成大物理系徽
光電所與量子資訊中心
演講題目: Molecular Bose-Einstein Condensate And High-Tc Fermionic Superfluid
演講人: 金 政 博士
Institut für Experimental physik, Universität Innsbruck, Austria
演講時間: 2004 年 4 月 16 日
星期五  下午 2 : 00
演講地點: 物理二館地下室 (49X04)
內容摘要:  
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Abstract

The formation of composite bosons by pairing fermions leads to intriguing phenomena in physics, with superconductivity and 3He superfluidity being prominent examples. In an ultracold gas of fermionic atoms, the tunable pairing interaction offers exciting possibilities to explore the crossover from a molecular Bose-Einstein condensate (BEC) in the strong-coupling regime to a Cooper-paired superfluid in the weak-coupling regime.

We achieve Bose-Einstein condensation of molecules by first converting fermionic atoms into bosonic molecules, and then cooling the molecules below the transition temperature. Remarkably, the molecular BEC has a long lifetime of >40s and provides a unique opportunity to study the BEC-BCS crossover, as well as the resonance superfluidity.

We have observed a smooth conversion from a molecular BEC to an degenerate Fermi gas with temperature T/TF<0.03. In collective modes and excitation spectra, we identify an abrupt phase transition and the formation of psuedogaps in the strongly interacting Fermi gas.