具有长程磁序的基态的块纠缠熵

Valence Bond and von Neumann Entanglement Entropy in Heisenberg Ladders

We present a direct comparison of the recently-proposed valence bond entanglement entropy and the von Neumann entanglement entropy on spin 1/2 Heisenberg systems using quantum Monte Carlo and density-matrix renormalization group simulations. For one-dimensional chains we show that the valence bond entropy can be either less or greater than the von Neumann entropy, hence it cannot provide a bound on the latter. On ladder geometries, simulations with up to seven legs are sufficient to indicate that the von Neumann entropy in two dimensions obeys an area law, even though the valence bond entangle…

耗散二能级系统的纠缠熵、退相干和量子相变

Entanglement Entropy, decoherence, and quantum phase transition of a dissipative two-level system

纠缠熵的概念出现在多个背景下，从黑洞物理到量子信息理论，它测量量子态的纠缠。我们在一个简单的模型中研究了纠缠熵，即自旋玻色子模型，该模型描述了一个量子比特（两能级系统）与一组谐振子的相互作用，这些谐振子模拟了导致退相干和耗散的环境。纠缠熵使得自旋与其环境的纠缠、退相干和量子相变之间得到了精确的统一。我们得到了精确的分析结果，证实了数值重整化群参数的欧姆和subohmic玻色子浴。这说明了纠缠熵服从普适标度。我们比较了量子伊辛模型和迪克模型中的纠缠性质。我们还强调了使用受电磁噪声影响的电荷量子比特测量这种纠缠熵的可能性;这种测量将提供纠缠熵存在的经验证据。