Adaptive homodyne phase discrimination and qubit measurement

TL;DR

This paper explores how adaptive measurement techniques can enhance the speed and accuracy of qubit readout in quantum computing architectures, especially those involving cavity-QED systems, by applying phase discrimination methods.

Contribution

It introduces adaptive measurement strategies for qubit detection in cavity-QED architectures, demonstrating their potential to improve measurement performance.

Findings

Adaptive schemes improve measurement speed.

Adaptive techniques increase accuracy of qubit discrimination.

Application to circuit-QED shows practical feasibility.

Abstract

Fast and accurate measurement is a highly desirable, if not vital, feature of quantum computing architectures. In this work we investigate the usefulness of adaptive measurements in improving the speed and accuracy of qubit measurement. We examine a particular class of quantum computing architectures, ones based on qubits coupled to well controlled harmonic oscillator modes (reminiscent of cavity-QED), where adaptive schemes for measurement are particularly appropriate. In such architectures, qubit measurement is equivalent to phase discrimination for a mode of the electromagnetic field, and we examine adaptive techniques for doing this. In the final section we present a concrete example of applying adaptive measurement to the particularly well-developed circuit-QED architecture.