Quantum fluctuations of a 1D bosonic gas in an optical lattice
NASA Astrophysics Data System (ADS)
Ruostekoski, Janne
2005-05-01
We numerically study the quantum dynamics of a 1D bosonic gas in a shallow optical lattice for both static and time-dependent lattices. In particular, we model the strongly damped dipole oscillations which have recently been observed experimentally at NIST by Fertig et al. cond-mat/0410491. We find a qualitative agreement with the experimentally observed damping rates which can be explained as being due to zero temperature quantum fluctuations.
Measurement-induced disturbance and thermal negativity in 1D optical lattice chain
Guo, Jin-Liang; Lin-Wang; Long, Gui-Lu
2013-03-15
We study the measurement-induced disturbance (MID) in a 1D optical lattice chain with nonlinear coupling. Special attention is paid to the difference between the thermal entanglement and MID when considering the influences of the linear coupling constant, nonlinear coupling constant and external magnetic field. It is shown that MID is more robust than thermal entanglement against temperature T and external magnetic field B, and MID may reveal more properties about quantum correlations of the system, which can be seen from the point of view that MID can be nonzero when there is no thermal entanglement and MID can detect the critical point of quantum phase transition at finite temperature. - Highlights: Black-Right-Pointing-Pointer The nonlinear coupling constant can strengthen the quantum correlation. Black-Right-Pointing-Pointer MID is more robust than entanglement against temperature and magnetic field. Black-Right-Pointing-Pointer MID exhibits more information about quantum correlation than entanglement. Black-Right-Pointing-Pointer MID can detect the critical point of quantum phase transition at finite temperature.
Emergent kinetics and fractionalized charge in 1D spin-orbit coupled flatband optical lattices.
Lin, Fei; Zhang, Chuanwei; Scarola, V W
2014-03-21
Recent ultracold atomic gas experiments implementing synthetic spin-orbit coupling allow access to flatbands that emphasize interactions. We model spin-orbit coupled fermions in a one-dimensional flatband optical lattice. We introduce an effective Luttinger-liquid theory to show that interactions generate collective excitations with emergent kinetics and fractionalized charge, analogous to properties found in the two-dimensional fractional quantum Hall regime. Observation of these excitations would provide an important platform for exploring exotic quantum states derived solely from interactions. PMID:24702335
Role of quantum fluctuations in the dissipative dynamics of a 1D Bose gas in an optical lattice
NASA Astrophysics Data System (ADS)
Rey, Ana Maria; Gea-Banacloche, Julio; Pupillo, Guido; Williams, Carl J.; Clark, Charles W.
2005-03-01
We will present a theoretical treatment[1] of the surprisingly large damping observed recently in a experiment done at NIST [2] where the transport properties of a harmonically trapped 1D Bose gas in a periodic (optical lattice) potential were studied by observing small amplitude dipole oscillations. In the absence of the lattice these oscillations are expected to be undamped (generalized Kohn's theorem), however, large damping of the dipole mode was observed in the experiment for very weak optical lattices and very small cloud displacements. We will show that the observed damping can be derived from a model whose main ingredients are (a) a large noncondensate fraction that arises as a direct consequence of the enhanced effective on-site interaction due to the tight transverse confinement, (b) the fact that a non-negligible part of it occupies high-momentum states and is therefore affected by dynamical instabilities, and (c) the interaction of the condensate atoms with the random field created by these noncondensate atoms when their equilibrium state is perturbed. We find good agreement between the model and the experimental results. [1] Julio Gea-Banacloche et al. cond-mat/0410677. [2] C. D. Fertig, K. et al.cond-mat/0410491.
Scratched-XY Universality and Phase Diagram of Disordered 1D Bosons in Optical Lattice
NASA Astrophysics Data System (ADS)
Yao, Zhiyuan; Pollet, Lode; Prokof'ev, Nikolay; Svistunov, Boris
The superfluid-insulator quantum phase transition in a 1D system with weak links belongs to the so-called scratched-XY universality class, provided the irrenormalizable exponent ζ characterizing the distribution of weak links is smaller than 2 / 3 . With a combination of worm-algorithm Monte Carlo simulations and asymptotically exact analytics, we accurately trace the position of the scratched-XY critical line on the ground-state phase diagram of bosonic Hubbard model at unity filling. In particular, we reveal the location of the tricritical point separating the scratched-XY criticality from the Giamarchi-Schulz one.
NASA Astrophysics Data System (ADS)
Zhou, Zheng; Yu, Hui-You; Ao, Sheng-Mei; Yan, Jia-Ren
2010-07-01
We study the formation of a dynamically-stabilized dissipation-managed bright soliton in a quasi-one-dimensional Bose-Einstein condensate by including an imaginary three-body recombination loss term and an imaginary linear feeding one in the Gross-Pitaevskii equation, trapped in a shallow optical-lattice potential. Based on the direct approach of perturbation theory for the nonlinear Schrödinger equation, we demonstrate that the height (as well as width) of bright soliton may have little change through selecting experimental parameters.
NASA Astrophysics Data System (ADS)
Kristensen, Tom; Simoni, Andrea; Launay, Jean-Michel
2016-05-01
We compute scattering and bound state properties for two ultracold molecules in a pure 1D optical lattice. We introduce reference functions with complex quasi-momentum that naturally account for the effect of excited energy bands. Our exact results for a short-range interaction are first compared with the simplest version of the standard Bose-Hubbard (BH) model. Such comparison allows us to highlight the effect of the excited bands, of the non-on-site interaction and of tunneling with distant neighbor, that are not taken into account in the BH model. The effective interaction can depend strongly on the particle quasi-momenta and can present a resonant behavior even in a deep lattice. As a second step, we study scattering of two polar particles in the optical lattice. Peculiar Wigner threshold laws stem from the interplay of the long range dipolar interaction and the presence of the energy bands. We finally assess the validity of an extended Bose-Hubbard model for dipolar gases based on our exact two-body calculations. This work was supported by the Agence Nationale de la Recherche (Contract No. ANR-12-BS04-0020-01).
Waves in a 1D electrorheological dusty plasma lattice
NASA Astrophysics Data System (ADS)
Rosenberg, M.
2015-08-01
The behavior of waves in a one-dimensional (1D) dusty plasma lattice where the dust interacts via Yukawa and electric dipole interactions is discussed theoretically. This study is motivated by recent reports on electrorheological dusty plasmas (e.g. Ivlev et al. 2008 Phys. Rev. Lett. 100, 095003) where the dipole interaction arises due to an external uniaxial AC electric field that distorts the Debye sphere surrounding each grain. Application to possible dusty plasma experimental parameters is discussed.
NASA Astrophysics Data System (ADS)
Singh, Kevin; Geiger, Zachary; Senaratne, Ruwan; Rajagopal, Shankari; Fujiwara, Kurt; Weld, David; Weld Group Team
2015-05-01
Quasiperiodicity is intimately involved in quantum phenomena from localization to the quantum Hall effect. Recent experimental investigation of quasiperiodic quantum effects in photonic and electronic systems have revealed intriguing connections to topological phenomena. However, such experiments have been limited by the absence of techniques for creating tunable quasiperiodic structures. We propose a new type of quasiperiodic optical lattice, constructed by intersecting a Gaussian beam with a 2D square lattice at an angle with an irrational tangent. The resulting potential, a generalization of the Fibonacci lattice, is a physical realization of the mathematical ``cut-and-project'' construction which underlies all quasiperiodic structures. Calculation of the energies and wavefunctions of atoms loaded into the proposed quasiperiodic lattice demonstrate a fractal energy spectrum and the existence of edge states. We acknowledge support from the ONR (award N00014-14-1-0805), the ARO and the PECASE program (award W911NF-14-1-0154), the AFOSR (award FA9550-12-1-0305), and the Alfred P. Sloan foundation (grant BR2013-110).
On-chip optical lattice for cold atom experiments.
Straatsma, Cameron J E; Ivory, Megan K; Duggan, Janet; Ramirez-Serrano, Jaime; Anderson, Dana Z; Salim, Evan A
2015-07-15
An atom-chip-based integrated optical lattice system for cold and ultracold atom applications is presented. The retroreflection optics necessary for forming the lattice are bonded directly to the atom chip, enabling a compact and robust on-chip optical lattice system. After achieving Bose-Einstein condensation in a magnetic chip trap, we load atoms directly into a vertically oriented 1D optical lattice and demonstrate Landau-Zener tunneling. The atom chip technology presented here can be readily extended to higher dimensional optical lattices. PMID:26176471
Narrow line photoassociation in an optical lattice.
Zelevinsky, T; Boyd, M M; Ludlow, A D; Ido, T; Ye, J; Ciuryło, R; Naidon, P; Julienne, P S
2006-05-26
With ultracold 88Sr in a 1D magic wavelength optical lattice, we performed narrow-line photoassociation spectroscopy near the 1S0 - 3P1 intercombination transition. Nine least-bound vibrational molecular levels associated with the long-range 0u and 1u potential energy surfaces were measured and identified. A simple theoretical model accurately describes the level positions and treats the effects of the lattice confinement on the line shapes. The measured resonance strengths show that optical tuning of the ground state scattering length should be possible without significant atom loss. PMID:16803171
Quantum Gases in Optical Lattices
NASA Astrophysics Data System (ADS)
Barmettler, Peter; Kollath, Corinna
2015-09-01
The experimental realization of correlated quantum phases with ultracold gases in optical lattices and their theoretical understanding has witnessed remarkable progress during the last decade. In this review we introduce basic concepts and tools to describe the many-body physics of quantum gases in optical lattices. This includes the derivation of effective lattice Hamiltonians from first principles and an overview of the emerging quantum phases. Additionally, state-of-the-art numerical tools to quantitatively treat bosons or fermions on different lattices are introduced.
Topological order in 1D super-lattice Bose-Hubbard models
NASA Astrophysics Data System (ADS)
Fleischhauer, Michael; Grusdt, Fabian; Hoening, Michael
2013-05-01
After the discovery of topological insulators as a new state of matter and their consequent classification for free fermions, the question arises what kind of topological order can be supported by incompressible systems of interacting bosons. We consider a 1D super-lattice Hamiltonian with a non-trivial band structure (the Su-Schrieffer-Heeger model) and show that its Mott-insulating (MI) states can be classified by a quantized many-body winding number. This quantization is protected by sub-lattice and time-reversal symmetries, and it allows the implementation of a quantized cyclic pumping process (Thouless pump) in a simple super-lattice Bose-Hubbard model (BHM). For extended BHMs we discuss a connection of such a pump with the fractional quantum Hall effect. Furthermore we show that the quantization of the winding number leads to localized, protected edge states at sharp interfaces between topologically distinct MI phases which can be experimentally realized using Bose-Fermi mixtures in optical superlattices. DMRG simulations show that these edge states manifest themself either in localized density maxima or localized density minima, which can easily be detected. Supported by research center OPTIMAS and graduate school MAINZ.
Statistical Transmutation in Floquet Driven Optical Lattices
NASA Astrophysics Data System (ADS)
Sedrakyan, Tigran A.; Galitski, Victor M.; Kamenev, Alex
2015-11-01
We show that interacting bosons in a periodically driven two dimensional (2D) optical lattice may effectively exhibit fermionic statistics. The phenomenon is similar to the celebrated Tonks-Girardeau regime in 1D. The Floquet band of a driven lattice develops the moat shape, i.e., a minimum along a closed contour in the Brillouin zone. Such degeneracy of the kinetic energy favors fermionic quasiparticles. The statistical transmutation is achieved by the Chern-Simons flux attachment similar to the fractional quantum Hall case. We show that the velocity distribution of the released bosons is a sensitive probe of the fermionic nature of their stationary Floquet state.
Statistical Transmutation in Floquet Driven Optical Lattices.
Sedrakyan, Tigran A; Galitski, Victor M; Kamenev, Alex
2015-11-01
We show that interacting bosons in a periodically driven two dimensional (2D) optical lattice may effectively exhibit fermionic statistics. The phenomenon is similar to the celebrated Tonks-Girardeau regime in 1D. The Floquet band of a driven lattice develops the moat shape, i.e., a minimum along a closed contour in the Brillouin zone. Such degeneracy of the kinetic energy favors fermionic quasiparticles. The statistical transmutation is achieved by the Chern-Simons flux attachment similar to the fractional quantum Hall case. We show that the velocity distribution of the released bosons is a sensitive probe of the fermionic nature of their stationary Floquet state. PMID:26588392
Optical Abelian lattice gauge theories
Tagliacozzo, L.; Celi, A.; Zamora, A.; Lewenstein, M.
2013-03-15
We discuss a general framework for the realization of a family of Abelian lattice gauge theories, i.e., link models or gauge magnets, in optical lattices. We analyze the properties of these models that make them suitable for quantum simulations. Within this class, we study in detail the phases of a U(1)-invariant lattice gauge theory in 2+1 dimensions, originally proposed by P. Orland. By using exact diagonalization, we extract the low-energy states for small lattices, up to 4 Multiplication-Sign 4. We confirm that the model has two phases, with the confined entangled one characterized by strings wrapping around the whole lattice. We explain how to study larger lattices by using either tensor network techniques or digital quantum simulations with Rydberg atoms loaded in optical lattices, where we discuss in detail a protocol for the preparation of the ground-state. We propose two key experimental tests that can be used as smoking gun of the proper implementation of a gauge theory in optical lattices. These tests consist in verifying the absence of spontaneous (gauge) symmetry breaking of the ground-state and the presence of charge confinement. We also comment on the relation between standard compact U(1) lattice gauge theory and the model considered in this paper. - Highlights: Black-Right-Pointing-Pointer We study the quantum simulation of dynamical gauge theories in optical lattices. Black-Right-Pointing-Pointer We focus on digital simulation of abelian lattice gauge theory. Black-Right-Pointing-Pointer We rediscover and discuss the puzzling phase diagram of gauge magnets. Black-Right-Pointing-Pointer We detail the protocol for time evolution and ground-state preparation in any phase. Black-Right-Pointing-Pointer We provide two experimental tests to validate gauge theory quantum simulators.
Integrated Atom Chip System for Optical Lattice Experiments
NASA Astrophysics Data System (ADS)
Salim, Evan A.; Ivory, Megan K.; Straatsma, Cameron J. E.; Anderson, Dana Z.
2015-05-01
We present an ultracold atom system incorporating a hybrid magnetic/optical atom chip for optical lattice experiments. The atom chip uses integrated, millimeter-scale optical elements to enable the production of optical lattice potentials near the atom chip traces and within a few hundred microns of a high-quality vacuum window. Due to their proximity to a window, the atoms are addressable by optics outside of vacuum operating at numerical apertures as high as 0.8. Demonstration of Bose-Einstein condensation in the chip trap and Landau-Zener tunneling in a 1D lattice are presented.
Grid Cell Responses in 1D Environments Assessed as Slices through a 2D Lattice.
Yoon, KiJung; Lewallen, Sam; Kinkhabwala, Amina A; Tank, David W; Fiete, Ila R
2016-03-01
Grid cells, defined by their striking periodic spatial responses in open 2D arenas, appear to respond differently on 1D tracks: the multiple response fields are not periodically arranged, peak amplitudes vary across fields, and the mean spacing between fields is larger than in 2D environments. We ask whether such 1D responses are consistent with the system's 2D dynamics. Combining analytical and numerical methods, we show that the 1D responses of grid cells with stable 1D fields are consistent with a linear slice through a 2D triangular lattice. Further, the 1D responses of comodular cells are well described by parallel slices, and the offsets in the starting points of the 1D slices can predict the measured 2D relative spatial phase between the cells. From these results, we conclude that the 2D dynamics of these cells is preserved in 1D, suggesting a common computation during both types of navigation behavior. PMID:26898777
Quantum vortices in optical lattices
Vignolo, P.; Fazio, R.; Tosi, M. P.
2007-08-15
A vortex in a superfluid gas inside an optical lattice can behave as a massive particle moving in a periodic potential and exhibiting quantum properties. In this paper we discuss these properties and show that the excitation of vortex dynamics in a two-dimensional lattice can lead to striking measurable changes in its dynamic response. It would be possible by means of Bragg spectroscopy to carry out the first direct measurement of the effective vortex mass. In addition, the experiments proposed here provide an alternative way to study the pinning to the underlying lattice and the dissipative damping.
Lattice study of (D¯ 1D*)± near-threshold scattering
NASA Astrophysics Data System (ADS)
Chen, Ting; Chen, Ying; Gong, Ming; Lei, Yu-Hong; Li, Ning; Liu, Chuan; Liu, Yu-Bin; Liu, Zhao-Feng; Ma, Jian-Ping; Wang, Zhan-Lin; Zhang, Jian-Bo; Clqcd Collaboration
2016-06-01
In this exploratory lattice study, low-energy near threshold scattering of the (D¯1D*)± meson system is analyzed using lattice QCD with Nf=2 twisted mass fermion configurations. Both s-wave (JP=0-) and p-wave (JP=1+) channels are investigated. It is found that the interaction between the two charmed mesons is attractive near the threshold in both channels. This calculation provides some hints in the searching of resonances or bound states around the threshold of (D¯1D*)± system.
Microparticle manipulation in optical lattices
NASA Astrophysics Data System (ADS)
Mu, Weiqiang
With the interference of several coherent beams, a periodical potential is produced for the particles trapped inside. The theoretical calculations show that the optical force applied on the particle in such optical lattice is in sinusoidal form. The force amplitudes vary greatly depending on the ratio of the particle size to the spacing of the optical lattice. A setup is constructed to demonstrate this dependence with two different methods: equipartition theorem and hydrodynamic-drag method. Based on this size dependence we develop an approach that allows tunable, size-dependent force selection of a subset of particles from an ensemble containing mixed particles. Combining a universal constant force with the sinusoidal optical force, a tilted washboard potential can be formed for the trapped particle. The diffusion of a particle over the barrier in this tilted washboard potential is briefly discussed. When the washboard potential oscillates, some interesting phenomena will happen: at high oscillation frequency, the particle's movement depends only on the oscillating amplitude; at low frequency, there are some combinations of the oscillation frequency and amplitude that induce the enhanced movement of the particle. This enhancement is first experimentally demonstrated with our setup. By implanting a single laser tweezers into the interferometric optical tweezers, we succeed in dynamically assembling designer colloidal lattices on the background of the interferometric optical tweezers. This new technique provides a flexible tool to design 2-d colloidal lattices.
Statistical Transmutation in Periodically Driven Optical Lattices
NASA Astrophysics Data System (ADS)
Sedrakyan, Tigran; Galitski, Victor; Kamenev, Alex
We show that interacting bosons in a periodically driven two dimensional (2D) optical lattice may effectively exhibit fermionic statistics. The phenomenon is similar to the celebrated Tonks-Girardeau regime in 1D. The Floquet band of a driven lattice develops the moat shape, i.e., a minimum along a closed contour in the Brillouin zone. Such degeneracy of the kinetic energy favors fermionic quasiparticles. The statistical transmutation is achieved by the Chern-Simons flux attachment similar to the fractional quantum Hall case. We show that the velocity distribution of the released bosons is a sensitive probe of the fermionic nature of their stationary Floquet state. This work was supported by the PFC-JQI (T.S.), USARO and Simons Foundation (V.G.), and DOE Contract DE-FG02-08ER46482 (A.K.).
A transportable optical lattice clock
NASA Astrophysics Data System (ADS)
Vogt, Stefan; Häfner, Sebastian; Grotti, Jacopo; Koller, Silvio; Al-Masoudi, Ali; Sterr, Uwe; Lisdat, Christian
2016-06-01
We present the experimental setup and first results of PTB's transportable 87Sr clock. It consists of a physics package, several compact laser breadboards, and a transportable high finesse cavity for the clock laser. A comparison of the transportable system with our stationary optical lattice clock yields an instability of 2.2 x 10-15 √s/τ for the transportable clock. The current fractional uncertainty of 1 × 10-15 is still limited by the not yet fully evaluated light shift from the free running optical lattice laser operated near the magic wavelength. We are currently improving our transportable system to reach an uncertainty at or below the 10-17 level, which will finaly be limited by the uncertainty in blackbody radiation shift correction.
Orbital optical lattices with bosons
NASA Astrophysics Data System (ADS)
Kock, T.; Hippler, C.; Ewerbeck, A.; Hemmerich, A.
2016-02-01
This article provides a synopsis of our recent experimental work exploring Bose-Einstein condensation in metastable higher Bloch bands of optical lattices. Bipartite lattice geometries have allowed us to implement appropriate band structures, which meet three basic requirements: the existence of metastable excited states sufficiently protected from collisional band relaxation, a mechanism to excite the atoms initially prepared in the lowest band with moderate entropy increase, and the possibility of cross-dimensional tunneling dynamics, necessary to establish coherence along all lattice axes. A variety of bands can be selectively populated and a subsequent thermalization process leads to the formation of a condensate in the lowest energy state of the chosen band. As examples the 2nd, 4th and 7th bands in a bipartite square lattice are discussed. The geometry of the 2nd and 7th bands can be tuned such that two inequivalent energetically degenerate energy minima arise at the X ±-points at the edge of the 1st Brillouin zone. In this case even a small interaction energy is sufficient to lock the phase between the two condensation points such that a complex-valued chiral superfluid order parameter can emerge, which breaks time reversal symmetry. In the 4th band a condensate can be formed at the Γ-point in the center of the 1st Brillouin zone, which can be used to explore topologically protected band touching points. The new techniques to access orbital degrees of freedom in higher bands greatly extend the class of many-body scenarios that can be explored with bosons in optical lattices.
Formation and Dynamics of Antiferromagnetic Correlations in Tunable Optical Lattices.
Greif, Daniel; Jotzu, Gregor; Messer, Michael; Desbuquois, Rémi; Esslinger, Tilman
2015-12-31
We report on the observation of antiferromagnetic correlations of ultracold fermions in a variety of optical lattice geometries that are well described by the Hubbard model, including dimers, 1D chains, ladders, isolated and coupled honeycomb planes, as well as square and cubic lattices. The dependence of the strength of spin correlations on the specific geometry is experimentally studied by measuring the correlations along different lattice tunneling links, where a redistribution of correlations between the different lattice links is observed. By measuring the correlations in a crossover between distinct geometries, we demonstrate an effective reduction of the dimensionality for our atom numbers and temperatures. We also investigate the formation and redistribution time of spin correlations by dynamically changing the lattice geometry and studying the time evolution of the system. Time scales ranging from a sudden quench of the lattice geometry to an adiabatic evolution are probed. PMID:26764974
Dipolar molecules in optical lattices.
Sowiński, Tomasz; Dutta, Omjyoti; Hauke, Philipp; Tagliacozzo, Luca; Lewenstein, Maciej
2012-03-16
We study the extended Bose-Hubbard model describing an ultracold gas of dipolar molecules in an optical lattice, taking into account all on-site and nearest-neighbor interactions, including occupation-dependent tunneling and pair tunneling terms. Using exact diagonalization and the multiscale entanglement renormalization ansatz, we show that these terms can destroy insulating phases and lead to novel quantum phases. These considerable changes of the phase diagram have to be taken into account in upcoming experiments with dipolar molecules. PMID:22540482
Experimental generation of optical coherence lattices
NASA Astrophysics Data System (ADS)
Chen, Yahong; Ponomarenko, Sergey A.; Cai, Yangjian
2016-08-01
We report experimental generation and measurement of recently introduced optical coherence lattices. The presented optical coherence lattice realization technique hinges on a superposition of mutually uncorrelated partially coherent Schell-model beams with tailored coherence properties. We show theoretically that information can be encoded into and, in principle, recovered from the lattice degree of coherence. Our results can find applications to image transmission and optical encryption.
Fractionalized topological defects in optical lattices
NASA Astrophysics Data System (ADS)
Zhang, Xing-Hai; Fan, Wen-Jun; Shi, Jin-Wei; Kou, Su-Peng
2015-10-01
Topological objects are interesting topics in various fields of physics ranging from condensed matter physics to the grand unified and superstring theories. Among those, ultracold atoms provide a playground to study the complex topological objects. In this paper we present a proposal to realize an optical lattice with stable fractionalized topological objects. In particular, we generate the fractionalized topological fluxes and fractionalized skyrmions on two-dimensional optical lattices and fractionalized monopoles on three-dimensional optical lattices. These results offer a new approach to study the quantum many-body systems on optical lattices of ultracold quantum gases with controllable topological defects, including dislocations, topological fluxes and monopoles.
Lattice-induced nonadiabatic frequency shifts in optical lattice clocks
Beloy, K.
2010-09-15
We consider the frequency shift in optical lattice clocks which arises from the coupling of the electronic motion to the atomic motion within the lattice. For the simplest of three-dimensional lattice geometries this coupling is shown to affect only clocks based on blue-detuned lattices. We have estimated the size of this shift for the prospective strontium lattice clock operating at the 390-nm blue-detuned magic wavelength. The resulting fractional frequency shift is found to be on the order of 10{sup -18} and is largely overshadowed by the electric quadrupole shift. For lattice clocks based on more complex geometries or other atomic systems, this shift could potentially be a limiting factor in clock accuracy.
Frequency Metrology with Optical Lattice Clocks
NASA Astrophysics Data System (ADS)
Hong, Feng-Lei; Katori, Hidetoshi
2010-08-01
The precision measurement of time and frequency is of great interest for a wide range of applications, including fundamental science and technologies that support broadband communication networks and the navigation with global positioning systems (GPSs). The development of optical frequency measurement based on frequency combs has revolutionized the field of frequency metrology, especially research on optical frequency standards. The proposal and realization of the optical lattice clock have further stimulated studies in the field of optical frequency metrology. Optical carrier transfer using optical fibers has been used to disseminate optical frequencies or compare two optical clocks without degrading their stability and accuracy. In this paper, we review the state-of-the-art development of optical frequency combs, standards, and transfer techniques with emphasis on optical lattice clocks. We address recent results achieved at the University of Tokyo and the National Metrology Institute of Japan in respect of frequency metrology with Sr and Yb optical lattice clocks.
Optical lattices with micromechanical mirrors
Hammerer, K.; Stannigel, K.; Genes, C.; Zoller, P.; Treutlein, P.; Camerer, S.; Hunger, D.; Haensch, T. W.
2010-08-15
We investigate a setup where a cloud of atoms is trapped in an optical lattice potential of a standing-wave laser field which is created by retroreflection on a micromembrane. The membrane vibrations itself realize a quantum mechanical degree of freedom. We show that the center-of-mass mode of atoms can be coupled to the vibrational mode of the membrane in free space. Via laser cooling of atoms a significant sympathetic cooling effect on the membrane vibrations can be achieved. Switching off laser cooling brings the system close to a regime of strong coherent coupling. This setup provides a controllable segregation between the cooling and coherent dynamics regimes, and allows one to keep the membrane in a cryogenic environment and atoms at a distance in a vacuum chamber.
A Deconstruction Lattice Description of the D1/D5 Brane World-Volume Gauge Theory
Giedt, Joel
2011-01-01
I genermore » alize the deconstruction lattice formulation of Endres and Kaplan to two-dimensional super-QCD with eight supercharges, denoted by (4,4), and bifundamental matter. I specialize to a particularly interesting (4,4) gauge theory, with gauge group U ( N c ) × U ( N f ) , and U ( N f ) being weakly gauged. It describes the infrared limit of the D1/D5 brane system, which has been studied extensively as an example of the AdS 3 /CFT 2 correspondence. The construction here preserves two supercharges exactly and has a lattice structure quite similar to that which has previously appeared in the deconstruction approach, that is, site, link, and diagonal fields with both the Bose and Fermi statistics. I remark on possible applications of the lattice theory that would test the AdS 3 /CFT 2 correspondence, particularly one that would exploit the recent worldsheet instanton analysis of Chen and Tong.« less
Trapping Rydberg Atoms in an Optical Lattice
NASA Astrophysics Data System (ADS)
Anderson, Sarah E.
2012-06-01
Optical lattice traps for Rydberg atoms are of interest in advanced science and in practical applications. After a brief discussion of these areas of interest, I will review some basics of optical Rydberg-atom trapping. The trapping potential experienced by a Rydberg atom in an optical lattice is given by the spatial average of the free-electron ponderomotive energy weighted by the Rydberg electron's probability distribution. I will then present experimental results on the trapping of ^85Rb Rydberg atoms in a one-dimensional ponderomotive optical lattice (wavelength 1064 nm). The principal methods employed to study the lattice performance are microwave spectroscopy, which is used to measure the lattice's trapping efficiency, and photo-ionization, which is used to measure the dwell time of the atoms in the lattice. I have achieved a 90% trapping efficiency for ^85Rb 50S atoms by inverting the lattice immediately after laser excitation of ground-state atoms into Rydberg states. I have characterized the dwell time of the atoms in the lattice using photo-ionization of 50D5/2 atoms. In continued work, I have explored the dependence of the Rydberg-atom trapping potential on the angular portion of the atomic wavefunction. Distinct angular states exhibit different trapping behavior in the optical lattice, depending on how their wavefunctions are oriented relative to the lattice planes. Specifically, I have measured the lattice potential depth of sublevels of ^85Rb nD atoms (50<=n<=65) in a one-dimensional optical lattice with a transverse DC electric field. The trapping behavior varies substantially for the various angular sublevels, in agreement with theory. The talk will conclude with an outlook into planned experiments.
