The field of atomic, molecular, and optical physics focuses on how atoms and molecules interact with light. In our experiment, we use several coupled optical lasers to create a series of potential wells, a pattern of high potential energy that causes atoms to become trapped in a three-dimensional gridlike layout, known as an optical lattice. We introduce a sample of ultracold 85Rb to spread throughout these wells. An additional laser, known as the probe beam, is set to interfere with the lattice, causing the lattice to shake, and atoms that oscillate in phase with the lattice’s own oscillation can propagate throughout the lattice. The atoms, while under the influence of the lattice and probe beams, have a random chance to spontaneously absorb and emit photons from the beams and jump to adjacent wells. This motion occurs only perpendicular to the probe beam and is known as Brillouin propagation. The specific focus of our experiment studies the effects of angling the probe beam with respect to the optical lattice. By altering the angle that the probe beam enters the lattice along the x-z plane, we have observed that it is possible to cause propagation in only a single direction at a time. The induced motion of the atoms creates a unidirectional nanoratchet effect, where there is net motion in a single direction, in this case along the positive or negative x-axis. This experiment represents the first demonstration of controlled nanoscale motion powered by random noise, applicable in the design of quantum computing. It is our hope that future work could create an efficient and repeatable method of inducing useful work from random fluctuations, and further the field of quantum mechanics.
Author: Daniel Wingert
Faculty Advisor: Samir Bali, Physics
Graduate Student Advisor: Ian Dilyard, Physics
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