A deterministic source of indistinguishable photons in a cluster state

TL;DR

This paper introduces a semiconductor quantum-dot source capable of rapidly producing highly indistinguishable, polarization-entangled photons in a cluster state, advancing quantum communication technologies.

Contribution

It presents a novel, deterministic, and high-rate photon source based on a quantum-dot device that generates large entangled cluster states with high indistinguishability.

Findings

Achieved >90% indistinguishability of photons

Demonstrated gigahertz rate cluster state generation

Produced cluster states with more than 10 photons

Abstract

Measurement-based quantum communication relies on the availability of highly entangled multi-photon cluster states. The inbuilt redundancy in the cluster allows communication between remote nodes using repeated local measurements, compensating for photon losses and probabilistic Bell-measurements. For feasible applications, the cluster generation should be fast, deterministic, and its photons - indistinguishable. We present a novel source based on a semiconductor quantum-dot device. The dot confines a heavy-hole, precessing in a finely tuned external weak magnetic field while periodically excited by a sequence of optical pulses. Consequently, the dot emits indistinguishable polarization-entangled photons, where the field strength optimizes the entanglement. We demonstrate Gigahertz rate deterministic generation of >90% indistinguishable photons in a cluster state with more than 10 photons characteristic entanglement-length.