Critical and multicritical semi-random (1 + d)-dimensional lattices and hard objects in d dimensions
NASA Astrophysics Data System (ADS)
Di Francesco, P.; Guitter, E.
2002-02-01
We investigate models of (1 + d)D Lorentzian semi-random lattices with one random (space-like) direction and d regular (time-like) ones. We prove a general inversion formula expressing the partition function of these models as the inverse of that of hard objects in d dimensions. This allows for an exact solution of a variety of new models including critical and multicritical generalized (1+1)D Lorentzian surfaces, with fractal dimensions dF = k + 1, k = 1,2,3,... , as well as a new model of (1+2)D critical tetrahedral complexes, with fractal dimension dF = 12/5. Critical exponents and universal scaling functions follow from this solution. We finally establish a general connection between (1 + d)D Lorentzian lattices and directed-site lattice animals in (1 + d) dimensions.
An anti-symmetric exclusion process for two particles on an infinite 1D lattice
NASA Astrophysics Data System (ADS)
Potts, J. R.; Harris, S.; Giuggioli, L.
2011-12-01
A system of two biased, mutually exclusive random walkers on an infinite 1D lattice is studied whereby the intrinsic bias of one particle is equal and opposite to that of the other. The propagator for this system is solved exactly and expressions for the mean displacement and mean square displacement (MSD) are found. Depending on the nature of the intrinsic bias, the system’s behaviour displays two regimes, characterised by (i) the particles moving towards each other and (ii) away from each other, both qualitatively different from the case of no bias. The continuous-space limit of the propagator is found and is shown to solve a Fokker-Planck equation for two biased, mutually exclusive Brownian particles with equal and opposite drift velocity. Connections to territorial dynamics in animal populations are discussed.
Tunneling Dynamics and Gauge Potentials in Optical Lattices
NASA Astrophysics Data System (ADS)
Dutta, S. K.; Teo, B. K.; Raithel, G.
1999-09-01
We study periodic well-to-well tunneling of 87Rb atoms on adiabatic potential surfaces of a 1D optical lattice. The observed dependence of the lowest-band tunneling period on the depth of the adiabatic potential can only be explained by an additional intensity-independent gauge potential predicted by Dum et al. The experimental data are in excellent agreement with our quantum Monte Carlo wave-function simulations and band structure calculations.
Subwavelength Lattice Optics by Evolutionary Design
2015-01-01
This paper describes a new class of structured optical materials—lattice opto-materials—that can manipulate the flow of visible light into a wide range of three-dimensional profiles using evolutionary design principles. Lattice opto-materials are based on the discretization of a surface into a two-dimensional (2D) subwavelength lattice whose individual lattice sites can be controlled to achieve a programmed optical response. To access a desired optical property, we designed a lattice evolutionary algorithm that includes and optimizes contributions from every element in the lattice. Lattice opto-materials can exhibit simple properties, such as on- and off-axis focusing, and can also concentrate light into multiple, discrete spots. We expanded the unit cell shapes of the lattice to achieve distinct, polarization-dependent optical responses from the same 2D patterned substrate. Finally, these lattice opto-materials can also be combined into architectures that resemble a new type of compound flat lens. PMID:25380062
Subwavelength lattice optics by evolutionary design.
Huntington, Mark D; Lauhon, Lincoln J; Odom, Teri W
2014-12-10
This paper describes a new class of structured optical materials--lattice opto-materials--that can manipulate the flow of visible light into a wide range of three-dimensional profiles using evolutionary design principles. Lattice opto-materials are based on the discretization of a surface into a two-dimensional (2D) subwavelength lattice whose individual lattice sites can be controlled to achieve a programmed optical response. To access a desired optical property, we designed a lattice evolutionary algorithm that includes and optimizes contributions from every element in the lattice. Lattice opto-materials can exhibit simple properties, such as on- and off-axis focusing, and can also concentrate light into multiple, discrete spots. We expanded the unit cell shapes of the lattice to achieve distinct, polarization-dependent optical responses from the same 2D patterned substrate. Finally, these lattice opto-materials can also be combined into architectures that resemble a new type of compound flat lens. PMID:25380062
Anyonic braiding in optical lattices
Zhang, Chuanwei; Scarola, V. W.; Tewari, Sumanta; Das Sarma, S.
2007-01-01
Topological quantum states of matter, both Abelian and non-Abelian, are characterized by excitations whose wavefunctions undergo nontrivial statistical transformations as one excitation is moved (braided) around another. Topological quantum computation proposes to use the topological protection and the braiding statistics of a non-Abelian topological state to perform quantum computation. The enormous technological prospect of topological quantum computation provides new motivation for experimentally observing a topological state. Here, we explicitly work out a realistic experimental scheme to create and braid the Abelian topological excitations in the Kitaev model built on a tunable robust system, a cold atom optical lattice. We also demonstrate how to detect the key feature of these excitations: their braiding statistics. Observation of this statistics would directly establish the existence of anyons, quantum particles that are neither fermions nor bosons. In addition to establishing topological matter, the experimental scheme we develop here can also be adapted to a non-Abelian topological state, supported by the same Kitaev model but in a different parameter regime, to eventually build topologically protected quantum gates. PMID:18000038
Direct Tunneling Delay Time Measurement in an Optical Lattice.
Fortun, A; Cabrera-Gutiérrez, C; Condon, G; Michon, E; Billy, J; Guéry-Odelin, D
2016-07-01
We report on the measurement of the time required for a wave packet to tunnel through the potential barriers of an optical lattice. The experiment is carried out by loading adiabatically a Bose-Einstein condensate into a 1D optical lattice. A sudden displacement of the lattice by a few tens of nanometers excites the micromotion of the dipole mode. We then directly observe in momentum space the splitting of the wave packet at the turning points and measure the delay between the reflected and the tunneled packets for various initial displacements. Using this atomic beam splitter twice, we realize a chain of coherent micron-size Mach-Zehnder interferometers at the exit of which we get essentially a wave packet with a negative momentum, a result opposite to the prediction of classical physics. PMID:27419545
Direct Tunneling Delay Time Measurement in an Optical Lattice
NASA Astrophysics Data System (ADS)
Fortun, A.; Cabrera-Gutiérrez, C.; Condon, G.; Michon, E.; Billy, J.; Guéry-Odelin, D.
2016-07-01
We report on the measurement of the time required for a wave packet to tunnel through the potential barriers of an optical lattice. The experiment is carried out by loading adiabatically a Bose-Einstein condensate into a 1D optical lattice. A sudden displacement of the lattice by a few tens of nanometers excites the micromotion of the dipole mode. We then directly observe in momentum space the splitting of the wave packet at the turning points and measure the delay between the reflected and the tunneled packets for various initial displacements. Using this atomic beam splitter twice, we realize a chain of coherent micron-size Mach-Zehnder interferometers at the exit of which we get essentially a wave packet with a negative momentum, a result opposite to the prediction of classical physics.
Spin-orbit coupling in a strontium optical lattice clock
NASA Astrophysics Data System (ADS)
Bothwell, Tobias; Bromley, Sarah; Kolkowitz, Shimon; Zhang, Xibo; Wall, Michael; Rey, Ana Maria; Ye, Jun
2016-05-01
Synthetic gauge fields are a promising tool for creating complex Hamiltonians with ultracold neutral atoms that may mimic the fractional Quantum Hall effect and other topological states. A promising approach is to use spin-orbit coupling to treat an internal degree of freedom as an effective `synthetic' spatial dimension. Here, this synthetic dimension is comprised by the internal ground and excited states used for high-precision clock spectroscopy in a fermionic strontium optical lattice clock. We report on our progress towards this goal in a system where atoms tunnel through a 1D optical lattice during clock interrogation. We present measurements of the lattice band structure under varying Lamb-Dicke parameters and in a regime where s-wave collisions are expected to contribute density dependent frequency shifts.
Cold atoms in a rotating optical lattice
NASA Astrophysics Data System (ADS)
Foot, Christopher J.
2009-05-01
We have demonstrated a novel experimental arrangement which can rotate a two-dimensional optical lattice at frequencies up to several kilohertz. Our arrangement also allows the periodicity of the optical lattice to be varied dynamically, producing a 2D ``accordion lattice'' [1]. The angles of the laser beams are controlled by acousto-optic deflectors and this allows smooth changes with little heating of the trapped cold (rubidium) atoms. We have loaded a BEC into lattices with periodicities ranging from 1.8μm to 18μm, observing the collapse and revival of the diffraction orders of the condensate over a large range of lattice parameters as recently reported by a group in NIST [2]. We have also imaged atoms in situ in a 2D lattice over a range of lattice periodicities. Ultracold atoms in a rotating lattice can be used for the direct quantum simulation of strongly correlated systems under large effective magnetic fields, i.e. the Hamiltonian of the atoms in the rotating frame resembles that of a charged particle in a strong magnetic field. In the future, we plan to use this to investigate a range of phenomena such as the analogue of the fractional quantum Hall effect. [4pt] [1] R. A. Williams, J. D. Pillet, S. Al-Assam, B. Fletcher, M. Shotter, and C. J. Foot, ``Dynamic optical lattices: two-dimensional rotating and accordion lattices for ultracold atoms,'' Opt. Express 16, 16977-16983 (2008) [0pt] [2] J. H. Huckans, I. B. Spielman, B. Laburthe Tolra, W. D. Phillips, and J. V. Porto, Quantum and Classical Dynamics of a BEC in a Large-Period Optical Lattice, arXiv:0901.1386v1
Optical vortex array in spatially varying lattice
NASA Astrophysics Data System (ADS)
Kapoor, Amit; Kumar, Manish; Senthilkumaran, P.; Joseph, Joby
2016-04-01
We present an experimental method based on a modified multiple beam interference approach to generate an optical vortex array arranged in a spatially varying lattice. This method involves two steps which are: numerical synthesis of a consistent phase mask by using two-dimensional integrated phase gradient calculations and experimental implementation of produced phase mask by utilizing a phase only spatial light modulator in an optical 4f Fourier filtering setup. This method enables an independent variation of the orientation and period of the vortex lattice. As working examples, we provide the experimental demonstration of various spatially variant optical vortex lattices. We further confirm the existence of optical vortices by formation of fork fringes. Such lattices may find applications in size dependent trapping, sorting, manipulation and photonic crystals.
Ultracold quantum gases in optical lattices
NASA Astrophysics Data System (ADS)
Bloch, Immanuel
2005-10-01
Artificial crystals of light, consisting of hundreds of thousands of optical microtraps, are routinely created by interfering optical laser beams. These so-called optical lattices act as versatile potential landscapes to trap ultracold quantum gases of bosons and fermions. They form powerful model systems of quantum many-body systems in periodic potentials for probing nonlinear wave dynamics and strongly correlated quantum phases, building fundamental quantum gates or observing Fermi surfaces in periodic potentials. Optical lattices represent a fast-paced modern and interdisciplinary field of research.
Ultracold quantum gases in triangular optical lattices
NASA Astrophysics Data System (ADS)
Becker, C.; Soltan-Panahi, P.; Kronjäger, J.; Dörscher, S.; Bongs, K.; Sengstock, K.
2010-06-01
Over recent years, exciting developments in the field of ultracold atoms confined in optical lattices have led to numerous theoretical proposals devoted to the quantum simulation of problems e.g. known from condensed matter physics. Many of those ideas demand experimental environments with non-cubic lattice geometries. In this paper, we report on the implementation of a versatile three-beam lattice allowing for the generation of triangular as well as hexagonal optical lattices. As an important step, the superfluid-Mott insulator (SF-MI) quantum phase transition has been observed and investigated in detail in this lattice geometry for the first time. In addition to this, we study the physics of spinor Bose-Einstein condensates (BEC) in the presence of the triangular optical lattice potential, especially spin changing dynamics across the SF-MI transition. Our results suggest that, below the SF-MI phase transition, a well-established mean-field model describes the observed data when renormalizing the spin-dependent interaction. Interestingly, this opens up new perspectives for a lattice-driven tuning of a spin dynamics resonance occurring through the interplay of the quadratic Zeeman effect and spin-dependent interaction. Finally, we discuss further lattice configurations that can be realized with our setup.
Thermometry via Light Shifts in Optical Lattices
NASA Astrophysics Data System (ADS)
McDonald, M.; McGuyer, B. H.; Iwata, G. Z.; Zelevinsky, T.
2015-01-01
For atoms or molecules in optical lattices, conventional thermometry methods are often unsuitable due to low particle numbers or a lack of cycling transitions. However, a differential spectroscopic light shift can map temperature onto the line shape with a low sensitivity to trap anharmonicity. We study narrow molecular transitions to demonstrate precise frequency-based lattice thermometry, as well as carrier cooling. This approach should be applicable down to nanokelvin temperatures. We also discuss how the thermal light shift can affect the accuracy of optical lattice clocks.
Trapping Rydberg Atoms in an Optical Lattice
Anderson, S. E.; Younge, K. C.; Raithel, G.
2011-12-23
Rubidium Rydberg atoms are laser excited and subsequently trapped in a one-dimensional optical lattice (wavelength 1064 nm). Efficient trapping is achieved by a lattice inversion immediately after laser excitation using an electro-optic technique. The trapping efficiency is probed via analysis of the trap-induced shift of the two-photon microwave transition 50S{yields}51S. The inversion technique allows us to reach a trapping efficiency of 90%. The dependence of the efficiency on the timing of the lattice inversion and on the trap laser power is studied. The dwell time of 50D{sub 5/2} Rydberg atoms in the lattice is analyzed using lattice-induced photoionization.
Coherent manipulations of atomic wavefunctions in optical lattices
NASA Astrophysics Data System (ADS)
Ivanov, Vladyslav
2010-03-01
We report on the realization of dynamical control of transport for ultra-cold ^88Sr atoms loaded in an accelerated and amplitude-modulated 1D optical lattice. Cold atoms trapped in vertical optical lattices give rise to localized states, the Wannier-Stark states. Delocalization can be recovered by introducing a resonant coupling among neighboring lattice sites. We demonstrated this by applying a modulation either to the phase or the amplitude of the lattice potential. Atomic sample loaded into a modulated vertical optical-lattice potential exhibit a resonant delocalization dynamics arising from intraband transitions among Wannier-Stark levels [1]. We demonstrate the coherent control of the spatial extent of atomic wavefunctions by reversibly stretching and shrinking the wavefunction over a distance of more than one millimeter [2]. [4pt] [1] V. V. Ivanov et al., Phys. Rev. Lett. 100, 043602 (2008) [0pt] [2] A. Alberti, V. V. Ivanov, G. M. Tino and G. Ferrari Nature Physics 5, 547 (2009)
Colloquium: Physics of optical lattice clocks
Derevianko, Andrei; Katori, Hidetoshi
2011-04-01
Recently invented and demonstrated optical lattice clocks hold great promise for improving the precision of modern time keeping. These clocks aim at the 10{sup -18} fractional accuracy, which translates into a clock that would neither lose nor gain a fraction of a second over an estimated age of the Universe. In these clocks, millions of atoms are trapped and interrogated simultaneously, dramatically improving clock stability. Here the principles of operation of these clocks are discussed and, in particular, a novel concept of magic trapping of atoms in optical lattices. Recently proposed microwave lattice clocks are also highlights and several applications that employ the optical lattice clocks as a platform for precision measurements and quantum information processing.
DESIGN OF THE RCMS LATTICE OPTICS.
CARDONA,J.; KEWISCH,J.; PEGGS,S.
2002-06-02
THE RAPID CYCLING MEDICAL SYNCHROTRON (RCMS) IS DESIGNED TO BE A VERY LIGHT AND INEXPENSIVE ACCELERATOR. THIS IS POSSIBLE DUE TO THE SMALL BEAM SIZE THAT HAS BEEN CHOSEN EARLY DURING THE DESIGN STAGE. THIS CHOICE HAS IMPLICATIONS IN THE DESIGN OF THE LATTICE OPTICS. IN THIS PAPER, WE PRESENT AN OVERVIEW OF THE RCMS OPTICS LATTICE, THE KIND OF MAGNETS TO BE USED AND ALSO A DESCRIPTION OF A SPECIAL OPTIC MODULE THAT MATCHES THE ROTATING GANTRY WITH THE REST OF THE FIXED ACCELERATOR. TECHNIQUESDEVELOPED TO WIN ADDITIONAL SPACE BETWEEN QUADRUPOLES WITHOUT DISTRUBING BETA FUNCTIONS ARE ALSO PRESENTED.
Visualization of 3D optical lattices
NASA Astrophysics Data System (ADS)
Lee, Hoseong; Clemens, James
2016-05-01
We describe the visualization of 3D optical lattices based on Sisyphus cooling implemented with open source software. We plot the adiabatic light shift potentials found by diagonalizing the effective Hamiltonian for the light shift operator. Our program incorporates a variety of atomic ground state configurations with total angular momentum ranging from j = 1 / 2 to j = 4 and a variety of laser beam configurations including the two-beam lin ⊥ lin configuration, the four-beam umbrella configuration, and four beams propagating in two orthogonal planes. In addition to visualizing the lattice the program also evaluates lattice parameters such as the oscillation frequency for atoms trapped deep in the wells. The program is intended to help guide experimental implementations of optical lattices.
Optical properties of LEDs with patterned 1D photonic crystal
NASA Astrophysics Data System (ADS)
Hronec, P.; Kuzma, A.; Å kriniarová, J.; Kováč, J.; Benčurová, A.; Haščík, Å.; Nemec, P.
2015-08-01
In this paper we focus on the application of the one-dimensional photonic crystal (1D PhC) structures on the top of Al0.295Ga0.705As/GaAs multi-quantum well light emitting diode (MQW LED). 1D PhC structures with periods of 600 nm, 700 nm, 800 nm, and 900 nm were fabricated by the E-Beam Direct Write (EBDW) Lithography. Effect of 1D PhC period on the light extraction enhancement was studied. 1D PhC LED radiation profiles were obtained from Near Surface Light Emission Images (NSLEI). Measurements showed the strongest light extraction enhancement using 800 nm period of PhC. Investigation of PhC LED radiation profiles showed strong light decoupling when light reaches PhC structure. Achieved LEE was from 22.6% for 600 nm PhC LED to 47.0% for 800 nm PhC LED. LED with PhC structure at its surface was simulated by FDTD simulation method under excitation of appropriate launch field.
The optical potential on the lattice
Agadjanov, Dimitri; Doring, Michael; Mai, Maxim; MeiBner, Ulf -G.; Rusetsky, Akaki
2016-06-08
The extraction of hadron-hadron scattering parameters from lattice data by using the Luscher approach becomes increasingly complicated in the presence of inelastic channels. We propose a method for the direct extraction of the complex hadron-hadron optical potential on the lattice, which does not require the use of the multi-channel Luscher formalism. Furthermore, this method is applicable without modifications if some inelastic channels contain three or more particles.
Excitations of quantum gases in optical lattices
NASA Astrophysics Data System (ADS)
Yesilada, Emek
This thesis describes experiments that studied the excitations of an ultra-cold atomic Rb gas in an optical lattice using Bragg spectroscopy. A Bose-Einstein condensate (BEC) of 87Rb was formed in a cloverleaf trap. An optical lattice of cubic symmetry, formed by the interference of six laser beams, was superimposed on the Rb BEC and turned on adiabatically. Such a system is well described by the Bose-Hubbard model, which predicts a quantum phase transition from a superfluid to a Mott insulator state at a critical lattice depth. In the first experiment, we studied the superfluid regime. The superfluid admits sound waves as phonon excitations. In two photon Bragg spectroscopy two laser beams intersecting at angle on the condensate create such excitations. The excitation spectrum of BEC was measured in a three dimensional optical lattice as a function of lattice strength. In the second experiment we studied the excitation spectrum of the Mott insulator. The lowest energy excitations in such a system are particle-hole excitations. These correspond to the hopping of atoms from one lattice site to another. The insulating phase is characterized by a gap in the excitation spectrum and we measured this particle-hole gap by Bragg spectroscopy. The precise nature of our measurement allowed us to study the opening of the excitation gap that has previously eluded experimental verification.
Fiber-optic lattice signal processing
NASA Astrophysics Data System (ADS)
Moslehi, B.; Goodman, J. W.; Shaw, H. J.; Tur, M.
1984-07-01
It is pointed out that fiber-optic signal processing devices can be constructed to perform various functions, such as convolution, correlation, matrix operations, and frequency filtering. Previous studies have concentrated on classical tapped-delay-line forms (transversal filters). The present investigation is concerned with different fiber-optic structures, taking into account lattice (or ladder) forms, which can be used as alternatives for performing optical signal processing. The elements to perform the various signal processing operations are considered along with fiber-optic lattice configurations. Aspects of mathematical analysis are discussed, taking into account Z-transform techniques, transfer-matrix and chain-matrix formulations, modern control theory formulations, and positive optical systems. Attention is given to time-domain signal processing applications, and frequency-domain signal processing applications.
NASA Astrophysics Data System (ADS)
Guillamon, I.; Vieira, S.; Suderow, H.; Cordoba, R.; Sese, J.; de Teresa, J. M.; Ibarra, R.
In two dimensional (2D) systems, theory has proposed that random disorder destroys long range correlations driving a transition to a glassy state. Here, I will discuss new insights into this issue obtained through the direct visualization of the critical behaviour of a 2D superconducting vortex lattice formed in a thin film with a smooth 1D thickness modulation. Using scanning tunneling microscopy at 0.1K, we have tracked the modification in the 2D vortex arrangements induced by the 1D thickness modulation while increasing the vortex density by three orders of magnitude. Upon increasing the field, we observed a two-step order-disorder transition in the 2D vortex lattice mediated by the appearance of dislocations and disclinations and accompanied by an increase in the local vortex density fluctuations. Through a detailed analysis of correlation functions, we find that the transition is driven by the incommensurate 1D thickness modulation. We calculate the critical points and exponents and find that they are well above theoretical expectation for random disorder. Our results show that long range 1D correlations in random potentials enhance the stability range of the ordered phase in a 2D vortex lattice. Work supported by Spanish MINECO, CIG Marie Curie Grant, Axa Research Fund and FBBVA.
Optical Lattices With Quantum Gas Microscope
NASA Astrophysics Data System (ADS)
Peng, Amy Wan-Chih
In this thesis, we demonstrate how the recent achievement of single site resolution using the "Quantum Gas Microscope" can be integrated with a system of ultra-cold atoms in a two dimensional optical lattice, to facilitate the study of condensed matter Hamiltonians in the strongly interacting regime. With the combination of magnetic and optical manipulation of atoms, we show how to reproducibly generate cold two dimensional Bose Einstein Condensates of 87Rb situated at the focus of our "Quantum Gas Microscope", allowing us to utilise the high numerical aperture for both lattice generation and single atom detection. As a first demonstration of the type of study we can perform with this apparatus, we implement the Bose-Hubbard Hamiltonian and give some evidence of the superfluid to Mott insulator transition in this system, seen on the single lattice site level.
Optical trapping of nanoscale plasmonic optical lattice in microfluidic environments
NASA Astrophysics Data System (ADS)
Hung, Chia-Chun; Huang, Jer-Shing; Yang, Ya-Tang
2014-09-01
Recent advances in optical manipulation have made it an ideal tool to create one, two, and three dimensional periodic optical potential. Such periodic potentials have found interesting technological and fundamental applications such as micro particle sorting and optical fractionation. Plasmon enhanced optical trapping techniques using metallic nanostructures can overcome the diffraction limits of far-field optical trap techniques and therefore permit trapping of nanoparticle with deep sub wavelength dimensions. Here we report the trapping of nanoparticles for a plasmon-enhanced two dimensional optical lattice integrated with microfluidic chip. We observe the trapping of nanoparticles over such an optical lattice. Such an integrated device allows the directional control of nano particles and provides a suitable platform for stochastic transport experiment such as nanoscale optical sorting.
Ultra-Cold Atoms on Optical Lattices
ERIC Educational Resources Information Center
Ghosh, Parag
2009-01-01
The field of ultra-cold atoms, since the achievement of Bose-Einstein Condensation (Anderson et al., 1995; Davis et al., 1995; Bradley et al., 1995), have seen an immensely growing interest over the past decade. With the creation of optical lattices, new possibilities of studying some of the widely used models in condensed matter have opened up.…
Ultracold Quantum Gases in Hexagonal Optical Lattices
NASA Astrophysics Data System (ADS)
Sengstock, Klaus
2010-03-01
Hexagonal structures occur in a vast variety of systems, ranging from honeycombs of bees in life sciences to carbon nanotubes in material sciences. The latter, in particular its unfolded two-dimensional layer -- Graphene -- has rapidly grown to one of the most discussed topics in condensed-matter physics. Not only does it show proximity to various carbon-based materials but also exceptional properties owing to its unusual energy spectrum. In quantum optics, ultracold quantum gases confined in periodic light fields have shown to be very general and versatile instruments to mimic solid state systems. However, so far nearly all experiments were performed in cubic lattice geometries only. Here we report on the first experimental realization of ultracold quantum gases in a state-dependent, two-dimensional, Graphene-like optical lattice with hexagonal symmetry. The lattice is realized via a spin-dependent optical lattice structure with alternating σ^+ and σ^- -sites and thus constitutes a so called `magnetic'-lattice with `antiferromagnetic'-structure. Atoms with different spin orientation can be loaded to specific lattice sites or -- depending on the parameters -- to the whole lattice. As a consequence e.g. superpositions of a superfluid spin component with a different spin component in the Mott-insulating phase can be realized as well as spin-dependent transport properties, disorder etc. After preparing an antiferromagnetically ordered state we e.g. measure sustainable changes of the transport properties of the atoms. This manifests in a significant reduction of the tunneling as compared to a single-component system. We attribute this observation to a partial tunneling blockade for one spin component induced by population in another spin component localized at alternating lattice sites. Within a Gutzwiller-Ansatz we calculate the phase diagrams for the mixed spin-states and find very good agreement with our experimental results. Moreover, by state-resolved recording
Dipolar bosons on an optical lattice ring
NASA Astrophysics Data System (ADS)
Maik, Michał; Buonsante, Pierfrancesco; Vezzani, Alessandro; Zakrzewski, Jakub
2011-11-01
We consider an ultrasmall system of polarized bosons on an optical lattice with a ring topology, interacting via long-range dipole-dipole interactions. Dipoles polarized perpendicular to the plane of the ring reveal sharp transitions between different density-wave phases. As the strength of the dipolar interactions is varied, the behavior of the transitions is first-order-like. For dipoles polarized in the plane of the ring, the transitions between possible phases show pronounced sensitivity to the lattice depth. The abundance of possible configurations may be useful for quantum-information applications.
Fibonacci optical lattices for tunable quantum quasicrystals
NASA Astrophysics Data System (ADS)
Singh, K.; Saha, K.; Parameswaran, S. A.; Weld, D. M.
2015-12-01
We describe a quasiperiodic optical lattice, created by a physical realization of the abstract cut-and-project construction underlying all quasicrystals. The resulting potential is a generalization of the Fibonacci tiling. Calculation of the energies and wave functions of ultracold atoms loaded into such a lattice demonstrate a multifractal energy spectrum, a singular continuous momentum-space structure, and the existence of controllable edge states. These results open the door to cold atom quantum simulation experiments in tunable or dynamic quasicrystalline potentials, including topological pumping of edge states and phasonic spectroscopy.
The Strontium Optical Lattice Clock: Optical Spectroscopy with Sub-Hertz Accuracy
NASA Astrophysics Data System (ADS)
Ludlow, Andrew
2009-05-01
Atomic clocks find significant roles in a number of scientific and technological settings. One interesting approach to a next-generation clock based on an optical transition uses atomic strontium confined in an optical lattice. The tight atomic confinement eliminates motional effects which otherwise trouble the atomic interrogation. At the same time, the optical lattice is equally perturbs the two electronic clock states so that the confinement introduces a net zero shift of the natural transition frequency. Here I describe the design and realization of an optical frequency standard using ^87Sr confined in a 1-D optical lattice. With an ultra-stable laser light source, atomic spectral linewidths of the optical clock transition are observed below 2 Hz. High accuracy spectroscopy of the clock transition is carried out utilizing a frequency comb referenced to the NIST-F1 Cs fountain. To explore the performance of an improved, spin-polarized Sr standard, a coherent optical phase transfer link is established between JILA and NIST. This enables remote comparison of the Sr standard against optical standards at NIST. The high frequency stability of a Sr-Ca comparison (3x10-16 at 200 s) is used to make measurements of Sr transition frequency shifts at the fractional frequency level below 10-16. These systematic shifts are discussed in detail, resulting in a total uncertainty of the Sr clock frequency at 1.5x10-16, the smallest for a neutral atom system.
