Antibunched photons emitted by a dc biased Josephson junction

TL;DR

This paper demonstrates that a dc biased Josephson junction coupled with a high-impedance microwave resonator emits antibunched photons, showing potential as an efficient microwave single-photon source.

Contribution

The authors experimentally show antibunched photon emission from a Josephson junction with a high-impedance resonator, aligning with theoretical predictions.

Findings

Photon antibunching with a correlation function of 0.3 at zero delay

Emission rate of 6×10^7 photons per second

Resonator with 4.4 GHz frequency and 1.97 kΩ impedance

Abstract

We show experimentally that a dc biased Josephson junction in series with a high-enough impedance microwave resonator emits antibunched photons. Our resonator is made of a simple micro-fabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97 k$\Omega$ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6 $10^7$ photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain.