Prospects for measurement and control of the scattering length of metastable helium using photoassociation techniques

TL;DR

This paper explores the potential of using two-laser photoassociation spectroscopy to measure and control the scattering length of metastable helium atoms, providing a theoretical framework and simulation results for experimental guidance.

Contribution

It presents a numerical model for two-laser PA spectroscopy on He* atoms, demonstrating the feasibility of measuring the least-bound state and modifying the scattering length via optical Feshbach resonances.

Findings

Feasibility of spectroscopic determination of the least-bound energy level.

Simulated PA spectra as a guide for experimental design.

Prospects for controlling scattering length with optical Feshbach resonances.

Abstract

A numerical investigation of two-laser photoassociation (PA) spectroscopy on spin-polarized metastable helium (He*) atoms is presented within the context of experimental observation of the least-bound energy level in the scattering potential and subsequent determination of the s-wave scattering length. Starting out from the model developed by Bohn and Julienne [Phys. Rev. A \textbf{60}, (1999) 414], PA rate coefficients are obtained as a function of the parameters of the two lasers. The rate coefficients are used to simulate one- and two-laser PA spectra. The results demonstrate the feasibility of a spectroscopic determination of the binding energy of the least-bound level. The simulated spectra may be used as a guideline when designing such an experiment, whereas the model may also be employed for fitting experimentally obtained PA spectra. In addition, the prospects for substantial modification of the He* scattering length by means of optical Feshbach resonances are considered. Several experimental issues relating to the numerical investigation presented here are discussed.