Cavity sideband cooling of the Josephson phase

TL;DR

This paper demonstrates cavity sideband cooling and heating of the Josephson phase by coupling an extended Josephson junction to a microwave cavity, showing control over phase temperature via microwave radiation.

Contribution

It introduces the observation of sidebands in the microwave cavity resonances of a Josephson junction and shows phase cooling and heating through anti-Stokes and Stokes scattering.

Findings

Sidebands observed in microwave cavity resonances.

Microwave radiation can cool or heat the Josephson phase.

Phase temperature control increases with microwave power.

Abstract

An extended Josephson junction intrinsically couples the superconducting current to the microwave cavity in the insulating barrier. We demonstrate that this coupling produces sidebands in the microwave cavity resonances of the junction. By measuring the switching current distribution, we show that microwave radiation at sidebands brings the Josephson phase out of equilibrium. In particular, the effective phase temperature is reduced or enhanced through anti-Stokes and Stokes scattering, respectively. Phase cooling and heating both increase with microwave power.