nemacka   NAD-BEC: Numerical and Analytical Investigation of Ultracold Bose Gases in Disordered Potentials
Bilateral project with Germany

Studies of atomic and molecular gases have greatly stimulated the development of statistical mechanics and later quantum statistical physics, by revealing that a quantum mechanical treatment is necessary for a proper description of such systems, even at moderate temperatures. Early theoretical studies have furthermore suggested that exotic ultra-quantum behaviour, dominated purely by quantum effects such as Bose-Einstein condensation, can be expected in the regime of very low temperatures. This has fuelled the development of sophisticated cooling techniques and eventually the Nobel-winning experimental discovery of Bose-Einstein condensation. These results have also instigated research related to optical lattices, studies of fermionic ultracold systems, as well as Fermi-Bose mixtures.

SCL's two-year bilateral research project "Numerical and Analytical Investigation of Ultracold Bose Gases in Disordered Potentials" is funded through the joint program by the Serbian Ministry of Science and German DAAD agency for the period 2011-2012. This project provides support to the ongoing collaboration established between SCL's group led by Dr. Antun Balaz, and a research group of Dr. Axel Pelster from the University of Duisburg-Essen, Germany, and presents a follow-up to the previous bilateral project Fast Converging Path Integral Approach to Bose-Einstein Condensation (PI-BEC).

In this project we address the highly relevant problem of ultracold Bose systems in the presence of weak and strong disorder. It is well known that the introduction of a stochastically disordered component of the trapping potential can lead to three different phases: the expected gas and superfluid phase, and a novel Bose-glass phase. The latter two appear due to a macroscopic occupation of the ground state, which leads to a global Bose-Einstein condensate in the case of the superfluid phase and to a set of local Bose-Einstein condensates in the minima of the disorder potential in the case of the Bose-glass phase. During the two-year period we plan to:

  • apply perturbative and non-perturbative analytical approaches to obtain approximate results for relevant disorder-averaged physical quantities in the case of weak disorder,
  • study numerical solutions of the Gross-Pitaveskii equation for different realizations of the disorder potential and calculate the relevant disorder-averaged physical quantities,
  • compare analytical and numerical approaches in the weak-disorder regime in order to address the problem of strong disorder where the emergence of a quantum phase transition from a superfluid to a Bose-glass phase is expected.

Activities and news related to the project: