Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 15: Poster: Quantum Optics and Photonics I

Q 15.14: Poster

Montag, 23. März 2015, 17:00–19:00, C/Foyer

Study of Phase Correlations in Trapped 2D Interacting Quantum Gas — •Dhruv Kedar, Luca Bayha, Puneet Murthy, Mathias Neidig, Martin Ries, Andre Wenz, Gerhard Zürn, and Selim Jochim — Physikalisches Institut, Universität Heidelberg

We study the phase correlations of a two dimensional strongly interacting ultracold gas of Lithium 6. In 3D true long range order and a constant phase is predicted in the superfluid low temperature phase. This differs from the physics in 2D where for uniform systems long range order is destroyed due to thermal fluctuations at finite temperatures. Instead, Berezinskii Kosterlitz Thouless (BKT) theory predicts a qualitative change from exponential to algebraically decaying coherence when the gas crosses the transition to the superfluid phase. Our measurements are in qualitative agreement with the theory. We extract a trap averaged spatial correlation function from the the pair momentum distribution for our inhomogeneous 2D system. We observe that the obtained algebraic decay differs from the behaviour expected for a homogeneous system, but is in agreement with QMC simulations for a trapped Bose gas.