Tailoring the escape rate of a Brownian particle by combining a vortex flow with a magnetic field

  • The probability per unit time for a thermally activated Brownian particle to escape over a potential well is, in general, well-described by Kramers’s theory. Kramers showed that the escape time decreases exponentially with increasing barrier height. The dynamics slow down when the particle is charged and subjected to a Lorentz force due to an external magnetic field. This is evident via a rescaling of the diffusion coefficient entering as a prefactor in the Kramers’s escape rate without any impact on the barrier-height-dependent exponent. Here, we show that the barrier height can be effectively changed when the charged particle is subjected to a vortex flow. While the vortex alone does not affect the mean escape time of the particle, when combined with a magnetic field, it effectively pushes the fluctuating particle either radially outside or inside depending on its sign relative to that of the magnetic field. In particular, the effective potential over which the particle escapes canThe probability per unit time for a thermally activated Brownian particle to escape over a potential well is, in general, well-described by Kramers’s theory. Kramers showed that the escape time decreases exponentially with increasing barrier height. The dynamics slow down when the particle is charged and subjected to a Lorentz force due to an external magnetic field. This is evident via a rescaling of the diffusion coefficient entering as a prefactor in the Kramers’s escape rate without any impact on the barrier-height-dependent exponent. Here, we show that the barrier height can be effectively changed when the charged particle is subjected to a vortex flow. While the vortex alone does not affect the mean escape time of the particle, when combined with a magnetic field, it effectively pushes the fluctuating particle either radially outside or inside depending on its sign relative to that of the magnetic field. In particular, the effective potential over which the particle escapes can be changed to a flat, a stable, and an unstable potential by tuning the signs and magnitudes of the vortex and the applied magnetic field. Notably, the last case corresponds to enhanced escape dynamics.show moreshow less

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Metadaten
Author:I. Abdoli, H. Löwen, J.-U. Sommer, Abhinav SharmaGND
URN:urn:nbn:de:bvb:384-opus4-1038654
Frontdoor URLhttps://opus.bibliothek.uni-augsburg.de/opus4/103865
ISSN:0021-9606OPAC
ISSN:1089-7690OPAC
Parent Title (English):The Journal of Chemical Physics
Publisher:AIP Publishing
Place of publication:Melville, NY
Type:Article
Language:English
Year of first Publication:2023
Publishing Institution:Universität Augsburg
Release Date:2023/04/28
Tag:Physical and Theoretical Chemistry; General Physics and Astronomy
Volume:158
Issue:10
First Page:101101
DOI:https://doi.org/10.1063/5.0139830
Institutes:Mathematisch-Naturwissenschaftlich-Technische Fakultät
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik / Lehrstuhl für Theoretische Physik II
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):CC-BY 4.0: Creative Commons: Namensnennung (mit Print on Demand)