The Abelian Higgs model on Optical Lattice?
NASA Astrophysics Data System (ADS)
Meurice, Yannick; Tsai, Shan-Wen; Bazavov, Alexei; Zhang, Jin
2015-03-01
We study the Lattice Gauge Theory of the U(1)-Higgs model in 1+1 dimensions in the strongly coupled regime. We discuss the plaquette corrections to the effective theory where link variables are integrated out. We discuss matching with the second-order perturbation theory effective Hamiltonian for various Bose-Hubbard models. This correspondence can be exploited for building a lattice gauge theory simulator on optical lattices. We propose to implement the quantum rotors which appear in the Hamiltonian formulation using Bose mixtures or p-orbitals. Recent progress on magnetic effects in 2+1 dimensions will be discussed. Supported by the Army Research Office of the Department of Defense under Award Number W911NF-13-1-0119.
Twisted complex superfluids in optical lattices.
Jürgensen, Ole; Sengstock, Klaus; Lühmann, Dirk-Sören
2015-01-01
We show that correlated pair tunneling drives a phase transition to a twisted superfluid with a complex order parameter. This unconventional superfluid phase spontaneously breaks the time-reversal symmetry and is characterized by a twisting of the complex phase angle between adjacent lattice sites. We discuss the entire phase diagram of the extended Bose-Hubbard model for a honeycomb optical lattice showing a multitude of quantum phases including twisted superfluids, pair superfluids, supersolids and twisted supersolids. Furthermore, we show that the nearest-neighbor interactions lead to a spontaneous breaking of the inversion symmetry of the lattice and give rise to dimerized density-wave insulators, where particles are delocalized on dimers. For two components, we find twisted superfluid phases with strong correlations between the species already for surprisingly small pair-tunneling amplitudes. Interestingly, this ground state shows an infinite degeneracy ranging continuously from a supersolid to a twisted superfluid. PMID:26345721
Twisted complex superfluids in optical lattices
NASA Astrophysics Data System (ADS)
Jürgensen, Ole; Sengstock, Klaus; Lühmann, Dirk-Sören
2015-09-01
We show that correlated pair tunneling drives a phase transition to a twisted superfluid with a complex order parameter. This unconventional superfluid phase spontaneously breaks the time-reversal symmetry and is characterized by a twisting of the complex phase angle between adjacent lattice sites. We discuss the entire phase diagram of the extended Bose—Hubbard model for a honeycomb optical lattice showing a multitude of quantum phases including twisted superfluids, pair superfluids, supersolids and twisted supersolids. Furthermore, we show that the nearest-neighbor interactions lead to a spontaneous breaking of the inversion symmetry of the lattice and give rise to dimerized density-wave insulators, where particles are delocalized on dimers. For two components, we find twisted superfluid phases with strong correlations between the species already for surprisingly small pair-tunneling amplitudes. Interestingly, this ground state shows an infinite degeneracy ranging continuously from a supersolid to a twisted superfluid.
Twisted complex superfluids in optical lattices
Jürgensen, Ole; Sengstock, Klaus; Lühmann, Dirk-Sören
2015-01-01
We show that correlated pair tunneling drives a phase transition to a twisted superfluid with a complex order parameter. This unconventional superfluid phase spontaneously breaks the time-reversal symmetry and is characterized by a twisting of the complex phase angle between adjacent lattice sites. We discuss the entire phase diagram of the extended Bose—Hubbard model for a honeycomb optical lattice showing a multitude of quantum phases including twisted superfluids, pair superfluids, supersolids and twisted supersolids. Furthermore, we show that the nearest-neighbor interactions lead to a spontaneous breaking of the inversion symmetry of the lattice and give rise to dimerized density-wave insulators, where particles are delocalized on dimers. For two components, we find twisted superfluid phases with strong correlations between the species already for surprisingly small pair-tunneling amplitudes. Interestingly, this ground state shows an infinite degeneracy ranging continuously from a supersolid to a twisted superfluid. PMID:26345721
Fast Dynamics for Atoms in Optical Lattices
NASA Astrophysics Data System (ADS)
Łącki, Mateusz; Zakrzewski, Jakub
2013-02-01
Cold atoms in optical lattices allow for accurate studies of many body dynamics. Rapid time-dependent modifications of optical lattice potentials may result in significant excitations in atomic systems. The dynamics in such a case is frequently quite incompletely described by standard applications of tight-binding models (such as, e.g., Bose-Hubbard model or its extensions) that typically neglect the effect of the dynamics on the transformation between the real space and the tight-binding basis. We illustrate the importance of a proper quantum mechanical description using a multiband extended Bose-Hubbard model with time-dependent Wannier functions. We apply it to situations directly related to experiments.
The NIM Sr Optical Lattice Clock
NASA Astrophysics Data System (ADS)
Lin, Y.; Wang, Q.; Li, Y.; Meng, F.; Lin, B.; Zang, E.; Sun, Z.; Fang, F.; Li, T.; Fang, Z.
2016-06-01
A 87Sr optical lattice clock is built at the National Institute of Metrology (NIM) of China. The atoms undergo two stages of laser cooling before being loaded into a horizontal optical lattice at the magic wavelength of 813 nm. After being interrogated by a narrow linewidth 698 nm clock laser pulse, the normalized excitation rate is measured to get the frequency error, which is then used to lock the clock laser to the ultra-narrow 1S0-3P0 clock transition. The total systematic uncertainty of the clock is evaluated to be 2.3 × 10-16, and the absolute frequency of the clock is measured to be 429 228 004 229 873.7(1.4) Hz with reference to the NIM5 cesium fountain.
NASA Astrophysics Data System (ADS)
Jiang, Lei; Qu, Chunlei; Zhang, Chuanwei
2016-06-01
The recent experimental realization of one-dimensional (1D) equal Rashba-Dresselhaus spin-orbit coupling (ERD-SOC) for cold atoms provides a disorder-free and highly controllable platform for the implementation and observation of Majorana fermions (MFs), analogous to the broadly studied solid-state nanowire-superconductor heterostructures. However, the corresponding 1D chains of cold atoms possess strong quantum fluctuation, which may destroy the superfluids and MFs. In this paper, we show that such 1D topological chains with MFs may be on demand generated in a two- or three-dimensional nontopological optical lattice with 1D ERD-SOC by modifying local potentials on target locations using experimentally already implemented atomic gas microscopes or patterned (e.g., double- or triple-well) optical lattices. All ingredients in our scheme have been experimentally realized, and the combination of them may pave the way for the experimental observation of MFs in a clean system.
Deviations from Boltzmann-Gibbs Statistics in Confined Optical Lattices.
Dechant, Andreas; Kessler, David A; Barkai, Eli
2015-10-23
We investigate the semiclassical phase-space probability distribution P(x,p) of cold atoms in a Sisyphus cooling lattice with an additional harmonic confinement. We pose the question of whether this nonequilibrium steady state satisfies the equivalence of energy and probability. This equivalence is the foundation of Boltzmann-Gibbs and generalized thermostatic statistics, and a prerequisite for the description in terms of a temperature. At large energies, P(x,p) depends only on the Hamiltonian H(x,p) and the answer to the question is yes. In distinction to the Boltzmann-Gibbs state, the large-energy tails are power laws P(x,p)∝H(x,p)(-1/D), where D is related to the depth of the optical lattice. At intermediate energies, however, P(x,p) cannot be expressed as a function of the Hamiltonian and the equivalence between energy and probability breaks down. As a consequence the average potential and kinetic energy differ and no well-defined temperature can be assigned. The Boltzmann-Gibbs state is regained only in the limit of deep optical lattices. For strong confinement relative to the damping, we derive an explicit expression for the stationary phase-space distribution. PMID:26551114
Spin-1/2 Optical Lattice Clock
Lemke, N. D.; Ludlow, A. D.; Barber, Z. W.; Fortier, T. M.; Diddams, S. A.; Jiang, Y.; Jefferts, S. R.; Heavner, T. P.; Parker, T. E.; Oates, C. W.
2009-08-07
We experimentally investigate an optical clock based on {sup 171}Yb (I=1/2) atoms confined in an optical lattice. We have evaluated all known frequency shifts to the clock transition, including a density-dependent collision shift, with a fractional uncertainty of 3.4x10{sup -16}, limited principally by uncertainty in the blackbody radiation Stark shift. We measured the absolute clock transition frequency relative to the NIST-F1 Cs fountain clock and find the frequency to be 518 295 836 590 865.2(0.7) Hz.
LETTER On the nonlinear response of a particle interacting with fermions in a 1D lattice
NASA Astrophysics Data System (ADS)
Zotos, X.
2010-12-01
By the Bethe ansatz method we study the energy dispersion of a particle interacting by a local interaction with fermions (or hard core bosons) of equal mass in a one-dimensional lattice. We focus on the period of the Bloch oscillations, which turns out to be related to the Fermi wavevector of the Fermi sea and in particular on how this dispersion emerges as a collective effect in the thermodynamic limit. We also discuss the adiabatic coherent collective response of the system to an applied field.
NASA Astrophysics Data System (ADS)
Minárik, Stanislav
2015-08-01
In this paper, we propose theoretical basis for investigation of dynamics of acoustic phonons in a thin layers containing nano-scale structural inhomogeneities. One-dimensional (1D) model of a crystal lattice was considered to reveal specific features of the processes arising in such system of phonons in equilibrium state. Standard quantization of energy of 1D ionic chain vibrating by acoustic frequencies was carried out while the presence of foreign ions in this chain was taken into account. Since only two dimensions are dominant in thin layers, only longitudinal vibrations of the chain in the plane of the layer were considered. Results showed that foreign ions affect the energy quantization. Phonon-phonon interaction between two phonon`s modes can be expected if the mass of foreign ions implanted by ion-beam differs from the mass of ions in the initial layer. We believe that the obtained results will help to understand the character of phonon systems in nanostructured thin layers prepared by ion-bem technology, and will allow better explain some thermal and electrical phenomena associated with lattice dynamics in such layers.
On the spectrum of the lattice spin-boson Hamiltonian for any coupling: 1D case
Muminov, M.; Neidhardt, H.; Rasulov, T.
2015-05-15
A lattice model of radiative decay (so-called spin-boson model) of a two level atom and at most two photons is considered. The location of the essential spectrum is described. For any coupling constant, the finiteness of the number of eigenvalues below the bottom of its essential spectrum is proved. The results are obtained by considering a more general model H for which the lower bound of its essential spectrum is estimated. Conditions which guarantee the finiteness of the number of eigenvalues of H below the bottom of its essential spectrum are found. It is shown that the discrete spectrum might be infinite if the parameter functions are chosen in a special form.
Quantum criticality in disordered bosonic optical lattices
Cai Xiaoming; Chen Shu; Wang Yupeng
2011-04-15
Using the exact Bose-Fermi mapping, we study universal properties of ground-state density distributions and finite-temperature quantum critical behavior of one-dimensional hard-core bosons in trapped incommensurate optical lattices. Through the analysis of universal scaling relations in the quantum critical regime, we demonstrate that the superfluid-to-Bose-glass transition and the general phase diagram of disordered hard-core bosons can be uniquely determined from finite-temperature density distributions of the trapped disordered system.
Excitations in disordered bosonic optical lattices
Knap, Michael; Arrigoni, Enrico; Linden, Wolfgang von der
2010-11-15
Spectral excitations of ultracold gases of bosonic atoms trapped in one-dimensional optical lattices with disorder are investigated by means of the variational cluster approach applied to the Bose-Hubbard model. Qualitatively different disorder distributions typically employed in experiments are considered. The computed spectra exhibit a strong dependence on the shape of the disorder distribution and the disorder strength. We compare alternative results for the Mott gap obtained from its formal definition and from the minimum peak distance, which is the quantity available from experiments.
Transport of an interacting Bose gas in 1D disordered lattices
D'Errico, C.; Chaudhuri, S.; Gori, L.; Kumar, A.; Lucioni, E.; Tanzi, L.; Inguscio, M.; Modugno, G.
2014-08-20
We use ultracold atoms in a quasiperiodic lattice to study two outstanding problems in the physics of disordered systems: a) the anomalous diffusion of a wavepacket in the presence of disorder, interactions and noise; b) the transport of a disordered superfluid. a) Our results show that the subdiffusion, observed when interaction alone is present, can be modelled with a nonlinear diffusion equation and the peculiar shape of the expanding density profiles can be connected to the microscopic nonlinear diffusion coefficients. Also when noise alone is present we can describe the observed normal diffusion dynamics by existing microscopic models. In the unexplored regime in which noise and interaction are combined, instead, we observe an anomalous diffusion, that we model with a generalized diffusion equation, where noise- and interaction-induced contributions add each other. b) We find that an instability appearing at relatively large momenta can be employed to locate the fluid-insulator crossover driven by disorder. By investigating the momentum-dependent transport, we observe a sharp crossover from a weakly dissipative regime to a strongly unstable one at a disorder-dependent critical momentum. The set of critical disorder and interaction strengths for which such critical momentum vanishes, can be identified with the separation between a fluid regime and an insulating one and can be related to the predicted zero-temperature superfluid-Bose glass transition.
A low maintenance Sr optical lattice clock
NASA Astrophysics Data System (ADS)
Hill, I. R.; Hobson, R.; Bowden, W.; Bridge, E. M.; Donnellan, S.; Curtis, E. A.; Gill, P.
2016-06-01
We describe the Sr optical lattice clock apparatus at NPL with particular emphasis on techniques used to increase reliability and minimise the human requirement in its operation. Central to this is a clock-referenced transfer cavity scheme for the stabilisation of cooling and trapping lasers. We highlight several measures to increase the reliability of the clock with a view towards the realisation of an optical time-scale. The clock contributed 502 hours of data over a 25 day period (84% uptime) in a recent measurement campaign with several uninterrupted periods of more than 48 hours. An instability of 2 x 10-17 was reached after 105 s of averaging in an interleaved self-comparison of the clock.
Observation of Stueckelberg oscillations in accelerated optical lattices
Zenesini, A.; Ciampini, D.; Arimondo, E.; Morsch, O.
2010-12-15
We report the experimental observation of Stueckelberg oscillations of matter waves in optical lattices. Extending previous work on Landau-Zener tunneling of Bose-Einstein condensates in optical lattices, we study the effects of the accumulated phase between two successive crossings of the Brillouin zone edge. Our results agree well with a simple model for multiple Landau-Zener tunneling events taking into account the band structure of the optical lattice.
Nuclear spin effects in optical lattice clocks
Boyd, Martin M.; Zelevinsky, Tanya; Ludlow, Andrew D.; Blatt, Sebastian; Zanon-Willette, Thomas; Foreman, Seth M.; Ye Jun
2007-08-15
We present a detailed experimental and theoretical study of the effect of nuclear spin on the performance of optical lattice clocks. With a state-mixing theory including spin-orbit and hyperfine interactions, we describe the origin of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition and the differential g factor between the two clock states for alkaline-earth-metal(-like) atoms, using {sup 87}Sr as an example. Clock frequency shifts due to magnetic and optical fields are discussed with an emphasis on those relating to nuclear structure. An experimental determination of the differential g factor in {sup 87}Sr is performed and is in good agreement with theory. The magnitude of the tensor light shift on the clock states is also explored experimentally. State specific measurements with controlled nuclear spin polarization are discussed as a method to reduce the nuclear spin-related systematic effects to below 10{sup -17} in lattice clocks.
Hybrid plasmonic lattices with tunable magneto-optical activity.
Kataja, Mikko; Pourjamal, Sara; Maccaferri, Nicolò; Vavassori, Paolo; Hakala, Tommi K; Huttunen, Mikko J; Törmä, Päivi; van Dijken, Sebastiaan
2016-02-22
We report on the optical and magneto-optical response of hybrid plasmonic lattices that consist of pure nickel and gold nanoparticles in a checkerboard arrangement. Diffractive far-field coupling between the individual emitters of the lattices results in the excitation of two orthogonal surface lattice resonance modes. Local analyses of the radiation fields indicate that both the nickel and gold nanoparticles contribute to these collective resonances and, thereby, to the magneto-optical activity of the hybrid arrays. The strong effect of noble metal nanoparticles on the magneto-optical response of hybrid lattices opens up new avenues for the realization of sensitive and tunable magneto-plasmonic nanostructures. PMID:26907022
Intrinsic Localized Modes in Optical Photonic Lattices and Arrays
NASA Astrophysics Data System (ADS)
Christodoulides, Demetrios
-locking and pulse compression. A strong signature of discrete X-wave formation was also demonstrated in such structures. In the last few years, Anderson localization was unequivocally observed in array systems where the transition from ballistic transport to diffusive, and the cross-over to Anderson localization was studied as a function of disorder and nonlinearity. In recent studies synthetic lattices exhibiting parity-time (PT) symmetry were also considered. The interplay of gain and loss in this latter family of structures leads to counterintuitive characteristics and behavior such as non-reciprocal propagation and power oscillations. The realization of discrete array systems at su-bwavelenth scales is another important direction that is nowadays intensively pursued. References 1. D. N. Christodoulides, F. Lederer, and Y. Silberberg, Nature 424, 817- 823 (2003). 2. F. Lederer, G. I. Stegeman, D. N. Christodoulides, G. Assanto, M. Segev and Y. Silberberg, Phys. Reports 463, 1-126 (2008). 3. M Wimmer, A Regensburger, MA Miri, C. Bersch, D.N Christodoulides, and U. Peschel, ''Observation of optical solitons in PT-symmetric lattices'' Nature Communications 6, 7782 (2015). Intrinsic Localized Modes in Optical Photonic Lattices and Arrays.
Chaotic dynamics in a two-dimensional optical lattice.
Horsley, Eric; Koppell, Stewart; Reichl, L E
2014-01-01
The classical nonlinear dynamics of a dilute gas of rubidium atoms in an optical lattice is studied for a range of polarizations of the laser beams forming the lattice. The dynamics ranges from integrable to chaotic, and mechanisms leading to the onset of chaos in the lattice are described. PMID:24580307
Chaos in the honeycomb optical-lattice unit cell
NASA Astrophysics Data System (ADS)
Porter, Max D.; Reichl, L. E.
2016-01-01
Natural and artificial honeycomb lattices are of great interest because the band structure of these lattices, if properly constructed, contains a Dirac point. Such lattices occur naturally in the form of graphene and carbon nanotubes. They have been created in the laboratory in the form of semiconductor 2DEGs, optical lattices, and photonic crystals. We show that, over a wide energy range, gases (of electrons, atoms, or photons) that propagate through these lattices are Lorentz gases and the corresponding classical dynamics is chaotic. Thus honeycomb lattices are also of interest for understanding eigenstate thermalization and the conductor-insulator transition due to dynamic Anderson localization.
Antiferromagnetic Spinor Condensates in a Two-Dimensional Optical Lattice.
Zhao, L; Jiang, J; Tang, T; Webb, M; Liu, Y
2015-06-01
We experimentally demonstrate that spin dynamics and the phase diagram of spinor condensates can be conveniently tuned by a two-dimensional optical lattice. Spin population oscillations and a lattice-tuned separatrix in phase space are observed in every lattice where a substantial superfluid fraction exists. In a sufficiently deep lattice, we observe a phase transition from a longitudinal polar phase to a broken-axisymmetry phase in steady states of lattice-confined spinor condensates. The steady states are found to depend sigmoidally on the lattice depth and exponentially on the magnetic field. We also introduce a phenomenological model that semiquantitatively describes our data without adjustable parameters. PMID:26196625
Arnold diffusion in a driven optical lattice.
Boretz, Yingyue; Reichl, L E
2016-03-01
The effect of time-periodic forces on matter has been a topic of growing interest since the advent of lasers. It is known that dynamical systems with 2.5 or more degrees of freedom are intrinsically unstable. As a consequence, time-periodic driven systems can experience large excursions in energy. We analyze the classical and quantum dynamics of rubidium atoms confined to a time-periodic optical lattice with 2.5 degrees of freedom. When the laser polarizations are orthogonal, the system consists of two 1.5 uncoupled dynamical systems. When laser polarizations are turned away from orthogonal, an Arnold web forms and the dynamics undergoes a fundamental change. For parallel polarizations, we find huge random excursions in the rubidium atom energies and significant entanglement of energies in the quantum dynamics. PMID:27078351
Arnold diffusion in a driven optical lattice
NASA Astrophysics Data System (ADS)
Boretz, Yingyue; Reichl, L. E.
2016-03-01
The effect of time-periodic forces on matter has been a topic of growing interest since the advent of lasers. It is known that dynamical systems with 2.5 or more degrees of freedom are intrinsically unstable. As a consequence, time-periodic driven systems can experience large excursions in energy. We analyze the classical and quantum dynamics of rubidium atoms confined to a time-periodic optical lattice with 2.5 degrees of freedom. When the laser polarizations are orthogonal, the system consists of two 1.5 uncoupled dynamical systems. When laser polarizations are turned away from orthogonal, an Arnold web forms and the dynamics undergoes a fundamental change. For parallel polarizations, we find huge random excursions in the rubidium atom energies and significant entanglement of energies in the quantum dynamics.
Detecting multiatomic composite states in optical lattices
NASA Astrophysics Data System (ADS)
Kuklov, Anatoly; Moritz, Henning
2007-01-01
We propose and discuss methods for detecting quasimolecular complexes which are expected to form in strongly interacting optical lattice systems. Particular emphasis is placed on the detection of composite fermions forming in Bose-Fermi mixtures. We argue that, as an indirect indication of the composite fermions and a generic consequence of strong interactions, periodic correlations must appear in the atom shot noise of bosonic absorption images, similar to the bosonic Mott insulator [S. Fölling , Nature (London) 434, 481 (2005)]. The composites can also be detected directly and their quasimomentum distribution measured. This method—an extension of the technique of noise correlation interferometry [E. Altman , Phys. Rev. A 79, 013603 (2004)]—relies on measuring higher order correlations between the bosonic and fermionic shot noise in the absorption images. However, it fails above a certain number of the constituents due to a dramatic increase of uncorrelated noise.
Landau Levels in Strained Optical Lattices
NASA Astrophysics Data System (ADS)
Tian, Binbin; Endres, Manuel; Pekker, David
2015-12-01
We propose a hexagonal optical lattice system with spatial variations in the hopping matrix elements. Just like in the valley Hall effect in strained graphene, for atoms near the Dirac points the variations in the hopping matrix elements can be described by a pseudomagnetic field and result in the formation of Landau levels. We show that the pseudomagnetic field leads to measurable experimental signatures in momentum resolved Bragg spectroscopy, Bloch oscillations, cyclotron motion, and quantization of in situ densities. Our proposal can be realized by a slight modification of existing experiments. In contrast to previous methods, pseudomagnetic fields are realized in a completely static system avoiding common heating effects and therefore opening the door to studying interaction effects in Landau levels with cold atoms.
Breakdown of adiabaticity when loading ultracold atoms in optical lattices
NASA Astrophysics Data System (ADS)
Zakrzewski, Jakub; Delande, Dominique
2009-07-01
Realistic simulations of current ultracold atom experiments in optical lattices show that the ramping up of the optical lattice is significantly nonadiabatic, implying that experimentally prepared Mott insulators are not really in the ground state of the atomic system. The nonadiabaticity is even larger in the presence of a secondary quasiperiodic lattice simulating “disorder.” Alternative ramping schemes are suggested that improve the adiabaticity when the disorder is not too large.
The strontium optical lattice clock: Optical spectroscopy with sub-hertz accuracy
NASA Astrophysics Data System (ADS)
Ludlow, Andrew D.
One of the most well-developed applications of coherent interaction with atoms is atomic frequency standards and clocks. Atomic clocks find significant roles in a number of scientific and technological settings. State-of-the-art, laser-cooled, Cs-fountain microwave clocks have demonstrated impressive frequency measurement accuracy, with fractional uncertainties below the 10-15 level. On the other hand, frequency standards based on optical transitions have made substantial steps forward over the last decade, benefiting from their high operational frequencies. An interesting approach to such an optical standard uses atomic strontium confined in an optical lattice. The tight atomic confinement allows for nearly complete elimination of Doppler and recoil-related effects which can otherwise trouble the precise atomic interrogation. At the same time, the optical lattice is designed to equally perturb the two electronic clock states so that the confinement introduces a net zero shift of the natural transition frequency. This thesis describes the design and realization of an optical frequency standard using 87Sr confined in a 1-D optical lattice. Techniques for atomic manipulation and control are described, including two-stage laser cooling, proper design of atomic confinement in a lattice potential, and optical pumping techniques. With the development of an ultra-stable coherent laser light source, atomic spectral linewidths of the optical clock transition are observed below 2 Hz. High accuracy spectroscopy of the clock transition is carried out utilizing a femtosecond frequency comb referenced to the NIST-F1 Cs fountain. To explore the performance of an improved, spin-polarized Sr standard, a coherent optical phase transfer link is established between JILA and NIST. This enables remote comparison of the Sr standard against optical standards at NIST, such as the cold Ca standard. The high frequency stability of a Sr-Ca comparison (3 x 10-16 at 200 s) is used to make
Chern Kondo Insulator in an Optical Lattice
NASA Astrophysics Data System (ADS)
Chen, Hua; Liu, Xiong-Jun; Xie, X. C.
2016-01-01
We propose to realize and observe Chern Kondo insulators in an optical superlattice with laser-assisted s and p orbital hybridization and a synthetic gauge field, which can be engineered based on the recent cold atom experiments. Considering a double-well square optical lattice, the localized s orbitals are decoupled from itinerant p bands and are driven into a Mott insulator due to the strong Hubbard interaction. Raman laser beams are then applied to induce tunnelings between s and p orbitals, and generate a staggered flux simultaneously. Because of the strong Hubbard interaction of s orbital states, we predict the existence of a critical Raman laser-assisted coupling, beyond which the Kondo screening is achieved, and then a fully gapped Chern Kondo phase emerges, with the topology characterized by integer Chern numbers. Being a strongly correlated topological state, the Chern Kondo phase is different from the single-particle quantum anomalous Hall state, and can be identified by measuring the band topology and double occupancy of s orbitals. The experimental realization and detection of the predicted Chern Kondo insulator are also proposed.
Chern Kondo Insulator in an Optical Lattice.
Chen, Hua; Liu, Xiong-Jun; Xie, X C
2016-01-29
We propose to realize and observe Chern Kondo insulators in an optical superlattice with laser-assisted s and p orbital hybridization and a synthetic gauge field, which can be engineered based on the recent cold atom experiments. Considering a double-well square optical lattice, the localized s orbitals are decoupled from itinerant p bands and are driven into a Mott insulator due to the strong Hubbard interaction. Raman laser beams are then applied to induce tunnelings between s and p orbitals, and generate a staggered flux simultaneously. Because of the strong Hubbard interaction of s orbital states, we predict the existence of a critical Raman laser-assisted coupling, beyond which the Kondo screening is achieved, and then a fully gapped Chern Kondo phase emerges, with the topology characterized by integer Chern numbers. Being a strongly correlated topological state, the Chern Kondo phase is different from the single-particle quantum anomalous Hall state, and can be identified by measuring the band topology and double occupancy of s orbitals. The experimental realization and detection of the predicted Chern Kondo insulator are also proposed. PMID:26871345
Dissipative dynamics of matter-wave solitons in a nonlinear optical lattice
Abdullaev, F. Kh.; Tomio, Lauro; Gammal, A.; Luz, H. L. F. da
2007-10-15
Dynamics and stability of solitons in two-dimensional (2D) Bose-Einstein condensates (BEC), with one-dimensional (1D) conservative plus dissipative nonlinear optical lattices, are investigated. In the case of focusing media (with attractive atomic systems), the collapse of the wave packet is arrested by the dissipative periodic nonlinearity. The adiabatic variation of the background scattering length leads to metastable matter-wave solitons. When the atom feeding mechanism is used, a dissipative soliton can exist in focusing 2D media with 1D periodic nonlinearity. In the defocusing media (repulsive BEC case) with harmonic trap in one direction and nonlinear optical lattice in the other direction, the stable soliton can exist. Variational approach simulations are confirmed by full numerical results for the 2D Gross-Pitaevskii equation.
Lattice gaugefixing and other optics in lattice gauge theory
Yee, Ken.
