Antibunched photons from inelastic Cooper-pair tunneling

TL;DR

This paper theoretically shows that a voltage-biased Josephson junction in a resistive environment can generate antibunched photons across a wide frequency range, with potential for high-rate photon sources.

Contribution

It introduces a continuous-mode theoretical model for photon emission from Josephson junctions, highlighting the role of Coulomb blockade in antibunching at high frequencies.

Findings

Antibunched photons can be generated at GHz to THz frequencies.

High zero-frequency impedance enables high-rate photon production.

Theoretical framework captures charging dynamics of tunneling Cooper pairs.

Abstract

We demonstrate theoretically that charge transport across a Josephson junction, voltage-biased through a resistive environment, produces antibunched photons. We develop a continuous-mode description of the emitted radiation field in a semi-infinite transmission line terminated by the Josephson junction. Within a perturbative treatment in powers of the tunneling coupling across the Josephson junction, we capture effects originating in charging dynamics of consecutively tunneling Cooper pairs. We find that within a feasible experimental setup the Coulomb blockade provided by high zero-frequency impedance can be used to create antibunched photons at a very high rate and in a very versatile frequency window ranging from a few GHz to a THz.