrometry (RBS) for elemental analysis in surfaces and thin films. Its main advantages lie in its capability of not only simultaneously depth profiling light elements (3{lt}Z{lt}9) but also with a superb depth resolution (a few nm). This paper describes the construction and calibration of a TOF-ERD system recently added to the NEC 5SDH-2 1.7 MV Tandem Pelletron{reg_sign} Accelerator at the University of Southwestern Louisiana. Initial results on varying-thickness carbon thin foils using MeV gold ion beams yielded a depth resolution of approximately 3.8 nm. TOF-ERD computer software written on site to simulate spectra and to convert time spectra into depth profiles is also presented. {copyright} {ital 1999 American Institute of Physics.}
Studying Binary AGN and Recoiling Black Holes with Chandra
NASA Astrophysics Data System (ADS)
Koss, Michael
2014-11-01
One of the leading theories for the growth of supermassive black holes is that disruptive events like galaxy mergers trigger AGN by sending gas toward the black hole. During this process there should be time when AGN can be detected in both of the merging galaxies as dual or binary AGN. However, initial surveys found dual AGN are exceedingly rare, with studies based on quasars measuring only 0.1%. I will discuss current results on measuring the dual AGN fraction of nearby AGN to the smallest physical separations using the highest resolutions from Chandra. Finally, as observations become increasingly focused on measuring dual or binary AGN in galaxy mergers at the smallest separations, we are also beginning to place important constraints on recoiling black holes.
Molecular Dynamics Simulation of Energetic Uranium Recoil Damage in Zircon
Devanathan, Ram; Corrales, Louis R.; Weber, William J.; Chartier, Alain; Meis, Constantin
2006-10-11
Defect production and amorphization due to energetic uranium recoils in zircon (ZrSiO4), which is a promising ceramic nuclear waste form, is studied using molecular dynamics simulations with a partial charge model. An algorithm that distinguishes between undamaged crystal, crystalline defects and amorphous regions is used to develop a fundamental understanding of the primary damage state. The amorphous cascade core is separated from the surrounding crystal by a defect-rich region. Small, chemically inhomogeneous amorphous clusters are also produced around the core. The amorphous regions consist of under-coordinated Zr and polymerized Si leading to amorphization and phase separation on a nanometer scale into Zr- and Si-rich regions. This separation could play an important role in the experimentally observed formation of nanoscale ZrO2 in ZrSiO4 irradiated at elevated temperatures.
Quantum Anomalous Hall Effect in Hetero Magnetic Topological Insulator Structures
NASA Astrophysics Data System (ADS)
Wang, Kang
2014-03-01
The quantum anomalous Hall effect (QAHE), which has the quantized Hall conductance of h /e2 in the absence of external field, was expected to happen in a magnetic 3-D topological insulators (TIs) system. In this talk, we report recent progress of QAHE-related physics in the TRS-breaking field. In the first part, we show the generation of robust magnetism by doping magnetic ions (Cr) into the host (BixSb1-x)2 Te3 materials. With gate-controlled magneto-transport measurements, we demonstrate the presence of both the hole-mediated RKKY coupling and carrier-independent van Vleck magnetism. By adjusting the Cr doping concentration and Bi/Sb ratio, we establish an effective way to experimentally approach to the QAHE region. The second part of this talk discusses the manipulation of surface-related magnetism in the modulation-doped TI/Cr-doped TI heterostructures. We investigate the role of massive surface Dirac fermions in the bulk RKKY mediation process. Both our theoretical models and experimental results reveal that the topological surface-related magnetic order can be either enhanced or suppressed, depending on the magnetic interaction range between the surface states and Cr ions. Based on such TI heterostructures, we also demonstrate the magnetization switching via giant spin-orbit torque induced by the in-plane current. Finally, in order to make these effects observable at 300K, we describe the use of magnetic proximity effects to manipulate the surface magnetism of TI. These results not only demonstrate additional important steps to further explore fundamental properties of the TRS-breaking TI systems but also may help the realization of many functionalities of TI-based spintronics applications. The work was in part supported by DARPA under N66001-12-1-40 and N66001-11-1-4105.
