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Measurement-Induced Crossover of Quantum Jump Statistics in Postselection-Free Many-Body Dynamics
Kazuki Yamamoto1,2,3,4, Ryusuke Hamazaki5
1Osaka Metropolitan University, Research Institute for Innovation and Co-Creation, Sakai, Osaka 599-8531, Japan.
Physical Review Letters
|August 10, 2026
Summary
We discovered a crossover in quantum jump fluctuations in monitored many-body systems. Stronger measurements lead to anomalous scaling, enhancing uncertainty in quantum jump rate estimation.
Area of Science:
- Quantum physics
- Many-body systems
- Quantum measurement
Background:
- Continuously monitored many-body systems often reach a maximally mixed steady state.
- Understanding subsystem fluctuations is crucial for characterizing system dynamics and measurement effects.
Purpose of the Study:
- To investigate the crossover of subsystem fluctuations in continuously monitored many-body systems.
- To understand the impact of measurement strength on quantum jump statistics and estimation precision.
Main Methods:
- Analysis of subsystem fluctuations in many-body systems under continuous monitoring.
- Investigating scaling laws and statistical properties (Poissonian vs. super-Poissonian) based on measurement strength.
- Examining the role of integrated autocorrelation functions and transient dynamics.
Main Results:
- A nontrivial crossover in subsystem fluctuations was observed with varying measurement strength.
- Weak measurement strength shows standard volume law scaling (Poissonian statistics).
- Strong measurement strength reveals an anomalous universal scaling law (super-Poissonian statistics), enhancing estimation uncertainty.
Conclusions:
- The anomalous scaling originates from integrated many-body autocorrelation functions and transient dynamics.
- Measurement-induced crossovers provide postselection-free information about quantum jump dynamics.
- These findings are experimentally testable in ultracold atom systems.
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