Cavity-enhanced optical readout of a single solid-state spin

TL;DR

This paper demonstrates a cavity quantum electrodynamics technique for optical readout of a single solid-state electron spin in a quantum dot, achieving a fidelity of 0.61 with potential for improved efficiency.

Contribution

It introduces a cavity-enhanced optical method for single-spin readout in quantum dots, enabling projective measurements with high fidelity.

Findings

Achieved spin readout fidelity of 0.61.

Demonstrated cavity reflectivity depends on spin state.

Showed potential for fidelity improvement with better photon collection.

Abstract

We demonstrate optical readout of a single electron spin using cavity quantum electrodynamics. The spin is trapped in a single quantum dot that is strongly coupled to a nanophotonic cavity. Selectively coupling one of the optical transitions of the quantum dot to the cavity mode results in a spin-dependent cavity reflectivity that enables projective spin measurements by monitoring the reflected intensity of an incident optical field. Using this approach, we demonstrate spin readout fidelity of 0.61 for a quantum dot that has a poor branching ratio of 0.43. Achieving this fidelity using resonance fluorescence from a bare dot would require 43 times improvement in photon collection efficiency.