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6,700
Impurity Scattering in a Bose-Einstein Condensate at finite temperature
cond-mat.quant-gas
We consider the effects of finite temperature on the scattering of impurity atoms in a BoseEinstein condensate, showing that the scattering rate is enhanced by the thermal atoms. Collisions can increase or decrease the impurity energy. Below the Landau velocity only the first process occurs, i.e., the collisions cool t...
physics
6,701
Macroscopic Quantum Coherence in a repulsive Bose-Einstein condensate
cond-mat.quant-gas
We consider a Bose-Einstein bicondensate (BEC) of $^{87}Rb$, trapped in two different internal levels, in a situation where the density undergoes a symmetry breaking in momentum space. This occurs for a suitable number of condensed atoms within a double well dispersion curve, obtained by Raman coupling two internal sta...
physics
6,702
Bose-Einstein condensation into non-equilibrium states studied by condensate focusing
cond-mat.quant-gas
We report the formation of Bose-Einstein condensates into non-equilibrium states. Our condensates are much longer than equilibrium condensates with the same number of atoms, show strong phase fluctuations, and have a dynamical evolution similar to that of quadrupole shape oscillations of regular condensates. The conden...
physics
6,703
Bose-Einstein condensation in a magnetic double-well potential
cond-mat.quant-gas
We present the first experimental realisation of Bose-Einstein condensation in a purely magnetic double-well potential. This has been realised by combining a static Ioffe-Pritchard trap with a time orbiting potential (TOP). The double trap can be rapidly switched to a single harmonic trap of identical oscillation frequ...
physics
6,704
Shape oscillations in non-degenerate Bose gases - transition from the collisionless to the hydrodynamic regime
cond-mat.quant-gas
We investigate collective oscillations of non-degenerate clouds of Rb-87 atoms as a function of density in an elongated magnetic trap. For the low-lying M=0 monopole-quadrupole shape oscillation we measure the oscillation frequencies and damping rates. At the highest densities the mean-free-path is smaller than the axi...
physics
6,705
Time-Averaged Adiabatic Potentials: Versatile traps and waveguides for ultracold quantum gases
cond-mat.quant-gas
We demonstrate a novel class of trapping potentials, time-averaged adiabatic potentials (TAAP) which allows the generation of a large variety of traps and waveguides for ultracold atoms. Multiple traps can be coupled through controllable tunneling barriers or merged altogether. We present analytical expressions for pan...
physics
6,706
Many-body approach to low-lying collective excitations in a BEC approaching collapse
cond-mat.quant-gas
An approximate many-body theory incorporating two-body correlations has been employed to calculate low-lying collective multipole frequencies in a Bose-Einstein condensate containing $A$ bosons, for different values of the interaction parameter $\lambda=\frac{Aa_{s}}{a_{ho}}$. Significant difference from the variationa...
physics
6,707
Antiferromagnetic Order of Repulsively Interacting Fermions on Optical lattices
cond-mat.quant-gas
The N\'eel state in fermionic mixtures of two pseudospin species in an optical lattice is analyzed at low temperatures. Experimentally it remains a challenge to demonstrate antiferromagnetic correlations in ultracold fermionic quantum gases. We find that, while in balanced systems the N\'eel order parameter can point i...
physics
6,708
Evaporative depolarization and spin transport in a unitary trapped Fermi gas
cond-mat.quant-gas
We consider a partially spin-polarized atomic Fermi gas in a high-aspect-ratio trap, with a flux of predominantly spin-up atoms exiting the center of the trap. We argue that such a scenario can be produced by evaporative cooling, and we find that it can result in a substantially non-equilibrium polarization pattern for...
physics
6,709
Repulsive Fermi gas in a harmonic trap: Ferromagnetism and spin textures
cond-mat.quant-gas
We study ferromagnetism in a repulsively interacting two-component Fermi gas in a harmonic trap. Within a local density approximation, the two components phase-separate beyond a critical interaction strength, with one species having a higher density at the trap center. We discuss several easily observable experimental ...
physics
6,710
Probing interaction-induced ferromagnetism in optical superlattices
cond-mat.quant-gas
We propose a controllable method for observing interaction induced ferromagnetism in ultracold fermionic atoms loaded in optical superlattices. We first discuss how to probe and control Nagaoka ferromagnetism in an array of isolated plaquettes (four lattice sites arranged in a square). Next, we show that introducing a ...
physics
6,711
Drag force on an impurity below the superfluid critical velocity in a quasi-one-dimensional Bose-Einstein condensate
cond-mat.quant-gas
The existence of frictionless flow below a critical velocity for obstacles moving in a superfluid is well established in the context of the mean-field Gross-Pitaevskii theory. We calculate the next order correction due to quantum and thermal fluctuations and find a non-zero force acting on a delta-function impurity mov...
