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New Equilibrium Ensembles for Isolated Quantum Systems.

Fabio Anza1

  • 1Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.

Entropy (Basel, Switzerland)
|December 3, 2020
PubMed
Summary
This summary is machine-generated.

Isolated quantum systems do not thermalize due to unitary dynamics. This study introduces a new method to approximate the diagonal ensemble (ρ DE), improving equilibrium state predictions beyond standard Gibbs ensembles.

Keywords:
entropyquantum informationquantum thermodynamicsthermalization

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Area of Science:

  • Quantum mechanics
  • Statistical mechanics
  • Quantum information theory

Background:

  • Unitary dynamics of isolated quantum systems prevent pure state thermalization.
  • Equilibration in isolated quantum systems aligns with the diagonal ensemble (ρ DE).
  • Jaynes' maximum entropy principle provides foundational intuition.

Purpose of the Study:

  • To present a novel technique for approximating the diagonal ensemble (ρ DE).
  • To develop progressively better approximations to ρ DE.
  • To offer a method that goes beyond the traditional Gibbs ensemble 'thermal ansatz'.

Main Methods:

  • Leveraging Jaynes' maximum entropy principle.
  • Developing a hierarchical set of ensembles.
  • Applying the technique to small isolated quantum systems.

Main Results:

  • A novel technique for approximating ρ DE is successfully developed.
  • Hierarchical ensembles are constructed to describe equilibrium physics.
  • The method provides a more refined description than Gibbs ensembles.

Conclusions:

  • The presented technique offers a more accurate way to describe equilibrium in isolated quantum systems.
  • This work extends beyond the limitations of the 'thermal ansatz'.
  • The findings are crucial for understanding thermalization and equilibration in quantum systems.