1. Lectures on Quantum Gases Lectures G. Shlyapnikov 2015 年 6 月 10, 17, 25, 30 日, 下午 3:30-5:00 频标楼 4 楼报告厅 About the speaker ： Director of Research at CNRS, LPTMS, Orsay, France, and Professor in Univ. Of Amsterdam. His work on the theory of quantum gases was awarded by the Humbioldt Prize (Germany) in 1999, by the Kurchatov Prize (Russia) in 2000, and by the International Bose-Einstein condensation Prize in 2011. He got the European Research Award in 2013. He published about 140 papers, got more than 9400 citations and H-index of 48. 主办单位 : 武汉物数所理论与交叉研究部 2015 年 6 月 10 日 ( 星期三 ) Bose-Einstein condensation of attractively interacting bosons 2015 年 6 月 25 日 ( 星期四 ) Feshbach molecules in two-component atomic Fermi gases. Remarkable collisional stability and molecular Bose- Einstein condensation I will discuss how an external trapping potential can astabilize a Bose-Einstein condensate (BEC) of attractively interacting bosonic atoms, which always collapses in free space. Employing a transparent variational approach it will be shown that the stabilization requires a large level spacing in the trap compared to the attractive interaction between particles. The lecture will be completed by the discussion of experimentally observed (R. Hulet, Rice) macroscopic oscillations of a trapped attractively interacting BEC of 7Li atoms under a continuous feeding of the gas. 2015 年 6 月 17 日 ( 星期三 ) Vortices and solitons in Bose-condensed gases. Dissipative dynamic Vortices in two- and three-dimensional Bose-condensed gases and (dark) solitons in quasi-one-dimensional geometries generally represent macroscopically excited BEC states. They are fundamentally different from each other. Vortices have a topological quantum number, circulation, and they can decay only at the border of the system. At the same time, vortices scatter excitations, which can induce the vortex motion to the border and the dissipative decay of the vortices. Solitons do not have a topological quantum number and can decay in the bulk. However, they are transparent for the excitations due to the integrability of the system. Therefore, their dissipative dynamics emerges only due to violation of integrability, in particular by an “effective interaction” arising due to a virtual admixture of the transverse degrees of freedom in quasi-one-dimensional geometries. The two types of dissipative dynamics are quite different from each other, but both proceed fairly slowly. The lecture will be completed by the discussion of dissipative dynamics in vortex experiments at ENS (J. Dalibard) and in soliton experiments in Hannover (K. Sengstock). The use of Feshbach resonances for the two-body intercomponent interaction strength allowed experiments to reach the strongly interacting regime in two-component ultracold atomic Fermi gases, which brings in analogies with neutron matter. On one side of the resonance the interaction is attractive, and on the other one repulsive, decreasing when departing from the resonance. On the repulsive side of the resonance two fermions belonging to different components form weakly bound molecular states. These composite bosons are the largest diatomic moleculews obtained so far, with the size up to 5000 A. I will discuss why and how they manifest a remarkable collisional stability and may form a Bose-Einstein condensate. The discussion will be linked to series of experiments on strongly interacting Fermi gases (JILA, MIT, Innsbruck, ENS). 2015 年 6 月 30 日 ( 星期二 ) Anderson localization of one-dimensional ultracold bosons in disorder The phenomenon of Anderson localization of particles in a random potential finds its origin in the destructive interference in the multiple scattering of a particle from impurities. This leads to an exponential decay of the particle wavefunction at large distances and the particle gets localized on a certain length scale, localization length. In one dimension all single-particle states are localiz`ed irrespective of the energy. I will discuss the manifestation of Anderson localization in experiments with dilute one-dimensional bosonic clouds expanding in disorder after switching off the confining potential (A. Aspect, Palaiseau), which was the start of the studies of quantum gases in disorder.