Chiral Gain-Induced Time-Reversal Symmetry Breaking in Quantum Systems

TL;DR

This paper introduces a theoretical framework showing how chiral optical gain can break time-reversal symmetry in quantum systems, leading to nonreciprocal steady states with potential applications in quantum photonics.

Contribution

It develops a novel formalism for qubits interacting with structured gain environments, revealing how chiral gain induces symmetry breaking and nonreciprocal quantum dynamics.

Findings

Chiral gain can break time-reversal symmetry in quantum systems.

Structured gain environments lead to nonreciprocal steady states.

Application to plasmonic substrates demonstrates selective amplification.

Abstract

Structured light offers a powerful approach to tailor light-matter interactions in quantum systems with chiral properties. While chirality has been extensively studied in passive platforms, the role of optical gain in controlling chiral quantum dynamics remains largely unexplored. In this work, we develop a general theoretical framework to describe the dynamics of qubits interacting with structured gain environments, where amplification depends on the light's polarization or momentum. By quantizing the electromagnetic field in linear bianisotropic media with gain and extending the Lindblad formalism to these settings, we derive a master equation governing the qubit's irreversible evolution. We show that chiral gain can break time-reversal symmetry and drive the system toward a symmetry-broken steady state with nonreciprocal properties. This effect is illustrated in detail for moving plasmonic substrates, which exhibit inherently chiral gain that selectively amplifies transitions of a given handedness. Our results establish chiral gain as a novel mechanism for engineering nonreciprocal quantum steady states.