physics
6,712
Theory of domain formation in inhomogeneous ferromagnetic dipolar condensates
cond-mat.quant-gas
Recent experimental studies of $^{87}$Rb spinor Bose Einstein condensates have shown the existence of a magnetic field driven quantum phase transition accompanied by structure formation on the ferromagnetic side of the transition. In this theoretical study we examine the dynamics of the unstable modes following the tra...
physics
6,713
Spectral Functions and rf Response of Ultracold Fermionic Atoms
cond-mat.quant-gas
We present a calculation of the spectral functions and the associated rf response of ultracold fermionic atoms near a Feshbach resonance. The single particle spectra are peaked at energies that can be modeled by a modified BCS dispersion. However, even at very low temperatures their width is comparable to their energy,...
physics
6,714
Quantum Phase Transitions in a Dimerized Bose-Hubbard Model: A DMRG Study
cond-mat.quant-gas
We investigate the phase diagram of a dimerized Bose-Hubbard model, using density matrix renormalization group technique. We find a new phase, which is the coexistence of superfluid and bond-wave phases, due to the effect of dimerization. Experimentally dimerization in optical lattice can be realized by using two count...
physics
6,715
In-situ Observation of Incompressible Mott-Insulating Domains of Ultracold Atomic Gases
cond-mat.quant-gas
We present a direct measurement of the density profile of a two-dimensional Mott Insulator formed by ultracold atoms in an optical lattice. High resolution absorption imaging is used to probe the "wedding-cake" structure of a trapped gas as it crosses the boundary from a unit-filled Mott insulating phase to the superfl...
physics
6,716
Induced interaction and crystallization of self-localized impurity fields in a Bose-Einstein condensate
cond-mat.quant-gas
We model the behavior of N classical impurity fields immersed in a larger Bose-Einstein condensate by N+1 coupled nonlinear Schrodinger equations in 1, 2, and 3 space dimensions. We discuss the stability of the uniform miscible system and show the importance of surface tension for self localization of the impurity fiel...
physics
6,717
Density ripples in expanding low-dimensional gases as a probe of correlations
cond-mat.quant-gas
We investigate theoretically the evolution of the two-point density correlation function of a low-dimensional ultracold Bose gas after release from a tight transverse confinement. In the course of expansion thermal and quantum fluctuations present in the trapped systems transform into density fluctuations. For the case...
physics
6,718
Rapid phase-diffusion between atomic and molecular Bose-Einstein condensates
cond-mat.quant-gas
We study the collisional loss of atom-molecule coherence after coherently dissociating a small fraction of a molecular Bose-Einstein condensate into atoms. The obtained $n$-atoms states are two-atom (SU(1,1)) coherent states with number variance $\Delta n\propto n$ compared to $\Delta n\propto \sqrt{n}$ for the spin (S...
physics
6,719
An ultra-cold, molecular Rydberg plasma with exceptionally long lifetime and strongly-coupled properties formed by threshold laser excitation in the expansion region of a supersonic jet
cond-mat.quant-gas
An ultra-cold molecular plasma with extraordinarily long lifetime (~0.5 ms) is generated under strong collisional cooling conditions in the expansion region of a seeded supersonic jet expansion close to the nozzle. A resonant two-photon one-color laser process excites para-difluorobenzene molecules into the high-n Rydb...
physics
6,720
Some properties of a long lifetime strongly-coupled molecular plasma produced by high Rydberg excitation of nitric oxide in a supersonic free jet
cond-mat.quant-gas
A long life-time (>0.3 ms) strongly-coupled molecular Rydberg plasma is generated by the excitation of nitric oxide into the high-n Rydberg threshold region in the high-density region of a supersonic jet expansion. After 310 \mus the plasma has expanded to a size of ca. 3 cm. When subjected to very small DC fields from...
physics
6,721
Spontaneous pattern formation in an anti-ferromagnetic quantum gas
cond-mat.quant-gas
Spontaneous pattern formation is a phenomenon ubiquitous in nature, examples ranging from Rayleigh-Benard convection to the emergence of complex organisms from a single cell. In physical systems, pattern formation is generally associated with the spontaneous breaking of translation symmetry and is closely related to ot...
physics
6,722
A supercritical superfluid and vortex unbinding following a quantum quench
cond-mat.quant-gas
We study the dynamics of the relative phase of a bilayer of two-dimensional superfluids after the two superfluids have been decoupled, using truncated Wigner approximation. On short time scales the relative phase shows "light cone" like thermalization and creates a metastable superfluid state, which can be supercritica...
physics
6,723
Creation and detection of vortices in polariton condensates
cond-mat.quant-gas
We investigate theoretically the creation, persistence and detection of quantized vortices in nonequilibrium polariton condensates within a stochastic classical field model. The life time of the quantized vortices is shown to increase with the spatial coherence and to depend on the geometry of the condensate. The relat...
