Ultracold molecules based on two-electron atoms

Matthieu Viteau, Amodsen Chotia, M. Allegrini +4 more

Using a nonselective broadband detection scheme we discovered an efficient mechanism of formation of ultracold ${\mathrm{Cs}}_{2}$ molecules in deeply bound vibrational levels $(v=1--9)$ of their electronic ground state $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}_{g}^{+}$. They are formed by a one-photon photoassociation of ultracold cesium atoms in a manifold of excited electronic states, followed by a two-step spontaneous emission cascade. This process creates about ${10}^{5}--{10}^{6}\phantom{\rule{0.3em}{0ex}}\text{molecules}\phantom{\rule{0.3em}{0ex}}\text{per}\phantom{\rule{0.3em}{0ex}}\text{second}$. This detection scheme is an advancement compare to previous ones and could be generalized to other molecular species for the systematic investigation of cold molecule formation mechanisms.

Jun Ye

Cindy A. Regal, Christopher Ticknor, John L. Bohn +1 more

Jin‐Tae Kim, Yonghoon Lee, Bongsoo Kim +4 more

We report the spectroscopic characterization of excited electronic states of KRb by combining spectra from molecular beam (MB) experiments with those from ultracold molecules (UM) formed by photoassociation (PA) of ultracold atoms. Spectra involving the 1(1)Π, 2(3)Σ(+), and b(3)Π states in a strongly perturbed region have been identified. This approach provides a powerful method to identify the vibrational levels of the excited electronic states perturbed globally by neighboring electronic states. This is because the two sets of spectra from the UM and the MB experiments probe the same energy region from very different initial electronic states. The UM experiments utilize high v'' levels of the a(3)Σ(+) state with large internuclear separations, while the MB experiments utilize low v'' levels of the ground X(1)Σ(+) state with near-equilibrium internuclear separations. Only the Ω = 1 levels of the 2(3)Σ(+) and b(3)Π states are observed in the MB spectra, while the Ω = 0(-), 1 levels of the 2(3)Σ(+) state and the Ω = 0(±), 1, 2 levels of the b(3)Π state are observed in the UM spectra.

Françoise Masnou-Seeuws, P. Pillet

Y. B. Band, Paul S. Julienne

We propose a method for copiously producing ultracold ground electronic-state molecules by two-photon absorption to a Rydberg molecular level (that spontaneously radiates to the ground molecular state) during collisions of ultracold atoms in a laser trap. Using the ${\mathrm{Na}}_{2}$ molecule as an example, the sequential two-photon absorption is via an intermediate high-lying vibrational level of the excited ${1}_{\mathit{g}}$ state and results in the formation of a given vibrational level of a $^{1}\mathrm{\ensuremath{\Pi}}_{\mathit{u}}$ Rydberg molecular state. Realistic calculations demonstrating the validity of the method are presented.