Structure, branching ratios, and a laser-cooling scheme for theBaF138molecule

Abstract

For laser cooling considerations, we have theoretically investigated the electronic, rovibrational and hyperfine structures of BaF molecule. The highly diagonal Franck-Condon factors and the branching ratios for all possible transitions within the lowest-lying four electronic states have also been calculated. Meanwhile, the mixing between metastable A 2 ∆ and A 2 Π states and further the lifetime of the ∆ state have been estimated since the loss procedure via ∆ state would like fatally destroy the main quasi-cycling Σ − Π transition for cooling and trapping. The resultant hyperfine splittings of each rovibrational states in X 2 Σ + state provide benchmarks for sideband modulations of cooling and repumping lasers and remixing microwaves to address all necessary levels. The calculated Zeeman shift and g-factors for both X and A states serve as benchmarks for selections of the trapping laser polarizations. Our study paves the way for future laser cooling and magneto-optical trapping of the BaF molecule.

Controlling the Scattering Length of Ultracold Dipolar Molecules

“…The values of the dipolar alkali molecules have been reported. For indication, we also report values for 2 Σ + molecules of current experimental interest [46][47][48][49][50][51][52][53]. Looking at the general feature of the figure, one can distinguish two main regions for the dipolar molecules: a region for whichB > 10 8 where the ratio can globally reach 10 3 or more, and a region for whichB < 10 7 where the ratio barely reach 10 2 .…”

Precision Measurement of Time-Reversal Symmetry Violation with Laser-Cooled Polyatomic Molecules

“…These features afford crucial robustness to systematic effects, especially as sensitivity continues to improve. There are a number of diatomic molecules with good sensitivity to BSM physics that are laser coolable, such as BaF [12], RaF [13], and YbF [14], though these molecules do not have closely spaced levels of opposite parity. They therefore require large and technically challenging lab electric fields ≳10 kV=cm in order to be sensitive to the EDM, cannot be fully polarized, and do not admit internal comagnetometers-all of which leave them vulnerable to challenging systematic effects.…”

Radiative deflection of a BaF molecular beam via optical cycling

“…Recalling the analysis in Ref. [35], a resonant-type electro-optic modulator (EOM) with a modulation frequency of 38 MHz is employed in our experiment, and a modulation depth of 2.6 results in the first and second sidebands with equal amplitude, nearly matching the four hyperfine transitions in X(N = 1, −) → A(J = 1/2, +). On the other hand, the Zeeman dark state could be remixed by applying either an angled magnetic field or time-dependent polarization modulation [36].…”

“…The cycling scheme has been described in detail in Ref. [35]. The N = 1 → J = 1/2 rotational transition is employed to eliminate the rotational branching, and a sideband modulation scheme to generate four frequency branches to cover the hyperfine levels.…”