Prospects for the formation of ultracold polar ground state KCs molecules via an optical process

Abstract

Heteronuclear alkali-metal dimers represent the class of molecules of choice for creating samples of ultracold molecules exhibiting an intrinsic large permanent electric dipole moment. Among them, the KCs molecule, with a permanent dipole moment of 1.92 Debye still remains to be observed in ultracold conditions. Based on spectroscopic studies available in the literature completed by accurate quantum chemistry calculations, we propose several optical coherent schemes to create ultracold bosonic and fermionic KCs molecules in their absolute rovibrational ground level, starting from a weakly bound level of their electronic ground state manifold. The processes rely on the existence of convenient electronically excited states allowing an efficient stimulated Raman adiabatic transfer of the level population.

The $a^3Σ^+$ state of KCs revisited: hyperfine structure analysis and potential refinement

“…In the present experiment we aimed to excite the F 2 (J c = N c ) levels in the c 3 Σ + state of 39 K 133 Cs. Overall we have recorded at the highest resolution 17 doublet P,R progressions with N a = J c ± 1 covering a 3 Σ + state rovibronic levels with v a ∈ [0, 27] and N a ∈ [24,90]. Detailed information on the c 3 Σ + state was obtained from the recent study [13].…”

“…Prospects for formation of cold KCs molecules have been evaluated in Refs. [23,24], based on the analysis of the ground and several excited states of the molecule. Experiments with mixed ultracold ensembles of K and Cs were reported in 2014 -2017 [25][26][27].…”

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Laser-induced fluorescence spectra of the c 3 Σ + (vc, Jc = Nc) → a 3 Σ + (va, Na = Jc ± 1) transitions excited from the ground X 1 Σ + state of 39 K 133 Cs molecule were recorded with Fourier-transform spectrometer IFS125-HR (Bruker) at the highest achievable spectral resolution of 0.0063 cm −1 . Systematic study of the hyperfine structure (HFS) of the a 3 Σ + state for levels with va ∈ [0, 27] and Na ∈ [24, 90] shows that the splitting monotonically increases with va. The spectroscopic study was supported by ab initio calculations of the magnetic hyperfine interaction in X 1 Σ + and a 3 Σ + states.

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High-resolution molecular spectroscopy for producing ultracold absolute-ground-state Na23Rb87 molecules

“…Following Ref. [14], we set up a four-coupled-channel hamiltonian [15] which accounts for the dominant SO interaction between the A state and the Ω = 0 + component b 0 + of the b state, and for the weak rotational interactions with the other b 1 and b 2 components. Note however that the b 2 component is not relevant here, as we limit our study to the J = 1 rotational levels of the excited state manifold.…”

“…The relevant coupling matrices were displayed in Ref. [15]. The hyperfine structure of the A − b 0 + levels is found too weak for being properly resolved.…”