Quantum analog of Landau-Lifshitz-Gilbert dynamics

Authors:
  • YLYuefei Liu
    Yuefei Liu
  • IMIvan P. Miranda
    Ivan P. Miranda
  • LJLee Johnson
    Lee Johnson
  • ABAnders Bergman
    Anders Bergman
  • ADAnna Delin
    Anna Delin
  • DTDanny Thonig
    Danny Thonig
  • MPManuel Pereiro
    Manuel Pereiro
  • OEOlle Eriksson
    Olle Eriksson
  • VMVahid Azimi Mousolou
    Vahid Azimi Mousolou
  • ESErik Sjöqvist
    Erik Sjöqvist
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Abstract
The Landau-Lifshitz-Gilbert (LLG) and Landau-Lifshitz (LL) equations play an essential role for describing the dynamics of magnetization in solids. While a quantum analog of the LL dynamics has been proposed in [Phys. Rev. Lett. 110, 147201 (2013)], the corresponding quantum version of LLG remains unknown. Here, we propose such a quantum LLG equation that inherently conserves purity of the quantum state. We examine the quantum LLG dynamics of a dimer consisting of two interacting spin-1/2 particles. Our analysis reveals that, in the case of ferromagnetic coupling, the evolution of initially uncorrelated spins mirrors the classical LLG dynamics. However, in the antiferromagnetic scenario, we observe pronounced deviations from classical behavior, underscoring the unique dynamics of becoming a spinless state, which is non-locally correlated. Moreover, when considering spins that are initially entangled, our study uncovers an unusual form of revival-type quantum correlation dynamics, which differs significantly from what is typically seen in open quantum systems.