Description of phase fluctuations in atomic quasicondensates via the Ornstein-Uhlenbeck stochastic process

Note: 2:00 PM
Speaker: Dr. Igor Mazets, Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien and Ioffe Physico-Technical Institute of the Russian Academy of Sciences

When: January 30, 2013 (Wed), 02:00PM to 03:00PM (add to my calendar)
Location: SCI 328
Hosted by: Anatoli Polkovnikov

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: Measurement of fluctuations and their correlations yields important information on regimes and phases of many-body quantum systems. A key question in the physics of many-body quantum systems at finite temperature is how many of the observed fluctuations and their correlations are fundamentally quantum and which are caused by the thermal excitations in the system. We develop a simple semiclassical model based on the spatial evolution of the relative phase according to an Ornstein-Uhlenbeck stochastic process with Gaussian phase fluctuations. This model enables us to describe fluctuations in one- and two-dimensional quasicondensates and relate the correlations observed in a time-of-flight experiment to the in-trap fluctuations. We find that, at typical experimental parameters, the observed fluctuations are essentially classical (thermal) and measuring the quantum noise poses challenging requirements to the precision and resolution of the measurement. Application of the method to the interpretation of the experimental data will be presented.

[1] H.-P. Stimming, N. J. Mauser, J. Schmiedmayer, and I. E. Mazets, Phys. Rev. Lett. 105, 015301 (2010). [2] T. Betz, S. Manz, R. Bücker, T. Berrada, Ch. Koller, G. Kazakov, I. E. Mazets, H.-P. Stimming, A. Perrin, T. Schumm, and J. Schmiedmayer, Phys. Rev. Lett. 106, 020407 (2011). [3] I. E. Mazets, Phys. Rev. A 86, 055603 (2012).