Macroscopic rotation of photon polarization induced by a single spin

• Published in: Nature communications 2015-02, Vol.6 (1), p.6236, Article 6236
• Main Authors: Arnold, Christophe, Demory, Justin, Loo, Vivien, Lemaître, Aristide, Sagnes, Isabelle, Glazov, Mikhaïl, Krebs, Olivier, Voisin, Paul, Senellart, Pascale, Lanco, Loïc
• Format: Article
• Language: English
• Subjects: 140/125; 639/624/400/3925; 639/766/119/1000/1017; 639/766/119/1001; 639/766/25; Electrons; Humanities and Social Sciences; multidisciplinary; Optics; Quantum dots; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms7236

Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon 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 enhancement by three orders of magnitude of the spin–photon interaction, using a cavity quantum electrodynamics device. A single hole spin 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 ±6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. The recently observed rotation of a photon's polarization by interaction with a single solid state spin has potential implications in quantum computing. Here, Arnold et al . demonstrate enhanced spin–photon coupling and polarization rotation via a coupled quantum dot/micropillar cavity system.