Realizing tunable non-Hermitian skin effects in dynamical quantum systems via the relative phase between multiple time-periodic driving

TL;DR

This paper shows how the relative phase in multiple time-periodic driving controls the emergence and direction of non-Hermitian skin effects in quantum systems, enabling tunable localization profiles.

Contribution

It introduces a method to manipulate non-Hermitian skin effects via the relative phase in dynamical driving, breaking temporal symmetry constraints.

Findings

Relative phase controls skin mode emergence and direction.

Dynamical driving reactivates skin effects in PT-symmetric chains.

Alteration of phase changes spatial structure and skin localization.

Abstract

We demonstrate how the relative phase between the multiple time periodic driving can decide the emergence and the favorable localization direction of non-Hermitian skin modes. For the static non-Hermitian quantum chain with parity time symmetry, non-Hermitian skin effects (NHSEs) can be prohibited. As the dynamical driving is turned on, NHSEs get artificially reactivated, where the relative phase can serve as the controlling switch by breaking the temporal symmetry constraints. Meanwhile, a change of relative phase can also alter the spatial structures of the long-time averaged effective Hamiltonian, which will consequently lead to the variation of skin localization direction for systems of higher dimensions. Our formalisms can be generally realized in diverse optical and mechanical platforms, and will pave the way for realizing tunable skin density profiles.