Quantum theory of magneto-optical trap

TL;DR

This paper develops a quantum kinetic model of magneto-optical traps (MOTs), revealing their non-equilibrium steady states, momentum distributions, and spatial structures influenced by magnetic field gradients, advancing understanding of cold atom trapping.

Contribution

It introduces a first-principles quantum kinetic theory of MOTs that accounts for recoil effects and provides new insights into their non-equilibrium distributions and spatial configurations.

Findings

Steady-state MOT atoms exhibit a non-equilibrium two-temperature distribution.

Momentum distribution in MOTs differs significantly from optical molasses.

Increased magnetic field gradient leads to a spatial two-component atom distribution.

Abstract

We present a quantum theory of a magneto-optical trap (MOT) from first principles based on the quantum kinetic equation for the atomic density matrix with taking into account the recoil effects caused by the interaction of atoms with the laser field. An efficient method for solving the quantum kinetic equation is proposed. It is shown that the steady-state solution describing the atoms in the MOT has a significantly non-equilibrium nature and can be described within the framework of a two-temperature distribution. The momentum distribution of cold atoms in the MOT depends on the magnetic field gradient and, in general, significantly differs from the momentum distribution of atoms in the optical molasses, which is usually used as an approximation to describe the MOT. We have also shown that with an increase in the magnetic field gradient, a spatial two-component distribution of atoms in the trap is formed even for a single particle approximation when interatomic interactions are neglected.