arXiv subjects

Linghua Wen

Publications and source records attributed to Linghua Wen.

17 recordsLinked to original sources

arXiv2025

Chiral supersolid and dissipative time crystal in Rydberg-dressed Bose-Einstein condensates with Raman-induced spin-orbit coupling

Spin-orbit coupling (SOC) is one of the crucial factors that affect the chiral symmetry of matter by causing the spatial symmetry breaking of the system. We find that Raman-induced SOC can induce a chiral supersolid phase with a helical antiskyrmion lattice in balanced Rydberg-dressed two-component Bose-Einstein condensates (BECs) in a harmonic trap by modulating the Raman coupling strength. This is in stark contrast to the mirror symmetric supersolid phase containing skyrmion-antiskyrmion lattice pair for the case of Rashba SOC. Two ground-state phase diagrams are presented as a function of the Rydberg interaction and the Raman-induced SOC. It is shown that the interplay among Raman-induced SOC, Rydberg interactions, and nonlinear contact interactions favors rich ground-state structures, including half-quantum vortex phase, stripe supersolid phase, toroidal stripe phase with a central Anderson-Toulouse coreless vortex, checkerboard supersolid phase, mirror symmetric supersolid phase, chiral supersolid phase and standing-wave supersolid phase. In addition, the effects of rotation and in-plane quadrupole magnetic field on the ground state of the system are analyzed. In these two cases, the chiral supersolid phase is broken and the ground state tends to form a miscible phase. Furthermore, we demonstrate that when the initial state is a chiral supersolid phase the rotating harmonic trapped system sustains dissipative continuous time crystal by studying the rotational dynamic behaviors of the system.

cond-mat.quant-gas↗

arXiv2024

Ground-state properties of dipolar Bose-Einstein condensates with spin-orbit coupling and quantum fluctuations

We study the ground-state properties of dipolar spin-1/2 Bose-Einstein condensates with quantum fluctuations and Rashba spin-orbit coupling (SOC). The combined effects of dipole-dipole interaction (DDI), SOC, and Lee-Huang-Yang (LHY) correction induced by quantum fluctuations on the ground-state structures and spin textures of the system are analyzed and discussed. For the nonrotating case and fixed nonlinear interspecies contact interaction strengths, our results show that structural phase transitions can be achieved by adjusting the strengths of the DDI and LHY correction. In the absence of SOC, a ground-state phase diagram is given with respect to the DDI strength and the LHY correction strength. We find that the system exhibits rich quantum phases including square droplet lattice phase, annular phase, loop-island structure, stripe-droplet coexistence phase, toroidal stripe phase, and Thomas-Fermi (TF) phase. For the rotating case, the increase of DDI strength can lead to a quantum phase transition from superfluid phase to supersolid phase. In the presence of SOC, the quantum droplets display obvious stretching and hidden vortex-antivortex clusters are formed in each component. In particular, weak or moderate SOC favors the formation of droplets while for strong SOC the ground state of the system develops into a stripe phase with hidden vortex-antivortex clusters. Furthermore, the system sustains exotic spin textures and topological excitations, such as composite skyrmion-antiskyrmion-meron-antimeron cluster, meron-antimeron string cluster, antimeron-meron-antimeron chain cluster, and peculiar skyrmion-antiskyrmion-meron-antimeron necklace with a meron-antimeron necklace embedded inside and a central spin Neel domain wall.

cond-mat.quant-gas↗

arXiv2021

Dynamics of rotating spin-orbit-coupled Bose-Einstein condensates in a quasicrystalline optical lattice

We investigate the dynamics of rotating pseudo-spin-1/2 Bose-Einstein condensates (BECs) with Rashba spin-orbit coupling (SOC) in a quasicrystalline optical lattice (QOL). For given parameters, the system evolves from an initial heliciform-stripe phase into a final visible vortex necklace with a giant vortex and a hidden vortex necklace. Simultaneously, the corresponding spin texture undergoes a transition from a meron-antimeron pair to a half-antiskyrmion necklace. During the dynamic evolution process, the angular momentum increases gradually, and then approaches to a convergent value. Furthermore, typical quantum phases of rotating two-component BECs with SOC in different external potentials are summarized.

