Rotating Optical Tubes: An Archimedes' Screw for Atoms

TL;DR

This paper explores the dynamics of cold atoms in a rotating helical optical tube, revealing how inertial forces influence atomic motion and enabling transport akin to an optical Archimedes' screw.

Contribution

It introduces a detailed numerical analysis of atom motion in a rotating optical tube, demonstrating control over atomic oscillations and transport mechanisms.

Findings

Rotation induces vertical atomic motion via inertial forces.

Angular velocity controls oscillation frequency and turning points.

At high rotation speeds, atoms can be transported along the tube axis.

Abstract

The classical dynamics of a cold atom trapped inside a vertical rotating helical optical tube (HOT) is investigated by taking also into account the gravitational field. The resulting equations of motion are solved numerically. The rotation induces a vertical motion for an atom initially at rest. The motion is a result of the action of two inertial forces, namely the centrifugal force and the Coriolis force. Both inertial forces force the atom to rotate in a direction opposite to that of the angular velocity of the HOT. The frequency and the turning points of the atom's global oscillation can be controlled by the value and the direction of the angular velocity of the HOT. However, at large values of the angular velocity of the HOT the atom can escape from the global oscillation and be transported along the axis of the HOT. In this case, the rotating HOT operates as an Optical Archimedes' Screw (OAS) for atoms.