טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentLeonid Beilin
SubjectExpansion of Ultracold Atoms in the Presence of Random
Potential
DepartmentDepartment of Physics
Supervisor Professor Emeritus Shapiro Boris
Full Thesis textFull thesis text - English Version


Abstract

Realization of Bose-Einstein condensation (BEC) in dilute vapors of alkali metals in 1995 has opened a new perspective in the area of ultracold atomic physics. In the beginning most of the theoretical studies and experiments have been devoted to quantum Bose gases, but more recently the attention had turned also to the study of Fermi gases. We study quantum dynamics of an atomic Fermi system with a finite number of particles N. Initially the system is prepared in a harmonic trap, in equilibrium. At time t=0, the harmonic trapping potential is switched off and the Fermi cloud expands in the presence of random potential. It spreads by diffusion and we study the evolution with time of the spatial shape of the atomic cloud. We investigate in detail the Thomas-Fermi regime. We are interested in the expansion of ultracold atoms in the presence of random potential in two and three dimensions. We calculate fundamental transport properties, such as scattering mean free path  ls , the Boltzmann transport mean free path  lB  and the Boltzmann diffusion coefficient D. At the beginning we solve the problem for constant Boltzmann diffusion coefficient and calculate the spatial density of Fermi cloud. Afterwards, we derive the corresponding expressions for matter wave transport in a correlated two-dimensional optical speckle potentials.