Contributed Talk: Bow-tie two-photon recoil interactions and gray molasses in a ring cavity

H. Eneriz^1,2, D. S. Naik¹, G. Santana-de-Figueiredo¹, P. Bouyer¹, and A. Bertoldi¹

¹LP2N, Universit ́e Bordeaux, IOGS, CNRS, Talence, France
²Universit ́e Cˆote d’Azur, INPHYNI, Valbonne, France

In our experiment, ultracold 87Rb atoms are charged at the center of the cross–shaped cavity at 1560 nm, where a far off–resonant dipole trap (FORT) is created. High–finesse at 780 nm allows for collective strong atom-cavity coupling via frequency doubling of the 1560 nm source which is locked to the cavity resonance. Cooling of an atomic gas to ultracold temperatures requires a multistage process: laser cooling in a magneto–optical trap (MOT); sub–Doppler cooling; loading into a conservative magnetic or optical trap; and often evaporative cooling. Sub–Doppler cooling schemes involving dark states have emerged as a powerful technique: they are known as gray molasses. In this context, we show that dark state cooling in a hyperfine two–photon Raman condition can be used in combination with FORT when strong differential light shifts are present. Additionally, we utilize this technique to cool the atomic ensemble in the FORT by further detuning the Raman beams to the red.
In another set of experiments, we exploit the doubly resonant character of the cavity, both at 1560 and 780 nm, to explore the interaction between the atoms and the cavity. Experimentally, continuous 780 nm laser light injection has been obtained by improving the 1560 nm frequency lock to the cavity, where ultracold atoms loaded into the FORT can collectively interact with the 780 nm light. Interactions between counter-propagating modes and BECs could reveal the existence of different phases of matter which we would like to explore in the future.

[1] D. S. Naik and G. Kuyumjyan and D. Pandey and P. Bouyer and A. Bertoldi, Q. Sci. and Tech. 3, 045009 (2018).
[2] D. S. Naik and H. Eneriz-Imaz and M. Carey and T. Freegarde and F. Minardi and B. Battelier and P. Bouyer and A. Bertoldi, Phys. Rev. Res. 2, 013212 (2020).
[3] G. Condon and M. Rabault and B. Barrett and L. Chichet and R. Arguel and H. Eneriz–Imaz and D. Naik, A. Bertoldi and B. Battelier and P. Bouyer and A. Landragin, Phys. Rev. Lett. 123, 240402 (2019).