SCL Seminar by A. Balaz
SCL's Antun Balaz presented a seminar:
"Nonlinear Excitations in BoseEinstein Condensates: Faraday Waves"
Abstract:
In addition to collective oscillation modes, BoseEinstein Condensates (BECs) exhibit a number of other excitations due to their inherent nonlinearity. Faraday (density) waves can be generated by a periodic modulation of the trapping potential or atomic interactions, and were first observed experimentally in 2007. Using the results of extensive numerical simulations and analytical variational calculations, we will show that elongated binary nonmiscible BECs subject to periodic modulations of the radial confinement exhibit a Faraday instability similar to that seen in onecomponent condensates. Considering the hyperfine states of 87Rb condensates, we will show that there are two experimentally relevant stationary state configurations: the one in which the components form a darkbright symbiotic pair (the ground state of the system), and the one in which the components are segregated (first excited state).
For each of these two configurations, we will numerically demonstrate that far from resonances the Faraday waves excited in the two BEC components are of similar periods, emerge simultaneously, and do not impact the dynamics of the bulk of the condensate. We will also analytically derive the period of the Faraday waves using a variational treatment of the coupled GrossPitaevskii equations combined with a Mathieutype analysis for the selection mechanism of the excited waves. Finally, we will show that for a modulation frequency close to twice that of the radial trapping, the emergent surface waves fade out in favor of a forceful collective mode that turns the two BEC components miscible.

20 July 2020

20 July 2020

14 February 2020

27 December 2019

26 December 2019

25 December 2019

24 December 2019

23 December 2019