physics
6,724
Vortex nucleation as a case study of symmetry breaking in quantum systems
cond-mat.quant-gas
Mean-field methods are a very powerful tool for investigating weakly interacting many-body systems in many branches of physics. In particular, they describe with excellent accuracy trapped Bose-Einstein condensates. A generic, but difficult question concerns the relation between the symmetry properties of the true many...
physics
6,725
Rapid production of $^{87}$Rb BECs in a combined magnetic and optical potential
cond-mat.quant-gas
We describe an apparatus for quickly and simply producing $\Rb87$ Bose-Einstein condensates. It is based on a magnetic quadrupole trap and a red detuned optical dipole trap. We collect atoms in a magneto-optical trap (MOT) and then capture the atom in a magnetic quadrupole trap and force rf evaporation. We then transfe...
physics
6,726
Stability and chaotic behavior of Bose-Einstein condensates in optical lattices with two- and three-body interactions
cond-mat.quant-gas
The stability and chaotic behaviors of Bose-Einstein condensates with two- and three-atom interactions in optical lattices are discussed with analytical and numerical methods. It is found that the steady-state relative population appears tuning-fork bifurcation when the system parameters are changed to certain critical...
physics
6,727
Feshbach resonant scattering of three fermions in one-dimensional wells
cond-mat.quant-gas
We study the weak-tunnelling limit for a system of cold 40K atoms trapped in a one-dimensional optical lattice close to an s-wave Feshbach resonance. We calculate the local spectrum for three atoms at one site of the lattice within a two-channel model. Our results indicate that, for this one-dimensional system, one- an...
physics
6,728
Phase Diagrams for Spin-1 Bosons in an Optical Lattice
cond-mat.quant-gas
In this paper, the phase diagrams of a polar spin-1 Bose gas in a three-dimensional optical lattice with linear and quadratic Zeeman effects both at zero and finite temperatures are obtained within mean-field theory. The phase diagrams can be regrouped to two different parameter regimes depending on the magnitude of th...
physics
6,729
Disorder effects during the evolution from BCS to BEC superfluidity
cond-mat.quant-gas
We describe the effects of disorder on the critical temperature of s-wave superfluids from the BCS to the BEC regime, with direct application to ultracold Fermi atoms. In the BCS regime the pair breaking and phase coherence temperature scales are essentially the same allowing strong correlations between the amplitude a...
physics
6,730
Spin-1/2 fermions with attractive interaction in an optical lattice
cond-mat.quant-gas
We study attractive fermions in an optical lattice superimposed by a trapping potential, such that fermions may form bosonic molecules. We map the model onto nonlinear field equations depending on the Nambu-Gor'kov propagator. The resulting field equations where solved numerically by a relaxation technique that allowed...
physics
6,731
Comment on "Spectral Signatures of the Fulde-Ferrell-Larkin-Ovchinnikov Order Parameter in One-Dimensional Optical lattices"
cond-mat.quant-gas
Comment on "Spectral Signatures of the Fulde-Ferrell-Larkin-Ovchinnikov Order Parameter in One-Dimensional Optical lattices" M. Reza Bakhtiari, M. J. Leskinen, and P. T\"orm\"a, Phys. Rev. lett. {\bf 101}, 120404 (2008).
physics
6,732
Bakhtiari, Leskinen and Torma Reply
cond-mat.quant-gas
This is a Reply to: Comment on "Spectral Signatures of the Fulde-Ferrell-Larkin-Ovchinnikov Order Parameter in One-Dimensional Optical Lattices" R. A. Molina J. Dukelksy, and P. Schmitteckert, Phys. Rev. Lett. 102, 168901 (2009)
physics
6,733
Phase Diagram of Bosons in Two-Color Superlattices from Experimental Parameters
cond-mat.quant-gas
We study the zero-temperature phase diagram of a gas of bosonic 87-Rb atoms in two-color superlattice potentials starting directly from the experimental parameters, such as wavelengths and intensities of the two lasers generating the superlattice. In a first step, we map the experimental setup to a Bose-Hubbard Hamilto...
physics
6,734
Anomalous suppression of the Bose glass at commensurate fillings in the disordered Bose-Hubbard model
cond-mat.quant-gas
We study the weakly disordered Bose-Hubbard model on a cubic lattice through a one-loop renormalization group analysis of the corresponding effective field theory which is explicitly derived by combining a strong-coupling expansion with a replica average over the disorder. The method is applied not only to generic unco...
physics
6,735
Inter-species Tunneling in One-dimensional Bose Mixtures
cond-mat.quant-gas
We study the ground-state properties and quantum dynamics of few-boson mixtures with strong inter-species repulsion in one-dimensional traps. If one species localizes at the center, e.g., due to a very large mass compared to the other component, it represents an effective barrier for the latter and the system can be ma...
physics
6,736
Hopping modulation in a one-dimensional Fermi-Hubbard Hamiltonian
cond-mat.quant-gas
We consider a strongly repulsive two-component Fermi gas in a one-dimensional (1D) optical lattice described in terms of a Hubbard Hamiltonian. We analyze the response of the system to a periodic modulation of the hopping amplitude in presence of large two body interaction. By (essentially) exact simulations of the tim...
