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Random matrix theory approach to quantum Fisher information in quantum ergodic systems
Venelin P Pavlov1, Yoana R Chorbadzhiyska1, Charlie Nation2
1Center for Quantum Technologies, Department of Physics, <a href="https://ror.org/02jv3k292">St. Kliment Ohridski University of Sofia</a>, James Bourchier 5 Blvd., 1164 Sofia, Bulgaria.
We explored quantum parameter estimation in chaotic systems using random matrix theory. Our findings reveal three distinct timescales governing information spread and extraction during quantum thermalization.
Area of Science:
- Quantum Information Science
- Quantum Many-Body Systems
- Statistical Physics
Background:
- Quantum chaotic systems exhibit complex dynamics.
- Quantum parameter estimation quantifies information obtainable from quantum states.
- Random matrix theory effectively describes quantum ergodic systems.
Purpose of the Study:
- To theoretically investigate quantum parameter estimation in quantum chaotic systems.
- To derive an analytical expression for the time evolution of quantum Fisher information (QFI).
- To understand the timescales of information spreading during quantum thermalization.
Main Methods:
- Utilizing an effective description of quantum ergodic systems via a random matrix Hamiltonian.
- Deriving an analytical expression for the time evolution of QFI.
- Performing exact diagonalization of a nonintegrable spin system for numerical validation.
Main Results:
- Identified three distinct timescales governing QFI evolution.
- Observed initial quadratic QFI increase, followed by linear increase, and a final quadratic long-time behavior.
- Numerical results from a nonintegrable spin system validated the random matrix theory predictions.
Conclusions:
- The study provides an analytical framework for quantum parameter estimation in chaotic systems.
- Information on local Hamiltonian parameters distributes throughout the system during quantum thermalization.
- The findings offer insights into the dynamics of information in complex quantum systems.
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