Virtual Journal of Atomic Quantum Fluids

Optimized sympathetic cooling of atomic mixtures via fast adiabatic strategies

Stephen Choi, Roberto Onofrio, and Bala Sundaram
We discuss fast frictionless cooling techniques in the framework of sympathetic cooling of cold atomic mixtures. It is argued that optimal cooling of an atomic speciesin which the deepest quantum degeneracy regime is achievedmay be obtained by means of sympathetic cooling with another species whose ... [Phys. Rev. A 84, 051601 ] published .

Doppler- and recoil-free laser excitation of Rydberg states via three-photon transitions

I. I. Ryabtsev, I. I. Beterov, D. B. Tretyakov, V. M. Entin, and E. A. Yakshina
Three-photon laser excitation of Rydberg states by three different laser beams can be arranged in a starlike geometry that simultaneously eliminates the recoil effect and Doppler broadening. Our analytical and numerical calculations for a particular laser excitation scheme 5S-->5P-->6S-->nP in Rb at ... [Phys. Rev. A 84, 053409 ] published .

Addendum to s-wave scattering for deep potentials with attractive tails falling off faster than 1/r

Tim-Oliver Muller, Alexander Kaiser, and Harald Friedrich
In a recent work, we derived a formula for the elastic s-wave phase shifts for deep potentials with attractive tails vanishing faster than 1/r asymptotically [Phys. Rev. A 84, 032701 (2011)]. As an addendum to that work, we reformulate its key result, i.e., the formula for the scattering phase shift ... [Phys. Rev. A 84, 054702 ] published .

Quasi-one-dimensional scattering in a discrete model

Manuel Valiente and Klaus Molmer
We study quasi-one-dimensional scattering of one and two particles with short-range interactions on a discrete lattice model in two dimensions. One of the directions is tightly confined by an arbitrary trapping potential. We obtain the collisional properties of these systems both at finite and zero ... [Phys. Rev. A 84, 053628 ] published .

Scattering lengths of calcium and barium isotopes

U. Dammalapati, L. Willmann, and S. Knoop
We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca d ... [Phys. Rev. A 84, 054703 ] published .

Numerical study of three-body recombination for systems with many bound states

Jia Wang, J. P. D'Incao, and Chris H. Greene
Three-body recombination processes are treated numerically for a system of three identical bosons. The two-body model potentials utilized support many bound states, a major leap in complexity that produces an intricate structure of sharp nonadiabatic avoided crossings in the three-body hyperradial a ... [Phys. Rev. A 84, 052721 ] published .

Stable heteronuclear few-atom bound states in mixed dimensions

Tao Yin, Peng Zhang, and Wei Zhang
We study few-body problems in mixed dimensions where two or three heavy atoms are trapped individually in parallel one-dimensional tubes or two-dimensional disks and a single light atom travels freely in three dimensions. Using the Born-Oppenheimer approximation, we find three- and four-body bound s ... [Phys. Rev. A 84, 052727 ] published .

Scattering and bound states in two-dimensional anisotropic potentials

Matthias Rosenkranz and Weizhu Bao
We propose a framework for calculating scattering and bound-state properties in anisotropic two-dimensional potentials. Using our method, we derive systematic approximations of partial wave phase shifts and binding energies. Moreover, the method is suitable for efficient numerical computations. We c ... [Phys. Rev. A 84, 050701 ] published .

Five- and Six-Body Resonances Tied to an Efimov Trimer

Javier von Stecher
We explore the properties of weakly bound bosonic states in the strongly interacting regime. Combining a correlated-Gaussian basis set expansion with a complex-scaling method, we extract the energies and structural properties of bosonic cluster states with N<=6 for different two-body potentials. The ... [Phys. Rev. Lett. 107, 200402 ] published .

Dipole-dipole interaction between rubidium Rydberg atoms

Emily Altiere, Donald P. Fahey, Michael W. Noel, Rachel J. Smith, and Thomas J. Carroll
Ultracold Rydberg atoms in a static electric field can exchange energy via the dipole-dipole interaction. The Stark effect shifts the energy levels of the atoms which tunes the energy exchange into resonance at specific values of the electric field (Forster resonances). We excite rubidium atoms to R ... [Phys. Rev. A 84, 053431 ] published .

Entanglement-based perturbation theory for highly anisotropic Bose-Einstein condensates

Alexandre B. Tacla and Carlton M. Caves
We investigate the emergence of three-dimensional behavior in a reduced-dimension Bose-Einstein condensate trapped by a highly anisotropic potential. We handle the problem analytically by performing a perturbative Schmidt decomposition of the condensate wave function between the tightly confined (tr ... [Phys. Rev. A 84, 053606 ] published .

Scalable Neutral Atom Quantum Computer with Interaction on Demand: Proposal for Selective Application of Two-Qubit Gate

Elham Hosseini Lapasar, Kenichi Kasamatsu, Yasushi Kondo, Mikio Nakahara, and Tetsuo Ohmi
We propose a scalable neutral atom quantum computer with an on-demand interaction through a selective two-qubit gate operation. Atoms are trapped by a lattice of near field Fresnel diffraction lights so that each trap captures a single atom. One-qubit gate operation is implemented by a gate control ... [J. Phys. Soc. Jpn. 80, 114003 (2011)] published Thu Nov 17, 2011.

