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

Abstract

We propose a method to suppress the chemical reactions between ultracold bosonic groundstate 23 Na 87 Rb molecules based on optical shielding. By applying a laser with a frequency bluedetuned from the transition between the lowest rovibrational level of the electronic ground state X 1 Σ + (vX = 0, jX = 0), and the long-lived excited level b 3 Π(v b = 0, j b = 1), we can engineer the long-range dipole-dipole interaction between the colliding molecules, 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 the long-lived b 3 Π(v b = 0, j b = 1) level 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.