High fidelity measurement of singlet-triplet states in a quantum dot

TL;DR

This paper presents an experimental method for high-fidelity measurement of singlet-triplet states in a quantum dot, achieving a 97% spin measurement fidelity by combining energy and tunnel rate differences for spin-to-charge conversion.

Contribution

The paper introduces a novel read-out scheme that enhances spin measurement fidelity in quantum dots by integrating two existing mechanisms for spin-to-charge conversion.

Findings

Achieved 97% spin measurement fidelity.

Demonstrated effective combination of energy and tunnel rate differences.

Improved upon previous fidelities significantly.

Abstract

We demonstrate experimentally a read-out method that distinguishes between two-electron spin states in a quantum dot. This scheme combines the advantages of the two existing mechanisms for spin-to-charge conversion with single-shot charge detection: a large difference in energy between the two states and a large difference in tunnel rate between the states and a reservoir. As a result, a spin measurement fidelity of 97% was achieved, which is much higher than previously reported fidelities.