Few-photon all-optical phase rotation in a quantum-well micropillar cavity

• Published in: Nature photonics Vol. 16; no. 8; pp. 566 - 569
• Main Authors: Kuriakose, Tintu, Walker, Paul M., Dowling, Toby, Kyriienko, Oleksandr, Shelykh, Ivan A., St-Jean, Phillipe, Zambon, Nicola Carlon, Lemaître, Aristide, Sagnes, Isabelle, Legratiet, Luc, Harouri, Abdelmounaim, Ravets, Sylvain, Skolnick, Maurice S., Amo, Alberto, Bloch, Jacqueline, Krizhanovskii, Dmitry N.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.08.2022; Nature Publishing Group
• Subjects: 639/624/400/2797; 639/624/400/385; 639/624/400/482; 639/766/119; Applied and Technical Physics; Atoms & subatomic particles; Data processing; Excitons; Information processing; Laser beams; Lasers; Lattices; Letter; Nonlinear systems; Nonlinearity; Optics; Phase modulation; Photonics; Photons; Physics; Physics and Astronomy; Polaritons; Quantum phenomena; Quantum Physics; Quantum wells
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-022-01019-6

Photonic platforms are an excellent setting for quantum technologies as weak photon–environment coupling ensures long coherence times. The second key ingredient for quantum photonics is interactions between photons, which can be provided by optical nonlinearities in the form of cross-phase modulation. This approach underpins many proposed applications in quantum optics 1 – 7 and information processing 8 , but achieving its potential requires strong single-photon-level nonlinear phase shifts as well as scalable nonlinear elements. In this work we show that the required nonlinearity can be provided by exciton–polaritons in micropillars with embedded quantum wells. These combine the strong interactions of excitons 9 , 10 with the scalability of micrometre-sized emitters 11 . We observe cross-phase modulation of up to 3 ± 1 mrad per polariton using laser beams attenuated to below the average intensity of a single photon. With our work serving as a stepping stone, we lay down a route for quantum information processing in polaritonic lattices. Giant effective photon–photon interactions are achieved by hybridizing light with excitons in an InGaAs-based quantum well micropillar cavity. Cross-phase modulation of up to 3 mrad per polariton is observed at the laser intensity below the single-photon level.