报告题目：Ultralong-Range Ytterbium Rydberg Molecules

报告人：Xin Wang （Institute of Applied Physics, University of Bonn, Germany）

报告时间：2025年4月26日（周六）下午3:00

报告地点：光电所二层报告厅

报告摘要：  

An ultralong-range Rydberg molecule forms through the interaction between the electron of a highly excited Rydberg atom and ground-state atoms, leading to molecular states characterized by extreme spatial extensions, permanent dipole moments and long lifetimes.

In this work, we present the first spectroscopic observation of ultralong-range ytterbium Rydberg molecules in a dense and ultracold atomic gas. Using two-photon excitation, we produce different Rydberg molecular states and detect their spectra by field ionization.

We use Fermi’s pseudopotential in first-order perturbation to fit the simplest dimer ground state for Rydberg  series and extract the singlet 𝑠-wave scattering length of ~ . At atomic densities of ~  we also observe polyatomic molecules with multiple ground-state atoms bound to a Rydberg atom.

For preparation of high-density ytterbium clouds, our apparatus features a compact two-chamber design comprising a dispenser-loaded 2D MOT and a two-color 3D MOT. This enables narrow-linewidth cooling and trapping of  atoms down to 7 𝜇K[1]. After loading into an optical trap, consecutive evaporation and compression we reach atomic densities of  at 4 uK. Electrodes around the atomic cloud allow for electric field background compensation, and field ionization of Rydberg atoms and molecules for their detection with a microchannel plate.

As a next step, we are currently using the nonperturbative Green’s function approach combined with the multichannel quantum defect theory to interpret additional peaks at both positive and negative binding energies, to study potential p-wave shape resonance and state mixing among different angular momentum states.