CAREER: Ultracold Molecules Assembled in a Tweezer Array for Quantum Simulation

Purdue University, West Lafayette IN

Investigators

Abstract

General audience abstract: The behavior of atoms and molecules is governed by quantum mechanics, but solving for the behavior of systems with many interacting particles is notoriously difficult even on the most powerful supercomputers. Scientists aim to learn about quantum systems by building a simulator that consists of many quantum particles with controlled interactions, but at a length and time scale amenable to observation and manipulation in the lab. The PI and his team will build a quantum simulator from an array of laser-trapped and cooled ultracold molecules. In contrast to atom-based simulators, the molecules introduce new types of interactions, for example, the long-range and anisotropic interaction from molecular dipole moments. The development of this novel simulation platform will potentially lead to the design of advanced, strongly interacting materials in energy transport, light harvesting, and quantum information science. It will provide invaluable insights into the fundamental properties of a wide range of correlated quantum systems, including black holes and nuclei. The PI will train an interdisciplinary team of students. The PI will also design a curriculum for chemists that integrates quantum sciences, thus helping train the next generation's quantum workforce. Technical audience abstract: The platform is based on a tweezer array of ultracold LiCs molecules, where the interactions between rotational states are mediated by the electric dipole moment and tuned using static and microwave fields. The long-range interaction and long rotational coherence times will be used to simulate an extended Hubbard model and generalized quantum spin model, leading to the observation of new topological, exotic superfluid, and supersolid phases. Several challenges remain before laser-assembled ultracold molecules become a robust simulation platform. First, the Stark shift from the trapping light leads to measured rotational coherence times orders of magnitude shorter than the theoretical limit, which should be minimized when the molecule is in the tweezer ground state. Second, laser-assembled molecules are currently detected through reverse-assembly back into atoms, and the PI will develop a non-destructive direct molecule imaging scheme based on either a forbidden cycling transition in LiCs or on Rydberg-molecule interactions. Finally, single molecule assembly efficiency is limited by two atom motional excitations in the tweezer, and the PI will develop new more robust tweezer ground state preparation methods beyond Raman sideband cooling. Together, these breakthroughs will result in record-level interaction fidelity, and the simulation of new classes of strongly interacting systems. 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.