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arXiv 1106.4173quant-phcond-mat.other
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自旋玻色子模型离域区的量子相变

Quantum phase transition in the delocalized regime of the spin-boson model

Qing-Jun Tong, Jun-Hong An, Hong-Gang Luo, C. H. Oh

摘要:

在欧姆自旋玻色子模型中,离域-局域量子相变(QPT)的存在已被普遍承认。定域态的物理过程相对简单,而离域态则表现出许多有趣的行为。在这里,我们发现,在这一制度存在一个新的QPT:即,从一个没有绑定状态的相位与绑定状态的相位,这导致在这两个阶段完全不同的动力学行为。如果贮存器最初处于移位真空状态(即,相干态)时,自旋动力学表现出无损振荡,否则,振荡将完全衰减.这一结果与发生在小隧穿极限的相干-非相干跃迁是一致的。我们的工作表明自旋玻色子模型中的QPT物理还需要进一步的探索。

英文摘要:

The existence of the delocalized-localized quantum phase transition (QPT) in the ohmic spin-boson model has been commonly recognized. While the physics in the localized regime is relatively simple, the delocalized regime shows many interesting behaviors. Here we reveal that in this regime there exists a novel QPT: namely, from a phase without a bound state to a phase with a bound state, which leads to completely different dynamical behaviors in these two phases. If the reservoir is initially in the displaced vacuum state (i.e., the coherent state), the spin dynamics exhibits lossless oscillation when the bound state exists; otherwise, the oscillation will decay completely. This result is compatible with the coherence-incoherence transition occurring in the small-tunneling limit. Our work indicates that the QPT physics in the spin-boson model needs further exploration.

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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