Cosmological fluctuations: Comparing Quantum and Classical Statistical and Stringy Effects
de Alwis, S P
2015-01-01
The theory of cosmological fluctuations assumes that the pre-inflationary state of the universe was the quantum vacuum of a scalar field(s) coupled to gravity. The observed cosmic microwave background fluctuations are then interpreted as quantum fluctuations. Here we consider alternate interpretations of the classic calculations of scalar and tensor power spectra by replacing the quantum vacuum with a classical statistical distribution, and suggest a way of distinguishing the quantum from the classical alternatives. The possibility that the latter is governed by a fundamental length scale as in string theory is also explored.
Sub-barrier reactions measured using a recoil mass separator
Betts, R.R.
1988-01-01
Few data exist in the sub-barrier region for reaction channels other than fusion. In particular, our experimental knowledge of quasi-elastic transfer reactions is sparse, despite the belief that this particular channel may be dominant in determining some features of the sub-barrier fusion enhancement. Transfer reactions are governed primarily by the closet approach of the colliding nuclei which, at low energies, results in a strong backward peaking of the angular distribution in the center-of-mass frame. For situations where the projectile has a significant fraction of the target mass, as is so in most cases of interest, the backscattered projectile-like fragment has such low energy that the usual techniques of measurement and identification become invalid. Here, we report on a solution to this problem which allows a systematic study of many aspects of transfer reactions in the energy regime of interest. We exploit the fact that associated with the low-energy backscattered projectile-like fragment is a complementary target-like fragment which recoils to forward angles with a large fraction of the incident beam energy. These target-like fragments were detected and identified using the Daresbury Recoil Mass Separator thus allowing the measurement of quasi-elastic transfer over hitherto inaccessible energy range from the vicinity of the barrier to several tens of MeV below. The experiments described here used VYNi beams of energies ranging from 180 to 260 MeV provided by the Daresbury Laboratory Nuclear Structure Facility tandem accelerator. Data on sub-barrier transfer for targets of /sup 116,118,120,122,124/Sn and /sup 144,148,150,152,154/Sm were obtained. 16 refs., 10 figs., 2 tabs.
Effects of a deep-level impurity on optical transitions of a quantum-well heterostructures
Peiji Zhao; H. L. Cui
1996-01-01
We investigate the effects of a deep impurity center, modeled by an attractive delta-function potential, on the optical transitions of a semiconductor quantum wells. Both the exciton binding energy and the oscillator strength are calculated as functions of the strength and center location of the potential, in an attempt to understand the photoluminescence of transition metal impurity doped semiconductor quantum
Effects of a Deep-Level Impurity on Optical Transitions of Quantum-Well Heterostructures
Peiji Zhao; H. L. Cui
1997-01-01
We investigate the effects of a deep impurity center, modeled by a -function potential, on the optical transitions of semiconductor quantum wells. Both the exciton binding energy and the oscillator strength are calculated as functions of the strength and the center location of the potential, in an attempt to understand the photoluminescence of transition-metal-impurity-doped semiconductor quantum confined structures. The calculation
Generalized decoding, effective channels, and simplified security proofs in quantum key distribution
information theory to solving a real-world problem that classical information theory cannot: secure expan, Universit¨at Karlsruhe, Am Fasanengarten 5, D-76131 Karlsruhe, Germany 2 Quantum Information Theory GroupGeneralized decoding, effective channels, and simplified security proofs in quantum key
Acceleration of positrons by a relativistic electron beam in the presence of quantum effects
Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of); Aki, H.; Khorashadizadeh, S. M. [Physics Department, Birjand University, Birjand (Iran, Islamic Republic of)] [Physics Department, Birjand University, Birjand (Iran, Islamic Republic of)
2013-09-15
Using the quantum magnetohydrodynamic model and obtaining the dispersion relation of the Cherenkov and cyclotron waves, the acceleration of positrons by a relativistic electron beam is investigated. The Cherenkov and cyclotron acceleration mechanisms of positrons are compared together. It is shown that growth rate and, therefore, the acceleration of positrons can be increased in the presence of quantum effects.
