Author(s): Kazuki Yamamoto and Ryusuke Hamazaki 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 $∝L$ following Poissonian statistics for suffic… [Phys. Rev. Lett. 137, 040402] Published Thu Jul 23, 2026