Randomization Times under Quantum Chaotic Hamiltonian Evolution

Fuente: arXiv
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Main Authors: Ghosh, Souradeep, Hunter-Jones, Nicholas, Rodriguez-Nieva, Joaquin F.
Format: Preprint
Published: 2025
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author Ghosh, Souradeep
Hunter-Jones, Nicholas
Rodriguez-Nieva, Joaquin F.
author_facet Ghosh, Souradeep
Hunter-Jones, Nicholas
Rodriguez-Nieva, Joaquin F.
contents Randomness generation through quantum-chaotic evolution underpins foundational questions in statistical mechanics and applications across quantum information science, including benchmarking, tomography, metrology, and demonstrations of quantum computational advantage. While statistical mechanics successfully captures the temporal averages of local observables, understanding randomness at the level of higher statistical moments remains a daunting challenge, with analytic progress largely confined to random quantum circuit models or fine-tuned systems exhibiting space-time duality. Here we study how much randomness can be dynamically generated by generic quantum-chaotic evolution under physical, non-random Hamiltonians. Combining theoretical insights with numerical simulations, we show that for broad classes of initially unentangled states, the dynamics become effectively Haar-random well before the system can ergodically explore the physically accessible Hilbert space. Both local and highly nonlocal observables, including entanglement measures, equilibrate to their Haar expectation values and fluctuations on polynomial timescales with remarkably high numerical precision, and with the fastest randomization occurring in regions of parameter space previously identified as maximally chaotic. Interestingly, this effective randomization can occur on timescales linear in system size, suggesting that the sub-ballistic growth of Renyi entropies typically observed in systems with conservation laws can be bypassed in non-random Hamiltonians with an appropriate choice of initial conditions.
format Preprint
id arxiv_https___arxiv_org_abs_2512_25074
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Randomization Times under Quantum Chaotic Hamiltonian Evolution
Ghosh, Souradeep
Hunter-Jones, Nicholas
Rodriguez-Nieva, Joaquin F.
Statistical Mechanics
Quantum Physics
Randomness generation through quantum-chaotic evolution underpins foundational questions in statistical mechanics and applications across quantum information science, including benchmarking, tomography, metrology, and demonstrations of quantum computational advantage. While statistical mechanics successfully captures the temporal averages of local observables, understanding randomness at the level of higher statistical moments remains a daunting challenge, with analytic progress largely confined to random quantum circuit models or fine-tuned systems exhibiting space-time duality. Here we study how much randomness can be dynamically generated by generic quantum-chaotic evolution under physical, non-random Hamiltonians. Combining theoretical insights with numerical simulations, we show that for broad classes of initially unentangled states, the dynamics become effectively Haar-random well before the system can ergodically explore the physically accessible Hilbert space. Both local and highly nonlocal observables, including entanglement measures, equilibrate to their Haar expectation values and fluctuations on polynomial timescales with remarkably high numerical precision, and with the fastest randomization occurring in regions of parameter space previously identified as maximally chaotic. Interestingly, this effective randomization can occur on timescales linear in system size, suggesting that the sub-ballistic growth of Renyi entropies typically observed in systems with conservation laws can be bypassed in non-random Hamiltonians with an appropriate choice of initial conditions.
title Randomization Times under Quantum Chaotic Hamiltonian Evolution
topic Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2512.25074