Non-destructive measurement of electron spins in a quantum dot

TL;DR

This paper introduces a non-destructive method for measuring electron spins in quantum dots, allowing repeated measurements that reveal spin state correlations without disturbing the system.

Contribution

It presents a novel non-destructive measurement technique that preserves the spin state, enabling consecutive measurements and analysis of spin relaxation dynamics.

Findings

Measured ~90% correlation between measurement outcome and post-measurement state.

Observed decay of correlations as wait time approaches T1.

Demonstrated repeated measurements within the relaxation time T1.

Abstract

We propose and implement a non-destructive measurement that distinguishes between two-electron spin states in a quantum dot. In contrast to earlier experiments with quantum dots, the spins are left behind in the state corresponding to the measurement outcome. By measuring the spin states twice within a time shorter than the relaxation time, T1, correlations between consecutive measurements are observed. They disappear as the wait time between measurements become comparable to T1. The correlation between the post-measurement state and the measurement outcome is measured to be ~90% on average.