physics
6,737
Generalized harmonic-fluid approach for the off-diagonal correlations of a one-dimensional interacting Bose gas
cond-mat.quant-gas
We develop a generalized harmonic-fluid approach, based on a regularization of the effective low-energy Luttinger-liquid Hamiltonian, for a one-dimensional Bose gas with repulsive contact interactions. The method enables us to compute the complete series corresponding to the large-distance, off-diagonal behavior of the...
physics
6,738
Zero-temperature phase transitions in dilute bosonic superfluids on a lattice
cond-mat.quant-gas
Kinetic energy driven phase transitions in Bose superfluids occur at low values of the repulsion when the values of the next-to-nearest and next-to-next-to-nearest hopping term attain certain critical values, resulting in alterations in the wave vector of the condensate. We map out the space of possible phases allowed ...
physics
6,739
First and second sound in a strongly interacting Fermi gas
cond-mat.quant-gas
Using a variational approach, we solve the equations of two-fluid hydrodynamics for a uniform and trapped Fermi gas at unitarity. In the uniform case, we find that the first and second sound modes are remarkably similar to those in superfluid Helium, a consequence of strong interactions. In the presence of harmonic tra...
physics
6,740
The physics of dipolar bosonic quantum gases
cond-mat.quant-gas
This article reviews the recent theoretical and experimental advances in the study of ultracold gases made of bosonic particles interacting via the long-range, anisotropic dipole-dipole interaction, in addition to the short-range and isotropic contact interaction usually at work in ultracold gases. The specific propert...
physics
6,741
Quantum dynamics of cavity assisted photoassociation of Bose-Einstein condensed atoms
cond-mat.quant-gas
We explore the quantum dynamics of photoassociation of Bose-Einstein condensed atoms into molecules using an optical cavity field. Inside of an optical resonator, photoassociation of quantum degenerate atoms involves the interaction of three coupled quantum fields for the atoms, molecules, and the photons. The feedback...
physics
6,742
Decoherence and entanglement in a bosonic Josephson junction: Bose-enhanced quantum-Zeno control of phase-diffusion
cond-mat.quant-gas
We study the effect of decoherence on dynamical phase diffusion in the two-site Bose-Hubbard model. Starting with an odd parity excited coherent state, the initial loss of single particle coherence varies from small bound oscillations in the Rabi regime, through hyperbolic depletion in the Josephson regime, to a Gaussi...
physics
6,743
A high-flux 2D MOT source for cold lithium atoms
cond-mat.quant-gas
We demonstrate a novel 2D MOT beam source for cold 6Li atoms. The source is side-loaded from an oven operated at temperatures in the range 600<T<700 K. The performance is analyzed by loading the atoms into a 3D MOT located 220 mm downstream from the source. The maximum recapture rate of ~10^9 /s is obtained for T=700 K...
physics
6,744
Supersolidity of cold-atom Bose-Fermi mixtures in optical lattices
cond-mat.quant-gas
We investigate a cold atomic mixture of spinless bosons and fermions in two-dimensional optical lattices. In the presence of a nested Fermi surface, the bosons may develop a fascinating supersolid behavior characterized by a finite superfluid density as well as a spatial density wave order. Focusing on the triangular l...
physics
6,745
Mesoscopic quantum switching of a Bose-Einstein condensate in an optical lattice governed by the parity of the number of atoms
cond-mat.quant-gas
It is shown that for a $N$-boson system the parity of $N$ can be responsible for a qualitative difference in the system response to variation of a parameter. The nonlinear boson model is considered, which describes tunneling of boson pairs between two distinct modes $X_{1,2}$ of the same energy and applies to a Bose-Ei...
physics
6,746
Atomic Josephson junction with two bosonic species
cond-mat.quant-gas
We study an atomic Josephson junction (AJJ) in presence of two interacting Bose-Einstein condensates (BECs) confined in a double well trap. We assume that bosons of different species interact with each other. The macroscopic wave functions of the two components obey to a system of two 3D coupled Gross-Pitaevskii equati...
physics
6,747
Localization by bichromatic potentials versus Anderson localization
cond-mat.quant-gas
The one-dimensional propagation of waves in a bichromatic potential may be modeled by the Aubry-Andr\'e Hamiltonian. The latter presents a delocalization-localization transition, which has been observed in recent experiments using ultracold atoms or light. It is shown here that, in contrast to Anderson localization, th...
physics
6,748
Mixtures of Bose Gases Confined in a Ring Potential
cond-mat.quant-gas
The rotational properties of a mixture of two distinguishable Bose gases that are confined in a ring potential provide novel physical effects that we demonstrate in this study. Persistent currents are shown to be stable for a range of the population imbalance between the two components at low angular momentum. At highe...
