Abstract:
This talk discusses two types of molecules and their interplay. The ultralong-range Rydberg molecule (ULRM) forms when the Rydberg electron from an excited Ryberg atom scatters with a nearby atom and generates an attractive potential to form a bound state. While ULRMs from bosonic atoms have been extensively studied and realized in experiments, there are relatively few studies on fermionic atoms. Meanwhile, the BCS-Bose Einstein condensation (BEC) crossover of atomic Fermi superfluid introduces molecules formed by tightly bound Cooper pairs when the pairing interaction is strong. When a Rydberg atom is immersed in a Fermi superfluid, we show that a diatomic ULRM with a fermionic atom from a broken Cooper pair forms in the BCS regime while a triatomic ULRM with a trapped Cooper pair forms in the BEC regime. Moreover, we consider spin-dependent ULRM potentials due to the hyperfine states in the Fermi superfluid and show several special states, including the Yu-Shiba-Rusinov (YSR) states which have been studied in superconductors and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) like states due to population imbalance. The wavefunctions and energy spectrum of those special states reveal how Fermi superfluid reacts to a local spin-polarization potential induced by the spin-dependent ULRMs.