Cooling Flexural Modes of a Mechanical Oscillator by Magnetic Trapped Bose-Einstein Condensate Atoms

TL;DR

This paper proposes a theoretical method to cool a mechanical oscillator's flexural modes using a trapped Bose-Einstein Condensate, potentially reaching the quantum ground state through resonant coupling.

Contribution

It introduces a novel hybrid system combining a mechanical oscillator with trapped BEC atoms for mode cooling via magnetic coupling.

Findings

Ground state phonon number less than 1 is achievable.

Optimal parameters can significantly reduce the mode temperature.

Theoretical analysis supports feasibility of quantum ground state cooling.

Abstract

We theoretically study cooling of flexural modes of a mechanical oscillator by Bose-Einstein Condensate (BEC) atoms (Rb87) trapped in a magnetic trap. The mechanical oscillator with a tiny magnet attached on one of its free ends produces an oscillating magnetic field. When its oscillating frequency matches certain hyperfine Zeeman energy of Rb87 atoms, the trapped BEC atoms are coupled out of the magnetic trap by the mechanical oscillator, flying away from the trap with stolen energy from the mechanical oscillator. Thus the mode temperature of the mechanical oscillator is reduced. The mode temperature of the steady state of a mechanical oscillator, measured by the mean steady-state phonon number in the flexural mode of the mechanical oscillator, is analyzed. It is found that ground state (phonon number less than 1) may be accessible with optimal parameters of the hybrid system of a mechanical oscillator and trapped BEC atoms.