Single-shot readout of electron spin states in a quantum dot using spin-dependent tunnel rates

TL;DR

This paper introduces a robust single-shot electron spin readout method in quantum dots that leverages spin-dependent tunnel rates, achieving high visibility and revealing long relaxation times influenced by magnetic fields.

Contribution

The paper presents a novel spin readout technique that is resilient to charge noise and effective at higher electron temperatures, with experimental validation showing high fidelity.

Findings

Achieved over 80% single-shot readout visibility.

Discovered long triplet-to-singlet relaxation times up to milliseconds.

Demonstrated magnetic field dependence of relaxation times.

Abstract

We present a method for reading out the spin state of electrons in a quantum dot that is robust against charge noise and can be used even when the electron temperature exceeds the energy splitting between the states. The spin states are first correlated to different charge states using a spin dependence of the tunnel rates. A subsequent fast measurement of the charge on the dot then reveals the original spin state. We experimentally demonstrate the method by performing read-out of the two-electron spin states, achieving a single-shot visibility of more than 80%. We find very long triplet-to-singlet relaxation times (up to several milliseconds), with a strong dependence on in-plane magnetic field.