An optomechanical elevator: Transport of a Bloch oscillating Bose-Einstein condensate up and down an optical lattice by cavity sideband amplification and cooling

TL;DR

This paper explores how a Bose-Einstein condensate in an optical lattice inside a cavity can be transported up or down by cavity-induced sideband effects, enabling force measurement without altering the Bloch frequency.

Contribution

It demonstrates the control of atomic transport via cavity backaction and shows the Bloch frequency remains unaffected by backaction, facilitating precise force sensing.

Findings

Transport of atoms up or down the lattice depending on pump detuning

Absence of optical spring effect on the Bloch frequency

Potential for continuous force measurement using the Bloch oscillator

Abstract

We analyze the optomechanics of an atomic Bose-Einstein condensate interacting with the optical lattice inside a laser-pumped optical cavity and subject to a uniform bias force such as gravity. An atomic wave packet in a tilted lattice undergoes Bloch oscillations; in a cavity the backaction of the atoms on the light leads to a time-dependent modulation of the intracavity lattice at the Bloch frequency. When the Bloch frequency is on the order of the cavity damping rate we find transport of the atoms either up or down the lattice. The transport dynamics can be interpreted as a manifestation of dynamical backaction-induced sideband damping/amplification of the optomechanical Bloch oscillator. Depending on the sign of the pump-cavity detuning, atoms are transported either with or against the bias force accompanied by an up- or down-conversion of the frequency of the pump laser light. We also evaluate the prospects for using the optomechanical Bloch oscillator to make continuous measurements of forces by reading out the Bloch frequency. In this context we establish the significant result that the optical spring effect is absent and the Bloch frequency is not modified by the backaction.