Exploring the Fidelity of Flux Qubit Measurement in Different Bases via the Quantum Flux Parametron

TL;DR

This paper analyzes how different measurement bases affect flux qubit readout fidelity using a quantum flux parametron, revealing optimal strategies for single and coupled qubit systems to improve quantum measurement accuracy.

Contribution

It provides a theoretical and numerical comparison of measurement bases and models, identifying optimal measurement strategies for flux qubits in quantum computing.

Findings

Energy basis yields higher fidelity than flux basis for single qubits.

Sequential measurement in a dressed basis offers more robust high-fidelity readouts.

Simultaneous measurement in a bare basis achieves high fidelity over shorter durations.

Abstract

High-fidelity qubit readout is a fundamental requirement for practical quantum computing systems. In this work, we investigate methods to enhance the measurement fidelity of flux qubits via a quantum flux parametron-mediated readout scheme. Through theoretical modeling and numerical simulations, we analyze the impact of different measurement bases on fidelity in single-qubit and coupled two-qubit systems. For single-qubit systems, we show that energy bases consistently outperform flux bases in achieving higher fidelity. In coupled two-qubit systems, we explore two measurement models: sequential and simultaneous measurements, both aimed at reading out a single target qubit. Our results indicate that the highest fidelity can be achieved either by performing sequential measurement in a dressed basis over a longer duration or by conducting simultaneous measurement in a bare basis over a shorter duration. Importantly, the sequential measurement model consistently yields more robust and higher fidelity readouts compared to the simultaneous approach. These findings quantify achievable fidelities and provide valuable guidance for optimizing measurement protocols in emerging quantum computing architectures.