Threshold-independent method for single-shot readout of spin qubits in semiconductor quantum dots

TL;DR

This paper introduces a threshold-independent method for single-shot spin qubit readout in semiconductor quantum dots, significantly improving efficiency and robustness over traditional threshold-based techniques, and demonstrating potential for higher temperature operation.

Contribution

The paper presents a novel threshold-independent approach for spin qubit readout that enhances accuracy and robustness, overcoming limitations of threshold sensitivity in existing methods.

Findings

Efficiency and robustness are 60 times greater than traditional methods.

Extrapolated spin state probabilities can be accurately obtained without threshold dependence.

The method remains effective up to 0.7 K/1.5T conditions.

Abstract

The single-shot readout data process is essential for the realization of high-fidelity qubits and fault-tolerant quantum algorithms in semiconductor quantum dots. However, the fidelity and visibility of the readout process is sensitive to the choice of the thresholds and limited by the experimental hardware. By demonstrating the linear dependence between the measured spin state probabilities and readout visibilities along with dark counts, we describe an alternative threshold-independent method for the single-shot readout of spin qubits in semiconductor quantum dots. We can obtain the extrapolated spin state probabilities of the prepared probabilities of the excited spin state through the threshold-independent method. Then, we analyze the corresponding errors of the method, finding that errors of the extrapolated probabilities cannot be neglected with no constraints on the readout time and threshold voltage. Therefore, by limiting the readout time and threshold voltage we ensure the accuracy of the extrapolated probability. Then, we prove that the efficiency and robustness of this method is 60 times larger than that of the most commonly used method. Moreover, we discuss the influence of the electron temperature on the effective area with a fixed external magnetic field and provide a preliminary demonstration for a single-shot readout up to 0.7 K/1.5T in the future.