# Laser-Assisted Self-Induced Feshbach resonance for ultracold polar molecule formation

## TL;DR

This paper introduces a novel laser-assisted Feshbach resonance mechanism, LASIFR, enabling enhanced control over ultracold polar molecule formation by manipulating atom pairs with laser light, applicable to all polar molecules.

## Contribution

It proposes and analyzes LASIFR, a new resonance mechanism that allows optical control of atom interactions and molecule formation in ultracold gases, demonstrated with Rb and Sr atoms.

## Key findings

- LASIFR exhibits a Fano profile in STIRAP pump transition.
- LASIFR enables increased atom pair probability density at short distances.
- Potential for optical control of interspecies scattering length without atom losses.

## Abstract

We propose a new type of Feshbach resonance occurring when two different ultracold atoms in their ground state undergo an s-wave collision in the presence of a continuous-wave laser light. The atoms collide in the dissociation continuum of the molecular electronic ground state which is coupled by the light to a rovibrational level of the same electronic ground state: we name this a Laser-Assisted Self-Induced Feshbach Resonance (LASIFR). This mechanism, valid for all polar molecules, is analyzed on the example of ultracold 87Rb and 84Sr atoms, for which the laser frequency falls in the THz range. The control of the LASIFR with the laser frequency and intensity allows for a strong increase of the pair probability density at short distances, which tremendously increases the number of atoms pairs transfered toward the absolute ground state level by STImulated Rapid Adiabatic Passage (STIRAP). The LASIFR results in the observation of a standard Fano profile in the pump transition of the STIRAP process, and is also promising for the optical control of the interspecies scattering length without atom losses.

---
Source: https://tomesphere.com/paper/1902.00323