cond-mat.quant-gas↗

arXiv2021

Dynamics of kicked spin-orbit-coupled Bose-Einstein condensates

We investigate the dynamics of kicked pseudo-spin-1/2 Bose-Einstein condensates (BECs) with spin-orbit coupling (SOC) in a tightly confined toroidal trap. The system exhibits different dynamical behaviors depending on the competition among SOC, kick strength, kick period and interatomic interaction. For weak kick strength, with the increase of SOC the density profiles of two components evolve from overlapped symmetric distributions into staggered antisymmetric distributions, and the evolution of energy experiences a transition from quasiperiodic motion to modulated quantum beating. For large kick strength, when the SOC strength increases, the overlapped symmetric density distributions become staggered irregular patterns, and the energy evolution undergoes a transition from quasiperiodic motion to dynamical localization. Furthermore, in the case of weak SOC, the increase of kick period leads to a transition of the system from quantum beating to Rabi oscillation, while for the case of strong SOC the system demonstrates complex quasiperiodic motion.

cond-mat.quant-gas↗

arXiv2020

Topological defects in rotating spin-orbit-coupled dipolar spin-1 Bose-Einstein condensates

We consider the topological defects and spin structures of spin-1 Bose-Einstein condensates (BECs) with spin-orbit coupling (SOC) and dipole-dipole interaction (DDI) in a rotating harmonic plus quartic trap. The combined effects of SOC, DDI and rotation on the ground-state phases of the system are analyzed. Our results show that for fixed rotation frequency structural phase transitions can be achieved by adjusting the magnitudes of the SOC and DDI. A ground-state phase diagram is given as a function of the SOC and DDI strengths. It is shown that the system exhibits rich quantum phases including vortex string phase with isolated density peaks (DPs), triangular (square) vortex lattice phase with DPs, checkerboard phase, and stripe phase with hidden vortices and antivortices. For given SOC and DDI strengths, the system can display pentagonal vortex lattice with DPs, vortex necklace with DPs, and exotic topological structure composed of multi-layer visible vortex necklaces, a hidden giant vortex and hidden vortex necklaces, depending on the rotation frequency. In addition, the system sustains fascinating novel spin textures and skyrmion excitations, such as an antiskyrmion pair, antiskyrmion-half-antiskyrmion (antiskyrmion-antimeron) cluster, skyrmion-antiskyrmion lattice, skyrmion-antiskyrmion cluster, skyrmion-antiskyrmion-meron-antimeron lattice, double-layer half-antiskyrmion necklaces, and composite giant-antiskyrmion-antimeron necklaces.

cond-mat.quant-gas↗

arXiv2019

Topological defects of spin-orbit coupled Bose-Einstein condensates in a rotating anharmonic trap

We investigate the topological defects and spin structures of binary Bose-Einstein condensates (BECs) with Dresselhaus spin-orbit coupling (D-SOC) in a rotating anharmonic trap. Our results show that for initially mixed BECs without SOC the increasing rotation frequency can lead to the structural phase transition of the system. In the presence of isotropic D-SOC, the system sustains vortex pair,Anderson--Toulouse coreless vortices, circular vortex sheets, and combined vortex structures. In particular, when the rotation frequency is fixed above the radial trapping frequency the strong D-SOC results in a peculiar topological structure which is comprised of multi-layer visible vortex necklaces, hidden vortex necklaces and a hidden giant vortex. In addition, the system exhibits rich spin textures including basic skyrmion, meron cluster, skyrmion string and various skyrmion lattices. The skyrmions will be destroyed in the limit of large D-SOC or rotation frequency. Furthermore, the effects of anisotropic D-SOC and Rashba-Dresselhaus SOC on the topological structures of the system are discussed.

cond-mat.quant-gas↗

arXiv2019

Ground-state properties of spin-orbit-coupled dipolar Bose-Einstein condensates with in-plane gradient magnetic field

