Understanding the effects of spin-orbit coupling (SOC) and many-body interactions on spin transport is important in condensed matter physics and spintronics. This topic has been intensively studied for spin carriers such as electrons but barely explored for charge-neutral bosonic quasiparticles (including their condensates), which hold promises for coherent spin transport over macroscopic distances. Here, we explore the effects of synthetic SOC (induced by optical Raman coupling) and atomic interactions on the spin transport in an atomic Bose-Einstein condensate (BEC), where the spin-dipole mode (SDM, actuated by quenching the Raman coupling) of two interacting spin components constitutes an alternating spin current. We experimentally observe that SOC significantly enhances the SDM damping while reducing the thermalization (the reduction of the condensate fraction). We also observe generation of BEC collective excitations such as shape oscillations. Our theory reveals that the SOC-modified interference, immiscibility, and interaction between the spin components can play crucial roles in spin transport. Spin-orbit coupling is interesting for fundamental understanding of spin transport and quench dynamics. Here the authors demonstrate spin-current generation and its relaxation in spin-orbit-coupled Bose-Einstein condensates of Rb atoms in different spin states.

The spin dynamics of a harmonically trapped Bose-Einstein condensed binary mixture of sodium atoms is experimentally investigated at finite temperature. In the collisional regime the motion of the thermal component is shown to be damped because of spin drag, while the two condensates exhibit a counter flow oscillation without friction, thereby providing direct evidence for spin superfluidity. Results are also reported in the collisionless regime where the spin components of both the condensate a...

#1Lei Feng(U of C: University of Chicago)H-Index: 11

#2Logan W. Clark(U of C: University of Chicago)H-Index: 15

Last. Cheng Chin(U of C: University of Chicago)H-Index: 52

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Quantum phase transitions, transitions between many-body ground states, are of extensive interest in research ranging from condensed-matter physics to cosmology 1–4 . Key features of the phase transitions include a stage with rapidly growing new order, called inflation in cosmology 5 , followed by the formation of topological defects 6–8 . How inflation is initiated and evolves into topological defects remains a hot topic of debate. Ultracold atomic gas offers a pristine and tunable platform to ...

We investigate the universal dynamics of a continuous magnetic phase transition from a unmagnetized phase to a ferromagnetic phase in a spin-1 spin-orbit-coupled Bose-Einstein condensate. When the system approaches the critical point, the Landau critical velocity gradually decreases to zero and so the correlation length diverges. Therefore, during the slow passage through the critical point, ferromagnetic domains are spontaneously created according to the Kibble-Zurek mechanism. Through calculat...

By developing the hydrodynamic theory of spinor superfluids we calculate the moment of inertia of a harmonically trapped Bose-Einstein condensate with spin-orbit coupling. We show that the velocity field associated with the rotation of the fluid exhibits diffused vorticity, in contrast to the irrotational behavior characterizing a superfluid. Both Raman-induced and Rashba spin-orbit couplings are considered. In the first case the moment of inertia takes the rigid value at the transition between ...

#1Shimon Kolkowitz(CU: University of Colorado Boulder)H-Index: 14

#2Sarah Bromley(CU: University of Colorado Boulder)H-Index: 9

Last. Jun Ye(CU: University of Colorado Boulder)H-Index: 126

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Spin–orbit coupling is implemented in an optical lattice clock using a narrow optical transition in fermionic 87Sr atoms, thus mitigating the heating problems of previous experiments with alkali atoms and offering new prospects for future investigations.

#1Dmytro A. Bozhko(TUK: Kaiserslautern University of Technology)H-Index: 16

#2Alexander A. Serga(TUK: Kaiserslautern University of Technology)H-Index: 48

Last. Burkard Hillebrands(TUK: Kaiserslautern University of Technology)H-Index: 89

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Studies of supercurrent phenomena, such as superconductivity and superfluidity, are usually restricted to cryogenic temperatures, but evidence suggests that a magnon supercurrent can be excited in a Bose–Einstein magnon condensate at room temperature.

Supersolidity is an intriguing concept. It combines the property of superfluid flow with the long-range spatial periodicity of solids, two properties which are often mutually exclusive. The original discussion of quantum crystals and supersolidity focuses on solid Helium-4 where it was predicted that vacancies could form dilute weakly interacting Bose-Einstein condensates. In this system, direct observation of supersolidity has been elusive. The concept of supersolidity was then generalized to i...

