Initial-state-dependent dephasing effect in non-Hermitian Su-Schrieffer-Heeger models

Abstract

Understanding the dynamical evolution of non-Hermitian systems under external dissipation is essential for devising realistic non-Hermitian quantum devices that surpass the capabilities of their Hermitian counterparts. Dephasing, a major realistic dissipation, has an impact on non-Hermitian systems that remains largely unexplored. Here, we focus on finite-sized non-Hermitian Su-Schrieffer-Heeger (SSH) lattice models with alternating gain and loss in real space and examine the dynamical evolution of the trace distance under pure dephasing. By tuning system parameters, this model supports phases with either parity-time or anti-parity-time symmetries, enabling us to explore the dephasing effect across different non-Hermitian symmetry regimes within a single platform. While the trace distance exhibits distinct dynamical behaviors across the different phases in the absence of dephasing, its response to dephasing is largely symmetry-independent but instead initial-state dependent. By varying the initial states, we find that dephasing affects the trace distance in two qualitatively different ways. For initial states that differ only in their coherences, dephasing accelerates the decay of the trace distance, destroying the phase information in much the same way as in Hermitian systems. In contrast, for initial states that differ only in their populations, strong dephasing can partially or completely stabilize the trace distance over a wide transient regime before its eventual decay. We attribute these metastable stabilization phenomena to the alternating gain and loss in the system and confirm their absence in Hermitian counterparts. Our findings reveal the intricate dynamical response of non-Hermitian SSH models to dephasing, thereby facilitating their potential applications.

17 pages, 9 figures. Comments are welcome!