Diode for Bose-Einstein condensates

J. Larson
Given a quantum state at some instant of time t, the underlying system Hamiltonian can not only predict how the state will evolve, but also the history of the state prior to t. Thereby, in order to have a directed motion, like in a diode, some sort of irreversibility must be considered. For the atom ... [EPL 96, 50004 (2011)] published Tue Nov 29, 2011.

All-optical transistor based on a cavity optomechanical system with a Bose-Einstein condensate

Bin Chen, Cheng Jiang, Jin-Jin Li, and Ka-Di Zhu
We propose a scheme of an all-optical transistor based on a coupled Bose-Einstein condensate cavity system. The calculated results show that, in such an optomechanical system, the transmission of the probe beam is strongly dependent on the optical pump power. Therefore, the optical pump field can se ... [Phys. Rev. A 84, 055802 ] published .

Cold-collision-shift cancellation and inelastic scattering in a Yb optical lattice clock

A. D. Ludlow, N. D. Lemke, J. A. Sherman, C. W. Oates, G. Quemener et al.
Recently, p-wave cold collisions were shown to dominate the density-dependent shift of the clock transition frequency in a Yb optical lattice clock. Here we demonstrate that by operating such a system at the proper excitation fraction, the cold-collision shift is canceled below the 5 x 10 fractional ... [Phys. Rev. A 84, 052724 ] published .

Inelastic collisions and density-dependent excitation suppression in a Sr optical lattice clock

M. Bishof, M. J. Martin, M. D. Swallows, C. Benko, Y. Lin et al.
We observe two-body loss of P Sr atoms trapped in a one-dimensional optical lattice. We measure loss rate coefficients for atomic samples between 1 and 6 [mu]K that are prepared either in a single nuclear-spin sublevel or with equal populations in two sublevels. The measured temperature and nuclea ... [Phys. Rev. A 84, 052716 ] published .

Twin Matter Waves for Interferometry Beyond the Classical Limit

B. Lcke, M. Scherer, J. Kruse, L. Pezz, F. Deuretzbacher et al.
Interferometers with atomic ensembles are an integral part of modern precision metrology. However, these interferometers are fundamentally restricted by the shot noise limit, which can only be overcome by creating quantum entanglement among the atoms. We used spin dynamics in Bose-Einstein condensat ... [Science 334, 773 (2011)] published Thu Nov 10, 2011.

Realization of an Optomechanical Interface Between Ultracold Atoms and a Membrane

Stephan Camerer, Maria Korppi, Andreas Jockel, David Hunger, Theodor W. Hansch et al.
We have realized a hybrid optomechanical system by coupling ultracold atoms to a micromechanical membrane. The atoms are trapped in an optical lattice, which is formed by retroreflection of a laser beam from the membrane surface. In this setup, the lattice laser light mediates an optomechanical coup ... [Phys. Rev. Lett. 107, 223001 ] published .

Realization of a Distributed Bragg Reflector for Propagating Guided Matter Waves

C. M. Fabre, P. Cheiney, G. L. Gattobigio, F. Vermersch, S. Faure et al.
We report on the experimental study of a Bragg reflector for guided, propagating Bose-Einstein condensates. A one-dimensional attractive optical lattice of finite length created by red-detuned laser beams selectively reflects some velocity components of the incident matter wave packet. We find quant ... [Phys. Rev. Lett. 107, 230401 ] published .

Efficient thermodynamic description of multicomponent one-dimensional Bose gases

Andreas Klumper and Ovidiu I. Patu
We present a method of obtaining nonlinear integral equations characterizing the thermodynamics of one-dimensional multicomponent gases interacting via a delta-function potential. In the case of the repulsive two-component Bose gas we obtain a simple system of two nonlinear integral equations, allow ... [Phys. Rev. A 84, 051604 ] published .

Pairing, ferromagnetism, and condensation of a normal spin-1 Bose gas

Stefan S. Natu and Erich J. Mueller
We find the conditions under which the normal state of a spin-1 Bose gas is unstable toward condensation, ferromagnetism, liquid crystalline-like nematicity, and Bardeen-Cooper-Schrieffer-like pairing. When the spin-dependent interactions are much weaker than the density-density interaction there is ... [Phys. Rev. A 84, 053625 ] published .

Symmetry classification of spinor Bose-Einstein condensates

Yuki Kawaguchi and Masahito Ueda
We propose a method for systematically finding ground states of spinor Bose-Einstein condensates by utilizing the symmetry properties of the system. By this method, we can find not only an inert state, whose symmetry is maximal in the manifold under consideration, but also a noninert state, which ha ... [Phys. Rev. A 84, 053616 ] published .

Rabi Flopping Induces Spatial Demixing Dynamics

E. Nicklas, H. Strobel, T. Zibold, C. Gross, B. A. Malomed et al.
We experimentally investigate the mixing and demixing dynamics of Bose-Einstein condensates in the presence of a linear coupling between two internal states. The observed amplitude reduction of the Rabi oscillations can be understood as a result of demixing dynamics of dressed states as experimental ... [Phys. Rev. Lett. 107, 193001 ] published .

