Spin current generation and relaxation in a quenched spin-orbit-coupled Bose-Einstein condensate

Abstract

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.

Rabi oscillations and Ramsey-type pulses in ultracold bosons: Role of interactions

“…When the discussion is specific to one of the scenarios, we use, respectively, Ω R (t) and Ω L (t) for the Raman and lattice coupling cases [correspondingly, Ω 0 in Eqs. ( 5) and (6) below are replaced by Ω 0,R and Ω 0,L , respectively]. The coupling, which is assumed to be real, is turned on at time t start , where t = 0 is the time at which the trapping potential is removed.…”

“…For an interacting ensemble of particles, the Rabi oscillations are, in general, further modified. In particular, the population oscillations may not be fully periodic and the amplitude of the oscillations may decrease or drift (dephase) due to many-body effects [4][5][6].…”

Supersolid-like solitons in spin-orbit coupled spin-2 condensate

“…The same was realized in experiments by creating non-abelian gauge potentials through Raman lasers which coherently couple the spin-component states of a spinor Bose-Einstein condensate (BEC) [2][3][4][5]. An SOcoupled BEC has been used as a quantum simulator to study spin-Hall effect [6], fractional topological insulators [7], and spin-current generation [8], etc. [9].…”

SU(3) Spin–Orbit Coupled Rotating Bose–Einstein Condensate Subject to a Gradient Magnetic Field

“…Recently, Han and his co-authors have considered a homogenous SU(3) SO-coupled Bose gas and obtained the double-quantum spin vortices [27]. On the base of their pioneering research work, Li and Chen have studied the SU(3) SO-coupled BEC confined in a harmonic plus quartic trap [28]. Very recently, the ground states of a harmonically trapped spin-1 BEC with SU(3) BEC affected by the external rotation are investigated in [29], where a clover-type ground-state structure is discovered.…”