Brownian motion was originally discovered as a biological phenomenon, when botanist Robert Brown observed rapid oscillatory motions of pollen grains in water under a microscope. This phenomenon was originally thought only to be present in living organisms, but further research showed that Brownian motion was observed in all physical systems, from particles of smoke to samples of granite. Our lab aims to study Brownian motion and demonstrate directed Brownian motion in a physical system; essentially having there be a net vector of motion without any net force present on the system. We use the technique of laser cooling and trapping cold atoms in an optical lattice to replicate directed Brownian motion. We cool down Rb 85 atoms to temperatures in the approximate range of tens of microkelvin and then construct an optical lattice using laser beams to provide potential peaks and wells for the atoms to settle into. We then use a weak laser beam to appropriately modulate the lattice at the speed of the oscillations of the atoms that are in the lattice to then propagate the atoms in a certain direction. We have achieved Brownian ratcheting by modulating the lattice in only one direction; our further work aims to be able to replicate the same phenomenon by modulating the lattice in a direction-agnostic manner.
Presenter(s): Chanakya Pandya, Physics and Computer Science Major
Advisor(s): Samir Bali, Department of Physics
Daniel Wingert, Department of Physics
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