2013/06/30 by M. Scala, M. S. Kim, G. W. Morley +2 · 3 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physrevlett.111.180403
published as Phys. Rev. Lett. 111, 180403 (2013) · 5 pages, 2 figures, version accepted for publication in Physical Review Letters
arxiv created 2013/10/15 · arxiv updated 2013/10/30
We show how the interference between spatially separated states of the center of mass (COM) of a mesoscopic harmonic oscillator can be evidenced by coupling it to a spin and performing solely spin manipulations and measurements (Ramsey Interferometry). We propose to use an optically levitated diamond bead containing an NV center spin. The nano-scale size of the bead makes the motional decoherence due to levitation negligible. The form of the spin-motion coupling ensures that the scheme works for thermal states so that moderate feedback cooling suffices. No separate control or observation of the COM state is required and thereby one dispenses with cavities, spatially resolved detection and low mass-dispersion ensembles. The controllable relative phase in the Ramsey interferometry stems from a gravitational potential difference so that it uniquely evidences coherence between states which involve the whole nano-crystal being in spatially distinct locations.