Development and operation of the twin radio frequency single electron transistor for solid state qubit readout

TL;DR

This paper introduces a twin radio frequency single electron transistor (rf-SET) system that enables fast, real-time, cross-correlated charge measurements with noise suppression, enhancing solid-state qubit readout capabilities.

Contribution

The work presents a novel twin rf-SET detector using wavelength division multiplexing for simultaneous, independent charge detection and noise reduction in quantum measurements.

Findings

Achieved charge sensitivities of 7.5 and 4.4 micro-electron charges per root Hz.

Demonstrated real-time suppression of charge noise through cross-correlation.

Validated the operation of the twin rf-SET as an effective charge detector.

Abstract

Ultra-sensitive detectors and readout devices based on the radio frequency single electron transistor (rf-SET) combine near quantum-limited sensitivity with fast operation. Here we describe a twin rf-SET detector that uses two superconducting rf-SETs to perform fast, real-time cross-correlated measurements in order to distinguish sub-electron signals from charge noise on microsecond time-scales. The twin rf-SET makes use of two tuned resonance circuits to simultaneously and independently address both rf-SETs using wavelength division multiplexing (WDM) and a single cryogenic amplifier. We focus on the operation of the twin rf-SET as a charge detector and evaluate the cross-talk between the two resonance circuits. Real time suppression of charge noise is demonstrated by cross correlating the signals from the two rf-SETs. For the case of simultaneous operation, the rf-SETs had charge sensitivities of $\delta q_{SET1} = 7.5 \mu e/\sqrt{Hz}$ and $\delta q_{SET2} = 4.4 \mu e/\sqrt{Hz}$.