Topology detection in cavity QED

TL;DR

This paper investigates how cavity transmission can serve as a topological marker in cavity QED systems, developing a new formalism to analyze topological phases beyond weak coupling and demonstrating the cavity's role as a quantum sensor.

Contribution

It introduces a novel approach combining input-output formalism with quantum fluctuation expansion to study topological lattice models in cavity QED beyond small coupling regimes.

Findings

Cavity transmission can indicate topological phases in c-QED systems.

The initial state preparation significantly affects topological sensing.

Topological features persist at higher coupling strengths, analyzed via an effective Hamiltonian.

Abstract

We explore the physics of topological lattice models in c-QED architectures for arbitrary coupling strength, and the use of the cavity transmission as a topological marker. For this, we develop an approach combining the input-output formalism with an expansion in quantum fluctuations which allows to go beyond the small-coupling regime. We apply our formalism to a fermionic Su-Schrieffer-Heeger (SSH) chain coupled to a single-mode cavity, and find that the cavity can indeed act as a quantum sensor for topological phases, where the initial state preparation plays a crutial role. Additionally, we discuss the persistence of topological features as the coupling strength increases, in terms of an effective Hamiltonian, and calculate the entanglement entropy.