监测玻色子中后选择纠缠相变的理论
Theory of post-selected entanglement transitions in monitored bosons
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中文总结 AI 辅助
本研究通过无副本Keldysh场论框架，揭示自由玻色子系统中测量诱导的纠缠相变机制，发现强监测导致玻色子凝聚及对数纠缠，弱监测产生体积律纠缠。
中文摘要 AI 辅助
由量子测量驱动的纠缠相变已成为开放量子多体物理中的核心范式。此类相变在具有有限局域希尔伯特空间维度的系统（如量子比特和费米子）中已被充分确立，而在具有无界局域占据数的玻色子系统中的实现仍知之甚少。即使在无相互作用的情况下，玻色子的数态本质上也是非高斯的，这阻碍了标准关联矩阵方法的使用。为解决此问题，我们发展了一个无副本的Keldysh场论框架，该框架将初始化于在位Fock态的玻色子系统的Renyi熵表示为由单粒子格林函数构造的矩阵的积和式。将该框架应用于连续监测的一维十字绣晶格并条件于无点击轨迹，我们发现了从体积律到对数纠缠标度的转变。我们表明，该转变由非厄米谱的重构控制，该重构将长寿命模式的数量从广延变为有限。在强监测区域，玻色子动态凝聚为少数最慢衰减模式，产生对数纠缠标度，而在弱监测下，广延的长寿命模式流形产生体积律纠缠。我们的结果为自由玻色子系统中测量诱导的纠缠相变建立了一种独特机制，并提供了一种计算高效的测量诱导玻色子凝聚的诊断方法。
英文摘要
Entanglement phase transitions driven by quantum measurements have emerged as a central paradigm in open quantum many-body physics. Such phase transitions are well established for systems with finite local Hilbert-space dimensions, such as qubits and fermions, while their realization in bosonic systems with unbounded local occupation numbers remains poorly understood. Even in the absence of interactions, number states of bosons are intrinsically non-Gaussian, preventing the use of standard correlation-matrix approaches. To address this problem, we develop a replica-free Keldysh field-theoretic framework that expresses the Renyi entropy of bosonic systems initialized in on-site Fock states in terms of permanents of matrices constructed from single-particle Green's functions. Applying this framework to a continuously monitored one-dimensional cross-stitch lattice conditioned on the no-click trajectory, we uncover a transition from volume-law to logarithmic entanglement scaling. We show that the transition is controlled by a restructuring of the non-Hermitian spectrum that changes the number of long-lived modes from extensive to finite. In the strongly monitored regime, bosons dynamically condense into a microscopic number of slowest-decaying modes, producing logarithmic entanglement scaling, whereas an extensive manifold of long-lived modes at weak monitoring gives rise to volume-law entanglement. Our results establish a distinct mechanism for measurement-induced entanglement transitions in free bosonic systems and provide a computationally efficient diagnostic of the measurement-induced bosonic condensation.
发表机构
- Louisiana State University（路易斯安那州立大学）
- Bar-Ilan University（巴伊兰大学）
机构由 AI 辅助整理，请以论文原文为准。
