arXiv:1406.3821 · Nature Communications

Dynamical phases in quenched spin–orbit-coupled degenerate Fermi gas

Ying Dong, Lin Dong, Ming Gong, Han Pu

Published Jan 20, 2015• 43 citations

Abstract

The spin–orbit-coupled degenerate Fermi gas provides a new platform for realizing topological superfluids and related topological excitations. However, previous studies have been mainly focused on the topological properties of the stationary ground state. Here, we investigate the quench dynamics of a spin–orbit-coupled two-dimensional Fermi gas in which the Zeeman field serves as the major quench parameter. Three post-quench dynamical phases are identified according to the asymptotic behaviour of the order parameter. In the undamped phase, a persistent oscillation of the order parameter may support a topological Floquet state with multiple edge states. In the damped phase, the magnitude of the order parameter approaches a constant via a power-law decay, which may support a dynamical topological phase with one edge state at the boundary. In the overdamped phase, the order parameter decays to zero exponentially although the condensate fraction remains finite. These predictions can be observed in the strong-coupling regime. Spin–orbit-coupled Fermi gases have been shown to support exotic topological quantum states. Here, the authors investigate quench dynamics of these gases in two dimensions, and find that three different phases with different topological properties emerge depending on the behaviour of the order parameter.

DOI: 10.1038/ncomms7103

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