physics
6,749
Collapse instability of solitons in the nonpolynomial Schrödinger equation with dipole-dipole interactions
cond-mat.quant-gas
A model of the Bose-Einstein condensate (BEC) of dipolar atoms, confined in a combination of a cigar-shaped trap and optical lattice acting in the axial direction, is studied in the framework of the one-dimensional (1D) nonpolynomial Schr\"{o}dinger equation (NPSE) with additional terms describing long-range dipole-dip...
physics
6,750
Transport of ultracold Bose gases beyond the Gross-Pitaevskii description
cond-mat.quant-gas
We explore atom-laser-like transport processes of ultracold Bose-condensed atomic vapors in mesoscopic waveguide structures beyond the Gross-Pitaevskii mean-field theory. Based on a microscopic description of the transport process in the presence of a coherent source which models the outcoupling from a reservoir of per...
physics
6,751
Critical temperature of a Bose gas in an optical lattice
cond-mat.quant-gas
We present theory for the critical temperature of a Bose gas in a combined harmonic lattice potential based on a mean-field description of the system. We develop practical expressions for the ideal-gas critical temperature, and corrections due to interactions, the finite-size effect, and the occupation of excited bands...
physics
6,752
Suppression of the critical temperature for superfluidity near the Mott transition: validating a quantum simulator
cond-mat.quant-gas
Ultracold atomic gases in optical lattices have proven to be a controllable, tunable and clean implementation of strongly interacting quantum many-body systems. An essential prospect for such quantum simulators is their ability to map out the phase diagram of fundamental many-body model Hamiltonians. However, the resul...
physics
6,753
Condensate density of interacting bosons: a functional renormalization group approach
cond-mat.quant-gas
We calculate the temperature dependent condensate density $\rho^0 (T)$ of interacting bosons in three dimensions using the functional renormalization group (FRG). From the numerical solution of suitably truncated FRG flow equations for the irreducible vertices we obtain $\rho^0 (T)$ for arbitrary temperatures. We caref...
physics
6,754
Polarization Suppression and Nonmonotonic Local Two-Body Correlations in the Two-Component Bose Gas in One Dimension
cond-mat.quant-gas
We study the interplay of quantum statistics, strong interactions and finite temperatures in the two-component (spinor) Bose gas with repulsive delta-function interactions in one dimension. Using the Thermodynamic Bethe Ansatz, we obtain the equation of state, population densities and local density correlation numerica...
physics
6,755
On the kinetic energy of unitary Fermi gas in a harmonic trap
cond-mat.quant-gas
We have considered the orbital-free approximation of the kinetic energy functional to investigate the zero temperature properties of dilute harmonically trapped two component Fermi gas at unitarity. It is shown that our approach provides a realible and inexpensive method to study superfluid strongly interacting dilute ...
physics
6,756
Frustrated Bose condensates in optical lattices
cond-mat.quant-gas
We study the Bose-condensed ground states of bosons in a two-dimensional optical lattice in the presence of frustration due to an effective vector potential, for example, due to lattice rotation. We use a mapping to a large-S frustrated magnet to study quantum fluctuations in the condensed state. Quantum effects are in...
physics
6,757
Non-destructive cavity QED probe of Bloch oscillations in a gas of ultracold atoms
cond-mat.quant-gas
We describe a scheme for probing a gas of ultracold atoms trapped in an optical lattice and moving in the presence of an external potential. The probe is non-destructive and uses the existing lattice fields as the measurement device. Two counter-propagating cavity fields simultaneously set up a conservative lattice pot...
physics
6,758
Signature of the FFLO phase in the collective modes of a trapped ultracold Fermi gas
cond-mat.quant-gas
We study theoretically the collective modes of a two-component Fermi gas with attractive interactions in a quasi-one-dimensional harmonic trap. We focus on an imbalanced gas in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. Using a mean-field theory, we study the response of the ground state to time-dependent poten...
physics
6,759
Two-photon nonlinear spectroscopy of periodically trapped ultracold atoms in a cavity
cond-mat.quant-gas
We study the transmission spectra of a Bose Einstein condensate confined in an optical lattice interacting with two modes of a cavity via nonlinear two-photon transition. In particular we show that a nonlinear two-photon interaction between the superfluid (SF) phase and the Mott insulating (MI) phase of a Bose-Einstein...
physics
6,760
Counterflow and paired superfluidity in one-dimensional Bose mixtures in optical lattices
cond-mat.quant-gas
We study the quantum phases of mixtures of ultra-cold bosonic atoms held in an optical lattice that confines motion or hopping to one spatial dimension. The phases are found by using Tomonaga-Luttinger liquid theory as well as the numerical method of time evolving block decimation (TEBD). We consider a binary mixture w...
physics
6,761
Entropy exchange in a mixture of ultracold atoms
cond-mat.quant-gas
We investigate experimentally the entropy transfer between two distinguishable atomic quantum gases at ultralow temperatures. Exploiting a species-selective trapping potential, we are able to control the entropy of one target gas in presence of a second auxiliary gas. With this method, we drive the target gas into the ...
