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Area of Science:

  • Quantum Physics
  • Open Quantum Systems
  • Quantum Information Theory

Background:

  • Understanding relaxation rates is crucial for characterizing open quantum systems.
  • Existing theories often focus on specific regimes like weak coupling.
  • A universal property for relaxation rates would significantly advance the field.

Purpose of the Study:

  • To identify and investigate a general constraint on relaxation rates in open quantum systems.
  • To explore the universality of this constraint across different quantum dynamics.
  • To establish a physical manifestation of complete positivity verifiable through experiments.

Main Methods:

  • Analysis of relaxation rates in various quantum dynamics, including weak coupling regimes.
  • Investigation of evolutions that are nondecreasing in entropy.
  • Numerical analysis to support the conjectured universality of the constraint.
  • Construction of a model that saturates the derived bound to demonstrate tightness.

Main Results:

  • A universal constraint on relaxation rates has been identified.
  • This constraint holds for broad classes of quantum dynamics and entropy-nondecreasing evolutions.
  • The constraint is shown to be tight, with a model saturating the bound.
  • The constraint provides a physical, experimentally verifiable manifestation of complete positivity.

Conclusions:

  • The discovered constraint offers a universal property for relaxation rates in open quantum systems.
  • This universality is a significant step towards physically characterizing complete positivity.
  • The conjecture implies universal constraints on quantum channel spectra and aids in identifying Markovian evolution.