Last. Jian-Wei Pan(USTC: University of Science and Technology of China)H-Index: 107

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Cold atoms with laser-induced spin-orbit (SO) interactions provide a platform to explore quantum physics beyond natural conditions of solids. Here we propose and experimentally realize two-dimensional (2D) SO coupling and topological bands for a rubidium-87 degenerate gas through an optical Raman lattice, without phase-locking or fine-tuning of optical potentials. A controllable crossover between 2D and 1D SO couplings is studied, and the SO effects and nontrivial band topology are observed by m...

We discuss the superfluid properties of a Bose-Einstein condensed gas with spin-orbit coupling, recently realized in experiments. We find a finite normal fluid density \rho_nat zero temperature which turns out to be a function of the Raman coupling. In particular, the entire fluid becomes normal at the transition point from the zero momentum to the plane wave phase, even though the condensate fraction remains finite. We emphasize the crucial role played by the gapped branch of the elementary ...

We explore the many-body phases of a two-dimensional Bose-Einstein condensate with cavity-mediated dynamic spin-orbit coupling. With the help of two transverse noninterfering, counterpropagating pump lasers and a single standing-wave cavity mode, two degenerate Zeeman sub-levels of the quantum gas are Raman coupled in a double-\mathrm{\ensuremath{\Lambda}}configuration. Beyond a critical pump strength the cavity mode is populated via coherent superradiant Raman scattering from the two pump la...

Geometry may arise from quantum systems in an unprecedented means such as the gauge theory/gravity dual. Whereas emergent geometries often occur in strongly correlated systems, one could ask whether simple quantum systems may also be used to unfold intriguing underlying geometries. Here, we show that quantum dynamics of Bose-Einstein condensates in the weakly interacting regime can be geometrized by a Poincar\'e disk. Each point on such a disk represents a thermofield double state, the fidelity ...

We study the dynamics of binary Bose-Einstein condensates made of ultracold and dilute alkali-metal atoms in a quasi-one-dimensional setting. Numerically solving the two coupled Gross-Pitaevskii equations which accurately describe the system dynamics, we demonstrate that the spin transport can be controlled by suitably quenching spin-orbit (SO) and Rabi coupling strengths. Moreover, we predict a variety of dynamical features induced by quenching: broken oscillations, breathers-like oscillating p...

#1Jieli Qin(Guangzhou Higher Education Mega Center)H-Index: 4

#2Lu Zhou(ECNU: East China Normal University)H-Index: 11

We study the transport of a spin-orbit-coupled atomic matter wave using a moving Dirac \deltapotential well. In a spin-orbit-coupled system, bound states can be formed in both ground and excited energy levels with a Dirac \deltapotential. Because Galilean invariance is broken in a spin-orbit-coupled system, moving of the potential will induce a velocity-dependent effective detuning. This induced detuning breaks the spin symmetry and makes the ground-state transporting channel be spin-$\upa...

#2Thomas Bersano(WSU: Washington State University)H-Index: 4

Last. Doerte Blume(OU: University of Oklahoma)H-Index: 17

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Double-well systems loaded with one, two, or many quantum particles give rise to intriguing dynamics, ranging from Josephson oscillation to self-trapping. This work presents theoretical and experimental results for two distinct double-well systems, both created using dilute rubidium Bose-Einstein condensates with particular emphasis placed on the role of interaction in the systems. The first is realized by creating an effective two-level system through Raman coupling of hyperfine states. The sec...

Last. Yongping Zhang(SHU: Shanghai University)H-Index: 18

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Synthetic spin-tensor-momentum coupling has recently been proposed to realize in atomic Bose-Einstein condensates. Here we study bright solitons in Bose-Einstein condensates with spin-tensor-momentum coupling and spin-orbit coupling. The properties and dynamics of spin-tensor-momentum-coupled and spin-orbit-coupled bright solitons are identified to be different. We contribute the difference to the different symmetries.

This authors predict that attractive spinor Bose-Einstein condensates under the action of spin-orbit coupling and Zeeman splitting form self-sustained stable two- and three-dimensional states in free space, even when spin-orbit coupling acts in a lower-dimensional form. The results offer an advantage for the potential experimental creation of multidimensional solitons

#1Maren Mossman(WSU: Washington State University)H-Index: 6

#2Junpeng Hou(UTD: University of Texas at Dallas)H-Index: 9

Last. Peter Engels(WSU: Washington State University)H-Index: 27

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Controlling magnetism through non-magnetic means is highly desirable for future electronic devices, as such means typically have ultra-low power requirements and can provide coherent control. In recent years, great experimental progress has been made in the field of electrical manipulation of magnetism in numerous material systems. These studies generally do not consider the directionality of the applied non-magnetic potentials and/or magnetism switching. Here, we theoretically conceive and expe...