1992-06-01
We present results from four projects. In the first, quark and gluon propagators and effective masses and {Delta}I = 1/2 Rule operator matching coefficients are computed numerically in gaugefixed lattice QCD. In the second, the same quantities are evaluated analytically in the strong coupling, N {yields} {infinity} limit. In the third project, the Schwinger model is studied in covariant gauges, where we show that the effective electron mass varies with the gauge parameter and that longitudinal gaugefixing ambiguities affect operator product expansion coefficients (analogous to {Delta}I = 1/2 Rule matching coefficients) determined by matching gauge variant matrix elements. However, we find that matching coefficients even if shifted by the unphysical modes are {xi} invariant. In the fourth project, we show that the strong coupling parallelogram lattice Schwinger model as a different thermodynamic limit than the weak coupling continuum limit. As a function of lattice skewness angle these models span the {Delta} = {minus}1 critical line of 6-vertex models which, in turn, have been identified as c = 1 conformal field theories.
Thermodynamics of quantum degenerate gases in optical lattices
NASA Astrophysics Data System (ADS)
Blakie, P. B.; Rey, A.-M.; Bezett, A.
2007-02-01
The entropy-temperature curves are calculated for non-interacting Bose and Fermi gases in a 3D optical lattice. These curves facilitate understanding of how adiabatic changes in the lattice depth affect the temperature, and we demonstrate regimes where the atomic sample can be significantly heated or cooled by the loading process. We assess the effects of interactions on a Bose gas in a deep optical lattice, and show that interactions ultimately limit the extent of cooling that can occur during lattice loading.
Effective Dirac Hamiltonian for anisotropic honeycomb lattices: Optical properties
NASA Astrophysics Data System (ADS)
Oliva-Leyva, M.; Naumis, Gerardo G.
2016-01-01
We derive the low-energy Hamiltonian for a honeycomb lattice with anisotropy in the hopping parameters. Taking the reported Dirac Hamiltonian for the anisotropic honeycomb lattice, we obtain its optical conductivity tensor and its transmittance for normal incidence of linearly polarized light. Also, we characterize its dichroic character due to the anisotropic optical absorption. As an application of our general findings, which reproduce the previous case of uniformly strained graphene, we study the optical properties of graphene under a nonmechanical distortion.
Critical point of a rotating Bose-Einstein condensates in optical lattice
NASA Astrophysics Data System (ADS)
El-Badry, Azza M.; Soliman, Shemi S. M.; Hassan, Ahmed S.
2016-06-01
In this paper, we have considered the critical point (critical atoms' number and the corresponding critical temperature) of rotating condensate bosons trapped in optical lattices. Our system is formed by loading three dimensional harmonically trapped boson atoms into a 1D (axial direction) or 2D (radial direction) optical lattice. The system subjected to rotating with angular velocity Ω around to the axial direction z-axis. We employ the semiclassical approximation to calculate the critical point. Effects of the optical lattice depth, direction (axial or radial) and the rotation rate on the critical point are investigated using the semiclassical approximation. The calculated results showed that the temperature dependence of the critical point is changed in an optical lattice and depends crucially on the rotation rate. The effect of the finite size for one-dimensional optical lattice case, as required by experiment, is discussed. The outcome results furnish useful qualitatively theoretical results for the future Bose-Einstein condensation experiments in such traps.
Collisional Losses, Decoherence, and Frequency Shifts in Optical Lattice Clocks with Bosons
Lisdat, Ch.; Winfred, J. S. R. Vellore; Middelmann, T.; Riehle, F.; Sterr, U.
2009-08-28
We have quantified collisional losses, decoherence and the collision shift in a one-dimensional optical lattice clock on the highly forbidden transition {sup 1}S{sub 0}-{sup 3}P{sub 0} at 698 nm with bosonic {sup 88}Sr. We were able to distinguish two loss channels: inelastic collisions between atoms in the upper and lower clock state and atoms in the upper clock state only. Based on the measured coefficients, we determine the operation parameters at which a 1D-lattice clock with {sup 88}Sr shows no degradation due to collisions on the fractional uncertainty level of 10{sup -16}.
Dynamic Optical Lattices of Subwavelength Spacing for Ultracold Atoms
NASA Astrophysics Data System (ADS)
Nascimbene, Sylvain; Goldman, Nathan; Cooper, Nigel R.; Dalibard, Jean
2015-10-01
We propose a scheme for realizing lattice potentials of subwavelength spacing for ultracold atoms. It is based on spin-dependent optical lattices with a time-periodic modulation. We show that the atomic motion is well described by the combined action of an effective, time-independent lattice of small spacing, together with a micromotion associated with the time modulation. A numerical simulation shows that an atomic gas can be adiabatically loaded into the effective lattice ground state, for time scales comparable to the ones required for adiabatic loading of standard optical lattices. We generalize our scheme to a two-dimensional geometry, leading to Bloch bands with nonzero Chern numbers. The realization of lattices of subwavelength spacing allows for the enhancement of energy scales, which could facilitate the achievement of strongly correlated (topological) states.
Ultracold atoms in an optical lattice with dynamically variable periodicity
Al-Assam, S.; Williams, R. A.; Foot, C. J.
2010-08-15
The use of a dynamic 'accordion' lattice with ultracold atoms is demonstrated. Ultracold atoms of {sup 87}Rb are trapped in a two-dimensional optical lattice, and the spacing of the lattice is then increased in both directions from 2.2 to 5.5 {mu}m. Atoms remain bound for expansion times as short as a few milliseconds, and the experimentally measured minimum ramp time is found to agree well with numerical calculations. This technique allows an experiment such as quantum simulations to be performed with a lattice spacing smaller than the resolution limit of the imaging system, while allowing imaging of the atoms at individual lattice sites by subsequent expansion of the optical lattice.
NASA Astrophysics Data System (ADS)
Tang, Cheng; Zhang, Teng; Weiss, David
2015-05-01
We present our progress towards measuring the electron EDM using laser-cooled cesium and rubidium atoms trapped in a one dimensional optical lattice. To date, we have collected Cs atoms in two parallel 1D optical lattices that thread three glass electric field plates in a region of well-shielded magnetic fields. As a precursor to the EDM measurement, we have performed a variant of a Hanle effect measurement and used it to study the vector light shifts due to the cavity-built up lattice beams. This gives us a very high sensitivity to the absolute linear polarization of the light, which we have demonstrated to be as good as ~10-8 in fractional power. NSF PHY-13-07096.
Novel Quantum Phases of Dipolar Bose Gases in Optical Lattices
NASA Astrophysics Data System (ADS)
Yi, S.; Li, T.; Sun, C. P.
2007-06-01
We investigate the quantum phases of polarized dipolar bosons loaded into a two-dimensional square and three-dimensional cubic optical lattices. We show that the long-range and anisotropic nature of the dipole-dipole interaction induces a rich variety of quantum phases, including the supersolid and striped supersolid phases in two-dimensional lattices, and the layered supersolid phase in three-dimensional lattices.
Optical properties of graphene nanostructures from first-principles: from 1D to 0D
NASA Astrophysics Data System (ADS)
Varsano, Daniele; Prezzi, Deborah; Ruini, Alice; Molinari, Elisa
2010-03-01
The possibility of patterning graphene sheets in a controllable manner to design semiconducting low-dimensional nanostructures opens exciting opportunities also in view of novel phenomena occurring under light excitation as well as nanoscale optoelectronics applications. We discuss the main characteristics of optical excitations in quasi-1D armchair graphene nanoribbons (A-GNRs) by means of ab-initio many-body calculations [1]. Our theoretical approach includes both self-energy corrections and excitonic effects through the GW-BSE formalism, providing full understanding of excited-state properties. Electron-hole interaction is found to suppress the van Hove singularities -as known for other 1D systems- and introduces strongly bound excitonic peaks. Starting from these ideal structures, we discuss the effect of width modulation on confinement and optical response [2]. Our results show that edge-modulated A-GNRs are efficient systems for the creation of carbon-based QD structures with prominent exciton localization features. [1] D. Prezzi, D. Varsano, A. Ruini, A. Marini, and E. Molinari, Phys. Rev. B 77, 041404 (2008). [2] D. Prezzi, D. Varsano, A. Ruini, and E. Molinari, to be published (2009)
Quantum simulation of 2D topological physics in a 1D array of optical cavities
Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei
2015-01-01
Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration. PMID:26145177
A transportable optical lattice clock using 171Yb
NASA Astrophysics Data System (ADS)
Mura, Gregor; SOC2 Team
2013-07-01
We present first results on the spectroscopy of the 1S0 - 3P0 transition at 578nm in a transportable 171Yb optical lattice clock. With the Yb atoms confined in a one-dimensional optical lattice, we have observed linewidths below 200 Hz, limited by saturation broadening. Currently the system is being upgraded towards full clock operation and use of more compact and robust subsystems.
Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses
NASA Astrophysics Data System (ADS)
Rathod, K. D.; Singh, P. K.; Natarajan, Vasant
2014-09-01
We demonstrate generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman Slower. They are then subjected to a pair of molasses beams inclined at $45^\\circ$ with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate selective deflection of the bosonic isotope $^{174}$Yb, and the fermionic isotope $^{171}$Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.
Dynamically generated flat-band phases in optical kagome lattices
NASA Astrophysics Data System (ADS)
Chern, Gia-Wei; Chien, Chih-Chun; Di Ventra, Massimiliano
2014-07-01
Motivated by recent advances in the realization of complex two-dimensional optical lattices, we investigate theoretically the quantum transport of ultracold fermions in an optical kagome lattice. In particular, we focus on its extensively degenerate localized states (flat band). By loading fermions in a partial region of the lattice and depleting the mobile atoms at the far boundary of the initially unoccupied region, we find a dynamically generated flat-band insulator, which is also a population-inverted state. We further show that inclusion of weak repulsion leads to a dynamical stripe phase for two-component fermions in a similar setup. Finally, by preparing a topological insulating state in a partially occupied kagome lattice, we find that the topological chiral current decays but exhibits an interesting oscillating dynamics during the nonequilibrium transport. Given the broad variety of lattice geometries supporting localized or topological states, our work suggests new possibilities for using geometrical effects and their dynamics in atomtronic devices.
E-beam to complement optical lithography for 1D layouts
NASA Astrophysics Data System (ADS)
Lam, David K.; Liu, Enden D.; Smayling, Michael C.; Prescop, Ted
2011-04-01
The semiconductor industry is moving to highly regular designs, or 1D gridded layouts, to enable scaling to advanced nodes, as well as improve process latitude, chip size and chip energy consumption. The fabrication of highly regular ICs is straightforward. Poly and metal layers are arranged into 1D layouts. These 1D layouts facilitate a two-step patterning approach: a line-creation step, followed by a line-cutting step, to form the desired IC pattern (See Figure 1). The first step, line creation, can be accomplished with a variety of lithography techniques including 193nm immersion (193i) and Self-Aligned Double Patterning (SADP). It appears feasible to create unidirectional parallel lines to at least 11 nm half-pitch, with two applications of SADP for pitch division by four. Potentially, this step can also be accomplished with interference lithography or directed self assembly in the future. The second step, line cutting, requires an extremely high-resolution lithography technique. At advanced nodes, the only options appear to be the costly quadruple patterning with 193i, or EUV or E-Beam Lithography (EBL). This paper focuses on the requirements for a lithography system for "line cutting", using EBL to complement Optical. EBL is the most cost-effective option for line cutting at advanced nodes for HVM.
Synthetic gauge fields and many-body physics in an optical lattice clock
NASA Astrophysics Data System (ADS)
Koller, Andrew P.; Wall, Michael L.; Li, Shuming; Zhang, Xibo; Cooper, Nigel R.; Ye, Jun; Rey, Ana Maria
2015-05-01
We propose the implementation of a synthetic gauge field in a 1D optical lattice clock and explore the resulting single-particle and many-body physics. The system can realize an effective two-leg ladder by using the two clock states as a synthetic dimension, together with the tunneling-coupled 1D lattice sites. A large flux per plaquette is naturally generated because the clock laser imprints a phase that varies significantly across lattice sites. We propose to use standard spectroscopic tools - Ramsey and Rabi spectroscopy - to probe the band structure and reveal signatures of the spin-orbit coupling, including chiral edge states and the modification of single-particle physics due to s-wave and p-wave interactions. These effects can be probed in spite of the relatively high temperatures (~ micro Kelvin) and weak interactions, thanks to the exquisite precision and sensitivity of the JILA Sr optical lattice clock. We also discuss the exciting possibility of using the nuclear spin degrees of freedom to realize more exotic synthetic dimension topologies and flux patterns. Supported by JILA-NSF-PFC-1125844, NSF-PIF- 1211914, ARO, AFOSR, AFOSR-MURI, and NDSEG.
Evolution of the Hofstadter butterfly in a tunable optical lattice
NASA Astrophysics Data System (ADS)
Yılmaz, F.; Ünal, F. Nur; Oktel, M. Ã.-.
2015-06-01
Recent advances in realizing artificial gauge fields on optical lattices promise experimental detection of topologically nontrivial energy spectra. Self-similar fractal energy structures generally known as Hofstadter butterflies depend sensitively on the geometry of the underlying lattice, as well as the applied magnetic field. The recent demonstration of an adjustable lattice geometry [L. Tarruell, D. Greif, T. Uehlinger, G. Jotzu, and T. Esslinger, Nature (London) 483, 302 (2012), 10.1038/nature10871] presents a unique opportunity to study this dependence. In this paper, we calculate the Hofstadter butterflies that can be obtained in such an adjustable lattice and find three qualitatively different regimes. We show that the existence of Dirac points at zero magnetic field does not imply the topological equivalence of spectra at finite field. As the real-space structure evolves from the checkerboard lattice to the honeycomb lattice, two square-lattice Hofstadter butterflies merge to form a honeycomb lattice butterfly. This merging is topologically nontrivial, as it is accomplished by sequential closings of gaps. Ensuing Chern number transfer between the bands can be probed with the adjustable lattice experiments. We also calculate the Chern numbers of the gaps for qualitatively different spectra and discuss the evolution of topological properties with underlying lattice geometry.
NASA Astrophysics Data System (ADS)
Halagačka, L.; Vanwolleghem, M.; Vaurette, F.; Ben-Youssef, J.; Gogol, P.; Yam, N.; Postava, K.; Dagens, B.; Pištora, J.
2014-03-01
In this paper we analyze the optical and transversal magnetooptical (MO) response of magnetoplasmonic (MP) nanostructures. The MP structure is a 1D periodic gold grating fabricated by lift-off technique on the MO dielectric substrate (Bi-substituted yttrium iron garnet BixY3-xFe5O12). Following our recent theoretical work (Opt. Express 21, pp. 2174121755, Sep 2013.), we confirm here experimentally the predicted dependence of the MO response on the geometry of the grating, that is directly attributed to the anticrossing behavior of the Fabry-Perot (FP) resonance in the grating's slits and the surface plasmon resonances (SPPs) at its interfaces. The experimental results were achieved by Mueller matrix spectroscopic ellipsometry. Observed fine tuning of the transverse magneto-optic Kerr opens up new possibilities for the design of compact nonreciprocal devices.
Three-dimensional optical lattice clock with bosonic {sup 88}Sr atoms
Akatsuka, Tomoya; Takamoto, Masao; Katori, Hidetoshi
2010-02-15
We present detailed analyses of our recent experiment on the three-dimensional (3D) optical lattice clock with bosonic {sup 88}Sr atoms in which the collisional frequency shift was suppressed by applying a single-occupancy lattice. Frequency shifts in magnetically induced spectroscopy on the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition ({lambda}=698 nm) of {sup 88}Sr were experimentally investigated by referencing a one-dimensional (1D) lattice clock based on spin-polarized {sup 87}Sr atoms. We discuss that the clock stability is limited by the current laser stability as well as the experimental sequence of the clock operation, which may be improved to {sigma}{sub y}({tau})=2x10{sup -16}/{radical}({tau}) by optimizing the cycle time of the clock operation.
Dissipation-Induced Symmetry Breaking in a Driven Optical Lattice
Gommers, R.; Bergamini, S.; Renzoni, F.
2005-08-12
We analyze the atomic dynamics in an ac driven periodic optical potential which is symmetric in both time and space. We experimentally demonstrate that in the presence of dissipation the symmetry is broken, and a current of atoms through the optical lattice is generated as a result.
Progress towards quantum-gas experiments in optical lattices
NASA Astrophysics Data System (ADS)
Pertot, Daniel; Greif, Daniel; Schiller, Rebekah; Schneble, Dominik
2008-05-01
We present our progress towards quantum simulation experiments with ultracold bosonic atoms in an optical lattice. We have achieved Bose-Einstein condensation of rubidium-87 in a transporter apparatus featuring a moving-coil TOP trap (McTOP). Quasi-pure condensates containing up to one million atoms are routinely produced with high stability. As atomic micro-motion in TOP traps precludes the direct loading of condensates into a single quasimomentum state of an optical lattice, we are in the process of implementing a loading scheme involving evaporation of nearly-condensed thermal clouds in a crossed optical dipole trap. We will discuss our recent experimental results.
Evolution of the Hofstadter butterfly in a tunable optical lattice
NASA Astrophysics Data System (ADS)
Oktel, Mehmet O.; Unal, Nur; Yilmaz, Firat
Advances in realizing artificial gauge fields on optical lattices promise experimental detection of topologically non-trivial energy spectra. Self-similar fractal energy structures, known as Hofstadter butterflies, depend sensitively on the geometry of the lattice, as well as the applied magnetic field. The recent demonstration of an adjustable lattice geometry [L. Tarruell et al., Nature 483, 302 (2012)] presents a unique opportunity to study this dependence. We calculate the Hofstadter butterflies that can be obtained in such an adjustable lattice and find three qualitatively different regimes. We show that the existence of Dirac points at zero magnetic field does not imply the topological equivalence of spectra at finite field. As the real-space structure evolves from the checkerboard to the honeycomb lattice, two square lattice Hofstadter butterflies merge to form a honeycomb lattice butterfly in a topologically non-trivial way, as it is accomplished by sequential closing of infinitely many gaps. We discuss the evolution of topological properties with underlying lattice geometry by calculating the Chern numbers and comment on the validity of simulating graphene in such an adjustable lattice
A Closer Look at Fermions in Optical Lattices
NASA Astrophysics Data System (ADS)
Pertot, Daniel; Miller, Luke; Cocchi, Eugenio; Bohn, Johanna; Drewes, Jan; Brennecke, Ferdinand; Koschorreck, Marco; Köhl, Michael
2014-05-01
Quantum gases of interacting fermionic atoms in optical lattices promise to shed new light on the low-temperature phases of Hubbard-type models, such as spin-ordered phases or, in particular, on possible d-wave superconductivity. However, reaching the very low temperatures required necessitates the implementation of novel cooling schemes. As a first step towards this goal, we employ high-resolution imaging together with radio-frequency spectroscopy in order to spatially resolve the in-trap distributions of singly and doubly-occupied lattice sites after having loaded a quantum degenerate two-component Fermi gas of 40K atoms into a three-dimensional optical lattice geometry. Here, I will report on our recent progress towards the observation and characterization of a fermionic Mott insulator, together with an outlook on future steps towards lowering the temperature in the lattice.
Incommensurability Effects on Dipolar Bosons in Optical Lattices
NASA Astrophysics Data System (ADS)
Cinti, Fabio
2016-03-01
We present a study that investigated a quantum dipolar gas in continuous space where a potential lattice was imposed. Employing exact quantum Monte Carlo techniques, we analysed the ground-state properties of the scrutinised system, varying the lattice depth and the dipolar interaction. For system densities corresponding to a commensurate filling with respect to the optical lattice, we observed a simple crystal-to-superfluid quantum phase transition, being consistent with the physics of dipolar bosons in continuous space. In contrast, an incommensurate density showed the presence of a supersolid phase. Indeed, such a result opens up the tempting opportunity to observe a defect-induced supersolidity with dipolar gases in combination with a tunable optical lattice. Finally, the stability of the condensate was analysed at finite temperature.
Twofold PT symmetry in doubly exponential optical lattices
NASA Astrophysics Data System (ADS)
Cole, J. T.; Makris, K. G.; Musslimani, Z. H.; Christodoulides, D. N.; Rotter, S.
2016-01-01
We introduce a family of non-Hermitian optical potentials that are given in terms of double-exponential periodic functions. The center of PT symmetry is not around zero and the potential satisfies a shifted PT -symmetry relation at two distinct locations. Motivated by wave transmission through thin phase screens and gratings, we examine these refractive index modulations from the perspective of optical lattices that are homogeneous along the propagation direction. The diffraction dynamics, abrupt phase transitions in the eigenvalue spectrum, and exceptional points in the band structure are examined in detail. In addition, the nonlinear properties of wave propagation in Kerr nonlinearity media are studied. In particular, coherent structures such as lattice solitons are numerically identified by applying the spectral renormalization method. The spatial symmetries of such lattice solitons follow the shifted PT -symmetric relations. Furthermore, such lattice solitons have a power threshold and their linear and nonlinear stabilities are critically dependent on their spatial symmetry point.
NASA Astrophysics Data System (ADS)
Zia, Shahneel; Banerjee, Anirudh
2016-05-01
This paper demonstrates a way to control spectrum tuning capability in one-dimensional (1D) ternary photonic band gap (PBG) material nano-layered structures electro-optically. It is shown that not only tuning range, but also tuning speed of tunable optical filters based on 1D ternary PBG structures can be controlled Electro-optically. This approach finds application in tuning range enhancement of 1D Ternary PBG structures and compensating temperature sensitive transmission spectrum shift in 1D Ternary PBG structures.
A mercury optical lattice clock at LNE-SYRTE
NASA Astrophysics Data System (ADS)
De Sarlo, L.; Favier, M.; Tyumenev, R.; Bize, S.
2016-06-01
We describe the development of an optical lattice clock based on mercury and the results obtained since the 7 th SFSM. We briefly present a new solution for the cooling laser system and an improved lattice trap that allows us to interrogate a few thousand atoms in parallel. This translates into a fractional short term stability of 1.2 x 10-15 at the clock frequency of 1.129 PHz.
Programmable lattices of optical vortices in nematic liquid crystal
NASA Astrophysics Data System (ADS)
Barboza, R.; Assanto, G.; Bortolozzo, U.; Clerc, M. G.; Residori, S.; Vidal-Henriquez, E.
2015-09-01
Using self-induced vortex-like defects in the nematic liquid crystal layer of a light valve with photo-sensible wall, we demonstrate the realization of programable optical vortices lattices with arbitrary configuration in space. On each lattice site, every matter vortex acts as a photonic spin-to-orbital momentum coupler and an array of circularly polarized input beams is converted into an output array of vortex beams with topological charges consistent with the vortex matter lattice. The vortex arrangements are explained the basis of light-induced matter defects and topological rules.
Assessment of a fast electro-optical shutter for 1D spontaneous Raman scattering in flames
NASA Astrophysics Data System (ADS)
Ajrouche, Hassan; Lo, Amath; Vervisch, Pierre; Cessou, Armelle
2015-07-01
A critical aspect of 1D single-shot spontaneous Raman scattering (SRS) experiments in turbulent flames is the need to ensure highly efficient detection associated with fast temporal gating to remove flame emission. Back-illuminated CCD cameras are remarkable for their high quantum efficiency, large dynamic range, good spatial resolution and low readout noise. However, their full-frame architecture makes these detectors difficult to use for SRS measurements in flame and requires the development of a high-speed shutter. The present work proposes a fast electro-optical shutter composed of a large aperture Pockels cell placed between two crossed polarizers, providing high-speed gating up to 500 ns. The throughput of the shutter and its spatial homogeneity are measured. The angular tolerance of the Pockels cell is determined and its suitability for 1D probing is assessed. Spectra acquired in a premixed methane-air flame show the capacity of the shutter to remove flame emission and increase the signal-to-noise ratio for major Raman species.
Optimized geometries for future generation optical lattice clocks
NASA Astrophysics Data System (ADS)
Krämer, S.; Ostermann, L.; Ritsch, H.
2016-04-01
Atoms deeply trapped in magic wavelength optical lattices provide a Doppler- and collision-free dense ensemble of quantum emitters ideal for high-precision spectroscopy and they are the basis of some of the best optical atomic clocks to date. However, despite their minute optical dipole moments the inherent long-range dipole-dipole interactions in such lattices still generate line shifts, dephasing and modified decay. We show that in a perfectly filled lattice line shifts and decay are resonantly enhanced depending on the lattice constant and geometry. Potentially, this yields clock shifts of many atomic linewidths and reduces the measurement by optimizing the lattice geometry. Such collective effects can be tailored to yield zero effective shifts and prolong dipole lifetimes beyond the single-atom decay. In particular, we identify dense 2D hexagonal or square lattices as the most promising configurations for an accuracy and precision well below the independent ensemble limit. This geometry should also be an ideal basis for related applications such as superradiant lasers, precision magnetometry or long-lived quantum memories.
Pressure Sensor via Optical Detection Based on a 1D Spin Transition Coordination Polymer
Jureschi, Cătălin M.; Linares, Jorge; Rotaru, Aurelian; Ritti, Marie Hélène; Parlier, Michel; Dîrtu, Marinela M.; Wolff, Mariusz; Garcia, Yann
2015-01-01
We have investigated the suitability of using the 1D spin crossover coordination polymer [Fe(4-(2′-hydroxyethyl)-1,2,4-triazole)3]I2·H2O, known to crossover around room temperature, as a pressure sensor via optical detection using various contact pressures up to 250 MPa. A dramatic persistent colour change is observed. The experimental data, obtained by calorimetric and Mössbauer measurements, have been used for a theoretical analysis, in the framework of the Ising-like model, of the thermal and pressure induced spin state switching. The pressure (P)-temperature (T) phase diagram calculated for this compound has been used to obtain the P-T bistability region. PMID:25621610
Bloch-Zener oscillations in a tunable optical honeycomb lattice
Uehlinger, Thomas; Greif, Daniel; Jotzu, Gregor; Esslinger, Tilman; Tarruell, Leticia
2013-12-04
Ultracold gases in optical lattices have proved to be a flexible tool to simulate many different phenomena of solid state physics [1, 2]. Recently, optical lattices with complex geometries have been realized [3, 4, 5, 6, 7], paving the way to simulating more realistic systems. The honeycomb structure has recently become accessible in an optical lattice composed of mutually perpendicular laser beams. This lattice structure exhibits topological features in its band structure – the Dirac points. At these points, two energy bands intersect linearly and the particles behave as relativistic Dirac fermions. In optical lattices, Bloch oscillations [8] resolved both in time and in quasi-momentum space can be directly observed. We make use of such Bloch-Zener oscillations to probe the vanishing energy gap at the Dirac points as well as their position in the band structure. In small band gap regions, we observe Landau-Zener tunneling [7, 9] to the second band and the regions of maximum transfer can be identified with the position of the Dirac points.
Coupled matter-wave solitons in optical lattices
NASA Astrophysics Data System (ADS)
Golam Ali, Sk; Talukdar, B.
2009-06-01
We make use of a potential model to study the dynamics of two coupled matter-wave or Bose-Einstein condensate (BEC) solitons loaded in optical lattices. With separate attention to linear and nonlinear lattices we find some remarkable differences for response of the system to effects of these lattices. As opposed to the case of linear optical lattice (LOL), the nonlinear lattice (NOL) can be used to control the mutual interaction between the two solitons. For a given lattice wave number k, the effective potentials in which the two solitons move are such that the well (Veff(NOL)), resulting from the juxtaposition of soliton interaction and nonlinear lattice potential, is deeper than the corresponding well Veff(LOL). But these effective potentials have opposite k dependence in the sense that the depth of Veff(LOL) increases as k increases and that of Veff(NOL) decreases for higher k values. We verify that the effectiveness of optical lattices to regulate the motion of the coupled solitons depends sensitively on the initial locations of the motionless solitons as well as values of the lattice wave number. For both LOL and NOL the two solitons meet each other due to mutual interaction if their initial locations are taken within the potential wells with the difference that the solitons in the NOL approach each other rather rapidly and take roughly half the time to meet as compared with the time needed for such coalescence in the LOL. In the NOL, the soliton profiles can move freely and respond to the lattice periodicity when the separation between their initial locations are as twice as that needed for a similar free movement in the LOL. We observe that, in both cases, slow tuning of the optical lattices by varying k with respect to a time parameter τ drags the oscillatory solitons apart to take them to different locations. In our potential model the oscillatory solitons appear to propagate undistorted. But a fully numerical calculation indicates that during evolution
Coupled matter-wave solitons in optical lattices
Golam Ali, Sk; Talukdar, B.
