Improved superconducting qubit state readout by path interference

TL;DR

This paper introduces a method using path interference between transmitted and reflected signals to enhance superconducting qubit state readout fidelity, offering a simple way to improve quantum measurement accuracy.

Contribution

The paper presents a novel interference-based approach to optimize qubit readout, improving state discrimination and fidelity in superconducting circuits.

Findings

Enhanced qubit readout fidelity through constructive interference

Better resolved state discrimination achieved

Compatible with existing cavity photon state discrimination methods

Abstract

High fidelity single shot qubit state readout is essential for many quantum information processing protocols. In superconducting quantum circuit, the qubit state is usually determined by detecting the dispersive frequency shift of a microwave cavity from either transmission or reflection. In this paper, we demonstrate the use of constructive interference between the transmitted and reflected signal to optimize the qubit state readout, with which we find a better resolved state discrimination and an improved qubit readout fidelity. As a simple and convenient approach, our scheme can be combined with other qubit readout methods based on the discrimination of cavity photon states to further improve the qubit state readout.