Quantum mechanical response to a driven Caldeira-Leggett bath.

Area of Science:

• Quantum Mechanics
• Condensed Matter Physics
• Statistical Mechanics

Background:

• Quantum systems often interact with their environment (bath), leading to dissipation and decoherence.
• The Caldeira-Leggett model describes a quantum system coupled to a bath of harmonic oscillators.
• Driven baths introduce time-dependent forces on the bath degrees of freedom, impacting system dynamics.

Purpose of the Study:

• To determine the frequency-dependent response of a quantum system coupled to a driven Caldeira-Leggett bath.
• To analyze the effects of external time-dependent forces on both the system and the bath.
• To investigate the Rubin model as a specific example of a driven dissipative quantum system.

Main Methods:

• General theoretical framework for driven Caldeira-Leggett baths.
• Mapping the Rubin model (chain of quantum particles) to a system coupled to a driven bath.
• Analysis of specific cases: harmonic potential and quantum two-state system.
• Evaluation of dynamical response to periodic driving of system and bath.

Main Results:

• Bath driving introduces a non-Markovian, time-dependent force on the central quantum system.
• The dynamic susceptibility is qualitatively altered by bath driving.
• The dispersive part of susceptibility is enhanced at low frequencies, peaking at zero frequency.
• The absorptive part exhibits a shoulder-like feature in the low-frequency regime.

Conclusions:

• The dynamic response of quantum systems to driven baths exhibits unique features.
• Bath driving can significantly modify system properties, such as susceptibility.
• Observed changes in dynamic susceptibility are likely generic for quantum systems in driven Caldeira-Leggett baths.