Engineered Global Gates for Advanced Simulations of Quantum Materials and Chemistry

A long-standing challenge of quantum information processing has been to predict the observable properties of complex physical systems found in nature. For instance, in state-of-the-art materials and chemical design, many behaviors may be fundamentally governed by quantum mechanics and too difficult to calculate classically. For the past 15 years, quantum technologies have pushed forward on this frontier to encode systems of interest into quantum bits, which may then be programmed to emulate the desired system properties. However, most of the work to date has been limited to studying constrained classes of quantum materials or has been limited by the large number of required gates and demanding technical overhead of universal quantum computing approaches. Here, this project combines enhanced analog quantum emulation capabilities with interspersed single-qubit gates to greatly expand the types of physical systems which may be studied, while avoiding the steep experimental resources required for full quantum computation. In addition, this project serves as a rich training environment for experimental graduate students and theory collaborators in this area of national priority. Using a customized trapped-ion quantum apparatus, this research probes disordered and topological systems in two dimensions, geometric versus long-ranged frustration in synthetic quantum materials, and the molecular dynamics and wavepacket evolution of hydrogen-bonded systems in quantum chemistry. These studies are each enabled by engineering the frequency spectrum of globally addressed laser beams used to generate entanglement between trapped ion qubits. Using this technique, there is a plethora of new interaction graphs required for materials and quantum chemistry studies (such as pure nearest-neighbor interactions, ring topologies, infinite-range couplings, and higher-dimensionality spin lattices), that all become accessible to trapped-ion quantum emulation devices. It is anticipated that the engineered global gate protocols developed by the team, which are not available on general purpose cloud-based quantum computing platforms, will allow for higher-fidelity emulations of complex physical systems when compared with more generic gate-model approaches. 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.