Physical Review X (Nov 2020)

Correlation-Picture Approach to Open-Quantum-System Dynamics

  • S. Alipour,
  • A. T. Rezakhani,
  • A. P. Babu,
  • K. Mølmer,
  • M. Möttönen,
  • T. Ala-Nissila

DOI
https://doi.org/10.1103/PhysRevX.10.041024
Journal volume & issue
Vol. 10, no. 4
p. 041024

Abstract

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We introduce a dynamical picture, referred to as correlation picture, which connects a correlated bipartite state to its uncorrelated counterpart. This picture allows us to derive an exact dynamical equation for a general open-system dynamics with system-environment correlations included. This exact dynamics is in the form of a Lindblad-like equation even in the presence of initial system-environment correlations. For explicit calculations, we also develop a weak-correlation expansion that allows us to introduce systematic perturbative approximations. This expansion provides approximate master equations that can feature advantages over existing weak-coupling techniques. As a special case, we derive a Markovian master equation, which is different from existing approaches. We compare our equations with corresponding standard weak-coupling equations using two examples, for which our correlation-picture formalism is more accurate, or at least as accurate as the weak-coupling equations.