Generation of heralded entanglement between distant hole spins

TL;DR

This paper demonstrates a highly efficient method for generating heralded entanglement between distant hole spins in quantum dots, significantly advancing quantum network capabilities with high-speed entanglement production and verification.

Contribution

It introduces a novel scheme for heralded entanglement of distant hole spins with a record generation rate, utilizing single-photon interference and microcavity structures.

Findings

Generated 2300 entangled pairs per second

Achieved entanglement over 5 meters distance

Improved entanglement rate by nearly three orders of magnitude

Abstract

Quantum entanglement emerges naturally in interacting quantum systems and plays a central role in quantum information processing. Remarkably, it is possible to generate entanglement even in the absence of direct interactions: provided that which path information is erased, weak spin-state dependent light scattering can be used to project two distant spins onto a maximally entangled state upon detection of a single photon. Even though this approach is necessarily probabilistic, successful generation of entanglement is heralded by the photon detection event. Here, we demonstrate heralded quantum entanglement of two quantum dot heavy-hole spins separated by 5 meters using single-photon interference. Thanks to the long coherence time of hole spins and the efficient spin-photon interface provided by self-assembled quantum dots embedded in leaky microcavity structures, we generate 2300 entangled spin pairs per second, which represents an improvement approaching three orders of magnitude as compared to prior experiments. Delayed two-photon interference scheme we developed allows for efficient verification of quantum correlations. Our results lay the groundwork for the realization of quantum networks in semiconductor nanostructures. Combined with schemes for transferring quantum information to a long-lived memory qubit, fast entanglement generation we demonstrate could also impact quantum repeater architectures.