Controlling topological phases of matter with quantum light

TL;DR

This paper demonstrates how quantum light in a cavity can control and induce topological phases in the SSH model, providing a new method to manipulate topological properties of quantum matter.

Contribution

It introduces a novel approach using cavity photons to influence topological phases, including phase transition control and spectroscopic probing via polariton spectra.

Findings

Quantum cavity fields can induce topological phase transitions.

The polariton spectrum reveals the topological transition point.

Quantum light can turn trivial phases into topological ones.

Abstract

Controlling the topological properties of quantum matter is a major goal of condensed matter physics. A major effort in this direction has been devoted to using classical light in the form of Floquet drives to manipulate and induce states with non-trivial topology. A different route can be achieved with cavity photons. Here we consider a prototypical model for topological phase transition, the one-dimensional Su-Schrieffer-Heeger (SSH) model, coupled to a single mode cavity. We show that quantum light can affect the topological properties of the system, including the finite-length energy spectrum hosting edge modes and the topological phase diagram. In particular we show that depending on the lattice geometry and the strength of light-matter coupling one can either turn a trivial phase into a topological one or viceversa using quantum cavity fields. Furthermore, we compute the polariton spectrum of the coupled electron-photon system, and we note that the lower polariton branch disappears at the topological transition point. This phenomenon can be used to probe the phase transition in the SSH model.