SCL Seminar by Antun Balaz

SCL seminar of the Center for the Study of Complex Systems, will be held on Friday, 18 November 2016 at 14:00 in the library reading room “Dr. Dragan Popović" of the Institute of Physics Belgrade. The talk entitled

"Dirty bosons in a quasi-one-dimensional harmonic trap"

will be given by Dr Antun Balaž (Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade).

Abstract of the talk:

We will consider the emergence of a Bose-glass region in a quasi one-dimensional Bose-Einstein-condensed gas in a harmonic trapping potential with an additional delta-correlated disorder potential at zero temperature using three approaches [1]. At first, we will solve the corresponding time-independent Gross-Pitaevskii equation numerically for the condensate wave function, and evaluate disorder ensemble averages. In particular, we will analyze quantitatively the emergence of mini-condensates in the local minima of the random potential, which occurs for weak disorder preferentially at the border of the condensate, while for intermediate disorder strength this happens in the trap centre. Second, in view of a more detailed physical understanding of this phenomenon, we will extend a recent non-perturbative approach towards the weakly interacting dirty boson problem, which relies on the Hartree-Fock theory and is worked out on the basis of the replica method, from the homogeneous case to a harmonic confinement. Finally, in the weak disorder regime we also apply the Thomas-Fermi approximation, while in the intermediate disorder regime we additionally use a variational ansatz in order to describe analytically the numerically observed redistribution of the fragmented mini-condensates with increasing disorder strength.

[1] T. Khellil, A. Balaž, and A. Pelster, New J. Phys. 18, 063003 (2016).