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Non-equilibrium dynamics of one-dimensional Bose gases

Event Details

Event Dates: 

Monday, February 2, 2015 - 2:00pm

Seminar Location: 

  • JILA X590

Speaker Name(s): 

Tim Langen

Speaker Affiliation(s): 

JILA
Seminar Type/Subject

Scientific Seminar Type: 

  • JILA Public Seminar

Event Details & Abstract: 

Understanding the non-equilibrium dynamics of isolated quantum many-body systems is an unsolved problem in many areas of physics. I will present a series of experiments with ultracold one-dimensional Bose gases, which establish these gases as an ideal model system to explore a wide range of non-equilibrium phenomena.

 

     In the experiments a single gas is coherently split into two parts. This creates a well-defined non-equilibrium situation that can be probed in great detail using matter-wave interferometry. The subsequent dynamics reveal the emergence of a prethermalized steady state, which differs strongly from thermal equilibrium [1,2]. Such thermal-like states had previously been predicted for a large variety of systems, but never been observed directly. A further detailed study of the relaxation process shows that the thermal correlations of the prethermalized state emerge locally in their final form and propagate through the system in a light-cone-like evolution [3]. This provides first experimental evidence for the local relaxation conjecture, which links relaxation processes in quantum many-body systems to the propagation of correlations. Moreover, engineering the initial state of the evolution enables the first direct observation of a generalized thermodynamical ensemble [4]. This points to a natural emergence of classical statistical properties from the microscopic unitary quantum evolution, and forms a cornerstone for a universal framework of non-equilibrium physics.

Finally, I will comment on recent advances in the tomography of quantum many-body states [5] and the study of tunnel-coupled one-dimensional Bose gases.

 

[1] M. Gring et al., Science 337, 1318 (2012) [2] M. Kuhnert et al., Phys. Rev. Lett. 110, 090405 (2013) [3] T. Langen et al., Nature Physics 9, 640 (2013) [4] T. Langen et al., arxiv:1411.7185, to appear in Science [5] A. Steffens et al., arxiv:1406.3632