Quantum Phase Transition in an Antiferromagnetic Spinor Bose-Einstein Condensate

E. M. Bookjans, A. Vinit, and C. Raman
We have experimentally observed the dynamics of an antiferromagnetic sodium Bose-Einstein condensate quenched through a quantum phase transition. Using an off-resonant microwave field coupling the F=1 and F=2 atomic hyperfine levels, we rapidly switched the quadratic energy shift q from positive to ... [Phys. Rev. Lett. 107, 195306 ] published .

Strong Quantum Spin Correlations Observed in Atomic Spin Mixing

Eva M. Bookjans, Christopher D. Hamley, and Michael S. Chapman
We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard quantum limit for the corresponding coherent spin states. T ... [Phys. Rev. Lett. 107, 210406 ] published .

Phase Separation and Pattern Formation in a Binary Bose-Einstein Condensate

Jacopo Sabbatini, Wojciech H. Zurek, and Matthew J. Davis
The miscibility-immiscibility phase transition in binary Bose-Einstein condensates (BECs) can be controlled by a coupling between the two components. Here we propose a new scheme that uses coupling-induced pattern formation to test the Kibble-Zurek mechanism (KZM) of topological-defect formation in ... [Phys. Rev. Lett. 107, 230402 ] published .

Optically induced conical intersections in traps for ultracold atoms and molecules

Alisdair O. G. Wallis and Jeremy M. Hutson
We show that conical intersections can be created in laboratory coordinates by dressing a parabolic trap for ultracold atoms or molecules with a combination of optical and static magnetic fields. The resulting ring trap can support single-particle states with half-integer rotational quantization and ... [Phys. Rev. A 84, 051402 ] published .

Nucleation of spontaneous vortices in trapped Fermi gases undergoing a BCS-BEC crossover

A. Glatz, H. L. L. Roberts, I. S. Aranson, and K. Levin
We study the spontaneous formation of vortices during the superfluid condensation in a trapped fermionic gas subjected to a rapid thermal quench via evaporative cooling. Our work is based on the numerical solution of the time-dependent crossover Ginzburg-Landau equation coupled to the heat diffusion ... [Phys. Rev. B 84, 180501 ] published .

Modulational instability and solitons in nonlocal media with competing nonlinearities

B. K. Esbensen, A. Wlotzka, M. Bache, O. Bang, and W. Krolikowski
We investigate analytically and numerically propagation and spatial localization of light in nonlocal media with competing nonlinearities. In particular, we discuss conditions for the modulational instability of plane waves and formation of spatial solitons. We show that the competing focusing and d ... [Phys. Rev. A 84, 053854 ] published .

Nonadiabatic creation of macroscopic superpositions with strongly correlated one-dimensional bosons in a ring trap

C. Schenke, A. Minguzzi, and F. W. J. Hekking
We consider a strongly interacting quasi-one-dimensional Bose gas on a tight ring trap subjected to a localized barrier potential. We explore the possibility of forming a macroscopic superposition of a rotating and a nonrotating state under nonequilibrium conditions, achieved by a sudden quench of t ... [Phys. Rev. A 84, 053636 ] published .

Matter-wave solitons in heteronuclear atomic Bose-Einstein condensates with synchronously controllable interactions and potentials

Cai-Ying Ding, Xiao-Fei Zhang, Dun Zhao, Hong-Gang Luo, and W. M. Liu
We investigate exact matter-wave soliton pairs of two-component heteronuclear atomic Bose-Einstein condensates with tunable interactions and harmonic potentials by using a combination of the homogeneous balance principle and the F-expansion technique. Our results show that exact matter-wave soliton ... [Phys. Rev. A 84, 053631 ] published .

Multiple dark-bright solitons in atomic Bose-Einstein condensates

D. Yan, J. J. Chang, C. Hamner, P. G. Kevrekidis, P. Engels et al.
Motivated by recent experimental results, we present a systematic theoretical analysis of dark-bright-soliton interactions and multiple-dark-bright-soliton complexes in atomic two-component Bose-Einstein condensates. We study analytically the interactions between two dark-bright solitons in a homoge ... [Phys. Rev. A 84, 053630 ] published .

Statics and dynamics of atomic dark-bright solitons in the presence of impurities

V. Achilleos, P. G. Kevrekidis, V. M. Rothos, and D. J. Frantzeskakis
Adopting a mean-field description for a two-component atomic Bose-Einstein condensate, we study the statics and dynamics of dark-bright solitons in the presence of localized impurities. We use adiabatic perturbation theory to derive an equation of motion for the dark-bright soliton center. We show t ... [Phys. Rev. A 84, 053626 ] published .

Layered quantum Hall insulators with ultracold atoms

A. Zamora, G. Szirmai, and M. Lewenstein
We consider a generalization of the two-dimensional (2D) quantum Hall insulator to a noncompact, non-Abelian gauge group, the Heisenberg-Weyl group. We show that this kind of insulator is actually a layered three-dimensional (3D) insulator with nontrivial topology. We further show that nontrivial co ... [Phys. Rev. A 84, 053620 ] published .