We investigate the ground-state properties of spin-orbit-coupled pseudo-spin-1/2 dipolar Bose-Einstein condensates (BECs) in a two-dimensional harmonic trap and an in-plane quadrupole field. The effects of spin-orbit coupling (SOC), dipole-dipole interaction (DDI) and the in-plane quadrupole field on the ground-state structures and spin textures of the system are systematically analyzed and discussed. For fixed SOC and DDI strengths, the system shows a quadrupole stripe phase with a half-quantum vortex, or a quadrupole Thomas-Fermi phase with a half-quantum antivortex for small quadrupole field strength, depending on the ratio between inter- and intraspecies interaction. As the quadrupole field strength enhances, the system realizes a ring mixed phase with a hidden vortex-antivortex cluster rather than an ordinary giant vortex in each component. Of particular interest, when the strengths of DDI and quadrupole field are fixed, strong SOC leads to the formation of criss-crossed vortex string structure. For given SOC and quadrupole field, the system for strong DDI displays a sandwich-like structure, or a special delaminated structure with a prolate antivortex in the spin-up component. In addition, typical spin textures for the ground states of the system are analyzed. It is shown that the system sustains exotic topological structures, such as a hyperbolic spin domain wall, skyrmion-half-antiskyrmion-antiskyrmion lattice, half-skyrmion-skyrmion-half-antiskyrmion lattice, and a drum-shaped antimeron.

cond-mat.quant-gas↗

arXiv2019

Topological excitations in rotating Bose-Einstein condensates with Rashba-Dresselhaus spin-orbit coupling in a two-dimensional optical lattice

We study the ground-state configurations and spin textures of rotating two-component Bose-Einstein condensates (BECs) with Rashba-Dresselhaus spin-orbit coupling (RD-SOC), which are confined in a two-dimensional (2D) optical lattice plus a 2D harmonic trap. In the absence of rotation, a relatively small isotropic 2D RD-SOC leads to the generation of ghost vortices for initially miscible BECs, while it gives rise to the creation of rectangular vortex-antivortex lattices for initially immiscible BECs. As the strength of the 2D RD-SOC enhances, the visible vortices or the 2D vortex-antivortex chains are created for the former case, whereas the rectangular vortex-antivortex lattices are transformed into vortex-antivortex rings for the later case. For the initially immiscible BECs with fixed 2D RD-SOC strength, the increase of rotation frequency can result in the structural phase transition from square vortex lattice to irregular triangular vortex lattice and the system transition from initial phase separation to phase mixing. In addition, we analyze the combined effects of 1D RD-SOC and rotation on the vortex configurations of the ground states for the case of initial phase separation. The increase of 1D SOC strength, rotation frequency or both of them may result in the formation of vortex chain and phase mixing. Furthermore, the typical spin textures for both the cases of 2D RD-SOC and 1D RD-SOC are discussed. It is shown that the system favors novel spin textures and skyrmion configurations including an exotic skyrmion-half-skyrmion lattice (skyrmion-meron lattice), a complicated meron lattice, a skyrmion chain, and a Bloch domain wall.

cond-mat.quant-gas↗

arXiv2019

Ground states of dipolar spin-orbit-coupled Bose-Einstein condensates in a toroidal trap

We investigate the ground-state structures of dipolar spin-orbit-coupled Bose-Einstein condensates in a toroidal trap. Combined effects of dipole-dipole interaction (DDI) and spin-orbit coupling (SOC) on the ground states of the system are discussed. A ground-state phase diagram is obtained as a function of the SOC and DDI strengths. As two new degrees of freedom, the DDI and SOC can be used to obtain the desired ground-state phases and to control the phase transition between various ground states. In particular, the system displays exotic topological structures and spin textures, such as half-quantum vortex, vortex string, vortex necklace, complex vortex lattice including giant vortex and hidden antivortex chains, different skyrmions, meron (half-skyrmion)-antimeron (half-antiskyrmion) necklace, and composite meron-antimeron lattice.

cond-mat.quant-gas↗

arXiv2017

Vortex states and spin textures of rotating spin-orbit-coupled Bose-Einstein condensates in a toroidal trap

