Colloquia

Quantum-controlled molecules are powerful sensors for physics beyond the Standard Model such as symmetry-violating interactions involving TeV-scale particles and the temporal variation of fundamental constants induced by ultralight dark matter. Furthermore, laser cooling of molecules provides an avenue for precision spectroscopy with large samples, long coherence times, and mitigation of systematic errors, which all optimize the sensitivity to signatures of new physics. Until a few years ago, the only molecules to be directly laser-cooled and trapped were diatomic species isoelectronic to alkali atoms (CaF, SrF, and YO). More complex molecules—including those with more than two atoms as well as those with fundamentally different electronic structures—can possess unique features that provide critical experimental tools such as the ability to easily orient the molecules in the laboratory and to populate pairs of low-energy, near-degenerate states. I will describe our recent achievement capturing >104 SrOH molecules in a magneto-optical trap at millikelvin temperatures. This brings SrOH into the realm of full quantum control, the fundamental step toward measurements of the electron electric dipole moment and proton-to-electron mass ratio variation. I will also outline experimental and theoretical evidence that nonlinear molecules with two-fold rotational symmetry (e.g., SrNH2) are ideal candidates for future precision measurements with even greater sensitivity. Finally, I will present a new direction in ultracold molecules: quantum control of highly magnetic species with large angular momentum, such as DyO, which promises to enable probes of beyond-Standard Model particles with masses greater than 100 TeV.