EQUS researchers have devised a scheme for performing analogue quantum simulations of ultrafast chemical dynamics using existing quantum systems.

One of the areas in which quantum computing is expected to offer substantial advantage over classical computing is chemistry, enabling tractable simulations of complex molecular dynamics and chemical reactions. To achieve this, laboratory-based systems need to be engineered that behave in the same way, and have the same properties, as the vibrational and electronic properties of molecules.

The team — including Research Fellow Ryan MacDonell, PhD student Claire Edmunds, Chief Investigator Mike Biercuk, and Associate Investigators Cornelis Hempel and Ivan Kassal — devised a scheme for simulating ultrafast chemical reactions using currently available technology. They showed that certain quantum technologies, such as trapped ions or superconducting circuits, can be used as analogue quantum simulators for molecular dynamics. After developing the initial proposal with two electronic states and two vibrational modes, the main challenges were to determine whether the idea could be scaled up to larger molecules and what additional effects could be simulated.

As a demonstration, they showed how the nonadiabatic dynamics (through a conical intersection) of pyrazine could be simulated using a single trapped ion. Their approach allows the dynamics to be slowed relative to the molecule, enabling the study of phenomena that would be difficult or impossible to study with molecules and ultrafast lasers. It also scales to large molecules in complex environments, potentially beyond the capabilities of classical computers, and enables the implementation of realistic bath– system interactions.

The team are now working to implement their simulator using trapped ions. They are also looking into further extensions, such as taking measurements to produce and characterise molecular absorption spectra and engineering anharmonic effects in vibrational modes. They hope the method will enable classically intractable chemical dynamics simulations in the near term.

This story was first published in the 2022 EQUS annual report, and was written by Kristen Harley.