Optical shielding of destructive chemical reactions between ultracold ground-state NaRb molecules

TL;DR

This paper introduces an optical shielding method using a blue-detuned laser to suppress destructive chemical reactions in ultracold NaRb molecules, potentially increasing trap lifetimes and aiding cooling.

Contribution

It presents a novel optical shielding technique that leverages laser-induced dipole interactions to prevent reactive collisions in ultracold molecules.

Findings

Laser detuning suppresses reactive collisions effectively.

Spontaneous emission does not impair the shielding.

Method applicable to other alkali-metal diatomics.

Abstract

We propose a method to suppress the chemical reactions between ultracold bosonic ground-state $^{23}$Na$^{87}$Rb molecules based on optical shielding. By applying a laser with a frequency blue-detuned from the transition between the lowest rovibrational level of the electronic ground state $X^1\Sigma^+ (v_X=0, j_X=0)$, and the long-lived excited level $b^3\Pi_0 (v_b=0, j_b=1)$, the long-range dipole-dipole interaction between the colliding molecules can be engineered, leading to a dramatic suppression of reactive and photoinduced inelastic collisions, for both linear and circular laser polarizations. We demonstrate that the spontaneous emission from $b^3\Pi_0 (v_b=0, j_b=1)$ does not deteriorate the shielding process. This opens the possibility for a strong increase of the lifetime of cold molecule traps, and for an efficient evaporative cooling. We also anticipate that the proposed mechanism is valid for alkali-metal diatomics with sufficiently large dipole-dipole interactions.