Senior Honors Thesis

Tuesday, May 31, 2016, Wilder 115, 10:00 AM

Lucas Valenca Soares Bezerra, Department of Physics and Astronomy, Dartmouth College

Title: Fast Wavefront Characterization of Optical Traps for Quantum Gases

Abstract: Ultracold quantum gases are frequently confined in optical dipole traps consisting of focused high power laser beams. In this project, we have designed and built a dynamically controllable dipole trap in which the changing beam characteristics can be monitored in real time. Ultracold gases are extremely sensitive to perturbations in the trapping potential, which can cause undesired heating. Our optical system uses an electronically tunable lens, which allows us to control the location of the trap with much less vibration and heating that traditional mechanical control. However, rapid changes of the focal length of the lens can potentially introduce aberrations that would distort the focal spot. Therefore, in order to determine the practical limits on high-speed operation of the lens, we incorporated a Shack-Hartmann wavefront sensor into the optical assembly, which can monitor the intensity distribution and wavefront parameters of the trapping beam in real time. With the data from the wavefront sensor, we can calculate the beam profile within the experimental chamber, and optimize the profile for different types of experiments with quantum degenerate gases, allowing us to probe the world of quantum effects in samples of macroscopic size.