Piezoelectric effect in InAs/InP quantum rod nanowires grown on silicon substrate
Anufriev, Roman; Chauvin, Nicolas, E-mail: nicolas.chauvin@insa-lyon.fr; Bru-Chevallier, Catherine [Université de Lyon, Institut des Nanotechnologies de Lyon (INL)-UMR5270-CNRS, INSA-Lyon, 7 avenue Jean Capelle, 69621 Villeurbanne (France); Khmissi, Hammadi [Université de Monastir, Laboratoire de Micro-Optoélectronique et Nanostructures (LMON), Faculté des Sciences, Avenue de l'environnement, 5019 Monastir (Tunisia); Naji, Khalid; Gendry, Michel [Université de Lyon, Institut des Nanotechnologies de Lyon (INL)-UMR5270-CNRS, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Patriarche, Gilles [Laboratoire de Photonique et de Nanostructures (LPN), UPR20-CNRS, route de Nozay, 91460 Marcoussis (France)
2014-05-05
We report on the evidence of a strain-induced piezoelectric field in wurtzite InAs/InP quantum rod nanowires. This electric field, caused by the lattice mismatch between InAs and InP, results in the quantum confined Stark effect and, as a consequence, affects the optical properties of the nanowire heterostructure. It is shown that the piezoelectric field can be screened by photogenerated carriers or removed by increasing temperature. Moreover, a dependence of the piezoelectric field on the quantum rod diameter is observed in agreement with simulations of wurtzite InAs/InP quantum rod nanowire heterostructures.
Piezoelectric effect in InAs/InP quantum rod nanowires grown on silicon substrate
NASA Astrophysics Data System (ADS)
Anufriev, Roman; Chauvin, Nicolas; Khmissi, Hammadi; Naji, Khalid; Patriarche, Gilles; Gendry, Michel; Bru-Chevallier, Catherine
2014-05-01
We report on the evidence of a strain-induced piezoelectric field in wurtzite InAs/InP quantum rod nanowires. This electric field, caused by the lattice mismatch between InAs and InP, results in the quantum confined Stark effect and, as a consequence, affects the optical properties of the nanowire heterostructure. It is shown that the piezoelectric field can be screened by photogenerated carriers or removed by increasing temperature. Moreover, a dependence of the piezoelectric field on the quantum rod diameter is observed in agreement with simulations of wurtzite InAs/InP quantum rod nanowire heterostructures.
All-Optical Switching Using the Quantum Zeno Effect and Two-Photon Absorption
B. C. Jacobs; J. D. Franson
2009-05-08
We have previously shown that the quantum Zeno effect can be used to implement quantum logic gates for quantum computing applications, where the Zeno effect was produced using a strong two-photon absorbing medium. Here we show that the Zeno effect can also be used to implement classical logic gates whose inputs and outputs are high-intensity fields (coherent states). The operation of the devices can be understood using a quasi-static analysis, and their switching times are calculated using a dynamic approach. The two-photon absorption coefficient of rubidium vapor is shown to allow operation of these devices at relatively low power levels.
Study of impurity position effect in pyramid and cone like quantum dots
NASA Astrophysics Data System (ADS)
Khordad, Reza; Bahramiyan, Hossein
2014-08-01
In the present work, we have studied the effect of impurity position on energy levels, the donor binding energy and third harmonic generation of a pyramid and a cone like quantum dot. For this goal, we have calculated the energy levels, wave functions and binding energy using finite element method for various impurity positions. Our results show that the impurity location plays an important and considerable role in the electronic and optical properties in a pyramid and a cone like quantum dot. We found that the third harmonic generation and binding energy of both quantum dots have a maximum value at a special impurity position. The special impurity location is different for the two quantum dots. Also, we have deduced that the third harmonic generation of a cone like quantum dot is larger than a pyramid quantum dot for same volumes and heights.
