Toward an Entangled Matterwave Interferometer

A current frontier is to apply recent advances in entanglement generation using cavity-QED [1,2,3] to enhance quantum sensors beyond the standard quantum limit (SQL). As part of this effort, we will describe a rubidium matterwave interferometer with atoms guided by a blue-detuned hollow optical dipole trap as they free-fall along the axis of a high-finesse cavity. The hollow guiding potential is created in the cavity by driving a Laguerre-Gauss LG₀₁ mode. Multiple adjacent longitudinal modes of the standing wave cavity are also excited to provide a smooth axial guiding potential. Raman beams are injected through the cavity to realize the interferometer’s beamsplitter operations as well as the necessary velocity selection for state preparation. The interferometer is read out using cavity-enhanced quantum non-demolition (QND) with added readout noise as much as 10 dB below the projection. We will conclude by discussing our efforts to further improve the QND measurements to realize an entangled interferometer with sensitivity surpassing the SQL.

[1] K.C. Cox, G.P. Greve, J.M. Weiner, J.K. Thompson. PRL 116 093602  (2016) 

[2] O. Hosten, N. J. Engelsen, R. Krishnakumar, M.A. Kasevich. Nature 529 505 (2016)

[3] E. Pedrozo-Peñafiel, S. Colombo, C. Shu, A.F. Adiyatullin, Z. Li, E. Mendez, B. Braverman, A. Kawasaki, D. Akamatsu, Y. Xiao, V. Vuletić. Nature 588 7838 (2020)