# Demonstration of an ac Josephson junction laser

## TL;DR

This paper demonstrates a superconducting Josephson junction laser that uses the ac Josephson effect to generate coherent microwave photons, showcasing a new approach to on-chip quantum device integration.

## Contribution

It introduces a novel superconducting laser based on a Josephson junction coupled to a multi-mode cavity, utilizing the ac Josephson effect for microwave photon generation.

## Key findings

- Successful demonstration of Josephson junction laser operation
- Efficient down-conversion of Josephson frequencies to cavity mode
- Easy integration with quantum devices for on-chip photon generation

## Abstract

Superconducting electronic devices have re-emerged as contenders for both classical and quantum computing due to their fast operation speeds, low dissipation and long coherence times. An ultimate demonstration of coherence is lasing. We use one of the fundamental aspects of superconductivity, the ac Josephson effect, to demonstrate a laser made from a Josephson junction strongly coupled to a multi-mode superconducting cavity. A dc voltage bias to the junction provides a source of microwave photons, while the circuit's nonlinearity allows for efficient down-conversion of higher order Josephson frequencies down to the cavity's fundamental mode. The simple fabrication and operation allows for easy integration with a range of quantum devices, allowing for efficient on-chip generation of coherent microwave photons at low temperatures.

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Source: https://tomesphere.com/paper/1703.05404