Non-linear dispersive regime of cavity QED: The dressed dephasing model

TL;DR

This paper introduces a nonlinear model for cavity QED in the dispersive regime, revealing how pure dephasing and photon interactions induce incoherent effects that limit measurement fidelity.

Contribution

It presents a novel nonlinear dressed dephasing model that accounts for higher-order corrections and their impact on atom-cavity dynamics in the dispersive regime.

Findings

Photon population acts as a heat bath causing incoherent relaxation and excitation.

Pure dephasing reduces the signal-to-noise ratio in cavity QED measurements.

In circuit QED, these effects are particularly significant.

Abstract

Systems in the dispersive regime of cavity quantum electrodynamics (QED) are approaching the limits of validity of the dispersive approximation. We present a model which takes into account nonlinear corrections to the dressing of the atom by the field. We find that in the presence of pure dephasing, photons populating the cavity act as a heat bath on the atom, inducing incoherent relaxation and excitation. These effects are shown to reduce the achievable signal-to-noise ratio in cavity QED realizations where the atom is measured indirectly through cavity transmission and in particular in circuit QED.