Central Limit Theorems for Outcome Records in Disordered Quantum Trajectories

TL;DR

This paper establishes annealed central limit theorems for measurement records in disordered quantum trajectories, demonstrating Gaussian limits under broad conditions and initial states.

Contribution

It introduces a coupling-based admissibility concept and provides universal CLT results for disordered quantum measurement processes.

Findings

Proves annealed CLT for pattern counts in disordered quantum trajectories.

Identifies conditions for Gaussian limits to hold universally across initial states.

Verifies assumptions in a broad class of disordered walk models.

Abstract

We prove annealed central limit theorems for finite pattern counts in the measurement record of discrete-time quantum trajectories generated by repeated measurements in a disordered environment. Under summable mixing assumptions on the environment and an annealed trace-norm forgetting property for the associated non-selective channel cocycle, we first establish the CLT under the annealed law determined by the dynamically stationary state. This part applies to general disordered quantum instruments and, in particular, is not restricted to the perfect-measurement regime; it complements both the corresponding law of large numbers for disordered measurement records and the homogeneous central limit theorem. We then introduce a coupling-based notion of admissibility for initial states and show that the same Gaussian limit extends to every admissible initial law, with unchanged centering and asymptotic variance. In the perfect-measurement setting, we further identify a general condition ensuring admissibility for every initial state, and hence obtain a universal annealed central limit theorem. We also provide practical sufficient criteria for this condition and verify the assumptions across a broad family of examples, including disordered walk-type models generated by finite group actions