Cramer M, Ospelkaus S, Ospelkaus C, Bongs K, Sengstock K, Eisert J
Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom.
Phys Rev Lett. 2008 Apr 11;100(14):140409. doi: 10.1103/PhysRevLett.100.140409.
Mixtures of bosonic and fermionic atoms in optical lattices provide a promising arena to study strongly correlated systems. In experiments realizing such mixtures in the quantum-degenerate regime the temperature is a key parameter. We investigate the intrinsic heating and cooling effects due to an entropy-preserving raising of the optical lattice, identify the generic behavior valid for a wide range of parameters, and discuss it quantitatively for the recent experiments with 87Rb and 40K atoms. In the absence of a lattice, we treat the bosons in the Hartree-Fock-Bogoliubov-Popov approximation, including the fermions in a self-consistent mean-field interaction. In the presence of the full three-dimensional lattice, we use a strong coupling expansion. We find the temperature of the mixture in the lattice to be always higher than for the pure bosonic case, shedding light onto a key point in the analysis of recent experiments.
光学晶格中玻色子和费米子原子的混合物为研究强关联系统提供了一个很有前景的领域。在量子简并状态下实现这种混合物的实验中，温度是一个关键参数。我们研究了由于光学晶格的熵守恒提升而产生的固有加热和冷却效应，确定了在广泛参数范围内有效的一般行为，并针对最近使用87Rb和40K原子的实验进行了定量讨论。在没有晶格的情况下，我们在哈特里 - 福克 - 博戈留波夫 - 波波夫近似下处理玻色子，包括在自洽平均场相互作用中处理费米子。在存在完整三维晶格的情况下，我们使用强耦合展开。我们发现晶格中混合物的温度总是高于纯玻色子情况，这为近期实验分析中的一个关键点提供了启示。
