CAREER: Laser-Cooled Molecules in an AC-Storage Ring

University Of California-Riverside, Riverside CA

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). General audience abstract: The Standard Model of Particle Physics represents our current understanding of the basic building blocks of the universe, but we know there must be additional undiscovered physics. There is, for example, an imbalance between matter and antimatter in the universe which cannot be fully accounted for by the Standard Model. Precise measurements on atoms and molecules can help search for beyond the Standard Model physics. This project seeks to produce a sample of cold molecules chosen to be particularly sensitive to one class of new physics. There are many other potential applications for cold molecules including the control of the outcome of chemical reactions and the realization of novel quantum computing and simulation platforms. All these applications require the cooling of the molecular species to very low temperatures where full control over the molecule is possible. The complex internal structure of molecules, however, renders laser cooling techniques that have been applied to many atomic species challenging and is only practical for a limited class of molecules. Extending laser cooling to a more diverse set of species is desirable as it opens the possibility for many novel applications. The PI and his students will develop an electric storage ring as a precursor for cooling and trapping species which are not suitable for traditional laser cooling schemes. This is achieved by combining the infinite travel distance in a ring with the intrinsic spontaneous decay of any long-lived state. Within the educational part of this program, the PI will develop a portable magneto-optical trap for rubidium atoms as part of a library of transportable setups to be used in local high schools and at local science fairs. A major focus of this program is to provide people in the local community of Riverside County with an experience of the microscopic quantum world of atoms and molecules, and to foster their interest in a future STEM career. Technical audience abstract: This CAREER award supports the development of an alternating-current storage ring for atoms and molecules, which acts as a slowing stage to bring a diverse set of molecules below the capture velocity of a magneto-optical trap. The cooling principle applies slowing laser pulses at each revolution inside the ring and relies on the spontaneous decay of long-lived intermediate states as a repumping mechanism to keep the particles in the photon scattering cycle. This combination of laser cooling and spontaneous decay in the storage ring opens up possibilities for new applications that require cooling and trapping atoms with metastable states or molecules with non-diagonal Franck-Condon factors. The ring will, for instance, allow for cooling and trapping mercury fluoride, which offers the potential to improve the current statistical sensitivity of searches for an electric dipole moment of the electron. Here, the repumping scheme through spontaneous decay can significantly reduce the optical overhead required to effectively repump excited vibrational states of mercury fluoride that get populated during the cooling process. Furthermore, this storage ring will allow for studies of cold quantum chemistry and collisions of atoms and molecules for which laser cooling is currently impractical. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.