2009-06-15
We make use of a potential model to study the dynamics of two coupled matter-wave or Bose-Einstein condensate (BEC) solitons loaded in optical lattices. With separate attention to linear and nonlinear lattices we find some remarkable differences for response of the system to effects of these lattices. As opposed to the case of linear optical lattice (LOL), the nonlinear lattice (NOL) can be used to control the mutual interaction between the two solitons. For a given lattice wave number k, the effective potentials in which the two solitons move are such that the well (V{sub eff}(NOL)), resulting from the juxtaposition of soliton interaction and nonlinear lattice potential, is deeper than the corresponding well V{sub eff}(LOL). But these effective potentials have opposite k dependence in the sense that the depth of V{sub eff}(LOL) increases as k increases and that of V{sub eff}(NOL) decreases for higher k values. We verify that the effectiveness of optical lattices to regulate the motion of the coupled solitons depends sensitively on the initial locations of the motionless solitons as well as values of the lattice wave number. For both LOL and NOL the two solitons meet each other due to mutual interaction if their initial locations are taken within the potential wells with the difference that the solitons in the NOL approach each other rather rapidly and take roughly half the time to meet as compared with the time needed for such coalescence in the LOL. In the NOL, the soliton profiles can move freely and respond to the lattice periodicity when the separation between their initial locations are as twice as that needed for a similar free movement in the LOL. We observe that, in both cases, slow tuning of the optical lattices by varying k with respect to a time parameter {tau} drags the oscillatory solitons apart to take them to different locations. In our potential model the oscillatory solitons appear to propagate undistorted. But a fully numerical calculation
Ballistic expansion of interacting fermions in one-dimensional optical lattices
NASA Astrophysics Data System (ADS)
Heidrich-Meisner, Fabian; Langer, Stephan; Schuetz, Martin J. A.; McCulloch, Ian; Schollwoeck, Ulrich
2012-02-01
In most quantum quenches, no net particle currents arise. Access to studying transport properties can be gained by letting a two-component Fermi gas that is originally confined by the presence of a trapping potential expand into an empty optical lattice. In recent experiments, this situation was addressed in 2D and 3D optical lattices [1]. We focus on the 1D case in which an exact numerical simulation of the time-evolution is possible by means of the DMRG method. Concretely, we study the expansion in the 1D Hubbard model with repulsive interactions, driven by quenching the trapping potential to zero, and we concentrate on the most direct experimental observable, namely density profiles [2]. In the strict 1D case, we identify conditions for which the expansion is ballistic, characterized by an increase of the cloud's radius that is linear in time. This behavior is found whenever initial densities are smaller or equal to one, both for the expansion from box and harmonic traps. We make quantitative predictions for the expansion velocity as a function of onsite repulsion and initial density that can be probed in experiments. [4pt] [1] Schneider et al., arXiv:1005.3545[0pt] [2] Langer et al., arXiv:1109.4364
Light storage in a magnetically dressed optical lattice
NASA Astrophysics Data System (ADS)
Dudin, Y. O.; Zhao, R.; Kennedy, T. A. B.; Kuzmich, A.
2010-04-01
Differential Stark shift compensation for ground-state Rb87 atoms trapped in an elliptically polarized optical lattice and “magic” magnetic field was recently proposed and demonstrated experimentally by N. Lundblad [e-print arXiv:0912.1528] and analyzed theoretically by A. Derevianko [e-print arXiv:0912.3233]. Here we demonstrate enhanced hyperfine coherence times using the magic field technique. We observe coherent light storage with a 0.32-s lifetime in an atomic Rb gas confined in a one-dimensional optical lattice and magnetic field.
Light storage in a magnetically dressed optical lattice
Dudin, Y. O.; Zhao, R.; Kennedy, T. A. B.; Kuzmich, A.
2010-04-15
Differential Stark shift compensation for ground-state {sup 87}Rb atoms trapped in an elliptically polarized optical lattice and 'magic' magnetic field was recently proposed and demonstrated experimentally by N. Lundblad et al. [e-print arXiv:0912.1528] and analyzed theoretically by A. Derevianko [e-print arXiv:0912.3233]. Here we demonstrate enhanced hyperfine coherence times using the magic field technique. We observe coherent light storage with a 0.32-s lifetime in an atomic Rb gas confined in a one-dimensional optical lattice and magnetic field.
Bose-Fermi mixtures in an optical lattice
Sengupta, K.; Majumdar, P.
2007-06-15
We study an atomic Bose-Fermi mixture with unpolarized fermions in an optical lattice. We obtain the Mott ground states of such a system in the limit of the deep optical lattice and discuss the effect of quantum fluctuations on these states. We also study the superfluid-insulator transitions of bosons and metal-insulator transition of fermions in such a mixture within a slave-rotor mean-field approximation, and obtain the corresponding phase diagram. We discuss experimental implications of our results.
Surface multipole solitons on photorefractive media with Bessel optical lattices
NASA Astrophysics Data System (ADS)
Hong, Woo-Pyo
2015-03-01
We find the existence conditions for new surface crescent, dipole, tripole, and quadrupole solitons formed at the interface of a focusing photorefractive medium and a medium imprinted with a Bessel optical lattice. We demonstrate by using numerical simulations that the crescent and the dipole solitons show oscillatory behaviors in their amplitude and shape while the tripole and the quadrupole solitons maintain a remarkable rigidity during propagation. Based on a linear stability analysis, we classify the stability region of the tripole and the quadrupole surface solitons in terms of the Bessel optical lattice strength and the Bessel index.
Manipulation of single neutral atoms in optical lattices
Zhang Chuanwei; Das Sarma, S.; Rolston, S. L.
2006-10-15
We analyze a scheme to manipulate quantum states of neutral atoms at individual sites of optical lattices using focused laser beams. Spatial distributions of focused laser intensities induce position-dependent energy shifts of hyperfine states, which, combined with microwave radiation, allow selective manipulation of quantum states of individual target atoms. We show that various errors in the manipulation process are suppressed below 10{sup -4} with properly chosen microwave pulse sequences and laser parameters. A similar idea is also applied to measure quantum states of single atoms in optical lattices.
Free Expansion of ultracold fermions in an optical lattice
NASA Astrophysics Data System (ADS)
Schneider, Ulrich; Hackermueller, Lucia; Ronzheimer, Jens Philipp; Will, Sebastian; Braun, Simon; Best, Thorsten; Schreiber, Michael; Chung Fong, Kin; Bloch, Immanuel
2010-03-01
Recent experiments with ultracold fermions in optical lattices face two main challenges in the quest of realizing complex strongly-correlated states: While the need to realize low entropy samples resulted in several recent proposals of advanced cooling schemes there remains the problem of the unknown adiabaticity timescales in these inhomogeneous systems. In order to measure the characteristic timescales of density redistribution, we experimentally investigate the free expansion of fermionic ^40K atoms in an homogeneous optical lattice. In an initially non-interacting band-insulater, created in the combination of a blue-detuned optical lattice and a red-detuned optical dipole trap, interactions are introduced by use of a Feshbach resonance. Subsequently the expansion is initiated by quickly ramping down the dipole trap while retaining the optical lattice. In the case of negligible interactions, the atoms expand ballistically performing a continuous quantum walk. For interacting fermions, the expansion becomes diffusive with a density dependent diffusion constant that is independent of the sign of interactions. These measurements demonstrate previously unobserved transport dynamics and give insight into the characteristic timescales of density redistribution.
Stability of matter-wave solitons in optical lattices
NASA Astrophysics Data System (ADS)
Ali, Sk. Golam; Roy, S. K.; Talukdar, B.
2010-08-01
We consider localized states of both single- and two-component Bose-Einstein condensates (BECs) confined in a potential resulting from the superposition of linear and nonlinear optical lattices and make use of Vakhitov-Kolokolov criterion to investigate the effect of nonlinear lattice on the stability of the soliton solutions in the linear optical lattice (LOL). For the single-component case we show that a weak nonlinear lattice has very little effect on the stability of such solitons while sufficiently strong nonlinear optical lattice (NOL) squeezes them to produce narrow bound states. For two-component condensates we find that when the strength of the NOL (γ1) is less than that of the LOL (V0) a relatively weak intra-atomic interaction (IAI) has little effect on the stability of the component solitons. This is true for both attractive and repulsive IAI. A strong attractive IAI, however, squeezes the BEC solitons while a similar repulsive IAI makes the component solitons wider. For γ1 > V0, only a strong attractive IAI squeezes the BEC solitons but the squeezing effect is less prominent than that found for γ1 < V0. We make useful checks on the results of our semianalytical stability analysis by solving the appropriate Gross-Pitaevskii equations numerically.
Atomic and molecular quantum gases in an optical lattice
NASA Astrophysics Data System (ADS)
Hecker Denschlag, Johannes
2007-06-01
We report on recent progress in preparing and manipulating ultracold atomic and molecular ensembles in a 3D optical lattice. Starting from an atomic ^87Rb condensate which is adiabatically loaded into a 3D optical lattice we can control the state and dynamics of the gas on the quantum level with the help of static magnetic fields, radio-frequency and laser radiation and a Feshbach resonance. For example, we can produce a pure molecular ensemble of Rb2 Feshbach molecules in the lattice [1] and can coherently transfer it to a more deeply molecular bound state via STIRAP [2] or radio-frequency transitions. Besides possible applications for investigating molecular collisions and producing ultracold molecules in the vibrational ground state, this can also be used for spectroscopic precision measurements of molecular levels. Besides studying chemically bound molecules, optical lattices also allow for forming a novel kind of stable bound state of two atoms which is based on repulsion rather than attraction between the particles [3]. We will explain how these lattice-induced repulsively bound atom pairs come about and discuss their interesting properties. [1] G. Thalhammer et al., Phys. Rev. Lett. 96, 050402 (2006). [2] K. Winkler, cond-mat/0611222 [3] K. Winkler et al., Nature 441, 853, (2006).
Mixtures of bosonic and fermionic atoms in optical lattices
Albus, Alexander; Illuminati, Fabrizio; Eisert, Jens
2003-08-01
We discuss the theory of mixtures of bosonic and fermionic atoms in periodic potentials at zero temperature. We derive a general Bose-Fermi Hubbard Hamiltonian in a one-dimensional optical lattice with a superimposed harmonic trapping potential. We study the conditions for linear stability of the mixture and derive a mean-field criterion for the onset of a bosonic superfluid transition. We investigate the ground-state properties of the mixture in the Gutzwiller formulation of mean-field theory, and present numerical studies of finite systems. The bosonic and fermionic density distributions and the onset of quantum phase transitions to demixing and to a bosonic Mott-insulator are studied as a function of the lattice potential strength. The existence is predicted of a disordered phase for mixtures loaded in very deep lattices. Such a disordered phase possessing many degenerate or quasidegenerate ground states is related to a breaking of the mirror symmetry in the lattice.
Atomic Bose and Anderson Glasses in Optical Lattices
NASA Astrophysics Data System (ADS)
Damski, B.; Zakrzewski, J.; Santos, L.; Zoller, P.; Lewenstein, M.
2003-08-01
An ultracold atomic Bose gas in an optical lattice is shown to provide an ideal system for the controlled analysis of disordered Bose lattice gases. This goal may be easily achieved under the current experimental conditions by introducing a pseudorandom potential created by a second additional lattice or, alternatively, by placing a speckle pattern on the main lattice. We show that, for a noncommensurable filling factor, in the strong-interaction limit, a controlled growing of the disorder drives a dynamical transition from superfluid to Bose-glass phase. Similarly, in the weak interaction limit, a dynamical transition from superfluid to Anderson-glass phase may be observed. In both regimes, we show that even very low-intensity disorder-inducing lasers cause large modifications of the superfluid fraction of the system.
Optical lattice polarization effects on magnetically induced optical atomic clock transitions
Taichenachev, A. V.; Yudin, V. I.; Oates, C. W.
2007-08-15
We derive the frequency shift for a forbidden optical transition J=0{yields}J{sup '}=0 caused by the simultaneous actions of an elliptically polarized lattice field and a static magnetic field. We find that a simple configuration of lattice and magnetic fields leads to a cancellation of this shift to first order in lattice intensity and magnetic field. In this geometry, the second-order lattice intensity shift can be minimized as well by use of optimal lattice polarization. Suppression of these shifts could considerably enhance the performance of the next generation of atomic clocks.
Superfluid fermi gas in optical lattices: self-trapping, stable, moving solitons and breathers.
Xue, Ju-Kui; Zhang, Ai-Xia
2008-10-31
We predict the existence of self-trapping, stable, moving solitons and breathers of Fermi wave packets along the Bose-Einstein condensation (BEC)-BCS crossover in one dimension (1D), 2D, and 3D optical lattices. The dynamical phase diagrams for self-trapping, solitons, and breathers of the Fermi matter waves along the BEC-BCS crossover are presented analytically and verified numerically by directly solving a discrete nonlinear Schrödinger equation. We find that the phase diagrams vary greatly along the BEC-BCS crossover; the dynamics of Fermi wave packet are different from that of Bose wave packet. PMID:18999797
Fermionic quantum gases with tunable interactions in optical lattices
NASA Astrophysics Data System (ADS)
Schneider, Ulrich; Hackermüller, Lucia; Best, Thorsten; Will, Sebastian; Braun, Simon; Moreno Cardoner, Maria; Paredes, Belen; Bloch, Immanuel
2009-03-01
Fermionic atoms in optical lattices can serve as a model system for condensed matter physics, as they present an implementation of the Hubbard hamiltonian with high experimental control of the relevant parameters. In our system we sympathetically cool ^87Rb and ^40K in an optically plugged quadrupole trap and an optical dipole trap. After evaporation, a balanced spin mixture of 40K atoms is loaded into a blue detuned optical lattice where the interactions can be changed via a Feshbach resonance. We present experimental and theoretical studies of the behaviour of fermionic atoms for both attractive and repulsive interactions. For repulsive interactions we show a transition from compressible, metallic states to Mott-insulating and finally band insulating states. On the attractive side we investigate an anomalous expansion when the interaction is strongly attractive and study the dynamics of atoms and repulsively and attractively bound pairs.
Veselago lensing with ultracold atoms in an optical lattice
NASA Astrophysics Data System (ADS)
Leder, Martin; Grossert, Christopher; Weitz, Martin
2014-05-01
Veselago pointed out that electromagnetic theory allows for materials with a negative index of refraction, in which most known optical phenomena are reversed. A slab of such a material can focus light by negative refraction, an imaging technique strikingly different from conventional positive refractive index optics, where curved surfaces bend the rays to form an image of an object. Here we demonstrate Veselago lensing for matter waves, using ultracold atoms in an optical lattice. A relativistic, i.e. photon-like, dispersion relation for rubidium atoms is realized with a bichromatic optical lattice potential. A Raman pi-pulse technique serves to transfer atoms between two different branches of the dispersion relation, and the relativistic lensing occurs by a backwards propagation of atomic wavepackets on an energetically mirrored branch of the dispersion relation. We observe negative refraction and Veselago lensing both in a one-dimensional geometry and perform a ray-tracing simulation of a two-dimensional Veselago lens.
Interaction-induced adiabatic cooling for antiferromagnetism in optical lattices
Dare, A.-M.; Raymond, L.; Albinet, G.; Tremblay, A.-M. S.
2007-08-01
In the experimental context of cold-fermion optical lattices, we discuss the possibilities to approach the pseudogap or ordered phases by manipulating the scattering length or the strength of the laser-induced lattice potential. Using the two-particle self-consistent approach, as well as quantum Monte Carlo simulations, we provide isentropic curves for the two- and three-dimensional Hubbard models at half-filling. These quantitative results are important for practical attempts to reach the ordered antiferromagnetic phase in experiments on optical lattices of two-component fermions. We find that adiabatically turning on the interaction in two dimensions to cool the system is not very effective. In three dimensions, adiabatic cooling to the antiferromagnetic phase can be achieved in such a manner, although the cooling efficiency is not as high as initially suggested by dynamical mean-field theory. Adiabatic cooling by turning off the repulsion beginning at strong coupling is possible in certain cases.
Topological phases via engineered orbital hybridization in noncentrosymmetric optical lattices
NASA Astrophysics Data System (ADS)
Liu, Bo; Li, Xiaopeng; Liu, W. Vincent
2016-03-01
We propose a symmetry-based method of using noncentrosymmetric optical lattices to systematically control topological nontrivial orbital hybridization. A crucial difference from the previous studies is the role of inversion symmetry breaking, which is applied to induce an exotic orbital-changing hopping perpendicular to the direction without inversion symmetry and opens a band gap, instead of reducing the codimension and producing gapless points. The orbital mixing here is reminiscent of the spin-orbit physics based on hyperfine states but differs in symmetry and origin. This nontrivial orbital hybridization produces a topological band structure. Attractively interacting fermionic atoms loaded in such a lattice are found to show an orbital topological Fulde-Ferrell superfluid state in the presence of onsite rotation. This state supports Majorana fermions on its edges. Our mechanism should pave an alternative way to achieve orbital topological phases in optical lattices of nonstandard geometry.
Collisional shifts in optical-lattice atom clocks
Band, Y. B.; Vardi, A.
2006-09-15
We theoretically study the effects of elastic collisions on the determination of frequency standards via Ramsey-fringe spectroscopy in optical-lattice atom clocks. Interparticle interactions of bosonic atoms in multiply occupied lattice sites can cause a linear frequency shift, as well as generate asymmetric Ramsey-fringe patterns and reduce fringe visibility due to interparticle entanglement. We propose a method of reducing these collisional effects in an optical lattice by introducing a phase difference of {pi} between the Ramsey driving fields in adjacent sites. This configuration suppresses site-to-site hopping due to interference of two tunneling pathways, without degrading fringe visibility. Consequently, the probability of double occupancy is reduced, leading to cancellation of collisional shifts.
Excitations of one-dimensional supersolids with optical lattices
NASA Astrophysics Data System (ADS)
Hsueh, C.-H.; Tsai, Y.-C.; Wu, W. C.
2016-06-01
Based on mean-field Gross-Pitaevskii and Bogoliubov-de Gennes approaches, we investigate excitations of a one-dimensional soft-core interacting ultracold Bose gas under the effect of an optical lattice. It is found that no matter how deep the lattice is, at q →0 the lowest mode corresponds to a gapless phonon, ω12=v12q2 , whereas the second lowest mode corresponds to a gapped optical phonon, ω22=Δ2±v22q2 . Determination of the velocities v1,v2 , the gap Δ , and the possible sign change in ω2 upon the change of lattice depth can give decisive measures to the transitions across various supersolid and solid states. The power law v1˜(fs) 1 /2 with fs the superfluid fraction is identified in the present system at the tight-binding regime.
Expansion of a Quantum Gas Released from an Optical Lattice
Gerbier, F.; Trotzky, S.; Schnorrberger, U.; Thompson, J. D.; Bloch, I.; Foelling, S.; Widera, A.; Pollet, L.; Troyer, M.; Capogrosso-Sansone, B.; Prokof'ev, N. V.; Svistunov, B. V.
2008-10-10
We analyze the interference pattern produced by ultracold atoms released from an optical lattice, commonly interpreted as the momentum distributions of the trapped quantum gas. We show that for finite times of flight the resulting density distribution can, however, be significantly altered, similar to a near-field diffraction regime in optics. We illustrate our findings with a simple model and realistic quantum Monte Carlo simulations for bosonic atoms and compare the latter to experiments.
Expansion of a Quantum Gas Released from an Optical Lattice
NASA Astrophysics Data System (ADS)
Gerbier, F.; Trotzky, S.; Fölling, S.; Schnorrberger, U.; Thompson, J. D.; Widera, A.; Bloch, I.; Pollet, L.; Troyer, M.; Capogrosso-Sansone, B.; Prokof'Ev, N. V.; Svistunov, B. V.
2008-10-01
We analyze the interference pattern produced by ultracold atoms released from an optical lattice, commonly interpreted as the momentum distributions of the trapped quantum gas. We show that for finite times of flight the resulting density distribution can, however, be significantly altered, similar to a near-field diffraction regime in optics. We illustrate our findings with a simple model and realistic quantum Monte Carlo simulations for bosonic atoms and compare the latter to experiments.
Quantum degenerate atomic gases in controlled optical lattice potentials
NASA Astrophysics Data System (ADS)
Gemelke, Nathan D.
2007-12-01
Since the achievement of Bose Einstein condensation in cold atomic gases, mean-field treatments of the condensed phase have provided an excellent description for the static and dynamic properties observed in experiments. Recent experimental efforts have focused on studying deviations from mean-field behavior. I will describe work on two experiments which introduce controlled single particle degeneracies with time-dependent optical potentials, aiming to induce correlated motion and nontrivial statistics in the gas. In the first experiment, an optical lattice with locally rotating site potentials is produced to investigate fractional quantum Hall effects (FQHE) in rotating Bose gases. Here, the necessary gauge potential is provided by the rotating reference frame of the gas, which, in direct analogy to the electronic system, organizes single particle states into degenerate Landau levels. At low temperatures the repulsive interaction provided by elastic scattering is expected to produce ground states with structure nearly identical to those in the FQHE. I will discuss how these effects are made experimentally feasible by working at small particle numbers in the tight trapping potentials of an optical lattice, and present first results on the use of photoassociation to probe correlation in this system. In the second experiment, a vibrated optical lattice potential alters the single-particle dispersion underlying a condensed Bose gas and offers tailored phase-matching for nonlinear atom optical processes. I will demonstrate how this leads to parametric instability in the condensed gas, and draw analogy to an optical parametric oscillator operating above threshold.
Doublon dynamics and polar molecule production in an optical lattice
Covey, Jacob P.; Moses, Steven A.; Gärttner, Martin; Safavi-Naini, Arghavan; Miecnikowski, Matthew T.; Fu, Zhengkun; Schachenmayer, Johannes; Julienne, Paul S.; Rey, Ana Maria; Jin, Deborah S.; Ye, Jun
2016-01-01
Polar molecules in an optical lattice provide a versatile platform to study quantum many-body dynamics. Here we use such a system to prepare a density distribution where lattice sites are either empty or occupied by a doublon composed of an interacting Bose-Fermi pair. By letting this out-of-equilibrium system evolve from a well-defined, but disordered, initial condition, we observe clear effects on pairing that arise from inter-species interactions, a higher partial-wave Feshbach resonance and excited Bloch-band population. These observations facilitate a detailed understanding of molecule formation in the lattice. Moreover, the interplay of tunnelling and interaction of fermions and bosons provides a controllable platform to study Bose-Fermi Hubbard dynamics. Additionally, we can probe the distribution of the atomic gases in the lattice by measuring the inelastic loss of doublons. These techniques realize tools that are generically applicable to studying the complex dynamics of atomic mixtures in optical lattices. PMID:27075831
Superfluid qubit systems with ring shaped optical lattices
Amico, Luigi; Aghamalyan, Davit; Auksztol, Filip; Crepaz, Herbert; Dumke, Rainer; Kwek, Leong Chuan
2014-01-01
We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit. PMID:24599096
Doublon dynamics and polar molecule production in an optical lattice
NASA Astrophysics Data System (ADS)
Covey, Jacob P.; Moses, Steven A.; Gärttner, Martin; Safavi-Naini, Arghavan; Miecnikowski, Matthew T.; Fu, Zhengkun; Schachenmayer, Johannes; Julienne, Paul S.; Rey, Ana Maria; Jin, Deborah S.; Ye, Jun
2016-04-01
Polar molecules in an optical lattice provide a versatile platform to study quantum many-body dynamics. Here we use such a system to prepare a density distribution where lattice sites are either empty or occupied by a doublon composed of an interacting Bose-Fermi pair. By letting this out-of-equilibrium system evolve from a well-defined, but disordered, initial condition, we observe clear effects on pairing that arise from inter-species interactions, a higher partial-wave Feshbach resonance and excited Bloch-band population. These observations facilitate a detailed understanding of molecule formation in the lattice. Moreover, the interplay of tunnelling and interaction of fermions and bosons provides a controllable platform to study Bose-Fermi Hubbard dynamics. Additionally, we can probe the distribution of the atomic gases in the lattice by measuring the inelastic loss of doublons. These techniques realize tools that are generically applicable to studying the complex dynamics of atomic mixtures in optical lattices.
Doublon dynamics and polar molecule production in an optical lattice.
Covey, Jacob P; Moses, Steven A; Gärttner, Martin; Safavi-Naini, Arghavan; Miecnikowski, Matthew T; Fu, Zhengkun; Schachenmayer, Johannes; Julienne, Paul S; Rey, Ana Maria; Jin, Deborah S; Ye, Jun
2016-01-01
Polar molecules in an optical lattice provide a versatile platform to study quantum many-body dynamics. Here we use such a system to prepare a density distribution where lattice sites are either empty or occupied by a doublon composed of an interacting Bose-Fermi pair. By letting this out-of-equilibrium system evolve from a well-defined, but disordered, initial condition, we observe clear effects on pairing that arise from inter-species interactions, a higher partial-wave Feshbach resonance and excited Bloch-band population. These observations facilitate a detailed understanding of molecule formation in the lattice. Moreover, the interplay of tunnelling and interaction of fermions and bosons provides a controllable platform to study Bose-Fermi Hubbard dynamics. Additionally, we can probe the distribution of the atomic gases in the lattice by measuring the inelastic loss of doublons. These techniques realize tools that are generically applicable to studying the complex dynamics of atomic mixtures in optical lattices. PMID:27075831
Label-free optical detection of bacteria on a 1-D photonic crystal of porous silicon
NASA Astrophysics Data System (ADS)
Wu, Chia-Chen; Alvarez, Sara D.; Rang, Camilla U.; Chao, Lin; Sailor, Michael J.
2009-02-01
The construction of a specific, label-free, bacteria biosensor using porous silicon 1-D photonic crystals will be described. Bacteria resident on the surface of porous silicon act as scattering centers for light resonant with the photonic crystal; the diffusely scattered light possesses the optical spectrum of the underlying photonic crystal. Using a spectrometer fitted to a light microscope, the bacteria are imaged without using exogenous dyes or labels and are quantified by measuring the intensity of scattered light. In order to selectively bind and identify bacteria using porous Si, we use surface modifications to reduce nonspecific binding to the surface and to engineer bacteria specificity onto the surface. Bovine serum albumin (BSA) was adsorbed to the porous Si surface to reduce nonspecific binding of bacteria. The coatings were then chemically activated to immobilize polyclonal antibodies specific to Escherichia coli. Two E. coli strains were used in our study, E. coli DH5α and non-pathogenic enterohemorrhagic Escherichia coli (EHEC) strain. The nonpathogenic Vibrio cholerae O1 strain was used to test for antibody specificity. Successful attachment of antibodies was measured using fluorescence microscopy and the scattering method was used to test for bacteria binding specificity.
NASA Astrophysics Data System (ADS)
Velarde, M. G.; Ebeling, W.; Chetverikov, A. P.
2013-01-01
We study the thermal excitation of intrinsic localized modes in the form of solitons in 1d and 2d anharmonic lattices at moderately high temperatures. Such finite-amplitude fluctuations form long-living dynamical structures with life-time in the pico-second range thus surviving a relatively long time in comparison to other thermal fluctuations. Further we discuss the influence of such long-living fluctuations on the dynamics of added excess free electrons. The atomic lattice units are treated as quasi-classical objects interacting by Morse forces and stochastically moving according to Langevin equations. In 2d the atoms are initially organized in a triangular lattice. The electron distributions are in a first estimate represented by equilibrium adiabatic distributions in the actual polarization fields. Computer simulations show that in 2d systems such excitations are moving with supersonic velocities along lattice rows oriented with the cristallographic axes. By following the electron distributions we have also been able to study the excitations of solectron type (electron-soliton dynamic bound states) and estimate their life times.
Exploring spin-orbit coupling in a non-degenerate optical lattice clock
NASA Astrophysics Data System (ADS)
Wall, Michael L.; Koller, Andrew P.; Li, Shuming; Rey, Ana Maria
2015-05-01
Optical lattice clocks have progressed in recent years to become not only precise timekeepers, but also sensitive probes of many-body physics. We consider a 1D optical lattice clock in which the wavelength of the laser that interrogates the clock transition is comparable to the optical lattice spacing. This light-matter coupling imprints a spatially dependent phase on the atomic internal state superposition, and this phase can be interpreted as a spin-orbit coupling. We show that this spin-orbit coupling manifests itself in Ramsey spectroscopy as an s-wave density shift in otherwise identically prepared fermions, even at temperatures significantly larger than the tunneling. Further, we show that Rabi spectroscopy can be mapped to a Hofstadter model on a two-leg ladder with chiral eigenstates. Using a modified Rabi procedure, we show how to extract momentum-resolved signatures of chirality solely by spectroscopic means. The effects of finite temperature, gaussian transverse confinement, and non-separability between transverse and axial degrees of freedom are discussed. This work has been financially supported by JILA-NSF-PFC-1125844, NSF-PIF-1211914, ARO, AFOSR, AFOSR-MURI, NDSEG, and NRC.
