Complete Hilbert-Space Ergodicity in Quantum Dynamics of Generalized Fibonacci Drives

Fuente: arXiv
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Main Authors: Pilatowsky-Cameo, Saúl, Dag, Ceren B., Ho, Wen Wei, Choi, Soonwon
Format: Preprint
Published: 2023
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author Pilatowsky-Cameo, Saúl
Dag, Ceren B.
Ho, Wen Wei
Choi, Soonwon
author_facet Pilatowsky-Cameo, Saúl
Dag, Ceren B.
Ho, Wen Wei
Choi, Soonwon
contents Ergodicity of quantum dynamics is often defined through statistical properties of energy eigenstates, as exemplified by Berry's conjecture in single-particle quantum chaos and the eigenstate thermalization hypothesis in many-body settings. In this work, we investigate whether quantum systems can exhibit a stronger form of ergodicity, wherein any time-evolved state uniformly visits the entire Hilbert space over time. We call such a phenomenon complete Hilbert-space ergodicity (CHSE), which is more akin to the intuitive notion of ergodicity as an inherently dynamical concept. CHSE cannot hold for time-independent or even time-periodic Hamiltonian dynamics, owing to the existence of (quasi)energy eigenstates which precludes exploration of the full Hilbert space. However, we find that there exists a family of aperiodic, yet deterministic drives with minimal symbolic complexity -- generated by the Fibonacci word and its generalizations -- for which CHSE can be proven to occur. Our results provide a basis for understanding thermalization in general time-dependent quantum systems.
format Preprint
id arxiv_https___arxiv_org_abs_2306_11792
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Complete Hilbert-Space Ergodicity in Quantum Dynamics of Generalized Fibonacci Drives
Pilatowsky-Cameo, Saúl
Dag, Ceren B.
Ho, Wen Wei
Choi, Soonwon
Quantum Physics
Statistical Mechanics
Ergodicity of quantum dynamics is often defined through statistical properties of energy eigenstates, as exemplified by Berry's conjecture in single-particle quantum chaos and the eigenstate thermalization hypothesis in many-body settings. In this work, we investigate whether quantum systems can exhibit a stronger form of ergodicity, wherein any time-evolved state uniformly visits the entire Hilbert space over time. We call such a phenomenon complete Hilbert-space ergodicity (CHSE), which is more akin to the intuitive notion of ergodicity as an inherently dynamical concept. CHSE cannot hold for time-independent or even time-periodic Hamiltonian dynamics, owing to the existence of (quasi)energy eigenstates which precludes exploration of the full Hilbert space. However, we find that there exists a family of aperiodic, yet deterministic drives with minimal symbolic complexity -- generated by the Fibonacci word and its generalizations -- for which CHSE can be proven to occur. Our results provide a basis for understanding thermalization in general time-dependent quantum systems.
title Complete Hilbert-Space Ergodicity in Quantum Dynamics of Generalized Fibonacci Drives
topic Quantum Physics
Statistical Mechanics
url https://arxiv.org/abs/2306.11792