Self-induced cooling of optically bound pairs of atoms

TL;DR

This paper investigates how light-induced forces affect the stability of atom pairs, revealing that spontaneous emission causes heating that prevents stable binding without additional cooling methods.

Contribution

It demonstrates that spontaneous emission-induced heating outweighs optical binding forces, highlighting the need for extra cooling to stabilize atom pairs.

Findings

Spontaneous emission causes stochastic heating in atom pairs.

Light-induced forces alone cannot stabilize atom pairs against heating.

Additional cooling mechanisms are necessary for stable optical binding.

Abstract

The light scattered by cold atoms induces mutual optical forces between them, which can lead to bound states. In addition to the trapping potential, this light-induced interaction generates a velocity-dependent force which damps or amplifies the stretching vibrational mode of the two-atom "molecule". This velocity-dependent force acts on time scales much longer than the mode period or the dipole dynamics, determining the true stability of the bound state. We show that for two atoms, the stochastic heating due to spontaneous emission always exceeds the bounding effect, so pairs of cold atoms cannot be truly stable without an extra cooling mechanism.