Scattering of coherent states on a single artificial atom

TL;DR

This paper theoretically investigates how propagating quantum microwaves interact with a single artificial atom in a circuit QED setup, deriving a master equation and analyzing photon antibunching effects under realistic conditions.

Contribution

It introduces a master equation for a circuit QED system with a Cooper pair box and explores photon antibunching measurements considering experimental imperfections.

Findings

Derived a master equation in the transmon regime including coherent drives.

Analyzed photon antibunching in reflected microwaves.

Discussed effects of temperature and detection bandwidth.

Abstract

In this work we theoretically analyze a circuit QED design where propagating quantum microwaves interact with a single artificial atom, a single Cooper pair box. In particular, we derive a master equation in the so-called transmon regime, including coherent drives. Inspired by recent experiments, we then apply the master equation to describe the dynamics in both a two-level and a three-level approximation of the atom. In the two-level case, we also discuss how to measure photon antibunching in the reflected field and how it is affected by finite temperature and finite detection bandwidth.