Cryogenic amplification of image-charge detection for readout of quantum states of electrons on liquid helium

TL;DR

This paper demonstrates a cryogenic two-stage amplification scheme that significantly enhances the sensitivity and bandwidth of image-charge detection for quantum state readout of electrons on liquid helium, enabling high-fidelity quantum measurements.

Contribution

It introduces a low-power, high-gain cryogenic amplification setup that improves detection sensitivity and bandwidth for quantum state readout on liquid helium.

Findings

Two-stage amplification achieves 40 dB gain with low power dissipation.

Cryogenic amplification improves detection bandwidth and sensitivity.

Comparison shows enhanced performance over single-stage schemes.

Abstract

Accurate detection of quantum states is a vital step in the development of quantum computing. Image-charge detection of quantum states of electrons on liquid helium can potentially be used for the readout of a single-electron qubit; however, low sensitivity due to added noise hinders its usage in high fidelity and bandwidth (BW) applications. One method to improve the readout accuracy and bandwidth is to use cryogenic amplifications near the signal source to minimize the effects of stray capacitance. We experimentally demonstrate a two-stage amplification scheme with a low power dissipation of 90 {\mu}W at the first stage located at the still plate of the dilution refrigerator and a high gain of 40 dB at the second stage located at the 4 K plate. The good impedance matching between different stages and output devices ensure high BW and constant gain in a wide frequency range. The detected image-charge signals are compared for one-stage and two-stage amplification schemes.