Protected quantum coherence by gain and loss in a noisy quantum kicked rotor

Abstract

We study the effects of non-Hermiticity on quantum coherence via a noisy quantum kicked rotor (NQKR). The random noise comes from the fluctuations in kick amplitude at each time. The non-Hermitian driving indicates the imaginary kicking potential, representing the environment-induced atom gain and loss. In the absence of gain and loss, the random noise destroys quantum coherence manifesting dynamical localization, which leads to classical diffusion. Interestingly, in the presence of non-Hermitian kicking potential, the occurrence of dynamical localization is highly sensitive to the gain and loss, manifesting the restoration of quantum coherence. Using the inverse participation ratio arguments, we numerically obtain a phase diagram of the classical diffusion and dynamical localization on the parameter plane of noise amplitude and non-Hermitian driving strength. With the help of analysis on the corresponding quasieigenstates, we achieve insight into dynamical localization, and uncover that the origin of the localization is interference between multiple quasi-eigenstates of the quantum kicked rotor. We further propose an experimental scheme to realize the NQKR in a dissipative cold atomic gas, which paves the way for future experimental investigation of an NQKR and its anomalous non-Hermitian properties.

Dynamical localization in a non-Hermitian Floquet synthetic system

“…[47][48][49] Recently, the extension of Floquet synthetic systems to non-Hermitian regime enables the investigations on novel physics that might not be easily achievable in Hermitian settings. It is found that the combination of non-Hermiticity and nonlinear interaction leads to superexponentially fast energy diffusion, [50] the non-Hermitian driven potential enhances the degree of DL [51][52][53][54] and induces the quantum criticality of information scrambling. [55] The versatile nature of Floquet synthetic systems opens the opportunity for exploring diverse regimes of quantum behavior by tailoring system parameters and controlling interactions.…”