7–10 Sept 2020
Europe/Zurich timezone
20. konference českých a slovenských fyziků

CALDEIRA-LEGGET MODEL FOR PARTICLE-BATH SYSTEMS IN THE PRESENCE OF A MAGNETIC FIELD

9 Sept 2020, 15:50
30m

Speaker

Lisý V. (Department of Physics, Faculty of Electrical Engineering and Informatics, Technical University of Košice)

Description

The Brownian motion of a particle immersed in a bath of charged particles is considered when
the system is placed in a magnetic field. The widely accepted Caldeira-Legget particle-bath
model is modified so that not only the charged Brownian particle (BP) but also the bath
particles respond to the external field. For stationary systems, two equations for the BP
motion across the field are derived. They are of the type of generalized Langevin equations
with two memory functions. The time correlation function of the thermal force is connected
with one of these functions through the fluctuation-dissipation theorem but, unlike all
previous theories, it is found to depend on the external field. In the absence of the magnetic
force, the other memory function disappears. Analytical expressions are obtained for the
velocity correlation functions and other relevant quantities such as the mean square
displacement and the diffusion coefficient of the BP for different distributions of the
eigenfrequencies of the bath oscillators. Assuming the Drude distribution of the frequencies, it
is found that at long times the motion of the particle is sub-diffusive, with the exponent 1/2.
The case of the fractional thermal noise is also analyzed.

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