arXiv subjects

Bo Xiong

Publications and source records attributed to Bo Xiong.

105 records · Page 6Linked to original sources

arXiv2013

Interaction-induced coherence among polar bosons stored in triple-well potentials

We study first-order spatial coherence for interacting polar bosons trapped in triple-well potentials. It is argued that besides the well-known coherence produced by couplings related to tunneling between the sites, there exists a nonlocal coherence predominantly determined by intersite interactions, which prevails between the outer sites of the triple well when their total filling is odd. We find that the nonlocal interaction-induced coherence originates from the superposition of degenerate many-body states in symmetric triple wells, and demonstrate its robustness against perturbations due to various tunneling mechanisms and thermal fluctuations.

cond-mat.quant-gas↗

arXiv2013

Robustness of fragmented condensate many-body states for continuous distribution amplitudes in Fock space

We consider a two-mode model describing scalar bosons with two-body interactions in a single trap, taking into account coherent pair-exchange between the modes. It is demonstrated that the resulting fragmented many-body states with continuous (nonsingular) Fock-space distribution amplitudes are robust against perturbations due to occupation number and relative phase fluctuations, Josephson-type tunneling between the modes, and weakly broken parity of orbitals, as well as against perturbations due to interaction with a third mode.

cond-mat.quant-gas↗

arXiv2013

P-wave Superfluidity by Blockade Effects in a Rydberg-Dressed Fermi Gas

We systematically investigate the p-wave superfluidity of a Rydberg-dressed Fermi gas, where the soft-core effective interaction is of finite radius $R_{c}$ due to blockade effects. After solving the BCS gap equation and comparing the free energy, we obtain the quantum phase diagram, which is composed of three different phases: polar ($p_{z}$), axial ($p_{x}+ip_{y}$), and axi-planar ($p_{x}+iβ_{p}p_{y}$) phases. The tri-critical point locates around $R_{c}k_{F}\sim1$, where $k_{F}$ is the Fermi wave vector. We further derive the Ginzburg-Landau theory to explain the phase diagram, and estimate the transition temperature to be about 0.1$E_{F}$ in the current experimental regime of $^{6}$Li. Our work paves the way for future studies on p-wave superfluids and related quantum phase transitions in ultracold atoms.

cond-mat.quant-gas↗

arXiv2013

Distortion of Interference Fringes and the Resulting Vortex Production of Merging Bose-Einstein Condensates

We investigate the effects of interatomic interactions and expansion on the distortion of interference fringes of a pair of initially well-separated, but coherent, condensate clouds trapped in a harmonic trap. The distortion of interference fringes, which can lead to the spontaneous formation of vortices in the atom clouds, depends crucially on two relevant parameters: the center-of-mass velocity and peak density of the initial state. We identify three qualitatively distinct regimes for the interfering condensates: collision, expansion, and merging, by the spatial and temporal features of the fringe spacings. Using a comprehensive set of numerical simulations based on the Gross-Pitaevskii equation, we specify the cross-overs between these regimes and propose the optimal the system parameters required for dynamical instabilities and vortex creation.

cond-mat.quant-gas↗

arXiv2012

Electromagnetic induced transparency and slow light in interacting quantum degenerate atomic gases

We systematically develop the full quantum theory for the electromagnetic induced transparency (EIT) and slow light properties in ultracold Bose and Fermi gases. It shows a very different property from the classical theory which assumes frozen atomic motion. For example, the speed of light inside the atomic gases can be changed dramatically near the Bose-Einstein condensation temperature, while the presence of the Fermi sea can destroy the EIT effect even at zero temperature. From experimental point of view, such quantum EIT property is mostly manifested in the counter-propagating excitation schemes in either the low-lying Rydberg transition with a narrow line width or in the D2 transitions with a very weak coupling field. We further investigate the interaction effects on the EIT for a weakly interacting Bose-Einstein condensate, showing an inhomogeneous broadening of the EIT profile and nontrivial change of the light speed due to the quantum many-body effects beyond mean field energy shifts.

cond-mat.quant-gas↗

arXiv2012

Identifying strongly correlated supersolid states on the optical lattice by quench-induced π-states

We consider the rapid quench of a one-dimensional strongly correlated supersolid to a localized density wave (checkerboard) phase, and calculate the first-order coherence signal following the quench. It is shown that unique coherence oscillations between the even and odd sublattice sites of the checkerboard are created by the quench, which are absent when the initial state is described by a Gutzwiller product state. This is a striking manifestation of the versatility of the far-from-equilbrium and nonperturbative collapse and revival phenomenon as a microscope for quantum correlations in complex many-body states. For the present example, this opens up the possibility to discriminate experimentally between mean-field and many-body origins of supersolidity.

cond-mat.quant-gas↗

arXiv2011

Many-site coherence revivals in the extended Bose-Hubbard model and the Gutzwiller approximation

