标题： 无后选择多体动力学中测量引起的量子跃迁统计交叉 显示英文标题

标题： Measurement-Induced Crossover of Quantum Jump Statistics in Postselection-Free Many-Body Dynamics

摘要： 我们揭示了连续测量的多体系统中量子跃迁的子系统涨落的非平凡交叉现象，这些系统的稳态密度矩阵为平凡的最大混合态。 当测量强度足够弱时，涨落表现出标准的体积律$\propto L$，并遵循泊松统计；而对于强测量强度，则出现异常但普适的标度律$\propto L^\alpha \:(\alpha\sim 2.7)$，表明超泊松统计。这显著影响了估计量子跃迁率的精度：对于强（弱）测量，随着系统尺寸增加，估计的不确定性被增强（抑制）。 我们证明了子系统涨落的异常标度来源于一个积分的多体自相关函数，并且瞬态动力学对这一标度律起作用，而不是李ouvillian间隙。由量子跃迁的时间和位置获得的无后选择信息才能触及这种测量诱导的交叉现象，且可以在超冷原子实验中进行验证。 显示英文摘要

摘要： We reveal a nontrivial crossover of subsystem fluctuations of quantum jumps in continuously monitored many-body systems, which have a trivial maximally mixed state as a steady-state density matrix. While the fluctuations exhibit the standard volume law $\propto L$ following Poissonian statistics for sufficiently weak measurement strength, anomalous yet universal scaling law $\propto L^\alpha \:(\alpha\sim 2.7)$ indicating super-Poissonian statistics appears for strong measurement strength. This drastically affects the precision of estimating the rate of quantum jumps: for strong (weak) measurement, the estimation uncertainty is enhanced (suppressed) as the system size increases. We demonstrate that the anomalous scaling of the subsystem fluctuation originates from an integrated many-body autocorrelation function and that the transient dynamics contributes to the scaling law rather than the Liouvillian gap. The measurement-induced crossover is accessed only from the postselection-free information obtained from the time and the position of quantum jumps and can be tested in ultracold atom experiments.