Super-resolution microscopy of single atoms in optical lattices
NASA Astrophysics Data System (ADS)
Alberti, Andrea; Robens, Carsten; Alt, Wolfgang; Brakhane, Stefan; Karski, Michał; Reimann, René; Widera, Artur; Meschede, Dieter
2016-05-01
We report on image processing techniques and experimental procedures to determine the lattice-site positions of single atoms in an optical lattice with high reliability, even for limited acquisition time or optical resolution. Determining the positions of atoms beyond the diffraction limit relies on parametric deconvolution in close analogy to methods employed in super-resolution microscopy. We develop a deconvolution method that makes effective use of the prior knowledge of the optical transfer function, noise properties, and discreteness of the optical lattice. We show that accurate knowledge of the image formation process enables a dramatic improvement on the localization reliability. This allows us to demonstrate super-resolution of the atoms’ position in closely packed ensembles where the separation between particles cannot be directly optically resolved. Furthermore, we demonstrate experimental methods to precisely reconstruct the point spread function with sub-pixel resolution from fluorescence images of single atoms, and we give a mathematical foundation thereof. We also discuss discretized image sampling in pixel detectors and provide a quantitative model of noise sources in electron multiplying CCD cameras. The techniques developed here are not only beneficial to neutral atom experiments, but could also be employed to improve the localization precision of trapped ions for ultra precise force sensing.
Fast, externally triggered, digital phase controller for an optical lattice
NASA Astrophysics Data System (ADS)
Sadgrove, Mark; Nakagawa, Ken'ichi
2011-11-01
We present a method to control the phase of an optical lattice according to an external trigger signal. The method has a latency of less than 30 μs. Two phase locked digital synthesizers provide the driving signal for two acousto-optic modulators which control the frequency and phase of the counter-propagating beams which form a standing wave (optical lattice). A micro-controller with an external interrupt function is connected to the desired external signal, and updates the phase register of one of the synthesizers when the external signal changes. The standing wave (period λ/2 = 390 nm) can be moved by units of 49 nm with a mean jitter of 28 nm. The phase change is well known due to the digital nature of the synthesizer, and does not need calibration. The uses of the scheme include coherent control of atomic matter-wave dynamics.
Mixtures of Strongly Interacting Bosons in Optical Lattices
Buonsante, P.; Penna, V.; Giampaolo, S. M.; Illuminati, F.; Vezzani, A.
2008-06-20
We investigate the properties of strongly interacting heteronuclear boson-boson mixtures loaded in realistic optical lattices, with particular emphasis on the physics of interfaces. In particular, we numerically reproduce the recent experimental observation that the addition of a small fraction of {sup 41}K induces a significant loss of coherence in {sup 87}Rb, providing a simple explanation. We then investigate the robustness against the inhomogeneity typical of realistic experimental realizations of the glassy quantum emulsions recently predicted to occur in strongly interacting boson-boson mixtures on ideal homogeneous lattices.
Continuous loading of an atom beam into an optical lattice
NASA Astrophysics Data System (ADS)
Ivanov, Vladyslav V.
I propose a method of deceleration and continuous loading of an atom beam into a far-off-resonance optical lattice. The loading of moving atoms into a conservative far-off-resonance potential requires the removal of the atom's excess kinetic energy. Here this is achieved by the Sisyphus cooling method, where a differential lattice-induced ac Stark shift is utilized. The proposed method is described for the case of ytterbium atoms. Numerical simulations demonstrate the possibility of reaching cold and dense samples in a continuous manner on the example of ytterbium atoms.
Mixtures of strongly interacting bosons in optical lattices.
Buonsante, P; Giampaolo, S M; Illuminati, F; Penna, V; Vezzani, A
2008-06-20
We investigate the properties of strongly interacting heteronuclear boson-boson mixtures loaded in realistic optical lattices, with particular emphasis on the physics of interfaces. In particular, we numerically reproduce the recent experimental observation that the addition of a small fraction of 41K induces a significant loss of coherence in 87Rb, providing a simple explanation. We then investigate the robustness against the inhomogeneity typical of realistic experimental realizations of the glassy quantum emulsions recently predicted to occur in strongly interacting boson-boson mixtures on ideal homogeneous lattices. PMID:18643555
Prospects for Optical Clocks with a Blue-Detuned Lattice
Takamoto, M.; Katori, H.; Marmo, S. I.; Ovsiannikov, V. D.; Pal'chikov, V. G.
2009-02-13
We investigated the properties of optical lattice clocks operated with a repulsive light-shift potential. The magic wavelength, where light-shift perturbation for the clock transition cancels, was experimentally determined to be 389.889(9) nm for {sup 87}Sr. The hyperpolarizability effects on the clock transition were investigated theoretically. With minimal trapping field perturbation provided by the blue-detuned lattice, the fractional uncertainty due to the hyperpolarizability effects was found to be 2x10{sup -19} in the relevant clock transition.
Optical-lattice Hamiltonians for relativistic quantum electrodynamics
Kapit, Eliot; Mueller, Erich
2011-03-15
We show how interpenetrating optical lattices containing Bose-Fermi mixtures can be constructed to emulate the thermodynamics of quantum electrodynamics (QED). We present models of neutral atoms on lattices in 1+1, 2+1, and 3+1 dimensions whose low-energy effective action reduces to that of photons coupled to Dirac fermions of the corresponding dimensionality. We give special attention to (2+1)-dimensional quantum electrodynamics (QED3) and discuss how two of its most interesting features, chiral symmetry breaking and Chern-Simons physics, could be observed experimentally.
Experimentally observed field–gas interaction in intense optical lattices
Graul, Jacob S.; Cornella, Barry M.; Ketsdever, Andrew D.; Lilly, Taylor C.; Shneider, Mikhail N.
2013-12-09
When a gas perturbed by a laser interference pattern, an optical lattice, exhibits a periodic modulation of its refractive index, strong Bragg diffraction of the perturbing light can occur. This scattering reduces the field's ability to further manipulate the gas. Experimental observations of Bragg scattering, evidence of a two-way coupling, are compared to the evolution of the light fields calculated by solutions to the wave equation. Comparison indicates momentum deposition as a prime contributor to the shape of the scattering function vs. lattice velocity, a rationale further supported through additional direct simulation Monte Carlo simulation.
Measuring spin correlations in optical lattices using superlattice potentials
Pedersen, K. G. L.; Andersen, B. M.; Soerensen, A. S.; Bruun, G. M.; Syljuaasen, O. F.
2011-10-15
We suggest two experimental methods for probing both short- and long-range spin correlations of atoms in optical lattices using superlattice potentials. The first method involves an adiabatic doubling of the periodicity of the underlying lattice to probe neighboring singlet (triplet) correlations for fermions (bosons) by the occupation of the resulting vibrational ground state. The second method utilizes a time-dependent superlattice potential to generate spin-dependent transport by any number of prescribed lattice sites, and probes correlations by the resulting number of doubly occupied sites. For experimentally relevant parameters, we demonstrate how both methods yield large signatures of antiferromagnetic correlations of strongly repulsive fermionic atoms in a single shot of the experiment. Lastly, we show how this method may also be applied to probe d-wave pairing, a possible ground-state candidate for the doped repulsive Hubbard model.
Dynamical phase interferometry of cold atoms in optical lattices
London, Uri; Gat, Omri
2011-12-15
We study the propagation of cold-atom wave packets in an interferometer with a Mach-Zehnder topology based on the dynamical phase of Bloch oscillation in a weakly forced optical lattice with a narrow potential barrier that functions as a cold-atom wave-packet splitter. We calculate analytically the atomic wave function, and show that the expected number of atoms in the two outputs of the interferometer oscillates rapidly as a function of the angle between the potential barrier and the forcing direction with period proportional to the external potential difference across a lattice spacing divided by the lattice band energy scale. The interferometer can be used as a high-precision force probe whose principle of operation is different from current interferometers based on the overall position of Bloch oscillating wave packets.
Towards Quantum Magnetism with Ultracold Quantum Gases in Optical Lattices
NASA Astrophysics Data System (ADS)
Bloch, Immanuel
2008-05-01
Quantum mechanical superexchange interactions form the basis of quantum magnetism in strongly correlated electronic media and are believed to play a major role in high-Tc superconducting materials. We report on the first direct measurement of such superexchange interactions with ultracold atoms in optical lattices. After preparing a spin-mixture of ultracold atoms with the help of optical superlattices in an antiferromagnetically ordered state, we are able to observe a coherent superexchange mediated spin dynamics down to coupling energies as low as 5 Hz. Furthermore, it is shown how these superexchange interactions can be fully controlled in magnitude and sign. The prospects of using such superexchange interactions for the investigation of dynamical behaviour in quantum spin systems and for quantum information processing will be outlined in the talk. In addition we present results on the dynamical resolved co-tunneling of repulsively bound atom pairs in optical superlattices and show how by using ``Coulomb-blockade'' type tunneling resonance one can count atoms one by one to determine their number statistics in the lattice potential. Finally, latest results on ultracold Fermions and Bose-Fermi mixtures in optical lattices will be presented.
Towards Quantum Magnetism with Ultracold Quantum Gases in Optical Lattices
NASA Astrophysics Data System (ADS)
Bloch, Immanuel
2008-03-01
Quantum mechanical superexchange interactions form the basis of quantum magnetism in strongly correlated electronic media and are believed to play a major role in high-Tc superconducting materials. We report on the first direct measurement of such superexchange interactions with ultracold atoms in optical lattices. After preparing a spin-mixture of ultracold atoms with the help of optical superlattices in an antiferromagnetically ordered state, we are able to observe a coherent superexchange mediated spin dynamics down to coupling energies as low as 5 Hz. Furthermore, it is shown how these superexchange interactions can be fully controlled in magnitude and sign. The prospects of using such superexchange interactions for the investigation of dynamical behaviour in quantum spin systems and for quantum information processing will be outlined in the talk. In addition we present results on the dynamical resolved co-tunnelling of repulsively bound atom pairs in optical superlattices and show how by using ``Coulomb-blockade'' type tunnelling resonance one can count atoms one by one to determine their number statistics in the lattice potential. Finally, latest results on ultracold Fermions and Bose-Fermi mixtures in optical lattices will be presented.
Damping of confined excitation modes of one-dimensional condensates in an optical lattice
NASA Astrophysics Data System (ADS)
Trallero-Giner, C.; Santiago-Pérez, Darío G.; Chung, Ming-Chiang; Marques, G. E.; Cipolatti, R.
2015-10-01
We study the damping of the collective excitations of Bose-Einstein condensates in a harmonic trap potential loaded in an optical lattice. In the presence of a confining potential the system is inhomogeneous and the collective excitations are characterized by a set of discrete confined phononlike excitations. We derive a general convenient analytical description for the damping rate, which takes into account the trapping potential and the optical lattice for the Landau and Beliaev processes at any temperature T . At high temperature or weak spatial confinement, we show that both mechanisms display a linear dependence on T . In the quantum limit, we find that the Landau damping is exponentially suppressed at low temperatures and the total damping is independent of T . Our theoretical predictions for the damping rate under the thermal regime is in complete correspondence with the experimental values reported for the one-dimensional (1D) condensate of sodium atoms. We show that the laser intensity can tune the collision process, allowing a resonant effect for the condensate lifetime. Also, we study the influence of the attractive or repulsive nonlinear terms on the decay rate of the collective excitations. A general expression for the renormalized Goldstone frequency is obtained as a function of the 1D nonlinear self-interaction parameter, laser intensity, and temperature.
Orso, G.; Stringari, S.; Menotti, C.
2006-11-10
We use Bogoliubov theory to calculate the beyond mean field correction to the equation of state of a weakly interacting Bose gas in the presence of a tight 2D optical lattice. We show that the lattice induces a characteristic 3D to 1D crossover in the behavior of quantum fluctuations. Using the hydrodynamic theory of superfluids, we calculate the corresponding shift of the collective frequencies of a harmonically trapped gas. We find that this correction can be of the order of a few percent and hence easily measurable in current experiments. The behavior of the quantum depletion of the condensate is also discussed.
Quasi-1D States Confined in a Self-Assembled Organic Super-Lattice of TTF-TCNQ on Ag(111)
NASA Astrophysics Data System (ADS)
Jeon, Seokmin; Ganesh, Panchapakesan; Sumpter, Bobby; Cerdá, Jorge Iribas; Maksymovych, Petro; CNMS Team; ICMM-CSIC Team
2015-03-01
Organic charge transfer complexes (CTC) have drawn much attention due to their potential applications to conducting or semiconducting organic thin films and contacts in devices. TTF-TCNQ is a historic organic CTC with one of the highest conductivity values among numerous organic conductors. As a two-component molecular material, TTF-TCNQ in a low-dimension form on a surface naturally creates monolayer super-lattices with corrugated electrostatic potential and adsorbate-induced strain. Generally this will lead to strong confinement of the surface states, although the detailed response of the surface electronic structure remains to be understood. We investigated TTF-TCNQ monolayer films grown on Ag(111), Au(111) and Ag(100) surfaces using STM/STS at 4.3 K. Confinement of sp-derived surface states was indeed ubiquitous, including spontaneous formation of quantum dots and quasi-1D bands. The small periodicity of the lattice caused a complete depopulation of the surface states, with up to 1 eV upshift of the band minimum - much stronger effect than normally observed in assemblies. This also allows us to infer the height of the confining potential using 1D Kronig-Penney model and critically assess the long-standing problem of molecule-surface charge transfer. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.
A quantum gas of polar molecules in an optical lattice
NASA Astrophysics Data System (ADS)
Moses, Steven A.
Ultracold polar molecules, because of their long-range, spatially anisotropic interactions, are a new quantum system in which to study novel many-body phenomena. In our lab, we have produced the first quantum gas of 40K 87Rb polar molecules. These molecules were found to undergo exothermic chemical reactions, and this led to interesting studies of chemistry near absolute zero. By creating the molecules at individual sites of a 3D optical lattice, we completely suppress these chemical reactions, and the polar molecule gas becomes stable and lives for tens of seconds. This thesis documents our efforts to explore coherent, many-body phenomena resulting from long-range dipolar interactions in the lattice. By encoding a spin-1/2 system in the rotational states of the molecules, we were able to realize spin-exchange interactions based on a spin Hamiltonian, which is one of the first steps in studying quantum magnetism with polar molecules. While this study was the first realization of such coherent dipolar interactions with polar molecules in a lattice, its full potential was limited by the low lattice filling fractions. Using our ability to exquisitely control the initial atomic gas mixture, we loaded a Mott insulator of Rb and a band insulator of K into the lattice. This quantum synthesis approach led to significantly higher molecular filling fractions and represents the first fully connected system of polar molecules in an optical lattice. This low-entropy quantum gas of polar molecules opens the door to interesting quantum simulations, which should be attainable in the next generation of the experiment.
Chiral topological orders in an optical Raman lattice
NASA Astrophysics Data System (ADS)
Liu, Xiong-Jun; Liu, Zheng-Xin; Law, K. T.; Liu, W. Vincent; Ng, T. K.
2016-03-01
We find an optical Raman lattice without spin-orbit coupling showing chiral topological orders for cold atoms. Two incident plane-wave lasers are applied to simultaneously generate a double-well square lattice and periodic Raman couplings, the latter of which drive the nearest-neighbor hopping and create a staggered flux pattern across the lattice. Such a minimal setup can yield the quantum anomalous Hall effect with a large gap-bandwidth ratio in the single particle regime, while in the interacting regime it achieves the J 1-J 2-K spin model, with the nearest-neighboring (J 1) and next-nearest-neightboring (J 2) exchange coupling coefficients, and the three three-spin interacting parameter (K) is controllable. We show that the J 1-J 2-K spin model may support a chiral spin liquid phase. It is interesting that the quantum anomalous Hall state can be detected by only measuring the Bloch states in the two symmetric momentum points of the first Brillouin zone. Further, we also show that heating in the present optical Raman lattice can be essentially reduced compared with the conventional laser-assisted tunneling schemes. This suggests that the predicted topological states be reachable with the current experimental capability.
Transverse Localization of Light in 1D Self-Focusing Parity-Time-Symmetric Optical Lattices
NASA Astrophysics Data System (ADS)
Xing, Wei; Bin, Chen; Chun-Fang, Wang
2016-03-01
Not Available Supported by the National Natural Science Foundation of China under Grant Nos 11104185, 11174084, 10934011 and 11504236, the National Basic Research Program of China under Grant No 2012CB921904, the Innovation Program of Shanghai Municipal Education Commission under Grant No 11YZ118, and the Natural Science Foundation of Shanghai under Grant No 14ZR1414300.
Quantum phase transition of condensed bosons in optical lattices
Liang Junjun; Liang, J.-Q.; Liu, W.-M.
2003-10-01
In this paper we study the superfluid-Mott-insulator phase transition of ultracold dilute gas of bosonic atoms in an optical lattice by means of Green function method and Bogliubov transformation as well. The superfluid-Mott-insulator phase transition condition is determined by the energy-band structure with an obvious interpretation of the transition mechanism. Moreover the superfluid phase is explained explicitly from the energy spectrum derived in terms of Bogliubov approach.
Self-similar solitary waves in Bessel optical lattices
Xu Siliu; Liang Jianchu; Yi Lin
2010-01-15
An analytical solitary wave solution to the generalized nonlinear Schroedinger equation (NLSE) with varying coefficients in Bessel optical lattices is obtained based on the self-similar method. Our results indicate that a new family of Bessel (BSL) self-similar spatial solitons can be formed in the Kerr nonlinear media in the confined cylindrical symmetric geometry in sizes. These soliton profiles are rather stable, independent of propagation distance.
Dynamic response of trapped ultracold bosons on optical lattices
Batrouni, G.G.; Assaad, F.F.; Scalettar, R.T.; Denteneer, P.J.H.
2005-09-15
We study the dynamic response of ultracold bosons trapped in one-dimensional optical lattices using Quantum Monte Carlo simulations of the boson Hubbard model with a confining potential. The dynamic structure factor reveals the inhomogeneous nature of the low temperature state, which contains coexisting Mott insulator and superfluid regions. We present new evidence for local quantum criticality and discuss implications for the experimental excitation spectrum of {sup 87}Rb atoms confined in one dimension.
Quantum gases in optical lattices : the atomic Mott insulator
NASA Astrophysics Data System (ADS)
van Oosten, D.
2004-09-01
An optical lattice is a periodic potential for atoms, created using a standing wave pattern of light. Due to the interaction between the light and the atoms, the atoms are attracted to either the nodes or the anti-nodes of the standing wave, depending on the exact wave lenght of the light. This means that if such a lattice is loaded with a sufficiently high number of ultracold atoms, a periodic array of atoms is obtained, we an interatomic distance of a few tenths of a micrometer. In order to obtain such a high number of cold atoms, one first has to create a so-called Bose-Einstein condensate. When an optical lattice is loaded from a Bose-Einstein condensate, it is possible to create a system in which every atom is in the lowest band of the lattice and there is on average one atom in each lattice site. Because the lattice potential is created with laser light, the depth of the lattice can easily be tuned by changing the intensity of the laser. When the intensity of the laser light is low, the atoms can tunnel from one site to the next. Due to this tunneling, the gas of atoms in the lattice will remain superfluid. However, if the intensity of the laser light is increased to above a certain critical value, a quantum phase transition occurs to a so-called Mott insulator. In this state, the atoms can no longer tunnel due to the fact that the on-site interaction between atoms becomes more important then the tunneling probability. In this PhD thesis, a description is given of the experimental setup that is being constructed in our group to create these systems in our lab. Also, a theoretical description is given of these systems and several important quantities our derived, such as the gap of the Mott-insulating state. Furthermore, an experiment is proposed that can be used to accurately measure this gap.
Dynamics of Hubbard-Band Quasiparticles in Disordered Optical Lattices
NASA Astrophysics Data System (ADS)
Scarola, Vito; Demarco, Brian
Recent experiments use transport of degenerate Fermi gases in optical lattices (Kondov et al. Phys. Rev. Lett. 114, 083002 (2015) to probe the interplay of disorder and strong interactions. These experiments find evidence for an intriguing insulating phase where quantum diffusion is completely suppressed by strong disorder. Quantitative interpretation of these experiments remains an open problem that requires inclusion of non-zero entropy, strong interaction, and trapping in an Anderson-Hubbard model. We construct a theory of dynamics of Hubbard-band quasiparticles tailored to trapped optical lattice experiments. We compare the theory directly with center-of-mass transport experiments of Kondov et al. with no fitting parameters. The close agreement between theory and experiments shows that the suppression of transport is only partly due to finite entropy effects. We argue that the complete suppression of transport is consistent with short-time, finite size precursors of Anderson localization of Hubbard-band quasiparticles. The combination of our theoretical framework and optical lattice experiments offers an important platform for studying localization in isolated many-body quantum systems. V.W.S. acknowledges support from AFOSR under Grant FA9550-11-1-0313.
Cold Atomic Gases in Optical Lattices with Disorder
NASA Astrophysics Data System (ADS)
Schulte, T.; Drenkelforth, S.; Kruse, J.; Ertmer, W.; Arlt, J. J.; Kantian, A.; Santos, L. Sanchez-Palencia L.; Sanpera, A.; Sacha, K.; Zoller, P.; Lewenstein, M.; Zakrzewski, J.
2007-01-01
Cold atomic gases placed in optical lattices enable studies of simple condensed matter theory models with parameters that may be tuned relatively easily. When the optical potential is randomized (e.g. using laser speckle to create a random intensity distribution) one may be able to observe Anderson localization of matter waves for non-interacting bosons, the so-called Bose glass in the presence of interactions, as well as the Fermi glass or quantum spin glass for mixtures of fermions and bosons.
NASA Astrophysics Data System (ADS)
Gui, Hong; Li, Xin; Zhao, Zhenjie; Xie, Wenhui
2016-03-01
In this paper, we have calculated the structural, electronic, magnetic and optical properties of Sr2NiO3 and Sr2CoO3 using density functional theory (DFT) within generalized gradient approximation (GGA). The crystal structure of both materials is well described with Immm (No. 71) symmetry which are isostructural with Sr2CuO3 and both are quasi-one-dimensional (1D) rectangular lattice G-type antiferromagnets, in consistent with the experimental data. Due to a distortion, Sr2CoO3 lifts the near-degeneracy dxz and dyz states of the local Co electronic configuration, which demonstrates a strong coupling between the structural lattice and the electronic configuration. The calculated band structure shows a band gap of 1.376 eV for Sr2NiO3 and a band gap of 1.735 eV for Sr2CoO3. Ni and Co ions are in the high-spin S = 1 and S = 3/2 configurations with the magnetic moments of 1.585 μB and 2.587 μB, respectively. Based on the Heisenberg Hamiltonian model, we conclude that the superexchange intrachain TM-O-TM superexchange interaction is predominant and interaction between the 1D chains is weak. According to the calculated dielectric function, absorption spectrum and electron energy loss spectrum, the optical responses suggest that Sr2NiO3 shows the unique anisotropic structure and interaction of the application in optoelectronics.
Non-equilibrium dynamics of ultracold atoms in optical lattices
NASA Astrophysics Data System (ADS)
Chen, David
This thesis describes experiments focused on investigating out-of-equilibrium phenomena in the Bose-Hubbard Model and exploring novel cooling techniques for ultracold gases in optical lattices. In the first experiment, we study quenches across the Mott-insulator-to-superfluid quantum phase transition in the 3D Bose-Hubbard Model. The quench is accomplished by continuously tuning the ratio of the Hubbard energies. We observe that the degree of excitation is proportional to the fraction of atoms that cross the phase boundary, and that the amount of excitations and energy produced during the quench have a power-law dependence on the quench rate. These phenomena suggest an excitation process analogous to the mechanism for defect generation in non-equilibrium classical phase transitions. This experiment constitutes the first observation of the Kibble-Zurek mechanism in a quantum quench. We have reported our findings in Ref. [1]. In a second experiment, published in Ref. [2], we investigate dissipation as a method for cooling a strongly interacting gas. We introduce dissipation via a bosonic reservoir to a strongly interacting bosonic gas in the Mott-insulator regime of a 3D spin-dependent optical lattice. The lattice atoms are excited to a higher energy band using laser-induced Bragg transitions. A weakly interacting superfluid comprised of atoms in a state that does not experience the lattice potential acts as a dissipative bath that interacts with the lattice atoms through collisions. We measure the resulting bath-induced decay using the atomic quasimomentum distribution, and we compare the decay rate with predictions from a weakly interacting model with no free parameters. A competing intrinsic decay mechanism arising from collisions between lattice atoms is also investigated. The presence of intrinsic decay can not be accommodated within a non-interacting framework and signals that strong interactions may play a central role in the lattice-atom dynamics. The
Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock
NASA Astrophysics Data System (ADS)
Lodewyck, Jérôme; Bilicki, Sławomir; Bookjans, Eva; Robyr, Jean-Luc; Shi, Chunyan; Vallet, Grégoire; Le Targat, Rodolphe; Nicolodi, Daniele; Le Coq, Yann; Guéna, Jocelyne; Abgrall, Michel; Rosenbusch, Peter; Bize, Sébastien
2016-08-01
Optical lattice clocks are at the forefront of frequency metrology. Both the instability and systematic uncertainty of these clocks have been reported to be two orders of magnitude smaller than the best microwave clocks. For this reason, a redefinition of the SI second based on optical clocks seems possible in the near future. However, the operation of optical lattice clocks has not yet reached the reliability that microwave clocks have achieved so far. In this paper, we report on the operation of a strontium optical lattice clock that spans several weeks, with more than 80% uptime. We make use of this long integration time to demonstrate a reproducible measurement of frequency ratios between the strontium clock transition and microwave Cs primary and Rb secondary frequency standards.
Artificial Staggered Magnetic Field for Ultracold Atoms in Optical Lattices
NASA Astrophysics Data System (ADS)
Morais Smith, Cristiane
2011-03-01
Uniform magnetic fields are ubiquitous in nature, but this is not the case for staggered magnetic fields. In this talk, I will discuss an experimental set-up for cold atoms recently proposed by us, which allows for the realization of a ``staggered gauge field'' in a 2D square optical lattice. If the lattice is loaded with bosons, it may be described by an effective Bose-Hubbard Hamiltonian, with complex and anisotropic hopping coefficients. A very rich phase diagram emerges: besides the usual Mott-insulator and zero-momentum condensate, a new phase with a finite momentum condensate becomes the ground-state at strong gauge fields. By using the technique of Feshbach resonance, the dynamics of a coherent superposition of a vortex-carrying atomic condensate and a conventional zero-momentum molecular condensate can also be studied within the same scheme. On the other hand, if the lattice is loaded with fermions, a highly tunable, graphene-like band structure can be realized, without requiring the honeycomb lattice symmetry. When the system is loaded with a mixture of bosons and two-species fermions, several features of the high-Tc phase diagram can be reproduced. A dome-shaped unconventional superconducting region arises, surrounded by a non-Fermi liquid and a Fermi liquid at low and high doping, respectively. We acknowledge financial support from the Netherlands Organization for Scientific Research (NWO).
A Mott insulator of fermionic atoms in an optical lattice
NASA Astrophysics Data System (ADS)
Moritz, Henning
2009-03-01
In a solid material strong interactions between the electrons can lead to surprising properties. A prime example is the Mott insulator, where the suppression of conductivity is a result of interactions and not the consequence of a filled Bloch band. The proximity to the Mott insulating phase in fermionic systems is the origin for many intriguing phenomena in condensed matter physics, most notably high-temperature superconductivity. Compared to real materials, a fermionic quantum gas trapped in an optical lattice offers a very pure realisation of the Hubbard model, giving a new approach to understand the physics of strongly correlated systems. We report on the formation of a Mott insulator of a repulsively interacting two-component Fermi gas in an optical lattice. It is signalled by three features: a drastic suppression of doubly occupied lattice sites, a strong reduction of the compressibility inferred from the response of double occupancy to atom number increase, and the appearance of a gapped mode in the excitation spectrum. In collaboration with Robert J"ordens, Niels Strohmaier, and Daniel Greif, ETH Zurich; Kenneth G"unter, ETH Zurich, ENS Paris; Leticia Tarruell and Tilman Esslinger, ETH Zurich.
Probing many-body interactions in an optical lattice clock
Rey, A.M.; Gorshkov, A.V.; Kraus, C.V.; Martin, M.J.; Bishof, M.; Swallows, M.D.; Zhang, X.; Benko, C.; Ye, J.; Lemke, N.D.; Ludlow, A.D.
2014-01-15
We present a unifying theoretical framework that describes recently observed many-body effects during the interrogation of an optical lattice clock operated with thousands of fermionic alkaline earth atoms. The framework is based on a many-body master equation that accounts for the interplay between elastic and inelastic p-wave and s-wave interactions, finite temperature effects and excitation inhomogeneity during the quantum dynamics of the interrogated atoms. Solutions of the master equation in different parameter regimes are presented and compared. It is shown that a general solution can be obtained by using the so called Truncated Wigner Approximation which is applied in our case in the context of an open quantum system. We use the developed framework to model the density shift and decay of the fringes observed during Ramsey spectroscopy in the JILA {sup 87}Sr and NIST {sup 171}Yb optical lattice clocks. The developed framework opens a suitable path for dealing with a variety of strongly-correlated and driven open-quantum spin systems. -- Highlights: •Derived a theoretical framework that describes many-body effects in a lattice clock. •Validated the analysis with recent experimental measurements. •Demonstrated the importance of beyond mean field corrections in the dynamics.
