Optical Feedback Trap: How to Create Double Well Potential with Single Laser?
John Andrew C. Albay1*, Yonggun Jun1
1Department of Physics, National Central University, Taoyuan, Taiwan
* Presenter:John Andrew C. Albay
Feedback traps are used to study problems in non-equilibrium physics because of its ability to create “virtual potential”. In a feedback trap, the particle’s position is measured then force is applied based on the gradient of the “virtual potential” at the particle’s position. In our experiment setting, optical force was used for the feedback mechanism. First, we check the dynamics of a single particle in the harmonic potential and double well potential. The dynamics of the particle in the “virtual potential” is equivalent to the dynamics in a real potential. We also study the nano-scale compression of the piston using the feedback trap and a colloidal particle. Our experimental result agrees with the theoretical prediction as in previous work [1]. Thus, we confirm that our optical feedback trap has potential in studying fundamental questions in non-equilibrium statistical mechanics.

[1] Dong Yun Lee, Chulan Kwon, and Hyuk Kyu Pak, Nonequilibrium Fluctuations for a Single-Particle Analog of Gas in a Soft Wall, Phys. Rev. Lett, 2015

Keywords: Optical Feedback trap, virtual potential, optical force, double well potential, non-equilibrium physics