# Robust Single-Shot Spin Measurement with 99.5% Fidelity in a Quantum Dot Array

## TL;DR

This paper introduces a highly accurate and robust method for single-shot spin measurement in quantum dot arrays, achieving 99.5% fidelity by leveraging a metastable charge state to improve measurement contrast and duration.

## Contribution

The authors develop a new projective measurement technique for electron spins in quantum dots that significantly enhances fidelity and robustness against environmental fluctuations.

## Key findings

- Achieved 99.5% measurement fidelity.
- Demonstrated robustness to electric and magnetic noise.
- Separated charge measurement error from spin-to-charge conversion error.

## Abstract

We demonstrate a new method for projective single-shot measurement of two electron spin states (singlet versus triplet) in an array of gate-defined lateral quantum dots in GaAs. The measurement has very high fidelity and is robust with respect to electric and magnetic fluctuations in the environment. It exploits a long-lived metastable charge state, which increases both the contrast and the duration of the charge signal distinguishing the two measurement outcomes. This method allows us to evaluate the charge measurement error and the spin-to-charge conversion error separately. We specify conditions under which this method can be used, and project its general applicability to scalable quantum dot arrays in GaAs or silicon.