We consider the ground-state properties of Rashba spin-orbit-coupled pseudo-spin-1/2 Bose-Einstein condensates (BECs) in a rotating two-dimensional (2D) toroidal trap. In the absence of spin-orbit coupling (SOC), the increasing rotation frequency enhances the creation of giant vortices for the initially miscible BECs, while it can lead to the formation of semiring density patterns with irregular hidden vortex structures for the initially immiscible BECs. Without rotation, strong 2D isotropic SOC yields a heliciform-stripe phase for the initially immiscible BECs. Combined effects of rotation, SOC, and interatomic interactions on the vortex structures and typical spin textures of the ground state of the system are discussed systematically. In particular, for fixed rotation frequency above the critical value, the increasing isotropic SOC favors a visible vortex ring in each component which is accompanied by a hidden giant vortex plus a (several) hidden vortex ring(s) in the central region. In the case of 1D anisotropic SOC, large SOC strength results in the generation of hidden linear vortex string and the transition from initial phase separation (phase mixing) to phase mixing (phase separation). Furthermore, the peculiar spin textures including skyrmion lattice, skyrmion pair and skyrmion string are revealed in this system.

cond-mat.quant-gas↗

arXiv2015

Stationary states and quantum quench dynamics of Bose-Einstein condensates in a double-well potential

We consider the properties of stationary states and the dynamics of Bose-Einstein condensates (BECs) in a double-well (DW) potential with pair tunneling by using a full quantum-mechanical treatment. Furthermore, we study the quantum quench dynamics of the DW system subjected to a sudden change of the Peierls phase. It is shown that strong pair tunneling evidently influences the energy spectrum structure of the stationary states. For relatively weak repulsive interatomic interactions, the dynamics of the DW system with a maximal initial population difference evolves from Josephson oscillations to quantum self-trapping as one increases the pair tunneling strength, while for large repulsion the strong pair tunneling inhibits the quantum self-trapping. In the case of attractive interatomic interactions, strong pair tunneling tends to destroy the Josephson oscillations and quantum self-trapping, and the system eventually enters a symmetric regime of zero population difference. Finally, the effect of the Peierls phase on the quantum quench dynamics of the system is analyzed and discussed. These new features are remarkably different from the usual dynamical behaviors of a BEC in a DW potential.

cond-mat.quant-gas↗

arXiv2014

Structure and dynamics of a rotating superfluid Bose-Fermi mixture

We investigate the structure and dynamics of a rotating superfluid Bose-Fermi mixture (SBFM) made of superfluid bosons and two-component (spin up and down) superfluid fermions. A ground-state phase diagram for the nonrotating case of a SBFM with specific parameters is given, where the ground-state configuration of a nonrotating SBFM is mainly determined by the boson-fermion interaction. For the rotating case of a SBFM with a sufficiently large rotation frequency, we show that the system supports a mixed phase and three typical layer separated phases. In particular, the visible vortex formation in the fermionic superfluid exhibits a remarkable hysteresis effect during the dynamical evolution of a rotating SBFM, which is evidently different from the case of rotating two-component Bose-Einstein condensates.

cond-mat.quant-gas↗

arXiv2013

Structure of two-component Bose-Einstein condensates with respective vortex-antivortex superposition states

We investigate the phase structure of two-component Bose-Einstein condensates (BECs) with repulsive intra- and interspecies interactions in the presence of respective vortex-antivortex superposition states (VAVSS). We show that different winding numbers of vortex and antivortex and different intra- and interspecies interaction strengths may lead to different phase configurations, such as fully separated phases, inlaid separated phases, asymmetric separated phase, and partially mixed phases, where the density profile of each component displays a petal-like (or modulated petal-like) structure. A phase diagram is given for the case of equal unit winding numbers of the vortex and antivortex in respective components, and it is shown that conventional criterion for phase separation of two-component BECs is not applicable for the present system due to the VAVSS. In addition, our nonlinear stability analysis indicates that the typical phase structures of two-component BECs with VAVSS allow to be detected in experiments. Moreover, for the case of unequal winding numbers of the vortex and antivortex in respective components, we find that each component in any of the possible phase structures is in a cluster state of vortices and antivortices, where the topological defects appear in the form of singly quantized visible vortex, or hidden vortex, or ghost vortex, depending on the specific parameters of the system. Finally, a general rule between the vortex-antivortex cluster state and the winding numbers of vortex and antivortex is revealed.

