Dynamical transition of quantum scrambling in a non-Hermitian Floquet synthetic system

TL;DR

This paper explores how non-Hermitian effects influence quantum scrambling dynamics in a Floquet system, revealing a transition between freezing and chaotic phases driven by the real and imaginary parts of the kicking potential.

Contribution

It introduces a non-Hermitian Floquet model with quasi-periodic modulation to study quantum scrambling and uncovers the mechanisms behind phase transitions in this context.

Findings

Transition from freezing to chaotic scrambling with increasing real part of potential

Suppression of scrambling by increasing imaginary part of potential

Extension of Floquet theory to non-Hermitian systems

Abstract

We investigate the dynamics of quantum scrambling, characterized by the out-of-time ordered correlators (OTOCs), in a non-Hermitian quantum kicked rotor subjected to quasi-periodical modulation in kicking potential. Quasi-periodic modulation with incommensurate frequencies creates a high-dimensional synthetic space, where two different phases of quantum scrambling emerge: the freezing phase characterized by the rapid increase of OTOCs towards saturation, and the chaotic scrambling featured by the linear growth of OTOCs with time. We find the dynamical transition from the freezing phase to the chaotic scrambling phase, which is assisted by increasing the real part of the kicking potential along with a zero value of its imaginary part. The opposite transition occurs with the increase in the imaginary part of the kicking potential, demonstrating the suppression of quantum scrambling by non-Hermiticity. The underlying mechanism is uncovered by the extension of the Floquet theory. Possible applications in the field of quantum information are discussed.