Quantum-dot-spin single-photon interface

TL;DR

This paper demonstrates a high-fidelity, fast quantum dot spin-photon interface using resonance fluorescence detection, enabling quantum information processing tasks like heralded spin entanglement.

Contribution

It introduces a single-photon interface with over 99% fidelity and shows potential for quantum non-demolition measurements by improving photon collection efficiency.

Findings

Achieved spin state projection with >99% fidelity.

Observed electron spin dynamics through photon bunching.

Proposed enhancement for quantum non-demolition measurement.

Abstract

Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0:1%, we realize a single spin-photon interface where the detection of a scattered photon with 300 picosecond time resolution projects the quantum dot spin to a definite spin eigenstate with fidelity exceeding 99%. The bunching of resonantly scattered photons reveals information about electron spin dynamics. High-fidelity fast spin-state initialization heralded by a single photon enables the realization of quantum information processing tasks such as non-deterministic distant spin entanglement. Given that we could suppress the measurement back-action to well below the natural spin-flip rate, realization of a quantum non-demolition measurement of a single spin could be achieved by increasing the fluorescence collection efficiency by a factor exceeding 20 using a photonic nanostructure.