Quantum state transfer of angular momentum via single electron photo-excitation from a Zeeman-resolved light hole

TL;DR

This paper demonstrates the transfer of angular momentum from single photons to electron spins in GaAs quantum dots via Zeeman-resolved light-hole excitation, advancing quantum communication and entanglement research.

Contribution

It provides the first experimental evidence of single photon to electron spin conversion through Zeeman-resolved light-hole excitation in quantum dots.

Findings

Photon polarization affects spin blockade probability.

Angular momentum transfer from photons to electron spins is confirmed.

Single shot readout of electron spins was achieved.

Abstract

Electron spins in GaAs quantum dots have been used to make qubits with high-fidelity gating and long coherence time, necessary ingredients in solid-state quantum computing. The quantum dots can also host photon qubits with energy applicable for optical communication, and can show a promising photon-to-spin conversion. The coherent interface is established through photo-excitation of a single pair of an electron and a Zeeman-resolved light-hole, not heavy-hole. However, no experiments on the single photon to spin conversion have been performed yet. Here we report on single shot readout of a single electron spin generated in a GaAs quantum dot by spin-selective excitation with linearly polarized light. A photo-electron spin generated from a Zeeman-resolved light-hole exciton is detected using an optical spin blockade method in a single quantum dot and a Pauli spin blockade method in a double quantum dot. We found that the blockade probability strongly depends on the photon polarization and the hole state, heavy- or light-hole, indicating a transfer of the angular momentum from single photons to single electron spins. Our demonstration will open a pathway to further investigation on fundamental quantum physics such as quantum entanglement between a wide variety of quantum systems and applications of quantum networking technology.