Atom walking in a traveling-wave light

TL;DR

This paper explores how ultra-slow atoms coherently coupled to traveling light can be made to walk in specific directions, with suppressed Doppler broadening, revealing potential for advanced atomic devices.

Contribution

It demonstrates that strong coupling suppresses Doppler broadening and enables controlled atomic walking based on internal states, revealing new mechanisms for atomic motion control.

Findings

Doppler broadening can be effectively suppressed in strong coupling regimes.

Atoms exhibit periodic walking influenced by internal state occupation.

The atomic motion is explained via spin-orbit coupling effects.

Abstract

In this paper, we investigate mechanical motion of ultra-slow single atoms considering each atom is coherently coupled to a traveling-wave light. The main noise in this system is originated from Doppler broadening due to the continuous momentum distribution in atom wave packet. Here, it is proved that the Doppler broadening could be effectively suppressed in strong coupling regime. Under the coherent coupling, individual neutral atoms periodically walk in a definite direction. Direction of the motion depends on occupation of the atom in its two internal states related to the optical transition, since the atom would be affected by attractive or repulsive forces depending on the internal states. It is analogous to the electric force acting on negatively or positively charged particles. We explain them with spin-orbit coupling of atoms which is hidden in our Hamiltonian. These results have potential applications for the construction of future atomic devices.