Time dynamics of multi-photon scattering in a two-level mixer

TL;DR

This paper investigates how a superconducting qubit in a waveguide exhibits quantum wave mixing, generating sidebands through multi-photon interactions, with control over non-linearity by adjusting pulse sequences.

Contribution

It demonstrates control over multi-photon interactions and non-linearity in a superconducting qubit via pulse sequence manipulation, revealing new spectral features.

Findings

Multiple coherent side peaks emerge with increasing pulses.

Spectrum maintains asymmetry despite additional peaks.

Control over photon interaction order through pulse parameters.

Abstract

A superconducting qubit in a waveguide behaves as a point-like nonlinear element. If irradiated with nearly resonant microwave pulses, the qubit undergoes quantum evolution and generates coherent fields at sideband frequencies due to elastic scattering. This effect is called Quantum Wave Mixing (QWM), and the number of emerged side components depends on the number of interacting photons. By driving a superconducting qubit with short pulses with alternating carrier frequencies, we control the maximal number of photons simultaneously interacting with a two-level system by varying the number and duration of applied pulses. Increasing the number of pulses results in consecutive growth of the order of non-linearity, which manifests in additional coherent side peaks appearing in the spectrum of scattered radiation while the whole spectrum maintains its asymmetry.