Chemical Physics at the University of Sydney

Quantum computing and quantum simulation

Image: Matthew Broome / EQuS

Quantum calculations of chemical and physical properties, such as molecular energies or reaction rates, increase in difficulty with the size of the system, sometimes exponentially fast. As a result, the most accurate techniques are restricted to small systems. The fundamental obstacle is the presence of entanglement (correlation), which is difficult to represent efficiently on a classical computer.

We have shown that quantum computers could circumvent this problem in a natural way, by using a controllable quantum process to run a simulation of the unknown process. We have developed a suite of quantum methods for chemical problems, including the simulation of chemical reactions and the determination of properties like the dipole moment. Our proposals have been implemented experimentally on small scales—including the first simulation of molecular energies every carried out on a quantum computer—and we continue to collaborate with experimentalists on pushing the limits of quantum technology.

We also have a strong interest in quantum simulators, purpose-built devices that can simulate a target quantum system without needing to be as powerful or as complicated as universal quantum computers. We have contributed to the development of quantum simulators that were the first to demonstrate partially coherent quantum walks, topologically protected bound states, and environment-assisted quantum transport (which we previously described in the context of photosynthetic energy transport).

Selected papers