Symmetric and asymmetric solitons trapped in H-shaped potentials

Nguyen Viet Hung, Marek Trippenbach, and Boris A. Malomed
We report results of numerical and analytical studies of the spontaneous symmetry breaking in solitons, both two- and one-dimensional (2D and 1D), which are trapped in H-shaped potential profiles built of two parallel potential troughs linked by a narrow rung in the transverse direction. This system ... [Phys. Rev. A 84, 053618 ] published .

Rotating superfluids in anharmonic traps: From vortex lattices to giant vortices

Michele Correggi, Florian Pinsker, Nicolas Rougerie, and Jakob Yngvason
We study a superfluid in a rotating anharmonic trap and explicate a rigorous proof of a transition from a vortex lattice to a giant vortex state as the rotation is increased beyond a limiting speed determined by the interaction strength. The transition is characterized by the disappearance of the vo ... [Phys. Rev. A 84, 053614 ] published .

Quantized vortices in a rotating Bose-Einstein condensate with spatiotemporally modulated interaction

Deng-Shan Wang, Shu-Wei Song, Bo Xiong, and W. M. Liu
We present theoretical analysis and numerical studies of the quantized vortices in a rotating Bose-Einstein condensate with spatiotemporally modulated interaction in harmonic and anharmonic potentials, respectively. The exact quantized vortex and giant vortex solutions are constructed explicitly by ... [Phys. Rev. A 84, 053607 ] published .

Superposition states of ultracold bosons in rotating rings with a realistic potential barrier

Andreas Nunnenkamp, Ana Maria Rey, and Keith Burnett
In a recent paper [Phys. Rev. A 82, 063623 (2010)] Hallwood et al. argued that it is feasible to create large superposition states with strongly interacting bosons in rotating rings. Here we investigate in detail how the superposition states in rotating-ring lattices depend on interaction strength a ... [Phys. Rev. A 84, 053604 ] published .

Dynamics of a tight-binding ring threaded by time-periodic magnetic flux

W. H. Hu and Z. Song
We analytically study the effects of periodically alternating magnetic fields on the dynamics of a tight-binding ring. It is shown that an arbitrary quantum state can be frozen coherently at will by the very frequent square-wave field as well as the monochromatic-wave field when the corresponding op ... [Phys. Rev. A 84, 052310 ] published .

Coherence vortices in one spatial dimension

Coherence vortices are screw-type topological defects in the phase of Glauber's two-point degree of quantum coherence, associated with pairs of spatial points at which an ensemble-averaged stochastic quantum field is uncorrelated. Coherence vortices may be present in systems whose dimensionality is ... [Phys. Rev. A 84, 052104 ] published .

Strongly correlated states of a small cold-atom cloud from geometric gauge fields

B. Julia-Diaz, D. Dagnino, K. J. Gunter, T. Grass, N. Barberan et al.
Using exact diagonalization for a small system of cold bosonic atoms, we analyze the emergence of strongly correlated states in the presence of an artificial magnetic field. This gauge field is generated by a laser beam that couples two internal atomic states, and it is related to Berry's geometrica ... [Phys. Rev. A 84, 053605 ] published .

Imaging of quantum Hall states in ultracold atomic gases

James S. Douglas and Keith Burnett
We examine off-resonant light scattering from ultracold atoms in the quantum Hall regime. When the light scattering is spin dependent, we show that images formed in the far field can be used to distinguish states of the system. The spatial dependence of the far-field images is determined by the two- ... [Phys. Rev. A 84, 053608 ] published .

Vortex formation of a Bose-Einstein condensate in a rotating deep optical lattice

Akira Kato, Yuki Nakano, Kenichi Kasamatsu, and Tetsuo Matsui
We study the dynamics of vortex nucleation and lattice formation in a BoseEinstein condensate in a rotating square optical lattice by numerical simulations of the GrossPitaevskii equation. Different dynamical regimes of vortex nucleation are found, depending on the depth and period of the optical la ... [Phys. Rev. A 84, 053623 ] published .

Topological liquids and valence cluster states in two-dimensional SU(N) magnets

Michael Hermele and Victor Gurarie
We study the zero-temperature phase diagram of a class of two-dimensional SU(N) antiferromagnets. These models are characterized by having the same type of SU(N) spin placed at each site of the lattice, and share the property that, in general, more than two spins must be combined to form a singlet. ... [Phys. Rev. B 84, 174441 ] published .

Quantum phase transition of ultracold bosons in the presence of a non-Abelian synthetic gauge field

T. Grass, K. Saha, K. Sengupta, and M. Lewenstein
We study the Mott phases and the superfluid-insulator transition of two-component ultracold bosons on a square optical lattice in the presence of a non-Abelian synthetic gauge field, which renders a SU(2)-hopping matrix for the bosons. Using a resummed hopping expansion, we calculate the excitation ... [Phys. Rev. A 84, 053632 ] published .

Trapped fermions in a synthetic non-Abelian gauge field

Sudeep Kumar Ghosh, Jayantha P. Vyasanakere, and Vijay B. Shenoy
On increasing the coupling strength (lambda) of a non-Abelian gauge field that induces a generalized Rashba spin-orbit interaction, the topology of the Fermi surface of a homogeneous gas of noninteracting fermions of density rho~k undergoes a change at a critical value, lambda[approximate]k [Phys. R ... [Phys. Rev. A 84, 053629 ] published .

