Quantum Dynamical Phase Transition in a Spin-Orbit Coupled Bose Condensate

TL;DR

This paper investigates a quantum dynamical phase transition in a spin-orbit coupled Bose condensate, revealing how external perturbations induce phase transitions between magnetized states, with implications for experimental observation.

Contribution

It introduces the concept of a quantum dynamical phase transition in a many-body Bose system, showing how particle interactions prevent transitions below a critical perturbation strength.

Findings

Transition occurs only when external perturbation exceeds a critical value.

The critical point behavior is exactly solvable.

Predicted effects are observable with current experimental setups.

Abstract

Spin-orbit coupled bosons can exhibit rich equilibrium phases at low temperature and in the presence of particle-particle interactions. In the case with a 1D synthetic spin-orbit interaction, it has been observed that the ground state of a Bose gas can be a normal phase, stripe phase, or magnetized phase in different experimentally controllable parameter regimes. The magnetized states are doubly degenerate and consist of a many-particle two-state system. In this work, we investigate the nonequilibrium quantum dynamics by switching on an external perturbation to induce resonant couplings between the magnetized phases, and predict the novel quantum spin dynamics which cannot be obtained in the single-particle systems. In particular, due to particle-particle interactions, the transition of the Bose condensate from one magnetized phase to the other is forbidden when the strength of external perturbation is less than a critical value, and a full transition can occur only when the perturbation exceeds such critical strength. This phenomenon manifests itself a quantum dynamical phase transition, with the critical point behavior being exactly solvable. From the numerical simulations and exact analytic studies we show that the predicted many-body effects can be well observed with the current experiments.