# Emission of non-classical radiation by inelastic Cooper pair tunneling

## TL;DR

This paper demonstrates that a dc-biased Josephson junction coupled with two microwave resonators emits non-classical photon pairs, exhibiting two-mode amplitude squeezing and matching theoretical predictions at high emission rates.

## Contribution

It provides experimental evidence of non-classical microwave radiation from inelastic Cooper pair tunneling, with quantitative agreement to theory and high photon pair emission rates.

## Key findings

- Observed two-mode amplitude squeezing below classical limit
- Achieved photon pair emission rate of 2 billion per second
- Confirmed theoretical predictions with experimental data

## Abstract

We show that a properly dc-biased Josephson junction in series with two microwave resonators of different frequencies emits photon pairs in the resonators. By measuring auto- and inter-correlations of the power leaking out of the resonators, we demonstrate two-mode amplitude squeezing below the classical limit. This non-classical microwave light emission is found to be in quantitative agreement with our theoretical predictions, up to an emission rate of 2 billion photon pairs per second.