The rapid control of interactions in a two-component Fermi gas
Open Access
- Author:
- Stites, Ronald William
- Graduate Program:
- Physics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- November 12, 2012
- Committee Members:
- Kenneth O'hara, Dissertation Advisor/Co-Advisor
Milton Walter Cole, Committee Member
Kurt Gibble, Committee Member
David Weiss, Committee Member
John V Badding, Committee Member - Keywords:
- two-component Fermi gases
controlling interactions
injection locking
solid state ring lasers - Abstract:
- In this dissertation, we describe a variety of experiments having application to ultra-cold atomic gases. While the majority of the experimental results focus on the development of a novel laser source for cooling and manipulating a gas of fermionic 6Li atoms, we also report on a preliminary investigation of rapidly controlling interactions in a two-component Fermi gas. One of the primary tools for our ultra-cold atomic physics experiments is 671 nm laser light nearly resonant with the D1 and D2 spectroscopic lines of ultracold fermionic 6Li atoms. Traditionally, this light is generated using dye lasers or tapered amplifier systems. Here we describe a diode pumped solid state ring laser system utilizing a Nd:YVO4 gain crystal. Nd:YVO4 has a 4F3/2 → 4I13/2 emission line at 1342 nm. This wavelength is double the 671 nm needed for our experiments. As a part of this investigation, we also measured the Verdet constant of undoped Y3Al5O12 in the near infrared for constructing a Faraday rotator used to drive unidirectional operation of our ring laser. As an alternative method to achieve unidirectional, single-frequency operation of the laser, we developed a novel scheme of “self-injection locking” where a small portion of the output beam is coupled back into the cavity to break the symmetry. This technique is useful for high-power, single-frequency operation of a ring laser because lossy elements needed for frequency selection and unidirectional operation of the laser can be removed from the internal cavity. In addition to our laser experiments, we also drive Raman transitions between different magnetic hyperfine states within 6Li atoms. For atoms in the two lowest hyperfine states, there exists a broad Feshbach resonance at 834.1 Gauss whereby the s-wave scattering length diverges, resulting in strong interactions between the two species. By using two phase locked lasers to drive a transition from a strongly interacting state to a weakly interacting state, we can rapidly control the interaction strength of a two component Fermi gas.