We investigate the collapse and revival of first-order coherence in deep optical lattices when long-range interactions are turned on, and find that the first few revival peaks are strongly attenuated already for moderate values of the nearest-neighbor interaction coupling. It is shown that the conventionally employed Gutzwiller wavefunction, with only onsite-number dependence of the variational amplitudes, leads to incorrect predictions for the collapse and revival oscillations. We provide a modified variant of the Gutzwiller ansatz, reproducing the analytically calculated time dependence of first-order coherence in the limit of zero tunneling.

cond-mat.quant-gas↗

arXiv2011

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

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 similarity transformation. Their stability behavior has been examined by numerical simulation, which shows that a new series of stable vortex states (defined by radial and angular quantum numbers) can be supported by the spatiotemporally modulated interaction in this system. We find that there exist stable quantized vortices with large topological charges in repulsive condensates with spatiotemporally modulated interaction. We also give an experimental protocol to observe these vortex states in future experiments.

cond-mat.quant-gas↗

arXiv2011

Emergence of a new pair-coherent phase in many-body quenches of repulsive bosons

We investigate the dynamical mode population statistics and associated first- and second-order coherence of an interacting bosonic two-mode model when the pair-exchange coupling is quenched from negative to positive values. It is shown that for moderately rapid second-order transitions, a new pair-coherent phase emerges on the positive coupling side in an excited state, which is not fragmented as the ground-state single-particle density matrix would prescribe it to be.

cond-mat.quant-gas↗

arXiv2010

Spontaneous Parity--Time Symmetry Breaking and Stability of Solitons in Bose-Einstein Condensates

We report explicitly a novel family of exact PT-symmetric solitons and further study their spontaneous PT symmetry breaking, stabilities and collisions in Bose-Einstein condensates trapped in a PT-symmetric harmonic trap and a Hermite-Gaussian gain/loss potential. We observe the significant effects of mean-field interaction by modifying the threshold point of spontaneous PT symmetry breaking in Bose-Einstein condensates. Our scenario provides a promising approach to study PT-related universal behaviors in non-Hermitian quantum system based on the manipulation of gain/loss potential in Bose-Einstein condensates.

cond-mat.quant-gas↗

arXiv2009

Symmetry Breaking and Self-trapping of a Dipolar Bose-Einstein Condensate in a Double-well Potential

The quantum self-trapping phenomenon of a Bose-Einstein condensate (BEC) represents a remarkable nonlinear effect of wide interest. By considering a purely dipolar BEC in a double-well potential, we study how the dipole orientation affects the ground state structure and the transition between self-trapping and Josephson oscillation in dynamics. Three-dimensional numerical results and an effective two-mode model demonstrate that the onset of self-trapping of a dipolar BEC can be radically modified by the dipole orientation. We also analyze the failure of the two-mode model in predicting the rate of Josephson oscillations. We hope that our results can motivate experimental work as well as future studies of self-trapping of ultracold dipolar gases in optical lattices.

cond-mat.other↗

arXiv2008

Formation and Transformation of Vector-Solitons in Two-Species Bose-Einstein Condensates with Tunable Interaction

Under a unified theory we investigate the formation of various types of vector-solitons in two-species Bose-Einstein condensates with arbitrary scattering lengths. We then show that by tuning the interaction parameter via Feshbach resonance, transformation between different types of vector solitons is possible. Our results open up new ways in the quantum control of multi-species Bose-Einstein condensates.

cond-mat.other↗

arXiv2007

Internal Josephson-Like Tunneling in Two-Component Bose-Einstein Condensates Affected by Sign of the Atomic Interaction and External Trapping Potential

We study the Josephson-like tunneling in two-component Bose-Einstein condensates coupled with microwave field in respond to various attractive and repulsive atomic interaction under the various aspect ratio of trapping potential and the gravitational field. It is very interesting to find that the dynamic of Josephson-like tunneling can be controlled from fast damped oscillations and asymmetric occupation to nondamped oscillation and symmetric occupation.

cond-mat.other↗

arXiv2007

Controllable Josephson-Like Tunneling in Two-Component Bose-Einstein Condensates Coupled with Microwave via Feshbach Resonance and Trapping Potential

We put forward a scheme for controlling Josephson-like tunneling in two-component Bose-Einstein condensates coupled with microwave field via Feshbach resonance and tuning aspect ratio of trapping potential. We prove how to realize a perfect periodic oscillation from a fast damped and irregular oscillation on relative number of atoms in future experiment. In particular, intensity of Josephson-like tunneling can be successfully controlled through controlling speed of recovering the initial value of intra-atomic interaction and aspect ratio of trapping potential. Interestingly, we find that relative number of atoms represents two different types of oscillation in respond to periodic modulation of attractive intra-atomic interaction.

cond-mat.other↗

arXiv2007

Localized Asymmetric Atomic Matter Waves in Two-Component Bose-Einstein Condensates Coupled with Two Photon Microwave Field

We investigate localized atomic matter waves in two-component Bose-Einstein condensates coupled by the two photon microwave field. Interestingly, the oscillations of localized atomic matter waves will gradually decay and finally become non-oscillating behavior even if existing coupling field. In particular, atom numbers occupied in two different hyperfine spin states will appear asymmetric occupations after some time evolution.

nlin.PS↗