Adiabatic geometric phase for a Bose-Einstein condensate coupled to a cavity

Sheng-Chang Li, Li-Bin Fu, and Jie Liu
We investigate the geometric phase in a model of a Bose-Einstein condensate coupled to an optical cavity in which both the condensate and the cavity are described with coherent states. When the argument of the atom-cavity coupling term varies in time slowly from zero to 2pi, we calculate the geometr ... [Phys. Rev. A 84, 053610 ] published .

Spin-Orbit Coupled Bose-Einstein Condensate Under Rotation

Xiao-Qiang Xu and Jung Hoon Han
We examine the combined effects of Rashba spin-orbit (SO) coupling and rotation on trapped spinor Bose-Einstein condensates. The nature of single particle states is thoroughly examined in the Landau level basis and is shown to support the formation of a half-quantum vortex. In the presence of weak s ... [Phys. Rev. Lett. 107, 200401 ] published .

BCS-BEC Crossover and Topological Phase Transition in 3D Spin-Orbit Coupled Degenerate Fermi Gases

Ming Gong, Sumanta Tewari, and Chuanwei Zhang
We investigate the BCS-BEC crossover in three-dimensional degenerate Fermi gases in the presence of spin-orbit coupling (SOC) and Zeeman field. We show that the superfluid order parameter destroyed by a large Zeeman field can be restored by the SOC. With increasing strengths of the Zeeman field, the ... [Phys. Rev. Lett. 107, 195303 ] published .

Seeing Topological Order in Time-of-Flight Measurements

E. Alba, X. Fernandez-Gonzalvo, J. Mur-Petit, J. K. Pachos, and J. J. Garcia-Ripoll
In this Letter, we provide a general methodology to directly measure topological order in cold atom systems. As an application, we propose the realization of a characteristic topological model, introduced by Haldane, using optical lattices loaded with fermionic atoms in two internal states. We demon ... [Phys. Rev. Lett. 107, 235301 ] published .

Critical exponents of the disorder-driven superfluid-insulator transition in one-dimensional Bose-Einstein condensates

J. C. C. Cestari, A. Foerster, M. A. Gusmao, and M. Continentino
We investigate the nature of the superfluid-insulator quantum phase transition driven by disorder for noninteracting ultracold atoms on one-dimensional lattices. We consider two different cases: Anderson-type disorder, with local energies randomly distributed, and pseudodisorder due to a potential i ... [Phys. Rev. A 84, 055601 ] published .

Matter-wave localization in a weakly perturbed optical lattice

Yongshan Cheng and S. K. Adhikari
By numerical solution and variational approximation of the Gross-Pitaevskii equation, we studied the localization of a noninteracting and weakly interacting Bose-Einstein condensate in a weakly perturbed optical lattice in one and three dimensions. The perturbation achieved through a weak delocalizi ... [Phys. Rev. A 84, 053634 ] published .

Proposed signature of Anderson localization and correlation-induced delocalization in an N-leg optical lattice

T. A. Sedrakyan, J. P. Kestner, and S. Das Sarma
We propose a realization of the one-dimensional random dimer model and certain N-leg generalizations using cold atoms in an optical lattice. We show that these models exhibit multiple delocalization energies that depend strongly on the symmetry properties of the corresponding Hamiltonian, and we pro ... [Phys. Rev. A 84, 053621 ] published .

Dipolar bosons on an optical lattice ring

Michal Maik, Pierfrancesco Buonsante, Alessandro Vezzani, and Jakub Zakrzewski
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 dipo ... [Phys. Rev. A 84, 053615 ] published .

Atom-atom correlations in time-of-flight imaging of ultracold bosons in optical lattices

T. A. Zaleski and T. K. Kopec
We study the spatial correlations of strongly interacting bosons in a ground state, confined in a two-dimensional square and a three-dimensional cubic lattice. Using the combined Bogoliubov method and the quantum rotor approach, we map the Hamiltonian of strongly interacting bosons onto U(1) phase a ... [Phys. Rev. A 84, 053613 ] published .

Thermodynamics of strongly interacting fermions in two-dimensional optical lattices

Ehsan Khatami and Marcos Rigol
We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting ... [Phys. Rev. A 84, 053611 ] published .

Internal Josephson oscillations for distinct momenta Bose-Einstein condensates

Lih-King Lim, T. Troppenz, and C. Morais Smith
The internal Josephson oscillations between an atomic Bose-Einstein condensate (BEC) and a molecular one are studied for atoms in a square optical lattice subjected to a staggered gauge field. The system is described by a Bose-Hubbard model with complex and anisotropic hopping parameters that are di ... [Phys. Rev. A 84, 053609 ] published .

Stability of a dipolar Bose-Einstein condensate in a one-dimensional lattice

S. Muller, J. Billy, E. A. L. Henn, H. Kadau, A. Griesmaier et al.
We show that in contrast with contact interacting gases, an optical lattice changes drastically the stability properties of a dipolar condensate, inducing a crossover from dipolar destabilization to dipolar stabilization for increasing lattice depths. Performing stability measurements on a Cr Bose-E ... [Phys. Rev. A 84, 053601 ] published .