Non-equilibrium effects upon the non-Markovian Caldeira-Leggett quantum master equation
Bolivar, A.O., E-mail: bolivar@cbpf.br [Departamento de Fisica, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte, Minas Gerais (Brazil)
2011-05-15
Highlights: > Classical Brownian motion described by a non-Markovian Fokker-Planck equation. > Quantization process. > Quantum Brownian motion described by a non-Markovian Caldeira-Leggett equation. > A non-equilibrium quantum thermal force is predicted. - Abstract: We obtain a non-Markovian quantum master equation directly from the quantization of a non-Markovian Fokker-Planck equation describing the Brownian motion of a particle immersed in a generic environment (e.g. a non-thermal fluid). As far as the especial case of a heat bath comprising of quantum harmonic oscillators is concerned, we derive a non-Markovian Caldeira-Leggett master equation on the basis of which we work out the concept of non-equilibrium quantum thermal force exerted by the harmonic heat bath upon the Brownian motion of a free particle. The classical limit (or dequantization process) of this sort of non-equilibrium quantum effect is scrutinized, as well.
Calendar effects in quantum mechanics in view of interactive holography
NASA Astrophysics Data System (ADS)
Berkovich, Simon
2013-04-01
Quantum mechanics in terms of interactive holography appears as `normal' science [1]. With the holography quantum behavior is determined by the interplay of material formations and their conjugate images. To begin with, this effortlessly elucidates the nonlocality in quantum entanglements. Then, it has been shown that Schr"odinger's dynamics for a single particle arises from Bi-Fragmental random walks of the particle itself and its holographic image. For many particles this picture blurs with fragments merging as bosons or fermions. In biomolecules, swapping of particles and their holographic placeholders leads to self-replication of the living matter. Because of broad interpretations of quantum formalism direct experiments attributing it to holography may not be very compelling. The holographic mechanism better reveals as an absolute frame of reference. A number of physical and biological events exhibit annual variations when Earth orbital position changes with respect to the universal holographic mechanism. The well established calendar variations of heart attacks can be regarded as a positive outcome of a generalization of the Michelson experiment, where holography is interferometry and ailing hearts are detectors of pathologically replicated proteins. Also, there have been already observed calendar changes in radioactive decay rates. The same could be expected for various fine quantum experiences, like, e.g., Josephson tunneling. In other words, Quantum Mechanics (February) Quantum Mechanics (August). [1] S. Berkovich, ``A comprehensive explanation of quantum mechanics,'' www.cs.gwu.edu/research/technical-report/170 .
On quantum effects on the surface of solid hydrogen
Marchenko, V. I. [Russian Academy of Sciences, Kapitza Institute for Physical Problems (Russian Federation)] [Russian Academy of Sciences, Kapitza Institute for Physical Problems (Russian Federation)
2013-10-15
The low-frequency spectrum of hypothetical superfluidity on the free surface of a quantum crystal of hydrogen is determined. In the quantum-rough state of the surface, crystallization waves with a quadratic spectrum should propagate. In the atomically smooth state, the spectrum is linear. Crystallization waves propagating along elementary steps are also considered.
A Novel method for modeling the recoil in W boson events at hadron collider
Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Abolins, Maris A.; /Michigan State U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Aguilo, Ernest; /Alberta U. /Simon Fraser U. /York U., Canada /McGill U.; Ahsan, Mahsana; /Kansas State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls /Northeastern U.
2009-07-01
We present a new method for modeling the hadronic recoil in W {yields} {ell}{nu} events produced at hadron colliders. The recoil is chosen from a library of recoils in Z {yields} {ell}{ell} data events and overlaid on a simulated W {yields} {ell}{nu} event. Implementation of this method requires that the data recoil library describe the properties of the measured recoil as a function of the true, rather than the measured, transverse momentum of the boson. We address this issue using a multidimensional Bayesian unfolding technique. We estimate the statistical and systematic uncertainties from this method for the W boson mass and width measurements assuming 1 fb{sup -1} of data from the Fermilab Tevatron. The uncertainties are found to be small and comparable to those of a more traditional parameterized recoil model. For the high precision measurements that will be possible with data from Run II of the Fermilab Tevatron and from the CERN LHC, the method presented in this paper may be advantageous, since it does not require an understanding of the measured recoil from first principles.
