Phys. Rev. Lett. 110, 153001 (2013)
Cavity-enhanced interactions between light and a moving mechanical structure provide a new framework for quantum-sensitive displacement measurements. Thierry Botter and co-workers from the University of California and Lawrence Berkeley National Laboratory, USA, have now demonstrated that the near-ground-state collective motion of as many as six atomic ensembles can be simultaneously measured with quantum-limited sensitivity. 87Rb atoms were inserted into a Fabry–Pérot optical cavity and trapped in the potential minima of the superlattice formed by spatial beats generated by two laser beams with wavelengths of 843 nm and 862 nm. The spectrum of motional sidebands modified by the atomic motion was then extracted through optomechanical interactions with a weak probe beam whose intensity corresponded to an average intracavity photon number of 2.9. The quantum nature of six collective motional modes was confirmed by the asymmetry between the rates of red- and blue-detuned scattered photons near the frequency of each collective motional mode. The researchers also demonstrated that one particular collective motional mode can be coherently driven by modulating the intensity of the 843 nm laser beam while preserving the near-quantum motion of neighbouring collective motional modes.
This is a preview of subscription content, access via your institution