Chaos-driven dynamics in spin-orbit coupled atomic gases

TL;DR

This paper investigates how chaos influences the quantum dynamics of spin-orbit coupled atomic gases after a quench, revealing thermalization, quantum scars, and effects near Dirac points within experimentally relevant conditions.

Contribution

It demonstrates the impact of anisotropic spin-orbit coupling on chaos and thermalization, and identifies quantum scars and non-adiabatic effects near Dirac points in atomic gases.

Findings

System thermalizes in a quantum sense within experimental timescales.

Equilibration time scales logarithmically with inverse Planck's constant.

Quantum scars characterized by localized atomic density at specific energies.

Abstract

The dynamics, appearing after a quantum quench, of a trapped, spin-orbit coupled, dilute atomic gas is studied. The characteristics of the evolution is greatly influenced by the symmetries of the system, and we especially compare evolution for an isotropic Rashba coupling and for an anisotropic spin-orbit coupling. As we make the spin-orbit coupling anisotropic, we break the rotational symmetry and the underlying classical model becomes chaotic; the quantum dynamics is affected accordingly. Within experimentally relevant time-scales and parameters, the system thermalizes in a quantum sense. The corresponding equilibration time is found to agree with the Ehrenfest time, i.e. we numerically verify a ~log(1/h) scaling. Upon thermalization, we find the equilibrated distributions show examples of quantum scars distinguished by accumulation of atomic density for certain energies. At shorter time-scales we discuss non-adiabatic effects deriving from the spin-orbit coupled induced Dirac point. In the vicinity of the Dirac point, spin fluctuations are large and, even at short times, a semi-classical analysis fails.