Ultra-fast optical switches using 1D polymeric photonic crystals
NASA Astrophysics Data System (ADS)
Katouf, R.; Komikado, T.; Itoh, M.; Yatagai, T.; Umegaki, S.
2005-12-01
We report fabrication of ultra-fast optical switches operated at a wavelength of 1064 nm using spin-coated one-dimensional polymeric photonic crystals doped with nonlinear-optical dyes. The optical switches are controlled either by an applied electric-field voltage or by a pump light by use of two different optical-configurations. The response time of the electro-optic switch and the all-optical switch are limited by the applied voltage and the laser used, respectively. The polymeric photonic crystals can be easily fabricated with low cost.
Bose-Einstein Condensates in Optical Lattices: Experiments
NASA Astrophysics Data System (ADS)
Morsch, O.
In the early days of laser cooling, which together with magnetic trapping techniques led to the first observation of BEC in 1995, it was realized that the optical interference between the cooling beams could lead to a spatially periodic density modulation of the trapped atoms. This notion of a "three-dimensional egg-carton" for cold atoms quickly led to a number of experiments confirming the existence of such a light-bound crystal and exploring its properties [1-3]. It was found that, indeed, cold atoms could be trapped in such periodic structures, and it was possible to measure, for example, the quantized motion of the atoms inside the potential wells. While early experiments were carried out in the dissipative regime using near-resonant lattices in which the atoms were continuously cooled through the Sisyphus mechanism involving light scattering [4], more sophisticated experimental techniques later enabled studies on far-detuned lattices in which atoms evolved coherently.
Pair tunneling of bosonic atoms in an optical lattice
Zhou Xiangfa; Zhang Yongsheng; Guo Guangcan
2009-07-15
We show that atom-molecule coupling with large detuning can cause effective hopping of pairs of bosonic atoms in a state-dependent optical lattice. Taking advantage of the high controllability of all relevant parameters in such systems, we discuss the pair-superfluid (PSF) to Mott insulator (MI) transition using the effective model within mean-field theory. In the presence of on-site disorder, simultaneous tunneling of bosonic atoms can result in a compressible weak Mott insulating phase. We have also investigated the coexistence of superfluid (SF) and PSF in the lattice, and found that the competition between the two hopping mechanisms can cause a first-order PSF(SF)-MI transition.
Spin Gradient Thermometry for Ultracold Atoms in Optical Lattices
Weld, David M.; Medley, Patrick; Miyake, Hirokazu; Hucul, David; Pritchard, David E.; Ketterle, Wolfgang
2009-12-11
We demonstrate spin gradient thermometry, a new general method of measuring the temperature of ultracold atoms in optical lattices. We realize a mixture of spins separated by a magnetic field gradient. Measurement of the width of the transition layer between the two spin domains serves as a new method of thermometry which is observed to work over a broad range of lattice depths and temperatures, including in the Mott insulator regime. We demonstrate the thermometry using ultracold rubidium atoms, and suggest that interesting spin physics can be realized in this system. The lowest measured temperature is 1 nK, indicating that the system has reached the quantum regime, where insulating shells are separated by superfluid layers.
Spin gradient thermometry for ultracold atoms in optical lattices.
Weld, David M; Medley, Patrick; Miyake, Hirokazu; Hucul, David; Pritchard, David E; Ketterle, Wolfgang
2009-12-11
We demonstrate spin gradient thermometry, a new general method of measuring the temperature of ultracold atoms in optical lattices. We realize a mixture of spins separated by a magnetic field gradient. Measurement of the width of the transition layer between the two spin domains serves as a new method of thermometry which is observed to work over a broad range of lattice depths and temperatures, including in the Mott insulator regime. We demonstrate the thermometry using ultracold rubidium atoms, and suggest that interesting spin physics can be realized in this system. The lowest measured temperature is 1 nK, indicating that the system has reached the quantum regime, where insulating shells are separated by superfluid layers. PMID:20366208
Birefringent breakup of Dirac fermions on a square optical lattice
Kennett, Malcolm P.; Komeilizadeh, Nazanin; Kaveh, Kamran; Smith, Peter M.
2011-05-15
We introduce a lattice model for fermions in a spatially periodic magnetic field that also has spatially periodic hopping amplitudes. We discuss how this model might be realized with cold atoms in an artificial magnetic field on a square optical lattice. When there is an average flux of half a flux quantum per plaquette, the spectrum of low-energy excitations can be described by massless Dirac fermions in which the usually doubly degenerate Dirac cones split into cones with different ''speeds of light.'' These gapless birefringent Dirac fermions arise because of broken chiral symmetry in the kinetic energy term of the effective low-energy Hamiltonian. We characterize the effects of various perturbations to the low-energy spectrum, including staggered potentials, interactions, and domain-wall topological defects.
Synthetic Spin-Orbit Coupling in an Optical Lattice Clock.
Wall, Michael L; Koller, Andrew P; Li, Shuming; Zhang, Xibo; Cooper, Nigel R; Ye, Jun; Rey, Ana Maria
2016-01-22
We propose the use of optical lattice clocks operated with fermionic alkaline-earth atoms to study spin-orbit coupling (SOC) in interacting many-body systems. The SOC emerges naturally during the clock interrogation, when atoms are allowed to tunnel and accumulate a phase set by the ratio of the "magic" lattice wavelength to the clock transition wavelength. We demonstrate how standard protocols such as Rabi and Ramsey spectroscopy that take advantage of the sub-Hertz resolution of state-of-the-art clock lasers can perform momentum-resolved band tomography and determine SOC-induced s-wave collisions in nuclear-spin-polarized fermions. With the use of a second counterpropagating clock beam, we propose a method for engineering controlled atomic transport and study how it is modified by p- and s-wave interactions. The proposed spectroscopic probes provide clean and well-resolved signatures at current clock operating temperatures. PMID:26849600
Tunneling, diffusion, and dissociation of Feshbach molecules in optical lattices
NASA Astrophysics Data System (ADS)
Bailey, Taylor; Bertulani, Carlos A.; Timmermans, Eddy
2012-03-01
The quantum dynamics of an ultracold diatomic molecule tunneling and diffusing in a one-dimensional optical lattice exhibits unusual features. While it is known that the process of quantum tunneling through potential barriers can break up a bound-state molecule into a pair of dissociated atoms, interference and reassociation produce intricate patterns in the time-evolving site-dependent probability distribution for finding atoms and bound-state molecules. We find that the bound-state molecule is unusually resilient against break up at ultralow binding energy Eb (Eb much smaller than the barrier height of the lattice potential). After an initial transient, the bound-state molecule spreads with a width that grows as the square root of time. Surprisingly, the width of the probability of finding dissociated atoms does not increase with time as a power law.
Synthetic Spin-Orbit Coupling in an Optical Lattice Clock
NASA Astrophysics Data System (ADS)
Wall, Michael L.; Koller, Andrew P.; Li, Shuming; Zhang, Xibo; Cooper, Nigel R.; Ye, Jun; Rey, Ana Maria
2016-01-01
We propose the use of optical lattice clocks operated with fermionic alkaline-earth atoms to study spin-orbit coupling (SOC) in interacting many-body systems. The SOC emerges naturally during the clock interrogation, when atoms are allowed to tunnel and accumulate a phase set by the ratio of the "magic" lattice wavelength to the clock transition wavelength. We demonstrate how standard protocols such as Rabi and Ramsey spectroscopy that take advantage of the sub-Hertz resolution of state-of-the-art clock lasers can perform momentum-resolved band tomography and determine SOC-induced s -wave collisions in nuclear-spin-polarized fermions. With the use of a second counterpropagating clock beam, we propose a method for engineering controlled atomic transport and study how it is modified by p - and s -wave interactions. The proposed spectroscopic probes provide clean and well-resolved signatures at current clock operating temperatures.
Dynamical properties of ultracold bosons in an optical lattice
Huber, S. D.; Blatter, G.; Altman, E.; Buechler, H. P.
2007-02-15
We study the excitation spectrum of strongly correlated lattice bosons for the Mott-insulating phase and for the superfluid phase close to localization. Within a Schwinger-boson mean-field approach we find two gapped modes in the Mott insulator and the combination of a sound mode (Goldstone) and a gapped (Higgs) mode in the superfluid. To make our findings comparable with experimental results, we calculate the dynamic structure factor as well as the linear response to the optical lattice modulation introduced by Stoeferle et al. [Phys. Rev. Lett. 92, 130403 (2004)]. We find that the puzzling finite frequency absorption observed in the superfluid phase could be explained via the excitation of the gapped (Higgs) mode. We check the consistency of our results with an adapted f-sum rule and propose an extension of the experimental technique by Stoeferle et al. to further verify our findings.
Optical lattice clock with atoms confined in a shallow trap
Lemonde, Pierre; Wolf, Peter
2005-09-15
We study the trap depth requirement for the realization of an optical clock using atoms confined in a lattice. We show that site-to-site tunneling leads to a residual sensitivity to the atom dynamics hence requiring large depths [(50-100)E{sub r} for Sr] to avoid any frequency shift or line broadening of the atomic transition at the 10{sup -17}-10{sup -18} level. Such large depths and the corresponding laser power may, however, lead to difficulties (e.g., higher-order light shifts, two-photon ionization, technical difficulties) and therefore one would like to operate the clock in much shallower traps. To circumvent this problem we propose the use of an accelerated lattice. Acceleration lifts the degeneracy between adjacents potential wells which strongly inhibits tunneling. We show that using the Earth's gravity, much shallower traps (down to 5E{sub r} for Sr) can be used for the same accuracy goal.
Zeptonewton force sensing with nanospheres in an optical lattice
NASA Astrophysics Data System (ADS)
Ranjit, Gambhir; Cunningham, Mark; Casey, Kirsten; Geraci, Andrew A.
2016-05-01
Optically trapped nanospheres in high vacuum experience little friction and hence are promising for ultrasensitive force detection. Here we demonstrate measurement times exceeding 105 s and zeptonewton force sensitivity with laser-cooled silica nanospheres trapped in an optical lattice. The sensitivity achieved exceeds that of conventional room-temperature solid-state force sensors by over an order of magnitude, and enables a variety of applications including electric-field sensing, inertial sensing, and gravimetry. The particle is confined at the antinodes of the optical standing wave, and by studying the motion of a particle which has been moved to an adjacent trapping site, the known spacing of the antinodes can be used to calibrate the displacement spectrum of the particle. Finally, we study the dependence of the trap stability and lifetime on the laser intensity and gas pressure, and examine the heating rate of the particle in vacuum without feedback cooling.
Development of 171Yb optical lattice clock at KRISS
NASA Astrophysics Data System (ADS)
Mun, Jongchul; Park, Chang Yong; Yu, Dai-Hyuk; Lee, Won-Kyu; Eon Park, Sang; Kwon, Taeg Yong; Lee, Sang-Bum
2012-06-01
We measured the absolute frequency of the optical clock transition 1S0 (F = 1/2) - 3P0 (F = 1/2) of 171Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 865.7 (9.2) Hz. The measured frequency was calibrated to the Coordinated Universal Time (UTC) by using an optical frequency comb of which frequency was phase-locked to a hydrogen maser as a flywheel oscillator traceable to the UTC. The magic wavelength was also measured as 394 798.48 (79) GHz. The results are in good agreement with two previous measurements of other institutes within the specified uncertainty of this work.
Quantum simulations of lattice gauge theories using ultracold atoms in optical lattices.
Zohar, Erez; Cirac, J Ignacio; Reznik, Benni
2016-01-01
Can high-energy physics be simulated by low-energy, non-relativistic, many-body systems such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in particular, they manifest neither local gauge invariance nor Lorentz invariance, which are crucial properties of the quantum field theories which are the building blocks of the standard model of elementary particles. However, it turns out, surprisingly, that there are ways to configure an atomic system to manifest both local gauge invariance and Lorentz invariance. In particular, local gauge invariance can arise either as an effective low-energy symmetry, or as an exact symmetry, following from the conservation laws in atomic interactions. Hence, one could hope that such quantum simulators may lead to a new type of (table-top) experiments which will be used to study various QCD (quantum chromodynamics) phenomena, such as the confinement of dynamical quarks, phase transitions and other effects, which are inaccessible using the currently known computational methods. In this report, we review the Hamiltonian formulation of lattice gauge theories, and then describe our recent progress in constructing the quantum simulation of Abelian and non-Abelian lattice gauge theories in 1 + 1 and 2 + 1 dimensions using ultracold atoms in optical lattices. PMID:26684222
Towards a lattice based neutral magnesium optical frequency standard
NASA Astrophysics Data System (ADS)
Kelkar, Hrishikesh; Riedmann, Matthias; Wuebbena, Temmo; Kulosa, Andre; Friebe, Jan; Pape, Andre; Amairi, Sana; Malobabic, Sina; Zipfel, Klaus; Ruehmann, Steffen; -Maria Rasel, Ernst; Ertmer, Wolfgang
2010-03-01
Magnesium is a promising candidate for a high performance neutral atom optical frequency standard. It offers a low sensitivity to frequency shifts of the ^1S0-^3P0 clock transition by room temperature blackbody radiation and has several isotopes of suitable abundance (two bosonic, one fermionic) to realize an optical clock. We report on recent progress towards creating a lattice clock of magnesium. ^24Mg atoms are pre-cooled in two stages. The singlet Magneto Optical Trap (MOT) captures and cools atoms from an atomic beam which are then loaded into a triplet MOT. The triplet MOT has a decay channel to the dark ^3P0 state which is used to load atoms into a 1064 nm dipole trap. The cooling stages are on simultaneously and atoms are continuously loaded in the dipole trap. We capture upto 9 10^4 atoms at a temperature below 100 μK. We are exploring different avenues for further cooling which will enable reaching the Lamb-Dicke regime in a magic wavelength lattice.
Topologically induced avoided band crossing in an optical checkerboard lattice.
Olschläger, Matthias; Wirth, Georg; Kock, Thorge; Hemmerich, Andreas
2012-02-17
We report on the condensation of bosons in the 4th band of an optical checkerboard lattice providing a topologically induced avoided band crossing involving the 2nd, 3rd, and 4th Bloch bands. When the condensate is slowly tuned through the avoided crossing, accelerated band relaxation arises and the zero momentum approximately C4-invariant condensate wave function acquires finite momentum order and reduced C2 symmetry. For faster tuning Landau-Zener oscillations between different superfluid orders arise, which are used to characterize the avoided crossing. PMID:22401220
Quantum phases of quadrupolar Fermi gases in optical lattices
NASA Astrophysics Data System (ADS)
Bhongale, Satyan; Mathey, Ludwig; Zhao, Erhai; Yellin, Susanne; Lemeshko, Mikhail
2013-05-01
We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moment but possessing a significant value of electric quadrupole moment. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities.
A new apparatus for studying quantum gases in optical lattices
NASA Astrophysics Data System (ADS)
Schneider, Ulrich; Duca, Lucia; Li, Tracy; Boll, Martin; Ronzheimer, Philipp; Braun, Simon; Will, Sebastian; Rom, Tim; Schreiber, Michael; Bloch, Immanuel
2011-05-01
We present the design of a new apparatus targeted at the study of equilibrium and out-of-equilibrium phenomena of quantum gases in 2D and 3D optical lattices. Specifically this apparatus will allow for a study of the crossover between 2D and 3D using bosonic and fermionic gases as well as Bose-Fermi mixtures. In addition we present a new analysis of previous results concerning the Fermi-Hubbard model and will analyze possible routes for creating many-body states with long range order, including antiferromagnetically ordered states and BCS-superfluids. This work is supported by DARPA/OLE MURI DFG MPQ.
Quantum Phases of Quadrupolar Fermi Gases in Optical Lattices
NASA Astrophysics Data System (ADS)
Bhongale, S. G.; Mathey, L.; Zhao, Erhai; Yelin, S. F.; Lemeshko, Mikhail
2013-04-01
We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities.
Floquet engineering with quasienergy bands of periodically driven optical lattices
NASA Astrophysics Data System (ADS)
Holthaus, Martin
2016-01-01
A primer on the Floquet theory of periodically time-dependent quantum systems is provided, and it is shown how to apply this framework for computing the quasienergy band structure governing the dynamics of ultracold atoms in driven optical cosine lattices. Such systems are viewed here as spatially and temporally periodic structures living in an extended Hilbert space, giving rise to spatio-temporal Bloch waves whose dispersion relations can be manipulated at will by exploiting ac-Stark shifts and multiphoton resonances. The elements required for numerical calculations are introduced in a tutorial manner, and some example calculations are discussed in detail, thereby illustrating future prospects of Floquet engineering.
Topological quantum matter with ultracold gases in optical lattices
NASA Astrophysics Data System (ADS)
Goldman, N.; Budich, J. C.; Zoller, P.
2016-07-01
Since the discovery of topological insulators, many topological phases have been predicted and realized in a range of different systems, providing both fascinating physics and exciting opportunities for devices. And although new materials are being developed and explored all the time, the prospects for probing exotic topological phases would be greatly enhanced if they could be realized in systems that were easily tuned. The flexibility offered by ultracold atoms could provide such a platform. Here, we review the tools available for creating topological states using ultracold atoms in optical lattices, give an overview of the theoretical and experimental advances and provide an outlook towards realizing strongly correlated topological phases.
Strongly correlated Fermi Bose mixtures in disordered optical lattices
NASA Astrophysics Data System (ADS)
Sanchez-Palencia, L.; Ahufinger, V.; Kantian, A.; Zakrzewski, J.; Sanpera, A.; Lewenstein, M.
2006-05-01
We investigate theoretically the low-temperature physics of a two-component ultracold mixture of bosons and fermions in disordered optical lattices. We focus on the strongly correlated regime. We show that, under specific conditions, composite fermions, made of one fermion plus one bosonic hole, form. The composite picture is used to derive an effective Hamiltonian whose parameters can be controlled via the boson-boson and the boson-fermion interactions, the tunnelling terms and the inhomogeneities. We finally investigate the quantum phase diagram of the composite fermions and show that it corresponds to the formation of Fermi glasses, spin glasses and quantum percolation regimes.
Bosonic Integer Quantum Hall Effect in Optical Flux Lattices
NASA Astrophysics Data System (ADS)
Sterdyniak, A.; Cooper, Nigel R.; Regnault, N.
2015-09-01
In two dimensions strongly interacting bosons in a magnetic field can realize a bosonic integer quantum Hall state, the simplest two-dimensional example of a symmetry-protected topological phase. We propose a realistic implementation of this phase using an optical flux lattice. Through exact diagonalization calculations, we show that the system exhibits a clear bulk gap and the topological signature of the bosonic integer quantum Hall state. In particular, the calculation of the many-body Chern number leads to a quantized Hall conductance in agreement with the analytical predictions. We also study the stability of the phase with respect to some of the experimentally relevant parameters.
Intrinsic photoconductivity of ultracold fermions in optical lattices.
Heinze, J; Krauser, J S; Fläschner, N; Hundt, B; Götze, S; Itin, A P; Mathey, L; Sengstock, K; Becker, C
2013-02-22
We report on the experimental observation of an analog to a persistent alternating photocurrent in an ultracold gas of fermionic atoms in an optical lattice. The dynamics is induced and sustained by an external harmonic confinement. While particles in the excited band exhibit long-lived oscillations with a momentum-dependent frequency, a strikingly different behavior is observed for holes in the lowest band. An initial fast collapse is followed by subsequent periodic revivals. Both observations are fully explained by mapping the system onto a nonlinear pendulum. PMID:23473159
Vortex configurations of bosons in an optical lattice
Wu Congjun; Zhang Shoucheng; Chen Handong; Hu Jiangpiang
2004-04-01
The single-vortex problem in a strongly correlated bosonic system is investigated self-consistently within the mean-field theory of the Bose-Hubbard model. Near the superfluid-Mott-insulator transition, the vortex core has a tendency toward the Mott-insulating phase, with the core particle density approaching the nearest commensurate value. If the nearest-neighbor repulsion exists, the charge-density wave order may develop locally in the core. The evolution of the vortex configuration from the strong- to weak-coupling regions is studied. This phenomenon can be observed in systems of rotating ultracold atoms in optical lattices and Josephson-junction arrays.
Wilson Fermions and Axion Electrodynamics in Optical Lattices
Bermudez, A.; Martin-Delgado, M. A.; Mazza, L.; Rizzi, M.; Goldman, N.; Lewenstein, M.
2010-11-05
We show that ultracold Fermi gases in optical superlattices can be used as quantum simulators of relativistic lattice fermions in 3+1 dimensions. By exploiting laser-assisted tunneling, we find an analogue of the so-called naive Dirac fermions, and thus provide a realization of the fermion doubling problem. Moreover, we show how to implement Wilson fermions, and discuss how their mass can be inverted by tuning the laser intensities. In this regime, our atomic gas corresponds to a phase of matter where Maxwell electrodynamics is replaced by axion electrodynamics: a 3D topological insulator.
Defect-mediated discrete solitons in optically induced photorefractive lattices
Li Yongyao; Pang Wei; Chen Yongzhu; Yu Zhiqiang; Zhou Jianying; Zhang Huarong
2009-10-15
Theoretical analysis to the defect mediated discrete solitons in one- and two-dimensional periodical waveguide lattices is presented. The waveguide arrays with these functional defects are assumed to respond to the light field as an optically induced photorefraction and they are patterned by a holographic technique. It is found that the spatial energy distributions of the solitary waves can be controlled by the defects in the waveguide arrays, and this gives rise to an additional freedom to externally shaping the light field distribution to a special shape.
Optical Lattice Induced Light Shifts in an Yb Atomic Clock
Barber, Z. W.; Stalnaker, J. E.; Lemke, N. D.; Poli, N.; Oates, C. W.; Fortier, T. M.; Diddams, S. A.; Hollberg, L.; Hoyt, C. W.; Taichenachev, A. V.; Yudin, V. I.
2008-03-14
We present an experimental study of the lattice-induced light shifts on the {sup 1}S{sub 0}{yields}{sup 3}P{sub 0} optical clock transition ({nu}{sub clock}{approx_equal}518 THz) in neutral ytterbium. The 'magic' frequency {nu}{sub magic} for the {sup 174}Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the hyperpolarizability shifts due to the nearby 6s6p{sup 3}P{sub 0}{yields}6s8p{sup 3}P{sub 0}, 6s8p{sup 3}P{sub 2}, and 6s5f{sup 3}F{sub 2} two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 {mu}K deep, lattice at the magic wavelength. These results indicate that the differential polarizability and hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10{sup -17}.
Subwavelength optical lattices induced by position-dependent dark states
Sun Qingqing; Evers, Joerg; Kiffner, Martin; Zubairy, M. Suhail
2011-05-15
A method for the generation of subwavelength optical lattices based on multilevel dark states is proposed. The dark state is formed by a suitable combination of standing wave light fields, leading to position-dependent populations of the ground states. An additional field coupling dispersively to one of the ground states translates this position dependence into a subwavelength optical potential. We provide two semiclassical approaches to understand the involved physics, and demonstrate that they lead to identical results in a certain meaningful limit. Then we apply a Monte Carlo simulation technique to study the full quantum dynamics of the subwavelength trapping. Finally, we discuss the relevant time scales for the trapping, optimum conditions, and possible implementations.
Generation and detection of atomic spin entanglement in optical lattices
NASA Astrophysics Data System (ADS)
Dai, Han-Ning; Yang, Bing; Reingruber, Andreas; Xu, Xiao-Fan; Jiang, Xiao; Chen, Yu-Ao; Yuan, Zhen-Sheng; Pan, Jian-Wei
2016-08-01
Ultracold atoms in optical lattices hold promise for the creation of entangled states for quantum technologies. Here we report on the generation, manipulation and detection of atomic spin entanglement in an optical superlattice. Using a spin-dependent superlattice, atomic spins in the left or right sites can be individually addressed and coherently manipulated with near-unity fidelities by microwave pulses. The spin entanglement of the two atoms in the double wells of the superlattice is generated via the dynamical evolution governed by spin superexchange. By monitoring the collisional atom loss with in situ absorption imaging we measure the spin correlations of the atoms inside the double wells and obtain a lower bound on the entanglement fidelity of 0.79 +/- 0.06, and a violation of a Bell's inequality S = 2.21 +/- 0.08.
Observation of optical solitons in PT-symmetric lattices
Wimmer, Martin; Regensburger, Alois; Miri, Mohammad-Ali; Bersch, Christoph; Christodoulides, Demetrios N.; Peschel, Ulf
2015-01-01
Controlling light transport in nonlinear active environments is a topic of considerable interest in the field of optics. In such complex arrangements, of particular importance is to devise strategies to subdue chaotic behaviour even in the presence of gain/loss and nonlinearity, which often assume adversarial roles. Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation. Here we report the experimental observation of optical solitons in PT-symmetric lattices. Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions. The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated. PMID:26215165
Accurate Optical Lattice Clock with {sup 87}Sr Atoms
Le Targat, Rodolphe; Baillard, Xavier; Fouche, Mathilde; Brusch, Anders; Tcherbakoff, Olivier; Rovera, Giovanni D.; Lemonde, Pierre
2006-09-29
We report a frequency measurement of the {sup 1}S{sub 0}-{sup 3}P{sub 0} transition of {sup 87}Sr atoms in an optical lattice clock. The frequency is determined to be 429 228 004 229 879(5) Hz with a fractional uncertainty that is comparable to state-of-the-art optical clocks with neutral atoms in free fall. The two previous measurements of this transition were found to disagree by about 2x10{sup -13}, i.e., almost 4 times the combined error bar and 4 to 5 orders of magnitude larger than the claimed ultimate accuracy of this new type of clocks. Our measurement is in agreement with one of these two values and essentially resolves this discrepancy.
Stability improvements for the NIST Yb optical lattice clock
NASA Astrophysics Data System (ADS)
Fasano, R. J.; Schioppo, M.; McGrew, W. F.; Brown, R. C.; Hinkley, N.; Yoon, T. H.; Beloy, K.; Oates, C. W.; Ludlow, A. D.
2016-05-01
To reach the fundamental limit given by quantum projection noise, optical lattice clocks require advanced laser stabilization techniques. The NIST ytterbium clock has benefited from several generations of extremely high finesse optical cavities, with cavity linewidths below 1 kHz. Characterization of the cavity drift rate has allowed compensation to the mHz/s level, improving the medium-term stability of the cavity. Based on recent measurements using Ramsey spectroscopy with synchronous interrogation, we report a fractional instability σy(1s) <=10-16 , dominated by atom number fluctuation noise. We also provide updates on our cryogenic sapphire cavity with a reduced thermal noise floor, which will improve our Dick-limited fractional instability at 1 s to below 10-16. Also at University of Colorado.
Proposal for generating synthetic magnetic fields in hexagonal optical lattices
NASA Astrophysics Data System (ADS)
Tian, Binbin; Endres, Manuel; Pekker, David
2015-05-01
We propose a new approach to generating synthetic magnetic fields in ultra cold atom systems that does not rely on either Raman transitions nor periodic drive. Instead, we consider a hexagonal optical lattice produced by the intersection of three laser beams at 120 degree angles, where the intensity of one or more of the beams is spatially non-uniform. The resulting optical lattice remains hexagonal, but has spatially varying hopping matrix elements. For atoms near the Dirac points, these spatial variations appear as a gauge field, similar to the fictitious gauge field that is induced for for electrons in strained graphene. We suggest that a robust way to generate a gauge field that corresponds to a uniform flux is to aligning three gaussian beams to intersect in an equilateral triangle. Using realistic experimental parameters, we show how the proposed setup can be used to observe cyclotron motion of an atom cloud - the conventional Hall effect and distinct Landau levels - the integer quantum Hall effect.
