Quantum capacitive phase detector

TL;DR

This paper proposes a quantum capacitive phase detector using a single Cooper-pair transistor to measure superconducting phase differences with low power dissipation, suitable for qubit readout.

Contribution

It introduces a novel phase detection method leveraging input capacitance dependence, enabling efficient, low-power qubit readout in isolated circuits.

Findings

Potential for high sensitivity in phase detection

Low power dissipation due to quasiparticle-free operation

Suitable for quantum computing applications

Abstract

We discuss how a single Cooper-pair transistor may be used to detect the superconducting phase difference by using the phase dependence of the input capacitance from gate to the ground. The proposed device has a low power dissipation because its operation is in principle free from quasiparticle generation. According to the sensitivity estimates the device may be used for efficient qubit readout in a galvanically isolated and symmetrized circuit.