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Quantum signatures of chaos, thermalization, and tunneling in the exactly solvable few-body kicked top
Published in American Physical Society
2019
PMID: 31330664
Volume: 99
   
Issue: 6
Abstract
Exactly solvable models that exhibit quantum signatures of classical chaos are both rare as well as important - more so in view of the fact that the mechanisms for ergodic behavior and thermalization in isolated quantum systems and its connections to nonintegrability are under active investigation. In this work, we study quantum systems of few qubits collectively modeled as a kicked top, a textbook example of quantum chaos. In particular, we show that the three- and four-qubit cases are exactly solvable and yet, interestingly, can display signatures of ergodicity and thermalization. Deriving analytical expressions for entanglement entropy and concurrence, we see agreement in certain parameter regimes between long-time average values and ensemble averages of random states with permutation symmetry. Comparing with results using the data of a recent transmons-based experiment realizing the three-qubit case, we find agreement for short times, including a peculiar steplike behavior in correlations of some states. In the case of four qubits we point to a precursor of dynamical tunneling between what in the classical limit would be two stable islands. Numerical results for larger number of qubits show the emergence of the classical limit including signatures of a bifurcation. © 2019 American Physical Society.
About the journal
JournalData powered by TypesetPhysical Review E
PublisherData powered by TypesetAmerican Physical Society
ISSN24700045
Open AccessNo
Concepts (11)
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    Quantum optics
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    QUBITS
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    Analytical expressions
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    ENSEMBLE AVERAGES
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    ENTANGLEMENT ENTROPY
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    EXACTLY SOLVABLE MODEL
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    Numerical results
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    Parameter regimes
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    PERMUTATION SYMMETRY
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    QUANTUM SIGNATURE
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    Quantum entanglement