Prospects for assembling ultracold radioactive molecules from laser-cooled atoms

Published

February 21, 2022

Author(s)

Jacek Klos, Hui Li, Eite Tiesinga, Svetlana Kotochigova

Abstract

Molecules with unstable isotopes often contain heavy and deformed nuclei and thus possess a high sensitivity to parity-violating effects, such as Schiff moments. Currently the best limits on Schiff moments are set with diamagnetic atoms. Polar molecules with quantum-enhanced sensing capabilities, however, can offer better sensitivity. In this work, we consider the prototypical $^223}$Fr$^107}$Ag molecule, as the octupole deformation of the unstable $^223}$Fr francium nucleus amplifies the nuclear Schiff moment of the molecule by two orders of magnitude relative to that of spherical nuclei and as the silver atom has a large electronegativity. To develop a competitive experimental platform based on molecular quantum systems, $^223}$Fr atoms and $^107}$Ag atoms have to be brought together at ultracold temperatures. That is, we explore the prospects of forming $^223}$Fr$^107}$Ag from laser-cooled Fr and Ag atoms. We have performed fully relativistic electronic-structure calculations of ground and excited states of FrAg that account for the strong spin-dependent relativistic effects of Fr and the strong ionic bond to Ag. In addition, we predict the nearest-neighbor densities of magnetic-field Feshbach resonances in ultracold $^223}$Fr+$^107}$Ag collisions with coupled-channel calculations. These resonances can be used for magneto-association into ultracold, weakly-bound FrAg. We also determine the conditions for creating $^223}$Fr$^107}$Ag molecules in their absolute ground state from these weakly-bound dimers via stimulated Raman adiabatic passage using our calculations of the relativistic transition electronic dipole moments.

Citation

New Journal of Physics

Volume

24

Pub Type

Journals

Download Paper

https://doi.org/10.1088/1367-2630/ac50ea

Local Download

Keywords

precision measurements, laser cooling, parity violation, francium, silver

Citation

Klos, J. , Li, H. , Tiesinga, E. and Kotochigova, S. (2022), Prospects for assembling ultracold radioactive molecules from laser-cooled atoms, New Journal of Physics, [online], https://doi.org/10.1088/1367-2630/ac50ea, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933895 (Accessed October 10, 2025)