Suppression of power-broadening in strong-coupling photoassociation in the presence of a Feshbach resonance

TL;DR

This paper presents an analytical approach to suppress power broadening in photoassociation spectra near Feshbach resonances by tuning magnetic fields, enabling line narrowing even at high laser intensities due to quantum interference.

Contribution

It provides a nonperturbative analytical solution for PA linewidth and shift applicable across various laser intensities and magnetic fields, revealing a method to suppress power broadening.

Findings

Power broadening can be suppressed near Fano minima.

Line narrowing occurs at high laser intensities with large spectral shifts.

Quantum interference enables control over PA spectral features.

Abstract

Photoassociation (PA) spectrum in the presence of a magnetic Feshbach resonance is analyzed. Nonperturbative solution of the problem yields analytical expressions for PA linewidth and shift which are applicable for arbitrary PA laser intensity and magnetic field tuning of Feshbach Resonance. We show that by tuning magnetic field close to Fano minimum, it is possible to suppress power broadening at increased laser intensities. This occurs due to quantum interference of PA transitions from unperturbed and perturbed continuum. Line narrowing at high laser intensities is accompanied by large spectral shifts. We briefly discuss important consequences of line narrowing in cold collisions.