CAREER: Ultrapolar Molecules: New Opportunities for Quantum Simulation

Quantum mechanics shapes how systems behave at every scale, from the dynamics of neutron stars to the rearrangement of electrons during chemical reactions. The PI and her group will use ultracold quantum gases—atoms or molecules cooled to nearly absolute zero temperature—to study and simulate such systems. A major recent advance has been the use of ultracold polar molecules, whose strong, tunable interactions provide powerful control over their internal states and motion. The next step is to produce more strongly interacting types of polar molecules (silver-potassium), to reach the interaction strengths needed to explore exotic new states of matter. With this leap in technology, the PI and students will advance ultracold polar molecules as a quantum platform for discovery on an equal footing to the successes of ultracold atoms, leading to better understanding of the microscopic origins behind exotic phases of matter. The work will train graduate and undergraduate students on quantum hardware and technologies. Furthermore, the PI will develop a new graduate-level course on atomic physics to train PhD students and advanced undergraduates, incorporating modern elements of quantum information science with atomic systems. The PI and her team will create and use a new molecule—potassium-silver (KAg), which is predicted to have an 8.5 Debye electric dipole moment in its ground state. Due to the multiple isotopes of potassium, KAg can be prepared either as a composite bosonic or fermionic molecule. Compared to existing ultracold molecules assembled from alkali elements, KAg will also be created by preparing the individual atomic constituents to sub-microkelvin temperatures, transferring to a bound state via a magnetic Feshbach resonance, and forming the ground state molecule through two-photon coherent Raman transfer. The molecule will inherit the ultracold temperature of the atoms. The benefit of KAg lies in its exceedingly high dipole-dipole interaction strength, an order of magnitude or more compared to the dipolar fermionic molecules currently created. A high dipole moment aids in (1) further evaporative cooling of the molecular gas to quantum degeneracy, requiring “shielding” techniques to prevent inelastic collisions, (2) higher critical temperatures for dipolar superfluid phases to be stabilized, and (3) novel mechanisms to load large, low-entropy molecular tweezer arrays. The creation and control of “ultrapolar” molecules represent a viable pathway for molecule-based quantum simulation to reveal microscopic details of the topological p+ip superfluid phase, dipolar supersolids, and dipolar quantum spin liquids. 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.