physics
6,762
Induced supersolidity in a normal and hardcore boson mixture
cond-mat.quant-gas
It is well known that the supersolid form of matter can arise in a single species of cold bosonic atoms in an optical lattice due to long range interactions. We present a scenario where a supersolid is induced in one of the components of a mixture of two species bosonic atoms where there is no long range interactions. ...
physics
6,763
Exotic superfluidity in cold atoms
cond-mat.quant-gas
We derived the low energy effective action for the collective modes in asymmetric fermionic systems with attractive interaction. We obtained the phase diagram in terms of the chemical potentials. It features a stable gapless superfluidity with one Fermi surface on the BEC side of the resonance. Also we predict a sharp ...
physics
6,764
Transition region properties of a trapped quasi-two-dimensional degenerate Bose gas
cond-mat.quant-gas
The c-field simulation technique is used to study a trapped quasi-two dimensional Bose gas. We calculate the central curvature of the system density and fluctuations of the condensate mode in the degenerate regime. These results provide new understanding of the system behavior in the region of the superfluid transition...
physics
6,765
Cavity Quantum Optomechanics of Ultracold Atoms in an Optical Lattice: Normal-Mode Splitting
cond-mat.quant-gas
We consider the dynamics of a movable mirror (cantilever) of a cavity coupled through radiation pressure to the light scattered from ultracold atoms in an optical lattice. Scattering from different atomic quantum states creates different quantum states of the scattered light, which can be distinguished by measurements ...
physics
6,766
Berry Phase in Atom-Molecule Conversion Systems and Fractional Monopole
cond-mat.quant-gas
We investigate the geometric phase or Berry phase of adiabatic quantum evolution in an atom-molecule conversion system, and find that the Berry phase in such system consists of two parts: the usual Berry connection term and a novel term from the nonlinearity brought forth by the atom-molecule conversion. The geometric ...
physics
6,767
Phase Separation and Dynamics of Two-component Bose-Einstein Condensates
cond-mat.quant-gas
We study the interactions between two atomic species in a binary Bose-Einstein condensate to revisit the conditions for miscibility, oscillatory dynamics between the species, steady state solutions and their stability. By employing a variational approach for a quasi one-dimensional, two-atomic species, condensate we ob...
physics
6,768
Controlled localization of interacting bosons in a disordered optical lattice
cond-mat.quant-gas
We show that tunneling and localization properties of interacting ultracold atoms in an optical lattice can be controlled by adiabatically turning on a fast oscillatory force even in the presence of disorder. Our calculations are based on the exact solution of the time-dependent Schroedinger equation, using the Floquet...
physics
6,769
Zero Sound in Dipolar Fermi Gases
cond-mat.quant-gas
We study the propagation of sound in a homogeneous dipolar gas at zero temperature, known as zero sound. We find that undamped sound propagation is possible only in a range of solid angles around the direction of polarization of the dipoles. Above a critical dipole moment, we find an unstable mode, by which the gas col...
physics
6,770
Pseudogap in fermionic density of states in the BCS-BEC crossover of atomic Fermi gases
cond-mat.quant-gas
We study pseudogap behaviors of ultracold Fermi gases in the BCS-BEC crossover region. We calculate the density of states (DOS), as well as the single-particle spectral weight, above the superfluid transition temperature $T_{\rm c}$ including pairing fluctuations within a $T$-matrix approximation. We find that DOS exhi...
physics
6,771
Vortices in dipolar condensates with dominant dipolar interactions
cond-mat.quant-gas
We present full three-dimensional numerical calculations of single vortex states in rotating dipolar condensates. We consider a Bose-Einstein condensate of 52Cr atoms with dipole-dipole and s-wave contact interactions confined in an axially symmetric harmonic trap. We obtain the vortex states by numerically solving the...
physics
6,772
BCS-BEC crossover with unequal mass fermions
cond-mat.quant-gas
We investigate the crossover from BCS pairing to molecular BEC in an atomic gas with two fermion species with masses $m_\up \ne m_\dn$ tuned through a Feshbach resonance. We present results for the T=0 equation of state as a function of the scattering length including the effects of Gaussian fluctuations about the mean...
physics
6,773
A Universal Trimer in a Three-Component Fermi Gas
cond-mat.quant-gas
We show that the recently measured magnetic field dependence of three-body loss in a three-component mixture of ultracold $^6$Li atoms [1,2] can be explained by the presence of a universal trimer state. Previous work suggested a universal trimer state as a probable explanation, yet failed to get good agreement between ...
physics
6,774
Feynman path-integral treatment of the BEC-impurity polaron
cond-mat.quant-gas
The description of an impurity atom in a Bose-Einstein condensate can be cast in the form of Frohlich's polaron Hamiltonian, where the Bogoliubov excitations play the role of the phonons. An expression for the corresponding polaronic coupling strength is derived, relating the coupling strength to the scattering lengths...
