Kassal, Ivan

Date: Friday, March 22, 2024
Time: 14:30
Place: ETH Campus Hönggerberg, HPF G 6
Host: Cornelius Hempel

Simulating Chemical Dynamics on Quantum Computers

Ivan Kassal - School of Chemistry, University of Sydney, Australia

Abstract: The ultimate goal of computational chemistry is to be able to calculate the properties of any molecule, material, or chemical reaction on a computer, and by doing so reduce the need for experimental trial and error. However, the computational resources currently required for the most accurate calculations grow rapidly with the size of the system being simulated because of the difficulty of representing the full quantum-mechanical motion of electrons and nuclei on conventional computers. In this talk, I will explain the power of quantum computers to solve this problem, allowing chemical simulations that are exponentially faster than what is possible currently. As a result, chemistry and materials science are considered to be the first real-world problem at which quantum computers are expected to outperform conventional ones.

I will also discuss my group’s recent results on using analog quantum simulators to bring forward useful quantum computing for chemistry through an order-of-magnitude reduction in required quantum resources [1]. We have shown how to perform fully non-adiabatic simulations of chemical dynamics using trapped-ion quantum computers by exploiting the motion of the trapped ions to represent the motion of the nuclei. Our experimental demonstrations have led to the best quantum simulation of spectroscopy to date [2] and the first direct observation of geometric-phase interference in dynamics around a conical intersection in any system [3]. These demonstrations pave the way for near-term demonstrations of quantum advantage with existing technology.

Overall, our work indicates that chemistry on quantum computers will be fundamentally different from chemistry on conventional computers. For example, on quantum computers, full dynamics simulations will be easier than calculating single-point energies and simulating open quantum systems (such as reactions in solution) could be easier than simulating molecules in vacuum. This indicates a useful complementarity between problems best solved classically and those better left to quantum computers.

[1] MacDonell, Dickerson, Birch, Kumar, Edmunds, Biercuk, Hempel, Kassal, Chemical Science 12, 9794 (2021).
[2] MacDonell, Navickas, Wohlers-Reichel, Valahu, Millican, Currington, Biercuk, Tan, Hempel, Kassal, Chemical Science 14, 9439 (2023).
[3] Valahu, Olaya-Agudelo, MacDonell, Navickas, Rao, Millican, Pérez-Sánchez, Yuen-Zhou, Biercuk, Hempel, Tan, Kassal, Nature Chemistry 15, 1503 (2023).