Generating and controlling chains of entangled atoms by coherent control techniques

Moshe Shapiro
A practical way of writing long sequences of entangled atomic qubits using coherent control with classical light sources is proposed. The method utilizes one-photon vs two-photon interference as a means of controlling the directionality of the motion of valence electrons during molecular dissociatio ... [Phys. Rev. A 84, 053432 ] published .

Orbital order of spinless fermions near an optical Feshbach resonance

Philipp Hauke, Erhai Zhao, Krittika Goyal, Ivan H. Deutsch, W. Vincent Liu et al.
We study the quantum phases of a three-color Hubbard model that arises in the dynamics of the p-band orbitals of spinless fermions in an optical lattice. Strong, color-dependent interactions are induced by an optical Feshbach resonance. Starting from the microscopic scattering properties of ultracol ... [Phys. Rev. A 84, 051603 ] published .

Novel Mechanism of Supersolid of Ultracold Polar Molecules in Optical Lattices

Takahiro Ohgoe, Takafumi Suzuki, and Naoki Kawashima
We study the checkerboard supersolid of the hard-core Bose--Hubbard model with the dipole--dipole interaction. This supersolid is different from all other supersolids found in lattice models in the sense that superflow paths through which interstitials or vacancies can hop freely are absent in the c ... [J. Phys. Soc. Jpn. 80, 113001 (2011)] published Thu Nov 17, 2011.

Stability and decay of Bloch oscillations in the presence of time-dependent nonlinearity

Christopher Gaul, Elena Diaz, Rodrigo P. A. Lima, Francisco Dominguez-Adame, and Cord A. Muller
We consider Bloch oscillations of Bose-Einstein condensates in the presence of a time-modulated s-wave scattering length. Generically, the interaction leads to dephasing and decay of the wave packet. Based on a cyclic-time argument, we findin addition to the linear Bloch oscillation and a rigid soli ... [Phys. Rev. A 84, 053627 ] published .

Phase diagram of the bosonic Kondo-Hubbard model

Michael Foss-Feig and Ana Maria Rey
We study a bosonic version of the Kondo lattice model with an onsite repulsion in the conduction band, implemented with alkali-metal atoms in two bands of an optical lattice. Using both weak- and strong-coupling perturbation theory, we find that at unit filling of the conduction bosons the superflui ... [Phys. Rev. A 84, 053619 ] published .

Quantum simulator for the Schwinger effect with atoms in bichromatic optical lattices

Nikodem Szpak and Ralf Schutzhold
Ultracold atoms in specifically designed optical lattices can be used to mimic the many-particle Hamiltonian (whose effective parameters can be tuned in a wide range) describing electrons and positrons in an external electric field. This analogy facilitates the experimental simulation of (so far uno ... [Phys. Rev. A 84, 050101 ] published .

Superfluid, solid, and supersolid phases of dipolar bosons in a quasi-one-dimensional optical lattice

Jonathan M. Fellows and Sam T. Carr
We discuss a model of dipolar bosons trapped in a weakly coupled planar array of one-dimensional tubes. We consider the situation where the dipolar moments are aligned by an external field, and we find a rich phase diagram as a function of the angle of this field exhibiting quantum phase transitions ... [Phys. Rev. A 84, 051602 ] published .

Strong-coupling expansion for bosons on the kagome lattice

Vipin Kerala Varma and Hartmut Monien
We use series-expansion techniques for analyzing properties of the phase transition between the Mott insulating and superfluid phase for bosons on the kagome lattice. The multicritical point in the ground-state phase diagram for unit filling is calculated. It is seen that, in a bond expansion, of th ... [Phys. Rev. B 84, 195131 ] published .

Quantum criticality of dipolar spin chains

Aldo Isidori, Annika Ruppel, Andreas Kreisel, Peter Kopietz, Alexander Mai et al.
We show that a chain of Heisenberg spins interacting with long-range dipolar forces in a magnetic field h perpendicular to the chain exhibits a quantum critical point belonging to the two-dimensional Ising universality class. Within linear spin-wave theory, the magnon dispersion for small momenta k ... [Phys. Rev. B 84, 184417 ] published .

Simultaneous Dimerization and SU(4) Symmetry Breaking of 4-Color Fermions on the Square Lattice

Philippe Corboz, Andreas M. Lauchli, Karlo Penc, Matthias Troyer, and Frederic Mila
Using infinite projected entangled-pair states, exact diagonalization, and flavor-wave theory, we show that the SU(4) Heisenberg model undergoes a spontaneous dimerization on the square lattice, in contrast with its SU(2) and SU(3) counterparts, which develop Neel and three-sublattice stripelike lon ... [Phys. Rev. Lett. 107, 215301 ] published .

