Entanglement of spin chains with general boundaries and of dissipative systems
Entanglement of spin chains with general boundaries and of dissipative systems
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自旋链与一般边界和耗散系统的纠缠
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
F. Guinea
中科院分区：
文献类型：
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作者：
T. Stauber;F. Guinea
我们分析了量子临界点附近自旋链边界附近的自旋（量子位）的纠缠性质，结果表明边界处的并发性与体自旋的并发性显着不同。我们还讨论了（边界）临界点附近的耗散环境的冯诺依曼熵，例如两个伊辛耦合近藤杂质或耗散双能级系统。我们的结果表明，纠缠（并发和/或冯·诺依曼熵）在相干量子振荡不再存在的点突然变化。如果不应用对称破缺场，相变对纠缠的影响会显着减少，我们认为这可能是耗散系统纠缠的一般性质。最后，我们分析了两端之间谐波链的纠缠作为系统尺寸的函数。
We analyze the entanglement properties of spins (qubits) close to the boundary of spin chains in the vicinity of a quantum critical point and show that the concurrence at the boundary is significantly different from the one of bulk spins. We also discuss the von Neumann entropy of dissipative environments in the vicinity of a (boundary) critical point, such as two Ising‐coupled Kondo‐impurities or the dissipative two‐level system. Our results indicate that the entanglement (concurrence and/or von Neumann entropy) changes abruptly at the point where coherent quantum oscillations cease to exist. The phase transition modifies significantly less the entanglement if no symmetry breaking field is applied and we argue that this might be a general property of the entanglement of dissipative systems. We finally analyze the entanglement of an harmonic chain between the two ends as function of the system size.