An optical tweezer array of ultracold molecules

Tweezing cold molecules Arrays of optical tweezers have been used to trap atoms, but trapping and laser-cooling molecules in this setting is tricky. Such an approach would, however, be generalizable to many molecular species. Anderegg et al. created an optical tweezer array of calcium monofluoride molecules, which were laser cooled to their ground state (see the Perspective by Kotochigova). By distinguishing between single and multiple molecules in the tweezers, the researchers were able to observe molecular collisions. Boasting exquisite control over individual molecules, the optical tweezer array platform holds much promise for extending the applications of ultracold molecules. Science , this issue p. 1156 ; see also p. 1079