Probing the statistics of coherent states by continuous wave mixing on a single artificial atom

TL;DR

This paper investigates four- and higher-order wave mixing of coherent states on a superconducting artificial atom, revealing nonlinear scattering effects and photon statistics through analytical and experimental methods.

Contribution

It introduces an analytical model for peak amplitudes in multi-photon scattering and demonstrates how peak ratios reveal photon statistics in non-classical coherent waves.

Findings

Observation of narrow side peaks from multi-photon elastic scattering

Derivation of an analytical expression linking peak ratios to photon statistics

Demonstration of Autler-Townes-like splitting scaling with scattering order

Abstract

We study four- and higher-order wave mixing of continuous coherent waves on a single superconducting artificial atom. Narrow side peaks of different orders of nonlinearity resulting from elastic multi-photon scattering on the atom are observed and investigated. We derive an analytical expression for the peak amplitudes and show that the ratio of any two adjacent peaks is a function of driving amplitudes and detuning. This is attributed to the photon distribution in the coherent states and provides a measure for characterisation of photon statistics in non-classical coherent waves. We also demonstrate an Autler-Townes-like splitting of side peaks, the magnitude of which scales with the scattering order.