Laser-coolable polyatomic molecules with heavy nuclei

Abstract

Recently a number of diatomic and polyatomics molecules has been identified as a prospective systems for Doppler/Sisyphus cooling. Doppler/Sisyphus cooling allows to decrease the kinetic energy of molecules down to microkelvin temperatures with high efficiency and then capture them to molecular traps, including magneto-optical trap. Trapped molecules can be used for creation of molecular fountains and/or performing controlled chemical reactions, high-precision spectra measurements and a multitude of other applications. Polyatomic molecules with heavy nuclei present considerable interest for the search for "new physics" outside of Standard Model and other applications including cold chemistry, photochemistry, quantum informatics etc. Herein we would like to attract attention to radium monohydroxide molecule (RaOH) which is on the one hand an amenable object for laser cooling and on the other hand provides extensive possibilities for searching for P-odd and P, T -odd effects. At the moment RaOH is the heaviest polyatomic molecule proposed for direct cooling with lasers.

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

“…However, the ideas discussed are generally applicable to other polyatomic species. We show that these molecules have the significant additional advantage of being laser coolable, as was recently demonstrated with the polyatomic molecule SrOH [16] and proposed for a number of other species [15,17,18]. The essential property is the nonbonding s electrons being removed from the bonding region by orbital hybridization [19], resulting in highly diagonal Franck-Condon factors (FCFs).…”

“…Species such as RaOH [15], RaCO, RaNC, TlOH, ThCH, LuCH, PbOH, HfCH, LuCO, and many more (both diamagnetic and paramagnetic) can be used to search for a wide array of BSM physics beyond the electron EDM, including nuclear magnetic quadrupole moments, nuclear EDMs, nuclear Schiff moments, parity violation, and so on. Some of these molecules may not be as readily laser cooled, though we could potentially create "custom" species with a laser-coolable atom, for example, TaCOCa.…”

“…Combining the requirement of laser cooling with the requirement of full polarization and internal comagnetometers eliminates all known choices of diatomic molecules. RaOH, a lasercoolable polyatomic molecule with BSM physics sensitivity, was previously considered for a precision measurement in the ground vibrational state [15], meaning that it would still suffer from the same drawbacks as diatomics.We show here that low-lying excited vibrational modes in polyatomic molecules, which have not been previously considered for precision measurements, allow full polarization and internal comagnetometry via generic degrees of freedom, and are excellent candidates for a new class of precision measurements. Degenerate bending modes in these states give rise to lab-accessible angular momentum with a projection along the molecular dipole, enabling full polarization in small fields analogous to Ω doublets.…”

“…Combining the requirement of laser cooling with the requirement of full polarization and internal comagnetometers eliminates all known choices of diatomic molecules. RaOH, a lasercoolable polyatomic molecule with BSM physics sensitivity, was previously considered for a precision measurement in the ground vibrational state [15], meaning that it would still suffer from the same drawbacks as diatomics.…”

“…Thus, polyatomic molecules isoelectronic to suitable diatomic candidates for fundamental physics searches such as BaF, YbF, HgF, and RaF have promise for laser cooling. Since the BSM physics sensitivity also comes from the nonbonding electron, it is largely independent of the bonding partners [15]. Furthermore, these polyatomic molecules are readily created in molecular beams and have well-studied and understood spectra [19].…”