Macroscopic Polarization Rotation Induced by a Single Spin

TL;DR

This paper demonstrates a significant enhancement in polarization rotation caused by a single spin in a quantum dot, paving the way for advanced quantum information processing and spin-based quantum networks.

Contribution

The study achieves a three-order magnitude increase in spin-photon interaction using cavity QED, enabling macroscopic polarization rotation by a single spin.

Findings

Polarization rotation of b16 degrees observed

Single-hole spin coupled to a micropillar cavity

Enhanced spin-photon interaction facilitates quantum network development

Abstract

Solid-state spins hold many promises for quantum information processing. Entangling the polarization of a single photon to the state of a single spin would open new paradigms in quantum optics like delayed-photons entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10-3 degrees, due to poor spin-photon coupling. Here we report the amplification by three orders of magnitude of the spin-photon interaction, using a cavity quantum electrodynamics device. A single hole spin trapped in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by \pm 6 degrees when the spin is optically initialized in either the up or down state. These results open the way towards a spin-based quantum network.