Photon-instanton collider implemented by a superconducting circuit

TL;DR

This paper proposes a superconducting circuit setup to observe and analyze inelastic collisions between microwave photons and instantons, providing a new method to study quantum field tunneling events.

Contribution

It introduces a formalism for photon-instanton scattering and demonstrates the potential for observing inelastic photon-instanton collisions exceeding traditional effects.

Findings

Inelastic scattering probability can reach order-unity values.

Formalism for calculating photon-instanton cross section is developed.

Superconducting circuits enable direct observation of instanton collisions.

Abstract

Instantons, spacetime-localized quantum field tunneling events, are ubiquitous in correlated condensed matter and high energy systems. However, their direct observation through collisions with conventional particles has not been considered possible. We show how recent advances in circuit quantum electrodynamics, specifically, the realization of galvanic coupling of a transmon qubit to a high-impedance transmission line, allows the observation of inelastic collisions of single microwave photons with instantons (phase slips). We develop a formalism for calculating the photon-instanton cross section, which should be useful in other quantum field theoretical contexts. In particular, we show that the inelastic scattering probability can significantly exceed the effect of conventional Josephson quartic anharmonicity, and reach order-unity values.