Inelastic scattering of a photon by a quantum phase-slip

TL;DR

This paper demonstrates that quantum phase-slip fluctuations in superconducting waveguides can efficiently split a single photon into many lower-energy photons, revealing novel inelastic photon interactions.

Contribution

It introduces a new model explaining inelastic photon decay via quantum impurity in a Luttinger liquid, connecting circuit QED to boundary quantum field theories.

Findings

Near-unit probability of photon splitting observed

Decay rates match the new theoretical model without adjustable parameters

Provides a quantum many-body simulation example

Abstract

Spontaneous decay of a single photon is a notoriously inefficient process in nature irrespective of the frequency range. We report that a quantum phase-slip fluctuation in high-impedance superconducting waveguides can split a single incident microwave photon into a large number of lower-energy photons with a near unit probability. The underlying inelastic photon-photon interaction has no analogs in non-linear optics. Instead, the measured decay rates are explained without adjustable parameters in the framework of a new model of a quantum impurity in a Luttinger liquid. Our result connects circuit quantum electrodynamics to critical phenomena in two-dimensional boundary quantum field theories, important in the physics of strongly-correlated systems. The photon lifetime data represents a rare example of verified and useful quantum many-body simulation.