Motion and gravity effects in the precision of quantum clocks
Lindkvist, Joel; Sabín, Carlos; Johansson, Göran; Fuentes, Ivette
2015-01-01
We show that motion and gravity affect the precision of quantum clocks. We consider a localised quantum field as a fundamental model of a quantum clock moving in spacetime and show that its state is modified due to changes in acceleration. By computing the quantum Fisher information we determine how relativistic motion modifies the ultimate bound in the precision of the measurement of time. While in the absence of motion the squeezed vacuum is the ideal state for time estimation, we find that it is highly sensitive to the motion-induced degradation of the quantum Fisher information. We show that coherent states are generally more resilient to this degradation and that in the case of very low initial number of photons, the optimal precision can be even increased by motion. These results can be tested with current technology by using superconducting resonators with tunable boundary conditions. PMID:25988238
Motion and gravity effects in the precision of quantum clocks.
Lindkvist, Joel; Sabín, Carlos; Johansson, Göran; Fuentes, Ivette
2015-01-01
We show that motion and gravity affect the precision of quantum clocks. We consider a localised quantum field as a fundamental model of a quantum clock moving in spacetime and show that its state is modified due to changes in acceleration. By computing the quantum Fisher information we determine how relativistic motion modifies the ultimate bound in the precision of the measurement of time. While in the absence of motion the squeezed vacuum is the ideal state for time estimation, we find that it is highly sensitive to the motion-induced degradation of the quantum Fisher information. We show that coherent states are generally more resilient to this degradation and that in the case of very low initial number of photons, the optimal precision can be even increased by motion. These results can be tested with current technology by using superconducting resonators with tunable boundary conditions. PMID:25988238
Öztekin, ?lhan; Akdere, Hakan; Can, Nuray; Aktoz, Tevfik; Turan, Fatma Nesrin
2015-01-01
This research aimed to compare anti-inflammatory effects of oligonol, acupuncture, and quantum light therapy in rat models of estrogen-induced prostatitis. Adult male Wistar albino rats were grouped as follows: Group I, control (n = 10); Group II, chronic prostatitis (n = 10); Group III, oligonol (n = 10); Group IV, acupuncture (n = 10); Group V, quantum (n = 10); Group VI, oligonol plus quantum (n = 10); Group VII, acupuncture plus oligonol (n = 10); Group VIII, quantum plus acupuncture (n = 10); and Group IX, acupuncture plus quantum plus oligonol (n = 10). Chronic prostatitis (CP) was induced by the administration of 17-beta-estradiol (E2) and dihydrotestosterone (DHT). Oligonol was given for 6 weeks at a dose of 60?mg/day. Acupuncture needles were inserted at CV 3/4 and bilaterally B 32/35 points with 1-hour manual stimulation. Quantum therapy was administered in 5-minute sessions three times weekly for 6 weeks. Lateral lobes of prostates were dissected for histopathologic evaluation. Although all of the treatment modalities tested in this study showed anti-inflammatory effects in the treatment of CP in male rats, a synergistic effect was observed for oligonol plus quantum light combination. Monotherapy with oligonol showed a superior anti-inflammatory efficacy as compared to quantum light and acupuncture monotherapies. PMID:26064171
Photooxidation and quantum confinement effects in exfoliated black phosphorus.
Favron, Alexandre; Gaufrès, Etienne; Fossard, Frédéric; Phaneuf-L'Heureux, Anne-Laurence; Tang, Nathalie Y-W; Lévesque, Pierre L; Loiseau, Annick; Leonelli, Richard; Francoeur, Sébastien; Martel, Richard
2015-08-01
Thin layers of black phosphorus have recently raised interest owing to their two-dimensional (2D) semiconducting properties, such as tunable direct bandgap and high carrier mobilities. This lamellar crystal of phosphorus atoms can be exfoliated down to monolayer 2D-phosphane (also called phosphorene) using procedures similar to those used for graphene. Probing the properties has, however, been challenged by a fast degradation of the thinnest layers on exposure to ambient conditions. Herein, we investigate this chemistry using in situ Raman and transmission electron spectroscopies. The results highlight a thickness-dependent photoassisted oxidation reaction with oxygen dissolved in adsorbed water. The oxidation kinetics is consistent with a phenomenological model involving electron transfer and quantum confinement as key parameters. A procedure carried out in a glove box is used to prepare mono-, bi- and multilayer 2D-phosphane in their pristine states for further studies on the effect of layer thickness on the Raman modes. Controlled experiments in ambient conditions are shown to lower the Ag(1)/Ag(2) intensity ratio for ultrathin layers, a signature of oxidation. PMID:26006004
Quantum tunneling observed without its characteristic large kinetic isotope effects.
