Resonance reactions and enhancement of weak interactions in collisions of cold molecules

TL;DR

This paper explores resonance chemistry in ultracold molecules, highlighting how weak interactions and external fields influence chemical reactions, with potential applications in measuring quantum chaos and parity violation.

Contribution

It proposes future research directions on resonance effects in ultracold molecules, emphasizing sensitivity to weak fields and the role of compound resonances in reaction dynamics.

Findings

Resonance chemistry enables reactions when collision energy matches bound states.

External fields can enhance or suppress specific reaction channels.

High density of narrow resonances allows for precise measurements of quantum properties.

Abstract

With the creation of ultracold atoms and molecules, a new type of chemistry - "resonance" chemistry - emerges: chemical reactions can occur when the energy of colliding atoms and molecules matches a bound state of the combined molecule (Feshbach resonance). This chemistry is rather similar to reactions that take place in nuclei at low energies. In this paper we suggest some problems for future experimental and theoretical work related to the resonance chemistry of ultracold molecules. Molecular Bose-Einstein condensates are particularly interesting because in this system collisions and chemical reactions are extremely sensitive to weak fields; also, a preferred reaction channel may be enhanced due to a finite number of final states. The sensitivity to weak fields arises due to the high density of narrow compound resonances and the macroscopic number of molecules with kinetic energy E=0 (in the ground state of a mean-field potential). The high sensitivity to the magnetic field may be used to measure the distribution of energy intervals, widths, and magnetic moments of compound resonances and study the onset of quantum chaos. A difference in the production rate of right-handed and left-handed chiral molecules may be produced by external electric and magnetic fields and the finite width of the resonance. The same effect may be produced by the parity-violating energy difference in chiral molecules.