含噪受监控振子中的量子-经典交叉
Quantum-classical crossover in noisy monitored oscillators
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中文总结 AI 辅助
本文研究受经典加性噪声驱动的简谐振子的首通时间，发现低阈值时量子与经典首通时间分布差异显著，高阈值时差异消失，两种动力学描述结果一致，为构建非经典资源态及研究量子-经典交叉提供框架。
中文摘要 AI 辅助
量子首通问题涉及以测量结果为条件的随机轨迹，这类轨迹的时间统计在开放量子系统中仍未得到充分探索。本文研究一类普遍模型——受经典加性噪声驱动的简谐振子——到达能量阈值的首通时间。我们发现，投影测量和能量量子化会在低阈值时使量子与经典首通时间分布产生显著差异，而随着阈值能量升高，这些差异会逐渐消失。我们采用系综平均的条件密度矩阵动力学和轨迹分辨的随机纯态动力学两种方法处理该问题，两种描述给出的时间统计结果完全一致。量子化效应体现在存活态的系综水平相空间分布中，并在较大阈值能量时消失。单个轨迹揭示出重复测量产生的涌现量子特征，如持续的维格纳负性。我们的结果提供了一个框架，可利用首通过程构建测量诱导的非经典资源态，并研究受监控系统的量子-经典交叉。
英文摘要
The quantum first-passage problem involves stochastic trajectories conditioned on measurement outcomes. The timing statistics of such trajectories remain largely unexplored in open quantum systems. Here, we investigate the first-passage time to an energy threshold for a ubiquitous model: a harmonic oscillator driven by classical additive noise. We find that projective measurements and energy quantization lead to substantial differences between the quantum and classical first-passage-time distributions at low thresholds, while these differences gradually diminish as the threshold energy increases. We treat the problem using both ensemble-averaged conditioned density-matrix dynamics and trajectory-resolved stochastic pure-state dynamics. The two descriptions yield indistinguishable timing statistics. Quantization effects appear in the ensemble-level phase-space distributions of the surviving states and vanish at larger threshold energies. Individual trajectories reveal emergent quantum signatures from the repeated measurements, such as persistent Wigner negativity. Our results provide a framework for using first-passage processes to create measurement-induced nonclassical resource states and to study the quantum-classical crossover of monitored systems.
