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arXiv 1208.2679quant-ph
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Dicke模型中有限原子数的相变

Phase transitions with finite atom number in the Dicke Model

J. G. Hirsch, O. Castaños, E. Nahmad-Achar, R. López-Penã

摘要:

零温下二能级原子与单模腔场相互作用系统的序参量反映了在原子-腔场耦合强度达到临界值时存在量子相变。两个流行的例子是腔内光子的数量和激发原子的数量。相干态提供了一个平均场描述,在热力学极限下变得精确。利用对称性自适应SU(2)相干态(SACS)可以描述有限个原子的临界行为。投影处理后的变化,涉及SA能量表面的数值最小化,关联的有限数量相变与序参量,这源于SA能量表面中的两个局部极小值之间的竞争的不连续性。

英文摘要:

Two-level atoms interacting with a one mode cavity field at zero temperature have order parameters which reflect the presence of a quantum phase transition at a critical value of the atom-cavity coupling strength. Two popular examples are the number of photons inside the cavity and the number of excited atoms. Coherent states provide a mean field description, which becomes exact in the thermodynamic limit. Employing symmetry adapted (SA) SU(2) coherent states (SACS) the critical behavior can be described for a finite number of atoms. A variation after projection treatment, involving a numerical minimization of the SA energy surface, associates the finite number phase transition with a discontinuity in the order parameters, which originates from a competition between two local minima in the SA energy surface.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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