Topologically protected long-range correlations in steady states of driven-dissipative bosonic chains

TL;DR

This paper establishes a link between topological phases in driven-dissipative bosonic systems and their steady-state correlations, revealing how non-Hermitian topology manifests as long-range order and frequency-resolved correlations.

Contribution

It introduces a framework connecting topological invariants to steady-state correlations via singular value decomposition in quadratic Liouvillians, extending topological concepts to non-Hermitian quantum systems.

Findings

Topological amplification induces disorder-robust long-range correlations.

Frequency-resolved correlations serve as signatures of non-Hermitian topological phases.

Spatial correlations decay Gaussianly in topological phases, unlike exponential decay in trivial phases.

Abstract

Driven-dissipative quantum systems can exhibit robust transport and amplification in topological regimes, yet the connection between topology and the extent of correlations remains largely unexplored. In this work, we develop a general framework that links topological phases in driven-dissipative systems to bosonic correlations via the singular value decomposition (SVD). In essence, we claim that non-Hermitian topology in quadratic Liouvillians is directly encoded in steady-state correlations, providing an intrinsic characterization of topology without external probes. We show that topological amplification induces disorder-robust long-range order (LRO) in steady-state correlations at fixed frequency, establishing frequency-resolved correlations as direct signatures of non-Hermitian topological phases. We introduce a vector-valued topological invariant that captures the total number of singular-value gap closings across the frequency axis, extending the concept of adiabatic deformation from topological insulators to the case of topological phases of quadratic Liouvillians. Within this framework, we further demonstrate that the spatial structure of equal-time correlations encodes global topological information, manifested as a Gaussian spatial decay with distance in the topological phase, in contrast to the exponential decay characteristic of trivial phases. These findings open new avenues for quantum sensing and correlation engineering in non-Hermitian systems, with feasible implementations in platforms such as trapped ions and superconducting circuits.