Antiresonance phase shift in strongly coupled cavity QED

TL;DR

This paper studies phase shifts in strongly coupled cavity QED, revealing an optically controllable antiresonance phase shift of up to 140 degrees, useful for quantum circuit characterization.

Contribution

It demonstrates a novel antiresonance phase shift in single-atom cavity QED that depends only on the atom, providing a new method for quantum circuit analysis.

Findings

Observed a 140-degree phase shift in transmitted light

Phase shift depends solely on the atom, not the cavity

Introduced a new technique for quantum circuit characterization

Abstract

We investigate phase shifts in the strong coupling regime of single-atom cavity quantum electrodynamics (QED). On the light transmitted through the system, we observe a phase shift associated with an antiresonance and show that both its frequency and width depend solely on the atom, despite the strong coupling to the cavity. This shift is optically controllable and reaches 140 degrees - the largest ever reported for a single emitter. Our result offers a new technique for the characterization of complex integrated quantum circuits.