Strong light-matter coupling in semiconductors
Strong light-matter interactions in semiconductor microcavities give birth to polaritons. These half-light half-matter quasiparticles can condense into a single macroscopically populated quantum state similar to a Bose-Einstein condensate of cold atoms and display collective quantum behaviour. Apart from being an excellent laboratory for investigating fundamental quantum phenomena, microcavity polaritons can find applications in the emerging field of spin-optronic devices. These include quantum beam splitters, polarisation filters and efficient sources of entangled photon pairs. Scientists working on the EU-funded POLAPHEN (Polarization phenomena in quantum microcavities) project undertook a theoretical study of spin phenomena in microcavities with embedded quantum wells and dots. From the beginning of their life in a microcavity, polaritons change their spin state under the effect of magnetic fields. The POLAPHEN project had the ultimate objective of providing guidelines to use well-controlled spin and optical polarisation effects for the creation of quantum optoelectronic devices. Research work covered aspects of fundamental physics, optoelectronics and nanotechnology. Not surprisingly, the POLAPHEN team brought together a network of partners from EU Member States, Associated Countries and third countries. By creating complementary synergies between the different partners, it was possible to accelerate progress towards the experimental realisation of spin-optronic devices. Scientists achieved the POLAPHEN initial goal, beginning with effectively controlling the polaritons' interactions occurring in nanostructures. The knowledge accumulated offers support for practical implementations, and the first results have already been disseminated within the scientific community.
Keywords
Polaritons, semiconductor microcavities, Bose-Einstein condensate, spin-optronic devices, nanotechnology