cond-mat.quant-gas↗

arXiv2012

Formation and structure of vortex lattices in a rotating double-well Bose-Einstein condensate

We investigate the dynamics of vortex formation and the structure of vortex lattices in a Bose-Einstein condensate confined within a rotating double-well (DW) potential. The dynamical process is a formation process of "ghost" vortices, "hidden" vortices and "visible" vortices. The critical rotation frequency for the creation of visible vortex is indicated by a sudden jump in the angular momentum evolution and an inflexion in the energy evolution. Different visible vortex structures can be formed by ruling the rotation frequency. In particular, structural change of visible vortex patterns can be achieved by regulating the anisotropy parameter of the DW potential. This feature allows to flexibly control the distribution of angular momentum in macroscopic quantum systems and study the interplay among rotation, interparticle interaction and external potential in superfluids.

cond-mat.quant-gas↗

arXiv2010

Structure and stability of quasi-two-dimensional boson-fermion mixtures with vortex-antivortex superposed states

We investigate the equilibrium properties of a quasi-two-dimensional degenerate boson-fermion mixture (DBFM) with a bosonic vortex-antivortex superposed state (VAVSS) using a quantum-hydrodynamic model. We show that, depending on the choice of parameters, the DBFM with a VAVSS can exhibit rich phase structures. For repulsive boson-fermion (BF) interaction, the Bose-Einstein condensate (BEC) may constitute a petal-shaped "core" inside the honeycomb-like fermionic component, or a ring-shaped joint "shell" around the onion-like fermionic cloud, or multiple segregated "islands" embedded in the disc-shaped Fermi gas. For attractive BF interaction just below the threshold for collapse, an almost complete mixing between the bosonic and fermionic components is formed, where the fermionic component tends to mimic a bosonic VAVSS. The influence of an anharmonic trap on the density distributions of the DBFM with a bosonic VAVSS is discussed. In addition, a stability region for different cases of DBFM (without vortex, with a bosonic vortex, and with a bosonic VAVSS) with specific parameters is given.

cond-mat.quant-gas↗

arXiv2010

Hidden vortices in a Bose-Einstein condensate in a rotating double-well potential

We study vortex formation in a Bose-Einstein condensate in a rotating double-well potential. Besides the ordinary quantized vortices and elusive ghost vortices, "hidden" vortices are found distributing along the central barrier. These hidden vortices are invisible like ghost vortex but carry angular momentum. Moreover, their core size is not given by the healing length, but is strongly influenced by the external potential. We find that the Feynman's rule can be well satisfied only after including the hidden vortices. There is no critical rotating frequency for the formation of hidden vortex while there is one for the formation of ordinary visible vortices. Hidden vortices can be revealed in the free expansion of the Bose-Einstein condensates. In addition, the hidden vortices in a Bose-Einstein condensate can appear in other external potentials, such as a rotating anisotropic toroidal trap.

cond-mat.quant-gas↗

arXiv2005

Interference of Bose-Einstein condensates and entangled single-atom state in a spin-dependent optical lattice

We present a theoretical model to investigate the interference of an array of Bose-Einstein condensates loaded in a one-dimensional spin-dependent optical lattice, which is based on an assumption that for the atoms in the entangled single-atom state between the internal and the external degrees of freedom each atom interferes only with itself. Our theoretical results agree well with the interference patterns observed in a recent experiment by Mandel et al. [Phys. Rev. Lett. 91, 010407 (2003)]. In addition, an experimental suggestion of nonuniform phase distribution is proposed to test further our theoretical model and prediction. The present work shows that the entanglement of a single atom is sufficient for the interference of the condensates confined in a spin-dependent optical lattice and this interference is irrelevant with the phases of individual condensates, i.e., this interference arises only between each condensate and itself and there is no interference effect between two arbitrary different condensates.

cond-mat.stat-mech↗