Controlling Correlated Tunneling and Superexchange Interactions with ac-Driven Optical Lattices

Yu-Ao Chen, Sylvain Nascimbene, Monika Aidelsburger, Marcos Atala, Stefan Trotzky et al.
The dynamical control of tunneling processes of single particles plays a major role in science ranging from Shapiro steps in Josephson junctions to the control of chemical reactions via light in molecules. Here we show how such control can be extended to the regime of correlated tunneling of strongl ... [Phys. Rev. Lett. 107, 210405 ] published .

Virial expansion with Feynman diagrams

X. Leyronas
We present a field theoretic method for the calculation of the second and third virial coefficients b and b of two-species fermions interacting via a contact interaction. The method is mostly analytic. We find a closed expression for b in terms of the two- and three-body T matrices. We recover numer ... [Phys. Rev. A 84, 053633 ] published .

Mean-field analysis of dimensional crossover from two dimensions to three dimensions in a weakly interacting Fermi gas

Hui Hu
We investigate theoretically the transition from two to three dimensions in a weakly interacting ultracold Fermi gas. This transition was recently observed by Dyke et al. [Phys. Rev. Lett. 106, 105304 (2011)] in a cloud of fermionic Li atoms trapped in an oblate harmonic potential. We calculate the ... [Phys. Rev. A 84, 053624 ] published .

Correlation energy of a homogeneous dipolar Fermi gas

Bo Liu and Lan Yin
We study the normal state of a 3d homogeneous dipolar Fermi gas beyond the Hartree-Fock approximation. The correlation energy is found of the same order as the Fock energy, unusually strong for a Fermi-liquid system. As a result, the critical density of mechanical collapse is smaller than that estim ... [Phys. Rev. A 84, 053603 ] published .

Supersonic and subsonic shock waves in the unitary Fermi gas

L. Salasnich
We investigate shock waves in the unitary Fermi gas by using the zero-temperature equations of superfluid hydrodynamics. We obtain analytical solutions for the dynamics of a localized perturbation of the uniform gas. These supersonic bright and subsonic dark solutions produce, after a transient time ... [EPL 96, 40007 (2011)] published Wed Nov 16, 2011.

Spin-orbit coupling induced enhancement of superconductivity in a two-dimensional repulsive gas of fermions

Oskar Vafek and Luyang Wang
We study a model of a two-dimensional repulsive Fermi gas with Rashba spin-orbit coupling alpha and investigate the superconducting instability using the renormalization-group approach. We find that, in general, superconductivity is enhanced as the dimensionless ratio (1/2)malpha/E increases, result ... [Phys. Rev. B 84, 172501 ] published .

Collision of two spin-polarized fermionic clouds

O. Goulko, F. Chevy, and C. Lobo
We study the collision of two spin-polarized Fermi clouds in a harmonic trap using a simulation of the Boltzmann equation. As observed in recent experiments, we find three distinct regimes of behavior. For weak interactions the clouds pass through each other. If interactions are increased they appro ... [Phys. Rev. A 84, 051605 ] published .

Spin-Orbit Coupled Fermi Gases across a Feshbach Resonance

Zeng-Qiang Yu and Hui Zhai
In this Letter we study both ground state properties and the superfluid transition temperature of a spin-1/2 Fermi gas across a Feshbach resonance with a synthetic spin-orbit coupling, using the mean-field theory and the exact solution of two-body problem. We show that a strong spin-orbit coupling c ... [Phys. Rev. Lett. 107, 195305 ] published .

Probing Anisotropic Superfluidity in Atomic Fermi Gases with Rashba Spin-Orbit Coupling

Hui Hu, Lei Jiang, Xia-Ji Liu, and Han Pu
Motivated by the prospect of realizing a Fermi gas with a synthetic non-Abelian gauge field, we investigate theoretically a strongly interacting Fermi gas in the presence of a Rashba spin-orbit coupling. As the twofold spin degeneracy is lifted by spin-orbit interaction, bound pairs with mixed singl ... [Phys. Rev. Lett. 107, 195304 ] published .

Nature and Properties of a Repulsive Fermi Gas in the Upper Branch of the Energy Spectrum

Vijay B. Shenoy and Tin-Lun Ho
We generalize the Nozieres-Schmitt-Rink method to study the repulsive Fermi gas in the absence of molecule formation, i.e., in the so-called upper branch. We find that the system remains stable except close to resonance at sufficiently low temperatures. With increasing scattering length, the energy ... [Phys. Rev. Lett. 107, 210401 ] published .

Anomalous Hall Conductivity from the Dipole Mode of Spin-Orbit-Coupled Cold-Atom Systems

E. van der Bijl and R. A. Duine
Motivated by recent experiments by Lin et al., [Nature (London) 471, 83 (2011)] that engineered spin-orbit coupling in ultracold mixtures of bosonic atoms, we study the dipole oscillation of trapped spin-orbit-coupled noncondensed Bose and Fermi gases. We find that different directions of oscillatio ... [Phys. Rev. Lett. 107, 195302 ] published .

Multi-impurity polarons in a dilute BoseEinstein condensate

D Santamore and Eddy Timmermans
We describe the ground state of a large, dilute, neutral atom BoseEinstein condensate (BEC) doped with N strongly coupled mutually indistinguishable, bosonic neutral atoms (referred to as impurity) in the polaron regime where the BEC density response to the impurity atoms remains significantly small ... [New J. Phys. 13, 103029 (2011)] published Thu Nov 3, 2011.