Hama, Tetsuya; Ueta, Hirokazu; Kouchi, Akira; Watanabe, Naoki
2015-06-16
Classical transition-state theory is fundamental to describing chemical kinetics; however, quantum tunneling is also important in explaining the unexpectedly large reaction efficiencies observed in many chemical systems. Tunneling is often indicated by anomalously large kinetic isotope effects (KIEs), because a particle's ability to tunnel decreases significantly with its increasing mass. Here we experimentally demonstrate that cold hydrogen (H) and deuterium (D) atoms can add to solid benzene by tunneling; however, the observed H/D KIE was very small (1-1.5) despite the large intrinsic H/D KIE of tunneling (?100). This strong reduction is due to the chemical kinetics being controlled not by tunneling but by the surface diffusion of the H/D atoms, a process not greatly affected by the isotope type. Because tunneling need not be accompanied by a large KIE in surface and interfacial chemical systems, it might be overlooked in other systems such as aerosols or enzymes. Our results suggest that surface tunneling reactions on interstellar dust may contribute to the deuteration of interstellar aromatic and aliphatic hydrocarbons, which could represent a major source of the deuterium enrichment observed in carbonaceous meteorites and interplanetary dust particles. These findings could improve our understanding of interstellar physicochemical processes, including those during the formation of the solar system. PMID:26034285
Effect of laser polarization on quantum electrodynamical cascading
Bashmakov, V. F.; Nerush, E. N.; Kostyukov, I. Yu., E-mail: kost@appl.sci-nnov.ru [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950 (Russian Federation); Fedotov, A. M.; Narozhny, N. B. [National Research Nuclear University MEPhI, Moscow 115409 (Russian Federation)] [National Research Nuclear University MEPhI, Moscow 115409 (Russian Federation)
2014-01-15
Development of quantum electrodynamical (QED) cascades in a standing electromagnetic wave for circular and linear polarizations is simulated numerically with a 3D PIC-MC code. It is demonstrated that for the same laser energy the number of particles produced in a circularly polarized field is greater than in a linearly polarized field, though the acquiring mean energy per particle is larger in the latter case. The qualitative model of laser-assisted QED cascades is extended by including the effect of polarization of the field. It turns out that cascade dynamics is notably more complicated in the case of linearly polarized field, where separation into the qualitatively different “electric” and “magnetic” regions (where the electric field is stronger than the magnetic field and vice versa) becomes essential. In the “magnetic” regions, acceleration is suppressed, and moreover the high-energy electrons are even getting cooled by photon emission. The volumes of the “electric” and “magnetic” regions evolve periodically in time and so does the cascade growth rate. In contrast to the linear polarization, the charged particles can be accelerated by circularly polarized wave even in “magnetic region.” The “electric” and “magnetic” regions do not evolve in time, and cascade growth rate almost does not depend on time for circular polarization.
Dynamic Charge Carrier Trapping in Quantum Dot Field Effect Transistors.
