Simulating Chemistry on Quantum Computers.

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. The chief obstacle facing this research programme is that the computational resources currently required for the most accurate calculations grow rapidly with the size of the system being simulated, a problem that arises because of the difficulty of representing the full quantum-mechanical motion of electrons and nuclei on conventional computers.

Quantum computers could solve this problem, allowing chemical simulations that are exponentially faster than what is possible currently. Their fundamental advantage is being able to natively represent quantum states, allowing for more efficient storage and manipulation of chemical information. As a result, chemistry and materials science are considered to be the killer app for quantum computers, the first real-world problem at which quantum computers are expected to outperform conventional ones.

In this talk, I will explain the power of quantum computers for problems in chemistry and survey the range of possible applications. I will also discuss my group’s work on fully nonadiabatic simulations of chemical dynamics using existing trapped-ion quantum computers, which exploits the otherwise-unused motion of the trapped ions to represent the motion of the nuclei. This work offers an order-of-magnitude reduction in quantum resources required, as well as a clear path to using near-term quantum devices to carry out chemical simulations impossible on current supercomputers.