Finite temperature and dissipative corrections to the Gross-Pitaevskii equation from one-loop contributions

T. Matos and A. Surez
Starting with a scalar field in a thermal bath and using the one-loop quantum correction potential, we rewrite the Klein-Gordon equation in its thermodynamical representation and study the behavior of this scalar field due to temperature variations in the equations of motion. We find the generalizat ... [EPL 96, 56005 (2011)] published Tue Nov 29, 2011.

Thermalization in a one-dimensional integrable system

Pjotrs Grisins and Igor E. Mazets
We present numerical results demonstrating the possibility of thermalization of single-particle observables in a one-dimensional system, which is integrable in both the quantum and classical (mean-field) descriptions (a quasicondensate of ultracold, weakly interacting bosonic atoms are studied as a ... [Phys. Rev. A 84, 053635 ] published .

Holographic power-law traps for the efficient production of Bose-Einstein condensates

Graham D. Bruce, Sarah L. Bromley, Giuseppe Smirne, Lara Torralbo-Campo, and Donatella Cassettari
We use a phase-only spatial light modulator to generate light distributions in which the intensity decays as a power law from a central maximum with order ranging from 2 (parabolic) to 0.5. We suggest that a sequence of these can be used as a time-dependent optical dipole trap for all-optical produc ... [Phys. Rev. A 84, 053410 ] published .

Nonequilibrium and local detection of the normal fraction of a trapped two-dimensional Bose gas

Iacopo Carusotto and Yvan Castin
We propose a method to measure the normal fraction of a two-dimensional Bose gas, a quantity that generally differs from the noncondensed fraction. The idea is based on applying a spatially oscillating artificial gauge field to the atoms. The response of the atoms to the gauge field can be read out ... [Phys. Rev. A 84, 053637 ] published .

Number fluctuations of cold, spatially split bosonic objects

Kaspar Sakmann, Alexej I. Streltsov, Ofir E. Alon, and Lorenz S. Cederbaum
We investigate the number fluctuations of spatially split many-boson systems employing a theorem about the maximally and minimally attainable variances of an observable. The number fluctuations of many-boson systems are given for different numbers of lattice sites and both mean-field and many-body w ... [Phys. Rev. A 84, 053622 ] published .

Behavior of heat capacity of an attractive Bose-Einstein condensate approaching collapse

Sanchari Goswami, Tapan Kumar Das, and Anindya Biswas
We report the calculation of heat capacity of an attractive Bose-Einstein condensate, with the number N of bosons increasing and eventually approaching the critical number N for collapse, using the correlated potential harmonics (CPH) method. Boson pairs interact via the realistic van der Waals pote ... [Phys. Rev. A 84, 053617 ] published .

Resonant wave formation in Bose-Einstein condensates

Alexandru I. Nicolin
We investigate analytically the dynamics of a trapped, quasi-one-dimensional Bose-Einstein condensate subject to resonant and nonresonant periodic modulation of the transverse confinement. The dynamics of the condensate is described variationally through a set of coupled ordinary differential equati ... [Phys. Rev. E 84, 056202 ] published .

Atomic momentum distribution and Bose-Einstein condensation in liquid He under pressure

H. R. Glyde, S. O. Diallo, R. T. Azuah, O. Kirichek, and J. W. Taylor
Neutron-scattering measurements of the dynamic structure factor, S(Q,omega), of liquid He as a function of pressure at high-momentum transfer, [h-bar]Q, are presented. At high [h-bar]Q the dynamics of single atoms in the liquid is observed. From S(Q,omega) the atomic momentum distribution, n(k), the ... [Phys. Rev. B 84, 184506 ] published .

Single-particle spectral density of a Bose gas in the two-fluid hydrodynamic regime

Emiko Arahata, Tetsuro Nikuni, and Allan Griffin
In Bose superfluids, the single-particle Green's function can be directly related to the superfluid velocity-velocity correlation function in the hydrodynamic regime. An explicit expression for the single-particle spectral density was originally written down by Hohenberg and Martin in 1965, starting ... [Phys. Rev. A 84, 053612 ] published .

Condensed Fraction of an Atomic Bose Gas Induced by Critical Correlations

Robert P. Smith, Naaman Tammuz, Robert L. D. Campbell, Markus Holzmann, and Zoran Hadzibabic
We study the condensed fraction of a harmonically trapped atomic Bose gas at the critical point predicted by mean-field theory. The nonzero condensed fraction f is induced by critical correlations which increase the transition temperature T above T. Unlike the T shift in a trapped gas, f is sensitiv ... [Phys. Rev. Lett. 107, 190403 ] published .

Colloquium: Artificial gauge potentials for neutral atoms

Jean Dalibard, Fabrice Gerbier, Gediminas Juzeliunas, and Patrik Ohberg
When a neutral atom moves in a properly designed laser field, its center-of-mass motion may mimic the dynamics of a charged particle in a magnetic field, with the emergence of a Lorentz-like force. In this Colloquium the physical principles at the basis of this artificial (synthetic) magnetism are p ... [Rev. Mod. Phys. 83, 1523 ] published .