Quench dynamics of an open quantum system

Pablo Bayona-Pena, Ryo Hanai, Takashi Mori +1 more

It has recently been established that open quantum systems may exhibit a strong spectral sensitivity to boundary conditions, known as the non-Hermitian/Liouvillian skin effect (NHSE/LSE), making the topological properties of the system boundary-condition sensitive. In this Letter, we ask the query: Can topological phase transitions of open quantum systems, captured by open boundary conditioned invariants, be observed in the dynamics of a system under periodic boundary conditions, even in the presence of NHSE/LSE? We affirmatively respond to this question, by considering the quench dynamics of entanglement spectrum in a periodic open quantum fermionic system. We demonstrate that the entanglement spectrum exhibits zero-crossings only when this periodic system is quenched from a topologically trivial to nontrivial phase, defined from the spectrum under open boundary conditions, even in systems featuring LSE. Our results reveal that non-Hermitian topological phases leave a distinctive imprint on the unconditional dynamics within a subsystem of fermionic systems.

Jarrett L. Lancaster

Zhexuan Gong

Andrei A. Zvyagin

Dynamical non-equilibrium effects after a quantum quench in a quantum spin system, which permits exact analytical solution in both closed and open cases, are studied. The exact analytic results are obtained for the bi-axial paramagnet, both for the “easy axis”- and the “easy-plane”-like situations, and for the field directed along both principal axes of the system. Quantum quench of the external magnetic field produces a nonlinear response. For the closed system the average magnetic moment oscillates with time and with the final value of the external field. Such oscillations exist also for the open system, connected to the bath, in the dynamical regime. For the steady-state regime in the open case the oscillations are damped. Non-equilibrium effects yield specific hysteresis phenomena in the considered single spin system.

Vincenzo Alba, Federico Carollo

The spreading of information forms the basis of several quantum nonequilibrium phenomena, such as seen in the emergence of thermodynamics and statistical physics. Recently, much progress has been made in understanding the dynamics of information in isolated integrable systems after a quantum quench, by using a quasiparticle picture predicting ballistic spreading of quantum correlations. This paper shows how to apply these ideas to describe the dissipative dynamics of correlations and of entanglement in open quantum many-body systems.

Gernot Schaller