Related Experiment Video
Updated: May 27, 2026

Optical Trap Loading of Dielectric Microparticles In Air
Published on: February 5, 2017
Noise associated with nonconservative forces in optical traps
Michel de Messieres1, Natalia A Denesyuk, Arthur La Porta
1Department of Physics, Institute for Physical Science and Technology Biophysics Program, University of Maryland, College Park, Maryland 20742, USA.
Abstract:
It is known that for a particle held in an optical trap the interaction of thermal fluctuations with a nonconservative scattering force can cause a persistent nonequilibrium probability flux in the particle position. We investigate position fluctuations associated with this nonequilibrium flux analytically and through simulation. We introduce a model which reproduces the nonequilibrium effects, and in which the magnitude of additional position fluctuations can be calculated in closed form. The ratio of additional nonconservative fluctuations to direct thermal fluctuations scales inversely with the square root of trap power, and is small for typical experimental parameters. In a simulated biophysical experiment the nonconservative scattering force does not significantly increase the observed fluctuations in the length of a double-stranded DNA tether.
Related Concept Videos
Non-conservative Forces
Also unlike their conservative counterparts, they are path-dependent; where the object starts and stops does matter. For example, a grinding wheel applies a...
Atomic Nuclei: Nuclear Relaxation Processes
Conservative Forces
Forced Oscillations
Damped Oscillations
Although friction and other non-conservative...

