Hot Prospects for Ultracold Molecules

Abstract

Over the past few decades, physicists have learned to cool atoms to lower and lower temperatures and to gain increasing control over them, with exciting and sometimes unforeseen consequences. The payoffs have included atom interferometry, precision spectroscopy, Bose–Einstein condensates (BECs), and even atom lasers. Not surprisingly, experimenters now want to play the same games with molecules. The challenges—formidable enough for atoms—loom even larger for molecules. Nevertheless, a number of groups have entered the quest, with the goal of bringing molecules to submillikelvin temperatures, which are slow enough to be trapped or otherwise manipulated.

Measurement of the Electron Electric Dipole Moment Using YbF Molecules

“…Even so, the sensitivity to stray magnetic fields and to the trapping fields is a very severe problem for paramagnetic atoms and the experiment would have to use two trapped species, a heavy one for measuring d e and one for monitoring the magnetic field. Trapped cold molecules offer the best prospect of all, but at present the required techniques are only in a very early stage of development [25].…”

Collisional Cooling of Polar Diatomics in 3He and 4He Buffer Gas: A Quantum Calculation at Ultralow Energies

“…The LiH case is still different from the other two: here, the 3 He elastic cross section is very large, with respect to the particularly low cross section that comes from the calculation with 4 He. The probable reason for this behavior is related to the presence of a bound state very near the threshold that should be much more spatially diffuse in the 3 He case (given the appreciable difference in the values of their scattering lengths shown in Table 1).…”

“…These molecules have been considered to relax collisionally in a buffer gas of either 3 He or 4 He atoms, and the corresponding calculations have been performed using a rigorous close-coupling approach within a quantum treatment of the dynamics. The aim of this work was to establish, via a reliable treatment of the relaxation dynamics, the possible differences that exist among these three molecules, in terms of the relative efficiency of collisional cooling within a cold buffer gas as the one often experimentally proposed and used for this purpose.…”

The Search for Parity Violation in Chiral Molecules

“…In the following sections, we review some attempts to measure P-odd frequency shifts in chiral molecules. We mention that one very promising future alternative experimental method is to trap molecules at ultracold temperatures (in the mK range or below) [86], for example, by pulsed electric fields [87,88], and subsequently perform ultrahigh-resolution spectroscopic measurements of vibration-rotation or electronic transitions. Tunable lasers for high-resolution measurements are already available in the 1-20 mm range, which can reach resolutions of 1 Hz or below [76,[89][90][91].…”