Zhang, Yingjie; Chen, Qian; Alivisatos, A Paul; Salmeron, Miquel
2015-07-01
Noncrystalline semiconductor materials often exhibit hysteresis in charge transport measurements whose mechanism is largely unknown. Here we study the dynamics of charge injection and transport in PbS quantum dot (QD) monolayers in a field effect transistor (FET). Using Kelvin probe force microscopy, we measured the temporal response of the QDs as the channel material in a FET following step function changes of gate bias. The measurements reveal an exponential decay of mobile carrier density with time constants of 3-5 s for holes and ?10 s for electrons. An Ohmic behavior, with uniform carrier density, was observed along the channel during the injection and transport processes. These slow, uniform carrier trapping processes are reversible, with time constants that depend critically on the gas environment. We propose that the underlying mechanism is some reversible electrochemical process involving dissociation and diffusion of water and/or oxygen related species. These trapping processes are dynamically activated by the injected charges, in contrast with static electronic traps whose presence is independent of the charge state. Understanding and controlling these processes is important for improving the performance of electronic, optoelectronic, and memory devices based on disordered semiconductors. PMID:26099508
Interaction effects and quantum phase transitions in topological insulators
Varney, Christopher N. [Department of Physics, Georgetown University, Washington, DC 20057 (United States); Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Sun Kai; Galitski, Victor [Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Rigol, Marcos [Department of Physics, Georgetown University, Washington, DC 20057 (United States)
2010-09-15
We study strong correlation effects in topological insulators via the Lanczos algorithm, which we utilize to calculate the exact many-particle ground-state wave function and its topological properties. We analyze the simple, noninteracting Haldane model on a honeycomb lattice with known topological properties and demonstrate that these properties are already evident in small clusters. Next, we consider interacting fermions by introducing repulsive nearest-neighbor interactions. A first-order quantum phase transition was discovered at finite interaction strength between the topological band insulator and a topologically trivial Mott insulating phase by use of the fidelity metric and the charge-density-wave structure factor. We construct the phase diagram at T=0 as a function of the interaction strength and the complex phase for the next-nearest-neighbor hoppings. Finally, we consider the Haldane model with interacting hard-core bosons, where no evidence for a topological phase is observed. An important general conclusion of our work is that despite the intrinsic nonlocality of topological phases their key topological properties manifest themselves already in small systems and therefore can be studied numerically via exact diagonalization and observed experimentally, e.g., with trapped ions and cold atoms in optical lattices.
Functional approach to quantum friction: Effective action and dissipative force
NASA Astrophysics Data System (ADS)
Belén Farías, M.; Fosco, César D.; Lombardo, Fernando C.; Mazzitelli, Francisco D.; Rubio López, Adrián E.
2015-05-01
We study the Casimir friction due to the relative, uniform, lateral motion of two parallel semitransparent mirrors coupled to a vacuum real scalar field ? . We follow a functional approach, whereby nonlocal terms in the action for ? , concentrated on the mirrors' loci, appear after functional integration of the microscopic degrees of freedom. This action for ? , which incorporates the relevant properties of the mirrors, is then used as the starting point for two complementary evaluations: Firstly, we calculate the in-out effective action for the system, which develops an imaginary part, hence a nonvanishing probability for the decay (because of friction) of the initial vacuum state. Secondly, we evaluate another observable: the vacuum expectation value of the frictional force, using the in-in or closed time path formalism. Explicit results are presented for zero-width mirrors and half-spaces, in a model where the microscopic degrees of freedom at the mirrors are a set of identical quantum harmonic oscillators, linearly coupled to ? .
NSDL National Science Digital Library
Haslam, Bryan
2005-08-05
Gain and Loss are the fundamental factors contributing to laser effectiveness. Simply put, the gain is the light produced by stimulated emission and loss is then the light lost. This can happen if a photon hits an electron in a low energy level state and the electron absorbs the energy and moves to a higher energy level state. It can also happen when light escapes the laser cavity. Lasing is the condition when the gain exceeds the loss. It is very important to know the gain to see how effective your laser really is. The traditional Hakki-Paoli Method was found to be ineffective for measuring gain in quantum cascade lasers. A new, more effective method of measuring gain in quantum cascade lasers was developed and tested.
Non-Markovian effects in quantum system: an exact stochastic mean-field treatment
G. Hupin; D. Lacroix
2009-09-25
A quantum Monte-Carlo is proposed to describe fusion/fission processes when fluctuation and dissipation, with memory effects, are important. The new theory is illustrated for systems with inverted harmonic potentials coupled to a heat-bath.
Quantum anomalous Hall effect with cold atoms trapped in a square lattice
Liu, Xiong-Jun; Liu, Xin; Wu, Congjun; Sinova, Jairo
2010-01-01
We propose an experimental scheme to realize the quantum anomalous Hall effect in an anisotropic square optical lattice which can be generated from available experimental setups of double-well lattices with minor modifications. A periodic gauge...
