Theory

Our projects cover two main aspects of the physics of cold gases and atomic Bose-Einstein condensates. The first one concerns fundamental properties, such as phase coherence, correlations, and multimode finite temperature aspects. The second one is on the use of Bose-Einstein condensates and cold gases to create non-classical states of the atomic field that may be useful in metrology (spin-squeezed states), in probing the frontiers between the quantum and the classical world (Schrödinger cats) and for quantum information.
We developed analytical and theoretical tools including classical field methods to describe a degenerate Bose gas including thermal and possibly quantum fluctuations. We then applied these methods to different problems as for example the nucleation and crystallization of a vortex lattice in a rotating Bose-Einstein condensate, or the spreading in time of the condensate phase at finite temperature. With Emilia Witkowska and Yvan Castin, we could show that the condensate phase spreads ballistically in time at finite temperature and we calculated the coefficient of phase spreading using a quantum extension of the classical concept of ergodicity in the system. With Hadrien Kurkjian and Yvan Castin we study phase coherence in fermionic pair-condensed systems.
Concerning spin squeezing in BEC, we investigate the role of decoherence, due to finite temperature and particle losses. We collaborate with the experimentalists of the Atomchips group and with the group of Philipp Treutlein in Basel Unversity. In particular we participated to one of the two first realizations of spin squeezed states in a bimodal condensate.
For further information, please visit the personal website of Alice Sinatra:
http://www.phys.ens.fr/~sinatra/