Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
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DOI：
10.1038/415039a
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发表时间：
2002-01-03
期刊：
影响因子：
64.8
通讯作者：
Bloch, I
中科院分区：
文献类型：
--
作者：
Greiner, M;Mandel, O;Bloch, I
对于处于绝对零度的系统，所有的热涨落都被冻结，而量子涨落占主导地位。当两个相互竞争的能量项的相对强度在临界值上变化时，这些微观量子涨落可以在多体系统的基态中诱导宏观相变。在这里，我们观察到这样的量子相变玻色-爱因斯坦凝聚体与排斥相互作用，在一个三维的光学晶格势。随着晶格势深的增加，观察到从超流到Mott绝缘体相的转变。在超流相中，每个原子分散在整个晶格中，具有长程相位相干性。但在绝缘相，确切数量的原子位于单个晶格位置，在整个晶格中没有相位相干性;该相的特征在于激发光谱中的间隙。我们可以诱导系统的两个基态之间的可逆变化。
For a system at a temperature of absolute zero, all thermal fluctuations are frozen out, while quantum fluctuations prevail. These microscopic quantum fluctuations can induce a macroscopic phase transition in the ground state of a many-body system when the relative strength of two competing energy terms is varied across a critical value. Here we observe such a quantum phase transition in a Bose-Einstein condensate with repulsive interactions, held in a three-dimensional optical lattice potential. As the potential depth of the lattice is increased, a transition is observed from a superfluid to a Mott insulator phase. In the superfluid phase, each atom is spread out over the entire lattice, with long-range phase coherence. But in the insulating phase, exact numbers of atoms are localized at individual lattice sites, with no phase coherence across the lattice; this phase is characterized by a gap in the excitation spectrum. We can induce reversible changes between the two ground states of the system.