physics
6,775
Finite temperature theory of superfluid bosons in optical lattices
cond-mat.quant-gas
A practical finite temperature theory is developed for the superfluid regime of a weakly interacting Bose gas in an optical lattice with additional harmonic confinement. We derive an extended Bose-Hubbard model that is valid for shallow lattices and when excited bands are occupied. Using the Hartree-Fock-Bogoliubov-Pop...
physics
6,776
Dark soliton decay due to trap anharmonicity in atomic Bose-Einstein condensates
cond-mat.quant-gas
A number of recent experiments with nearly pure atomic Bose-Einstein condensates have confirmed the predicted dark soliton oscillations when under harmonic trapping. However, a dark soliton propagating in an inhomogeneous condensate has also been predicted to be unstable to the emission of sound waves. Although harmoni...
physics
6,777
Excitation spectrum of Mott shells in optical lattices
cond-mat.quant-gas
We theoretically study the excitation spectrum of confined macroscopic optical lattices in the Mott-insulating limit. For large systems, a fast numerical method is proposed to calculate the ground state filling and excitation energies. We introduce many-particle on-site energies capturing multi-band effects and discuss...
physics
6,778
Effect of realistic interatomic interactions and two-body correlation on the heat capacity of a trapped BEC
cond-mat.quant-gas
An approximate many-body theory has been used to calculate the heat capacity and the condensate fraction of a BEC with effective repulsive interaction. The effect of interactions has been analyzed and compared with the non-interacting case. It has been found that the repulsive interaction lowers the critical temperatur...
physics
6,779
Radio-frequency dressing of multiple Feshbach resonances
cond-mat.quant-gas
We demonstrate and theoretically analyze the dressing of several proximate Feshbach resonances in Rb-87 using radio-frequency (rf) radiation. We present accurate measurements and characterizations of the resonances, and the dramatic changes in scattering properties that can arise through the rf dressing. Our scattering...
physics
6,780
Is an Ultra-Cold Strongly Interacting Fermi Gas a Perfect Fluid?
cond-mat.quant-gas
Fermi gases with magnetically tunable interactions provide a clean and controllable laboratory system for modeling interparticle interactions between fermions in nature. The s-wave scattering length, which is dominant a low temperature, is made to diverge by tuning near a collisional (Feshbach) resonance. In this regim...
physics
6,781
Vortex nucleation in mesoscopic Bose superfluid and breaking of the parity symmetry
cond-mat.quant-gas
We analyze vortex nucleation in mezoscopic 2D Bose superfluid in a rotating trap. We explicitly include a weakly anisotropic stirring potential, breaking thus explicitly the axial symmetry. As the rotation frequency passes the critical value $\Omega_c$ the system undergoes an extra symmetry change/breaking. Well below ...
physics
6,782
Antiferromagnetic noise correlations in optical lattices
cond-mat.quant-gas
We analyze how noise correlations probed by time-of-flight (TOF) experiments reveal antiferromagnetic (AF) correlations of fermionic atoms in two-dimensional (2D) and three-dimensional (3D) optical lattices. Combining analytical and quantum Monte Carlo (QMC) calculations using experimentally realistic parameters, we sh...
physics
6,783
Coherence time of a Bose-Einstein condensate
cond-mat.quant-gas
Temporal coherence is a fundamental property of macroscopic quantum systems, such as lasers in optics and Bose-Einstein condensates in atomic gases and it is a crucial issue for interferometry applications with light or matter waves. Whereas the laser is an "open" quantum system, ultracold atomic gases are weakly coupl...
physics
6,784
Two-dimensional boson-fermion mixtures
cond-mat.quant-gas
Using mean-field theory, we study the equilibrium properties of boson-fermion mixtures confined in a harmonic pancake-shaped trap at zero temperature. When the modulus of the s-wave scattering lengths are comparable to the mixture thickness, two-dimensional scattering events introduce a logarithmic dependence on densit...
physics
6,785
Generalized nonpolynomial Schrodinger equations for matter waves under anisotropic transverse confinement
cond-mat.quant-gas
Starting from the three-dimensional Gross-Pitaevskii equation we derive a 1D generalized nonpolynomial Schrodinger equation, which describes the dynamics of Bose-Einstein condensates under the action of a generic potential in the longitudinal axial direction and of an anisotropic harmonic potential in the transverse ra...
physics
6,786
Versatile transporter apparatus for experiments with optically trapped Bose-Einstein condensates
cond-mat.quant-gas
We describe a versatile and simple scheme for producing magnetically and optically-trapped Rb-87 Bose-Einstein condensates, based on a moving-coil transporter apparatus. The apparatus features a TOP trap that incorporates the movable quadrupole coils used for magneto-optical trapping and long-distance magnetic transpor...