An analytical framework for field electron emission, incorporating quantum- confinement effects
Patterson. Alex A. (Alex Andrew)
2013-01-01
As field electron emitters shrink to nanoscale dimensions, the effects of quantum confinement of the electron supply and electric field enhancement at the emitter tip play a significant role in determining the emitted ...
Non-abelian fractional quantum hall effect for fault-resistant topological quantum computation.
Pan, Wei; Thalakulam, Madhu; Shi, Xiaoyan; Crawford, Matthew; Nielsen, Erik; Cederberg, Jeffrey George
2013-10-01
Topological quantum computation (TQC) has emerged as one of the most promising approaches to quantum computation. Under this approach, the topological properties of a non-Abelian quantum system, which are insensitive to local perturbations, are utilized to process and transport quantum information. The encoded information can be protected and rendered immune from nearly all environmental decoherence processes without additional error-correction. It is believed that the low energy excitations of the so-called =5/2 fractional quantum Hall (FQH) state may obey non-Abelian statistics. Our goal is to explore this novel FQH state and to understand and create a scientific foundation of this quantum matter state for the emerging TQC technology. We present in this report the results from a coherent study that focused on obtaining a knowledge base of the physics that underpins TQC. We first present the results of bulk transport properties, including the nature of disorder on the 5/2 state and spin transitions in the second Landau level. We then describe the development and application of edge tunneling techniques to quantify and understand the quasiparticle physics of the 5/2 state.
The effect of finite Larmor radius corrections on Jeans instability of quantum plasma
Sharma, Prerana [Physics Department, Ujjain Engineering College, Ujjain, Madhya Pradesh 465010 (India)] [Physics Department, Ujjain Engineering College, Ujjain, Madhya Pradesh 465010 (India); Chhajlani, R. K. [School of Studies in Physics, Vikram University Ujjain, Madhya Pradesh 465010 (India)] [School of Studies in Physics, Vikram University Ujjain, Madhya Pradesh 465010 (India)
2013-09-15
The influence of finite Larmor radius (FLR) effects on the Jeans instability of infinitely conducting homogeneous quantum plasma is investigated. The quantum magnetohydrodynamic (QMHD) model is used to formulate the problem. The contribution of FLR is incorporated to the QMHD set of equations in the present analysis. The general dispersion relation is obtained analytically using the normal mode analysis technique which is modified due to the contribution of FLR corrections. From general dispersion relation, the condition of instability is obtained and it is found that Jeans condition is modified due to quantum effect. The general dispersion relation is reduced for both transverse and longitudinal mode of propagations. The condition of gravitational instability is modified due to the presence of both FLR and quantum corrections in the transverse mode of propagation. In longitudinal case, it is found to be unaffected by the FLR effects but modified due to the quantum corrections. The growth rate of Jeans instability is discussed numerically for various values of quantum and FLR corrections of the medium. It is found that the quantum parameter and FLR effects have stabilizing influence on the growth rate of instability of the system.
Effect of state-selective reactive decay on the evolution of quantum systems
NASA Astrophysics Data System (ADS)
Shushin, A. I.
2010-07-01
The effect of state-selective reactive decay on the relaxation kinetics of quantum multistate systems is studied in detail in the Bloch-Redfield approach (BRA). The results are applied to the analysis of this effect in radical pair recombination kinetics. The BRA is shown to be able to describe quantitatively most important specific features of the recombination kinetics including those predicted by phenomenological treatment and by recently proposed approaches based on quantum measurement theories.
Unconventional quantum Hall effect and Berry’s phase of 2? in bilayer graphene
K. S. Novoselov; E. McCann; S. V. Morozov; V. I. Fal’ko; M. I. Katsnelson; U. Zeitler; D. Jiang; F. Schedin; A. K. Geim
2006-01-01
There are known two distinct types of the integer quantum Hall effect. One is\\u000athe conventional quantum Hall effect, characteristic of two-dimensional\\u000asemiconductor systems, and the other is its relativistic counterpart recently\\u000aobserved in graphene, where charge carriers mimic Dirac fermions characterized\\u000aby Berry's phase pi, which results in a shifted positions of Hall plateaus.\\u000aHere we report a third