Spin-photon entanglement with direct photon emission in the telecom C-band

TL;DR

This paper demonstrates the first spin-photon entanglement in a solid-state quantum dot system emitting directly into the telecom C-band, advancing quantum communication technology with high-fidelity control and coherence measurement.

Contribution

It introduces a novel solid-state platform using InAs/InP quantum dots for spin-photon entanglement at telecom wavelengths, enabling practical quantum networks.

Findings

Achieved high-fidelity spin initialization and coherent control.

Measured electron spin coherence in the quantum dot system.

First demonstration of spin-photon entanglement emitting directly into telecom C-band.

Abstract

The ever-evolving demands for computational power and for a securely connected world dictate the development of quantum networks where entanglement is distributed between connected parties. Solid-state quantum emitters in the telecom C-band are a promising platform for quantum communication applications due to the minimal absorption of photons at these wavelengths, "on-demand" generation of single photon flying qubits, and ease of integration with existing network infrastructure. Here, we use an InAs/InP quantum dot to implement an optically active spin-qubit, based on a negatively charged exciton where the electron spin degeneracy is lifted using a Voigt magnetic field. We investigate the coherent interactions of the spin-qubit system under resonant excitation, demonstrating high fidelity spin initialisation and coherent control using picosecond pulses. We further use these tools to measure the coherence of a single, undisturbed electron spin in our system. Finally, we report the first demonstration of spin-photon entanglement in a solid-state system capable of direct emission into the telecom C-band.