Emergence and scaling of spin turbulence in quenched antiferromagnetic spinor Bose-Einstein condensates

Abstract

We investigate the phase transition dynamics of a quasi-2D antiferromagnetic spin-1 Bose-Einstein condensate from the easy-axis polar phase to the easy-plane polar phase, which is initiated by suddenly changing the sign of the quadratic Zeeman energy q. We observe the emergence and decay of spin turbulence and the formation of half-quantum vortices (HQVs) in the quenched condensate. The characteristic time and length scales of the turbulence generation dynamics are proportional to |q| −1/2 as inherited from the dynamic instability of the initial state. In the evolution of the spin turbulence, spin wave excitations develop from large to small length scales, suggesting a direct energy cascade, and the spin population for the axial polar domains exhibit a nonexponential decay. The final equilibrated condensate contains HQVs, and the number is found to increase and saturate with increasing |q|. Our results demonstrate the time-space scaling properties of the phase transition dynamics near the critical point and the peculiarities of the spin turbulence state of the antiferromagnetic spinor condensate.

Crossover from weak to strong quench in a spinor Bose-Einstein condensate

“…We can see that, at around this point, the domain walls start forming in the quenched condensate, and the change indicates that the system enters a late-time stage where it undergoes coarsening and relaxation dynamics of the spin domains. This two-step evolution of the spin composition was also observed in the EAP-to-EPP transition dynamics [5,30].…”

“…[20,21]. Note that in our previous studies [5,7], we used a value of as = 0.823a 0 from [22]. tally verified in our recent measurement of the speed of spin sound [21].…”

“…Quantum-phase-transition dynamics is a fundamentally important subject concerning how a many-body quantum system evolves into a newly ordered state [1][2][3]. Recently, the quantum phase transition of spin-1 Bose-Einstein condensates (BECs) with antiferromagnetic interactions was investigated in ultracold atom experiments [4][5][6][7]. Involving both the superfluidity and magnetic ordering, the spinor BEC system has a rich phase diagram [8].…”

Exploring the thermodynamics of spin-1 Bose gases with synthetic magnetization

“…In addition, we demonstrated experimentally that controlling the synthetic magnetization we were able to explore the phase diagram of a spin-1 Bose gas using an atomic sample with total zero magnetization. The extension of the technique presented in this work opens new exciting possibilities to study out-of-equilibrium physics in ferromagnetic spinor gases after a sudden (isothermal) quench of the synthetic magnetization, a situation that remains unexplored in the burgeoning field of quenched spinor BECs, that is attracting increasing interest both theoretically [37,38] and experimentally [39].…”

Domain percolation in a quenched ferromagnetic spinor condensate

“…Spinor condensates have spin and gauge degrees of freedom and are novel systems for exploring various types of symmetry breaking phase transitions in an isolated and highly controllable quantum system [1,2]. For more than a decade a range of beautiful experiments have explored phase transitions and associated dynamics in spinor condensates [3][4][5][6][7][8][9][10][11][12]. Much theoretical work has been concerned with defect formation arising from how the phase transition is crossed (e.g.…”