Quantum Coherence in Momentum Space of Light-matter Condensates

When: Wednesday, 19th November (2014), 12:00h
Place: Departamento de Física Teórica de la Materia Condensada, Facultad Ciencias, Module 5, Seminar Room (5th Floor).
Speaker: Carlos Antón, Departamento de Física de Materiales and Instituto de Ciencia de Materiales “Nicolás Cabrera”, Universidad Autónoma de Madrid, Spain.

Exciton-polariton Bose-Einstein condensates, due to their dual wave-particle nature, share many properties with classical waves as, for instance, interference phenomena, which are crucial to gain insight into their ondulatory character. We show that the use of momentum-space optical interferometry, which avoids any spatial overlap between two parts of a macroscopic quantum state, presents a unique way to study coherence phenomena in polariton condensates. We address a longstanding question in quantum mechanics: “Do two components of a condensate, which have never seen each other, possess a definitive phase?”. A positive answer to this question is experimentally obtained here for light-matter condensates, created under precise symmetry conditions, in semiconductor microcavities, taking advantage of the direct relation between the angle of emission and the in-plane momentum of polaritons.