Micro-resonators coupled to atoms in an optical lattice
NASA Astrophysics Data System (ADS)
Geraci, Andrew; Kitching, John
2010-03-01
Recently there has been a convergence of ideas between the fields of solid-state and atomic physics -- examples range from using atoms for quantum simulation of condensed-matter Hamiltonians to physically coupling atoms with solid-state devices such as micro-resonators. In this talk, we discuss an experimental proposal involving an array of cooled microcantilevers coupled to a sample of ultracold atoms trapped near a microfabricated surface [1]. The cantilevers allow individual lattice site addressing for atomic state control and readout, and potentially may be useful in optical lattice quantum computation schemes. Assuming resonators can be cooled to their vibrational ground state, we describe the implementation of a two-qubit controlled-NOT gate with atomic internal states and the motional states of the resonators, along with a protocol for entangling two or more cantilevers on the atom chip using the trapped atoms as an intermediary. Although similar experiments could be carried out with magnetic microchip traps, the optical confinement scheme we consider may exhibit reduced near-field magnetic noise and decoherence. Prospects for using this system for tests of quantum mechanics at macroscopic scales or quantum information processing will be discussed. [4pt] [1] A. Geraci and J. Kitching, Phys. Rev. A 80, 032317 (2009)
Coherent control of atomic transport in spinor optical lattices
Mischuck, Brian; Deutsch, Ivan H.; Jessen, Poul S.
2010-02-15
Coherent transport of atoms trapped in an optical lattice can be controlled by microwave-induced spin flips that correlate with site-to-site hopping. We study the controllability of homogeneous one-dimensional systems of noninteracting atoms in the absence of site addressability. Given these restrictions, we construct a deterministic protocol to map an initially localized Wannier state to a wave packet that is coherently distributed over n sites. As an example, we consider a one dimensional quantum walk in the presence of both realistic photon scattering and inhomogeneous broadening of the microwave transition due to the optical lattice. Using composite pulses to suppress errors, fidelities of over 95% can be achieved for a 25-step walk. We extend the protocol for state preparation to analytic solutions for arbitrary unitary maps given homogeneous systems and in the presence of time-dependent uniform forces. Such control is important for applications in quantum information processing, such as quantum computing and quantum simulations of condensed matter phenomena.
NASA Astrophysics Data System (ADS)
Arahata, Emiko; Nikuni, Tetsuro
2008-03-01
We study damping of the dipole oscillation in a Bose-condensed gas in a combined cigar-shaped harmonic trap and one-dimensional (1D) optical lattice potential at finite temperatures. In order to include the effect of thermal excitations in the radial direction, we derive a quasi-1D model of the Gross-Pitaevskii equation and the Bogoliubov equations. We use the Popov approximation to calculate the temperature dependence of the condensate fraction with varying lattice depth. We then calculate the Landau damping rate of the dipole oscillation as a function of the lattice depth and temperature. The damping rate increases with increasing lattice depth, which is consistent with experimental observations. The magnitude of the damping rate is in reasonable agreement with experimental data. We also find that the damping rate has a strong temperature dependence, showing a sharp increase with increasing temperature. Finally, we emphasize the importance of the radial thermal excitations in both equilibrium properties and the Landau damping.
Generalized 1D photopyroelectric technique for optical and thermal characterization of liquids
NASA Astrophysics Data System (ADS)
Balderas-López, J. A.
2012-06-01
The analytical solution for the one-dimensional heat diffusion problem for a three-layer system, in the Beer-Lambert model for light absorption, is used for the implementation of a photopyroelectric (PPE) methodology for thermal and optical characterization of pigments in liquid solution, even for those ones potentially harmful to the pyroelectric sensor, taking the liquid sample's thickness as the only variable. Exponential decay of the PPE amplitude followed by a constant PPE phase for solutions at low pigment concentration, and exponential decay of the PPE amplitude but a linear decrease of the PPE phase for the concentrated ones are theoretically shown, allowing measurements of the optical absorption coefficient (at the wavelength used for the analysis) and the thermal diffusivity for the liquid sample, respectively. This PPE methodology was tested by measuring the thermal diffusivity of a concentrated solution of methylene blue in distilled water and the optical absorption coefficient, at two wavelengths (658 and 785 nm), of water solutions of copper sulfate at various concentrations. These optical parameters were used for measuring the molar absorption coefficient of this last pigment in water solution at these two wavelengths. This last optical property was also measured using a commercial spectrometer, finding very good agreement with the corresponding ones using this PPE technique.
Optical signatures of a hypercritical 1D potential in a 2D Dirac metal
NASA Astrophysics Data System (ADS)
Jiang, Bor-Yuan; Ni, Guangxin; Pan, Cheng; Fei, Zhe; Cheng, Bin; Lau, Chun Ning; Bockrath, Marc; Basov, Dimitri; Fogler, Michael
Generation of quasi-bound states in graphene near strong charged perturbations is a solid-state analog of atomic collapse of superheavy elements or particle production by hypothetical cosmic strings. We show, for the case of a linelike perturbation, that as the perturbation grows in strength, quasi-bound states are generated sequentially. Each of these critical events is signaled by a sharp change in the local optical conductivity. Tunable linelike perturbations can be realized in experiment using nanowire or nanotube electrostatic gates. We report measurements of local conductivity for such systems obtained through near-field optical microscopy.
Strongly Correlated Quantum Gases Trapped in 3D Spin-Dependent Optical Lattices
NASA Astrophysics Data System (ADS)
Demarco, Brian
2011-03-01
Optical lattices have emerged as ideal systems for exploring Hubbard model physics, since the equivalent of material parameters such as the ratio of tunneling to interaction energy are easily and widely tunable. In this talk I will discuss our recent measurements using novel lattice potentials to realize more complex Hubbard models for bosonic 87 Rb atoms. In these experiments, we adjust the polarization of the lattice laser beams to realize fully three-dimensional, spin-dependent cubic optical lattices. We demonstrate that atoms can be trapped in combinations of spin states for which superfluid and Mott-insulator phases exist simultaneously in the lattice. We also co-trap states that experience a strong lattice potential and no lattice potential whatsoever. I will discuss recent measurements revealing a mechanism similar to Kapitza resistance that leads to thermal decoupling in this latter combination. The implications for sympathetic cooling and thermometry using species-dependent lattices will be outlined.
Optical bullets in (2+1)D photonic structures and their interaction with localized defects
NASA Astrophysics Data System (ADS)
Dohnal, Tomas
2005-11-01
This dissertation studies light propagation in Kerr-nonlinear two dimensional waveguides with a Bragg resonant, periodic structure in the propagation direction. The model describing evolution of the electric field envelopes is the system of 2D Nonlinear Coupled Mode Equations (2D CME). The periodic structure induces a range of frequencies (frequency gap) in which linear waves do not propagate. It is shown that, similarly to the ID case of a fiber grating, the 2D nonlinear system supports localized solitary wave solutions, referred to as 2D gap solitons, which have frequencies inside the linear gap and can travel at, any speed smaller than or equal to the speed of light in the corresponding homogeneous medium. Such solutions are constructed numerically via Newton's iteration. Convergence is obtained only near the upper edge of the gap. Gap solitons with a nonzero velocity are constructed by numerically following a bifurcation curve parameterized by the velocity v. It is shown that gap solitons are saddle points of the corresponding Hamiltonian functional and that no (constrained) local minima of the Hamiltonian exist. The linear stability problem is formulated and reasons for the failure of the standard Hamiltonian PDE approach for determining linear stability are discussed. In the second part of the dissertation interaction of 2D gap solitons with localized defects is studied and trapping of slow enough 2D gap solitons is demonstrated. This study builds on [JOSA B 19, 1635 (2002)], where such trapping of 1D gap solitons is considered. Analogously to this 1D problem trapping in the 2D model is explained as a resonant energy transfer into one or more defect modes existent for the particular defect. For special localized defects exact linear modes are found explicitly via the separation of variables. Numerical computation of linear defect modes is used for more general defects. Corresponding nonlinear modes are then constructed via Newton's iteration by following a
Phases of d-orbital bosons in optical lattices
NASA Astrophysics Data System (ADS)
Pinheiro, Fernanda; Matrikainen, Jani-Petri; Larson, Jonas
2015-05-01
We explore the properties of bosonic atoms loaded into the d bands of an isotropic square optical lattice. Following the recent experimental success reported in Zhai et al (2013 Phys. Rev. A 87 063638), in which populating d bands with a 99 % fidelity was demonstrated, we present a theoretical study of the possible phases that can appear in this system. Using the Gutzwiller ansatz for the three d band orbitals we map the boundaries of the Mott insulating phases. For not too large occupation, two of the orbitals are predominantly occupied, while the third, of a slightly higher energy, remains almost unpopulated. In this regime, in the superfluid phase we find the formation of a vortex lattice, where the vortices come in vortex/anti-vortex pairs with two pairs locked to every site. Due to the orientation of the vortices time-reversal symmetry is spontaneously broken. This state also breaks a discrete {{{Z}}2}-symmetry. We further derive an effective spin-1/2 model that describe the relevant physics of the lowest Mott-phase with unit filling. We argue that the corresponding two dimensional phase diagram should be rich with several different phases. We also explain how to generate anti-symmetric spin interactions that can give rise to novel effects like spin canting.
Squeezing out the entropy of fermions in optical lattices
Ho, Tin-Lun; Zhou, Qi
2009-01-01
At present, there is considerable interest in using atomic fermions in optical lattices to emulate the mathematical models that have been used to study strongly correlated electronic systems. Some of these models, such as the 2-dimensional fermion Hubbard model, are notoriously difficult to solve, and their key properties remain controversial despite decades of studies. It is hoped that the emulation experiments will shed light on some of these long-standing problems. A successful emulation, however, requires reaching temperatures as low as 10−12 K and beyond, with entropy per particle far lower than what can be achieved today. Achieving such low-entropy states is an essential step and a grand challenge of the whole emulation enterprise. In this article, we point out a method to literally squeeze the entropy out from a Fermi gas into a surrounding Bose–Einstein condensed gas, which acts as a heat reservoir. This method allows one to reduce the entropy per particle of a lattice Fermi gas to a few percent of the lowest value obtainable today. PMID:19365065
Measuring Z2 topological invariants in optical lattices using interferometry
NASA Astrophysics Data System (ADS)
Grusdt, F.; Abanin, D.; Demler, E.
2014-04-01
We propose an interferometric method to measure Z2 topological invariants of time-reversal invariant topological insulators realized with optical lattices in two and three dimensions. We suggest two schemes which both rely on a combination of Bloch oscillations with Ramsey interferometry and can be implemented using standard tools of atomic physics. In contrast to topological Zak phase and Chern number, defined for individual one-dimensional and two-dimensional Bloch bands, the formulation of the Z2 invariant involves at least two Bloch bands related by time-reversal symmetry which one must keep track of in measurements. In one of our schemes this can be achieved by the measurement of Wilson loops, which are non-Abelian generalizations of Zak phases. The winding of their eigenvalues is related to the Z2 invariant. We thereby demonstrate that Wilson loops are not just theoretical concepts but can be measured experimentally. For the second scheme we introduce a generalization of time-reversal polarization which is continuous throughout the Brillouin zone. We show that its winding over half the Brillouin zone yields the Z2 invariant. To measure this winding, our protocol only requires Bloch oscillations within a single band, supplemented by coherent transitions to a second band which can be realized by lattice shaking.
Pressure tuning the lattice and optical response of silver sulfide
NASA Astrophysics Data System (ADS)
Zhao, Zhao; Wei, Hua; Mao, Wendy L.
2016-06-01
Binary transition metal chalcogenides have attracted increasing attention for their unique structural and electronic properties. High pressure is a powerful tool for tuning the lattice and electronic structure of transition metal chalcogenides away from their pristine states. In this work, we systematically studied the in situ structural and optical behavior of silver sulfide (Ag2S) under pressure by synchrotron X-ray diffraction and infrared spectroscopy measurements in a diamond anvil cell. Upon compression, Ag2S undergoes structural symmetrization accompanied by a series of structural transitions while the crystallographic inequivalence of the two Ag sites is maintained. Electronically, pressure effectively tunes the ambient semiconducting Ag2S into a metal at ˜22 GPa. Drude model analysis shows that the optical conductivity evolves significantly, reaching the highest value of 100 Ω-1 cm-1 at ˜40 GPa. Our results highlight the structural and electronic tunability of silver chalcogenides as a function of pressure and suggest the potential of Ag2S as a platform for developing optical and opto-electronic applications.
Experimental realization of an optical second with strontium lattice clocks.
Le Targat, R; Lorini, L; Le Coq, Y; Zawada, M; Guéna, J; Abgrall, M; Gurov, M; Rosenbusch, P; Rovera, D G; Nagórny, B; Gartman, R; Westergaard, P G; Tobar, M E; Lours, M; Santarelli, G; Clairon, A; Bize, S; Laurent, P; Lemonde, P; Lodewyck, J
2013-01-01
Progress in realizing the SI second had multiple technological impacts and enabled further constraint of theoretical models in fundamental physics. Caesium microwave fountains, realizing best the second according to its current definition with a relative uncertainty of 2-4 × 10(-16), have already been overtaken by atomic clocks referenced to an optical transition, which are both more stable and more accurate. Here we present an important step in the direction of a possible new definition of the second. Our system of five clocks connects with an unprecedented consistency the optical and the microwave worlds. For the first time, two state-of-the-art strontium optical lattice clocks are proven to agree within their accuracy budget, with a total uncertainty of 1.5 × 10(-16). Their comparison with three independent caesium fountains shows a degree of accuracy now only limited by the best realizations of the microwave-defined second, at the level of 3.1 × 10(-16). PMID:23839206
Quantum states of p-band bosons in optical lattices
Collin, A.; Larson, J.; Martikainen, J.-P.
2010-02-15
We study a gas of repulsively interacting bosons in the first excited band of an optical lattice. We explore this p-band physics both within the framework of a standard mean-field theory as well as with the more accurate generalized Gutzwiller ansatz. We find the phase diagrams for two- and three-dimensional systems and characterize the first Mott-states which typically possess an integer or half-integer vortex structure. Furthermore, we find that even though the p-band model has strongly anisotropic kinetic energies and interflavor interaction terms are missing in the lowest band theory, the mean-field theory becomes useful quite rapidly once the transition from the Mott insulator to the superfluid is crossed.
Simulating the Wess-Zumino Supersymmetry Model in Optical Lattices
Yu Yue; Yang Kun
2010-10-08
We study a cold atom-molecule mixture in two-dimensional optical lattices. We show that, by fine-tuning the atomic and molecular interactions, the Wess-Zumino supersymmetry (SUSY) model in 2+1 dimensions emerges in the low-energy limit and can be simulated in such mixtures. At zero temperature, SUSY is not spontaneously broken, which implies identical relativistic dispersions of the atom and its superpartner, a bosonic diatom molecule. This defining signature of SUSY can be probed by single-particle spectroscopies. Thermal breaking of SUSY at a finite temperature is accompanied by a thermal Goldstone fermion, i.e., phonino excitation. This and other signatures of broken SUSY can also be probed experimentally.
Localization of collisionally inhomogeneous condensates in a bichromatic optical lattice
NASA Astrophysics Data System (ADS)
Cheng, Yongshan; Adhikari, S. K.
2011-02-01
By direct numerical simulation and variational solution of the Gross-Pitaevskii equation, we studied the stationary and dynamic characteristics of a cigar-shaped, localized, collisionally inhomogeneous Bose-Einstein condensate trapped in a one-dimensional bichromatic quasiperiodic optical-lattice potential, as used in a recent experiment on the localization of a Bose-Einstein condensate [Roati , Nature (London)NATUAS0028-083610.1038/nature07071 453, 895 (2008)]. The effective potential characterizing the spatially modulated nonlinearity is obtained. It is found that the collisional inhomogeneity has influence not only on the central region but also on the tail of the Bose-Einstein condensate. The influence depends on the sign and value of the spatially modulated nonlinearity coefficient. We also demonstrate the stability of the stationary localized state by performing a standard linear stability analysis. Where possible, the numerical results are shown to be in good agreement with the variational results.
Anyon Hubbard Model in One-Dimensional Optical Lattices.
Greschner, Sebastian; Santos, Luis
2015-07-31
Raman-assisted hopping may be used to realize the anyon Hubbard model in one-dimensional optical lattices. We propose a feasible scenario that significantly improves the proposal of T. Keilmann et al. [Nat. Commun. 2, 361 (2011)], allowing as well for an exact realization of the two-body hard-core constraint, and for controllable effective interactions without the need of Feshbach resonances. We show that the combination of anyonic statistics and two-body hard-core constraint leads to a rich ground-state physics, including Mott insulators with attractive interactions, pair superfluids, dimer phases, and multicritical points. Moreover, the anyonic statistics results in a novel two-component superfluid of holon and doublon dimers, characterized by a large but finite compressibility and a multipeaked momentum distribution, which may be easily revealed experimentally. PMID:26274417
Quantum phases of quadrupolar Fermi gases in optical lattices.
Bhongale, S G; Mathey, L; Zhao, Erhai; Yelin, S F; Lemeshko, Mikhail
2013-04-12
We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities. PMID:25167282
Ultraviolet laser spectroscopy of neutral mercury in a one-dimensional optical lattice
Mejri, S.; McFerran, J. J.; Yi, L.; Le Coq, Y.; Bize, S.
2011-09-15
We present details on the ultraviolet lattice spectroscopy of the (6s{sup 2}) {sup 1}S{sub 0}{r_reversible} (6s6p) {sup 3}P{sub 0} transition in neutral mercury, specifically {sup 199}Hg. Mercury atoms are loaded into a one-dimensional vertically aligned optical lattice from a magneto-optical trap with an rms temperature of {approx}60 {mu}K. We describe aspects of the magneto-optical trapping, the lattice cavity design, and the techniques employed to trap and detect mercury in an optical lattice. The clock-line frequency dependence on lattice depth is measured at a range of lattice wavelengths. We confirm the magic wavelength to be 362.51(0.16) nm. Further observations to those reported by Yi et al.[Phys. Rev. Lett. 106, 073005 (2011)] are presented regarding the laser excitation of a Wannier-Stark ladder of states.
Non-standard Hubbard models in optical lattices: a review
NASA Astrophysics Data System (ADS)
Dutta, Omjyoti; Gajda, Mariusz; Hauke, Philipp; Lewenstein, Maciej; Lühmann, Dirk-Sören; Malomed, Boris A.; Sowiński, Tomasz; Zakrzewski, Jakub
2015-06-01
Originally, the Hubbard model was derived for describing the behavior of strongly correlated electrons in solids. However, for over a decade now, variations of it have also routinely been implemented with ultracold atoms in optical lattices, allowing their study in a clean, essentially defect-free environment. Here, we review some of the vast literature on this subject, with a focus on more recent non-standard forms of the Hubbard model. After giving an introduction to standard (fermionic and bosonic) Hubbard models, we discuss briefly common models for mixtures, as well as the so-called extended Bose-Hubbard models, that include interactions between neighboring sites, next-neighbor sites, and so on. The main part of the review discusses the importance of additional terms appearing when refining the tight-binding approximation for the original physical Hamiltonian. Even when restricting the models to the lowest Bloch band is justified, the standard approach neglects the density-induced tunneling (which has the same origin as the usual on-site interaction). The importance of these contributions is discussed for both contact and dipolar interactions. For sufficiently strong interactions, the effects related to higher Bloch bands also become important even for deep optical lattices. Different approaches that aim at incorporating these effects, mainly via dressing the basis, Wannier functions with interactions, leading to effective, density-dependent Hubbard-type models, are reviewed. We discuss also examples of Hubbard-like models that explicitly involve higher p orbitals, as well as models that dynamically couple spin and orbital degrees of freedom. Finally, we review mean-field nonlinear Schrödinger models of the Salerno type that share with the non-standard Hubbard models nonlinear coupling between the adjacent sites. In that part, discrete solitons are the main subject of consideration. We conclude by listing some open problems, to be addressed in the future.
Non-standard Hubbard models in optical lattices: a review.
Dutta, Omjyoti; Gajda, Mariusz; Hauke, Philipp; Lewenstein, Maciej; Lühmann, Dirk-Sören; Malomed, Boris A; Sowiński, Tomasz; Zakrzewski, Jakub
2015-06-01
Originally, the Hubbard model was derived for describing the behavior of strongly correlated electrons in solids. However, for over a decade now, variations of it have also routinely been implemented with ultracold atoms in optical lattices, allowing their study in a clean, essentially defect-free environment. Here, we review some of the vast literature on this subject, with a focus on more recent non-standard forms of the Hubbard model. After giving an introduction to standard (fermionic and bosonic) Hubbard models, we discuss briefly common models for mixtures, as well as the so-called extended Bose-Hubbard models, that include interactions between neighboring sites, next-neighbor sites, and so on. The main part of the review discusses the importance of additional terms appearing when refining the tight-binding approximation for the original physical Hamiltonian. Even when restricting the models to the lowest Bloch band is justified, the standard approach neglects the density-induced tunneling (which has the same origin as the usual on-site interaction). The importance of these contributions is discussed for both contact and dipolar interactions. For sufficiently strong interactions, the effects related to higher Bloch bands also become important even for deep optical lattices. Different approaches that aim at incorporating these effects, mainly via dressing the basis, Wannier functions with interactions, leading to effective, density-dependent Hubbard-type models, are reviewed. We discuss also examples of Hubbard-like models that explicitly involve higher p orbitals, as well as models that dynamically couple spin and orbital degrees of freedom. Finally, we review mean-field nonlinear Schrödinger models of the Salerno type that share with the non-standard Hubbard models nonlinear coupling between the adjacent sites. In that part, discrete solitons are the main subject of consideration. We conclude by listing some open problems, to be addressed in the future
Photoassociation experiments on ultracold and quantum gases in optical lattices
NASA Astrophysics Data System (ADS)
Ryu, Changhyun
This thesis describes the results of several experiments that studied the photoassociation of an ultracold atomic Rb gas. In the first experiment, we produced ultracold diatomic molecules from an atomic gas via single-color photoassociation. The molecules were detected with resonance-enhanced multiphoton ionization. Trapping of these molecules in a quadrupole magnetic trap, with lifetimes up to 20 seconds, was also demonstrated. In addition, the rate constant for inelastic collisions between the trapped molecules and atoms was determined from measurements of the atomic density dependence of the decay rate of the trapped molecules. In another experiment, stimulated Raman photoassociation of Rb atoms in a Mott insulator state was studied. A Bose-Einstein condensate (BEC) of 87Rb atoms was loaded into a three-dimensional optical lattice formed by the interference pattern of three orthogonal standing wave laser fields. This system constitutes a very good realization of the Bose-Hubbard model; which predicts a quantum phase transition between a superfluid state and a Mott insulator state at a particular lattice height. A time-of-flight imaging method was used to study the state of the atomic gas, and the quantum phase transition was observed at the predicted lattice height. The signature of the phase transition was the disappearance and reappearance of peaks in the image that arose from the interference of atoms originating from different lattice sites. Two coherent laser fields were applied to the gas in its Mott insulating state, and tuned close to a Raman photoassociation resonance, and this resulted in an observable loss of atoms due to the formation of molecules. This transition exhibited a double-peaked spectrum, with one of the peaks arising from photoassociation of atoms in sites containing only two atoms, and the other from sites containing three atoms. Also, the loss of atoms vs. the duration of the Raman photoassociation period was studied, with the lasers
Superfluidity of ultracold atomic gases of Fermi-Fermi mixtures on an optical lattice
NASA Astrophysics Data System (ADS)
Wang, Jibiao; Chen, Qijin
Superfluidity of ultracold atomic gases of Fermi-Fermi mixtures has been under active investigation recently. Experimentally, mixtures of 6Li-40K, 171Yb-173Yband6Li-173Yb, for example, have been prepared and cooled down to the quantum degeneracy regime, making the superfluid phase accessible in the near future. In this talk, we will address the superfluidity of ultracold Fermi-Fermi mixtures on 1D through 3D optical lattices, with varying mass and population imbalances and different densities, as they undergo BCS-BEC crossover, within a pairing fluctuation theory which includes self-consistently the important pseudogap effects at finite temperatures. We will present various phase diagrams and show the dramatic combined effects of mass and population imbalances and lattice periodicity. Implications for future experiment will be discussed. References: [1]Q. J. Chen, I. Kosztin, B. Janko, and K. Levin, Phys. Rev. B 59, 7083 (1999). [2] C. -C. Chien, Y. He, Q. J. Chen, and K. Levin, Phys. Rev. A 77, 011601(R) (2008). [3] C. -C. Chien, Q. J. Chen, and K. Levin, Phys. Rev. A 78, 043612 (2008). [4] Q. J. Chen, Phys. Rev. A 86, 023610 (2012). Work supported by NSF of China and the National Basic Research Program of China.
NASA Astrophysics Data System (ADS)
Singh, Bipin K.; Thapa, Khem B.; Pandey, Praveen C.
2013-06-01
A theoretical study of optical reflectance and reflection bands of 1-D photonic quasi-crystals (Fibonacci type arrangement) composed of exponentially graded material is presented. The proposed structures consist of two different layers, one of them is of constant refractive index (L) and the other one is of exponentially graded refractive index (S) dielectric materials. Four different generations (2nd, 3rd, 4th and 5th) of the Fibonacci sequence for 10 periods in one dimension (1-D) are considered and compared in view of their optical reflectance and bandgaps for both TE and TM polarisations. Also, we proposed some heterostructures made by the combination of different Fibonacci generations and their periods to obtain suitable omnidirectional reflection band. We used the transfer matrix method (TMM) to obtain the reflectance, bandgaps and omnidirectional reflectional bandgaps (ODR) of such structures in near infrared spectrum (800-2200 nm) at different angles of incidence. We show that ODR exists in these types of structures. The number of ODRs and total bandgap depend on the Fibonacci generations. Extraordinary ODR bandgaps are obtained in the case of heterostructures formed by the combination of different generations of the Fibonacci sequence. The ODR for these structures is similar to the ODR of photonic crystals containing left-handed materials. This work would be useful to study the Fibonacci type photonic crystals having graded index materials and also it will open new window to design several photonic crystal devices like sensors, reflectors, etc. in the infrared region.
Orbit, optics and chromaticity correction for PS2 negative momentum compaction lattices
Papaphilippou,Y.; Barranco, J.; Bartmann, W.; Benedikt, M.; Carli, C.; de Maria, R.; Peggs, S.; Trbojevic, D.
2009-05-04
The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattice of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the lattice is finally evaluated.
CP(N - 1) quantum field theories with alkaline-earth atoms in optical lattices
NASA Astrophysics Data System (ADS)
Laflamme, C.; Evans, W.; Dalmonte, M.; Gerber, U.; Mejía-Díaz, H.; Bietenholz, W.; Wiese, U.-J.; Zoller, P.
2016-07-01
We propose a cold atom implementation to attain the continuum limit of (1 + 1) -d CP(N - 1) quantum field theories. These theories share important features with (3 + 1) -d QCD, such as asymptotic freedom and θ-vacua. Moreover, their continuum limit can be accessed via the mechanism of dimensional reduction. In our scheme, the CP(N - 1) degrees of freedom emerge at low energies from a ladder system of SU(N) quantum spins, where the N spin states are embodied by the nuclear Zeeman states of alkaline-earth atoms, trapped in an optical lattice. Based on Monte Carlo results, we establish that the continuum limit can be demonstrated by an atomic quantum simulation by employing the feature of asymptotic freedom. We discuss a protocol for the adiabatic preparation of the ground state of the system, the real-time evolution of a false θ-vacuum state after a quench, and we propose experiments to unravel the phase diagram at non-zero density.
Hu Ying; Liang Zhaoxin; Hu Bambi
2010-05-15
We investigate the combined effects of weak disorder and a two-dimensional (2D) optical lattice on the collective excitations of a harmonically trapped Bose-Einstein condensate (BEC) at zero temperature. Accordingly, we generalize the hydrodynamic equations of superfluid for a weakly interacting Bose gas in a 2D optical lattice to include the effects of weak disorder. Our analytical results for the collective frequencies beyond the mean-field approximation reveal the peculiar role of disorder, interplaying with the 2D optical lattice and interatomic interaction, on elementary excitations along the 3D to 1D crossover. In particular, consequences of disorder on the phonon propagation and surface modes are analyzed in detail. The experimental scenario is also proposed.
Towards quantum many-body physics with Sr in optical lattices
NASA Astrophysics Data System (ADS)
Blatt, Sebastian; Jansa, Nejc; Escudero, Rodrigo G.; Heinz, André; Park, Annie Jihyun; Snigirev, Stepan; Dalibard, Jean; Bloch, Immanuel
2016-05-01
Within the last decade, fermionic alkaline earth atoms in optical lattices have become a platform for precision measurements, culminating in the realization of an atomic clock with the currently highest stability and accuracy at the 2 ×10-18 level. In the meantime, quantum degenerate gases of all bosonic and fermionic isotopes of Sr have been realized. With the extension of the quantum gas microscopy technique to fermionic alkali metal atoms, experiments with quantum degenerate gases in optical lattices have taken another step towards full control over the internal and external degrees of freedom of fermions in optical lattices. Here, we report on the construction of a new experiment with quantum degenerate gases of Sr in optical lattices. Our experiment aims to combine the high spatial control over the atomic degrees of freedom from quantum gas microscopy with the precision control over the internal degrees of freedom enabled by optical lattice clock techniques.