physics
6,787
Many-body physics in the radio frequency spectrum of lattice bosons
cond-mat.quant-gas
We calculate the radio-frequency spectrum of a trapped cloud of cold bosonic atoms in an optical lattice. Using random phase and local density approximations we produce both trap averaged and spatially resolved spectra, identifying simple features in the spectra that reveal information about both superfluidity and corr...
physics
6,788
Three-vortex configurations in trapped Bose-Einstein condensates
cond-mat.quant-gas
We report on the creation of three-vortex clusters in a $^{87}Rb$ Bose-Einstein condensate by oscillatory excitation of the condensate. This procedure can create vortices of both circulation, so that we are able to create several types of vortex clusters using the same mechanism. The three-vortex configurations are dom...
physics
6,789
Free Expansion of a Weakly-interacting Dipolar Fermi Gas
cond-mat.quant-gas
We theoretically investigate a polarized dipolar Fermi gas in free expansion. The inter-particle dipolar interaction deforms phase-space distribution in trap and also in the expansion. We exactly predict the minimal quadrupole deformation in the expansion for the high-temperature Maxwell-Boltzmann and zero-temperature ...
physics
6,790
Density profiles and density oscillations of an interacting three-component normal Fermi gas
cond-mat.quant-gas
We use a semiclassical approximation to investigate density variations and dipole oscillations of an interacting three-component normal Fermi gas in a harmonic trap. We consider both attractive and repulsive interactions between different pairs of fermions and study the effect of population imbalance on densities. We f...
physics
6,791
Self-consistent Single-band Approximation for Interacting Boson Systems
cond-mat.quant-gas
Traditionally, the single-band approximation for interacting many-body systems is done with pre-determined single-particle Wannier functions, ignoring the dependence of the Wannier function on interaction. We show that the single-band approximation has to be done self-consistently to properly account the interaction ef...
physics
6,792
Infrared behavior and spectral function of a Bose superfluid at zero temperature
cond-mat.quant-gas
In a Bose superfluid, the coupling between transverse (phase) and longitudinal fluctuations leads to a divergence of the longitudinal correlation function, which is responsible for the occurrence of infrared divergences in the perturbation theory and the breakdown of the Bogoliubov approximation. We report a non-pertur...
physics
6,793
Anharmonicity Induced Resonances for Ultracold Atoms and their Detection
cond-mat.quant-gas
When two atoms interact in the presence of an anharmonic potential, such as an optical lattice, the center of mass motion cannot be separated from the relative motion. In addition to generating a confinement-induced resonance (or shifting the position of an existing Feshbach resonance), the external potential changes t...
physics
6,794
Spin drag in noncondensed Bose gases
cond-mat.quant-gas
We show how time-dependent magnetic fields lead to spin motive forces and spin drag in a spinor Bose gas. We propose to observe these effects in a toroidal trap and analyze this particular proposal in some detail. In the linear-response regime we define a transport coefficient that is analogous to the usual drag resist...
physics
6,795
Core sizes and dynamical instabilities of giant vortices in dilute Bose-Einstein condensates
cond-mat.quant-gas
Motivated by a recent demonstration of cyclic addition of quantized vorticity into a Bose-Einstein condensate, the vortex pump, we study dynamical instabilities and core sizes of giant vortices. The core size is found to increase roughly as a square-root function of the quantum number of the vortex, whereas the strengt...
physics
6,796
Second Josephson oscillations
cond-mat.quant-gas
As a model for mesoscopic quantum systems in thermal contact, we consider a four-mode Bose-Hubbard model with two greatly differing tunneling rates. By a series of Holstein-Primakoff transformations we show that the low-frequency dynamics of this system consists in general of two slow Josephson oscillations, rather tha...
physics
6,797
Detection of coherent superpositions of phase states by full counting statistics in a Bose Josephson junction
cond-mat.quant-gas
For a Bose Josephson junction realized with a double-well potential we propose a strategy to observe the coherent superpositions of phase states occurring during the time evolution after a sudden rise of the barrier separating the two wells. We show that their phase content can be obtained by the full-counting statisti...
physics
6,798
Parametric amplification of vacuum fluctuations in a spinor condensate
cond-mat.quant-gas
Parametric amplification of vacuum fluctuations is crucial in modern quantum optics, enabling the creation of squeezing and entanglement. We demonstrate the parametric amplification of vacuum fluctuations for matter waves using a spinor F=2 Rb-87 condensate. Interatomic interactions lead to correlated pair creation in ...
physics
6,799
Localization of a Bose-Einstein condensate in a bichromatic optical lattice
cond-mat.quant-gas
By direct numerical simulation of the time-dependent Gross-Pitaevskii equation we study different aspects of the localization of a non-interacting ideal Bose-Einstein condensate (BEC) in a one-dimensional bichromatic quasi-periodic optical-lattice potential. Such a quasi-periodic potential, used in a recent experiment ...
physics