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arXiv 1901.07682cond-mat.stat-mech
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具有长程相互作用的开放量子自旋系统的非平衡相变

Nonequilibrium phase transition in an open quantum spin system with long-range interaction

Minjae Jo, Jaegon Um, B. Kahng

摘要:

利用量子朗之万方程和平均场论研究了耗散相干量子自旋系统中的非平衡相变。最近,量子接触过程(QCP)的理论研究,特别是当里德伯原子被激发在s-态,使它们的相互作用被认为是最近的邻居之间的里德伯反封锁效应。然而,当原子被激发到d态时,偶极-偶极相互作用变得有效,并且必须考虑长程相互作用。在这里,我们考虑一个具有长程QCP的量子自旋模型,其中不仅允许最近邻对的分支和凝聚过程,而且允许长程对的相干和非相干分支和凝聚过程。使用半经典的方法,我们表明,我们的长程模型的平均场相图是类似的最近邻QCP,连续(不连续)的过渡被发现在弱(强)量子制度。然而,在三临界点,我们发现了一个新的普适类,这既不是在三临界点的QCP,也不是经典的定向渗流模型与长程相互作用。讨论了利用相互作用冷气体实现远程QCP的方法。

英文摘要:

We investigate a nonequilibrium phase transition in a dissipative and coherent quantum spin system using the quantum Langevin equation and mean-field theory. Recently, the quantum contact process (QCP) was theoretically investigated using the Rydberg antiblockade effect, in particular, when the Rydberg atoms were excited in s-states so that their interactions were regarded as being between the nearest neighbors. However, when the atoms are excited to d-states, the dipole-dipole interactions become effective, and long-range interactions must be considered. Here, we consider a quantum spin model with a long-range QCP, where the branching and coagulation processes are allowed not only for the nearest-neighbor pairs, but also for long-distance pairs, coherently and incoherently. Using the semiclassical approach, we show that the mean-field phase diagram of our long-range model is similar to that of the nearest-neighbor QCP, where the continuous (discontinuous) transition is found in the weak (strong) quantum regime. However, at the tricritical point, we find a new universality class, which was neither that of the QCP at the tricritical point nor that of the classical directed percolation model with long-range interactions. Implementation of the long-range QCP using interacting cold gases is discussed.

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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