Narrow band microwave radiation from a biased single-Cooper-pair transistor

TL;DR

This paper demonstrates that a biased single-Cooper-pair transistor emits narrow-band microwave radiation, which can be spectroscopically detected, revealing insights into Josephson radiation and the impact of dissipative electrometers on quantum systems.

Contribution

It introduces the observation of narrow-band microwave emission from a biased SCPT and analyzes its implications for quantum measurement and electrometer design.

Findings

Detection of narrow-band microwave radiation from SCPT

Identification of Josephson radiation lines

Dissipative electrometers can disrupt quantum systems

Abstract

We show that a single-Cooper-pair transistor (SCPT) electrometer emits narrow-band microwave radiation when biased in its sub-gap region. Photo activation of quasiparticle tunneling in a nearby SCPT is used to spectroscopically detect this radiation, in a configuration that closely mimics a qubit-electrometer integrated circuit. We identify emission lines due to Josephson radiation and radiative transport processes in the electrometer, and argue that a dissipative superconducting electrometer can severely disrupt the system it attempts to measure.