School of Physics Masters Thesis Defense

John Karnosh

Dr. Colin Parker, School of Physics, Georgia Institute of Technology (Advisor)

BEC-BCS Crossover of an Ultracold Lithium-6 Gas in a Shaken Optical Lattice

Date: Thursday, April 16, 2026

Time: 2:00 p.m.

Location: Howey Physics Building, W505

Committee members:

Dr. Michael Chapman, School of Physics, Georgia Institute of Technology

Dr. Dragomir Davidovic, School of Physics, Georgia Institute of Technology

Dr. Carlos Sá de Melo, School of Physics, Georgia Institute of Technology

Abstract:

Ultracold atoms serve as a useful platform for studying a wide variety of quantum systems due to the high degree of control and tunability which is experimentally achievable. A particularly interesting system is the unitary fermi gas in which the scattering length diverges and interactions become very strong. The broad magnetic Feshbach resonance present in lithium-6 at 834 Gauss allows tuning of the scattering length and interaction strength across the BEC-BCS crossover. This thesis investigates the dynamics of a molecular Bose-Einstein condensate in a double well dispersion generated by a 1 dimensional shaken optical lattice, resulting in a bifurcation of the condensate in momentum space. The effects of magnetic field ramps towards the resonance from the BEC side are studied to begin to build a picture of how the interaction strength modifies these dynamics. Additionally, this thesis studies aspects of the experimental system regarding efficient operation and troubleshooting.