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Area of Science:

  • Quantum dynamics
  • Condensed matter physics
  • Statistical mechanics

Background:

  • Two-level systems (TLS) coupled to harmonic baths are fundamental models.
  • Previous studies focused on TLS properties, averaging over bath dynamics.
  • Understanding system-bath interactions is crucial for quantum phenomena.

Purpose of the Study:

  • Investigate the behavior of specific bath degrees of freedom during TLS dynamics.
  • Utilize real-time path integral methods to calculate system-bath densities (SBD) and coordinate expectation values.
  • Analyze the influence of coupling strength and dissipation on system-bath dynamics.

Main Methods:

  • Real-time path integral formulation.
  • Calculation of system-bath densities (SBD).
  • Analysis of coordinate expectation values for select bath modes.

Main Results:

  • SBD motion on each diabatic state is simpler than the total density.
  • In weak coupling, SBD remains Gaussian-like, with peaks tracked by mode expectation values.
  • Dissipation stabilizes dynamics, synchronizes SBD, and regularizes trajectories to Lissajous-like shapes.

Conclusions:

  • Dissipative environments significantly regularize quantum system-bath dynamics.
  • The behavior of bath degrees of freedom can mimic classical trajectories, especially under dissipation.
  • This work provides insights into quantum dissipation and system-bath interactions.