Breaking Feshbach molecules

Felix Klose

Published Oct 9, 2026• 0 citations

Abstract

This thesis studies the effects of breaking Feshbach molecules of ⁶Li confined in an Optical-Dipole Trap (ODT). We discuss the effects of breaking molecules using background collisions between Feshbach molecules and H₂ particles in our vacuum system and resonant photons. In the case of background collisions we show that despite the collisions being energetic enough to always eject one of the constituent atoms, the remaining atom will only receive a weak kick. We show that the probability of the magnitude of the kick is related to the Feshbach molecule wavefunction. We describe an experiment for measuring this probability distribution, through measuring the time dynamics of the number of atoms and molecules in our trap as a function of the trap-depth and magnetic field, and discuss some preliminary results. Our results reveal that breaking molecules using pulses of light, resonant with one of the atomic transitions, results in similar dynamics. For both experiments we derive and discuss a phenomenological rate-equation model. We also characterized the magnetic trapping potential through a measurement of the associated trap-frequencies. Using the results of these measurements and incorporating the optical trapping potential due to the ODT and effects due to gravity, we calculate the trap-depth as a function of the magnetic field, power, and small vertical displacements. We demonstrate that vertical misalignment affects the trap similarly to changes in the magnetic field.

DOI: 10.14288/1.0456545

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