Boosting the accuracy of chemical simulations on Quantum Computers

Left: a preliminary calculation, carried out on a classical computer, provides a transcorrelated Hamiltonian, that is used in a subsequent quantum computation. Right: potential energy curves from quantum simulations based on a transcorrelated Hamiltonian (red) are more accurate than from a regular Hamiltonian (mauve), and closer to the complete basis set limit (black). Image: Motta, Gujarati, and Rice via Physical Chemistry Chemical Physics)

Some interesting article in Medium written by an interdisciplinary team of IBM researchers with partners from Daimler AG and Virginia Tech.

Quantum computers are, by their very nature, well-suited to help scientists achieve breakthrough discoveries in chemistry by simulating intrinsically quantum mechanical objects like molecules more efficiently than classical computers can. And as the capabilities of quantum computers and our understanding of how to best use them improve, we shall soon have the potential to predict the properties of molecules with precision on par with actual lab experiments.

Accurately describing molecules requires capturing the delicate balance of many competing effects, which in turn requires large numbers of qubits and quantum operations. To help quantum computers approach the accuracy requirements needed for chemical discovery — or to “punch above their weight,” to use a boxing metaphor — our interdisciplinary team of IBM researchers together with partners from Daimler AG and Virginia Tech has employed the help of classical computers to radically reduce the number of qubits necessary for a quantum computer to simulate molecules. We demonstrate that properties for paradigmatic molecules such as hydrogen fluoride (HF) can be calculated with a higher degree of accuracy on today’s small quantum computers — compared to calculations done with the same basis set functions where the simulation method does not model the electron-electron cusp, explicitly.

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