Symmetry protected topological edge modes and emergent partial time reversal symmetry breaking in open quantum many-body systems

TL;DR

This paper investigates how quantum baths influence symmetry-protected topological edge modes in open quantum systems, revealing that partial time-reversal symmetry breaking can cause edge modes to diffuse into the bath, affecting quantum information applications.

Contribution

It introduces a quantitative analysis of the impact of system-bath interactions on topological edge modes, highlighting the role of partial time-reversal symmetry breaking.

Findings

Time-reversal symmetry is crucial for topological edge modes in open systems.

Partial TRS breaking causes edge modes to diffuse into the bath.

Topological protection can be compromised by system-bath coupling.

Abstract

Symmetry-protected topological edge modes are one of the most remarkable phenomena in topological physics. Here, we formulate and quantitatively examine the effect of a quantum bath on these topological edge modes. Using the density matrix renormalization group method, we study the ground state of a composite system of spin-1 quantum chain, where the system and the bath degrees of freedom are treated on the same footing. We focus on the dependence of these edge modes on the global/partial symmetries of system-bath coupling and on the features of the quantum bath. It is shown that the time-reversal symmetry(TRS) plays a special role for an open quantum system, where an emergent partial TRS breaking will result in a TRS-protected topological mode diffusing from the system edge into the bath, thus make it useless for quantum computation.