Atoms and Molecules Immersed in a Bose-Einstein Condensate

Abstract

In this thesis work, I demonstrate the creation of dipolar ²³Na⁴⁰K molecules in their absolute ground state directly from Bose polarons, which are dressed fermionic ⁴⁰K impurities immersed in a ²³Na Bose-Einstein condensate. In contrast to Feshbach molecules, Bose polarons at negative scattering length are long-lived in the presence of the BEC. We demonstrate direct photoassociation from Bose polarons to electron- ically excited molecular states, dark resonance spectroscopy of the absolute ground state molecular state, and finally stimulated rapid adiabatic passage (STIRAP) of Bose polarons into the molecular ground state, all in the presence of the Na BEC. This leads to a dense molecular gas at temperatures on the order of 70 nK immersed inside a 𝑇/𝑇 subscript 𝑐 = 0.1 BEC.