Alumnus and Colleagues Use Quantum Computer to Model Electron Interactions

Thursday, August 18, 2016

An alumnus of the Department of Energy Computational Science Graduate Fellowship (DOE CSGF) is part of a team that used a quantum computer to model electron interactions in a complex molecule for the first time.

Jarrod McClean, a Luis Alvarez Fellow in Computing Science at Lawrence Berkeley National Laboratory, is a coauthor on a paper describing the calculation, published in July in the journal Physical Review X. His Harvard University doctoral advisor, Alán Aspuru-Guzik, is among 31 other authors.

Quantum computers rely on the strange physics that govern interactions at the tiniest scales to greatly accelerate calculations. Rather than using binary data, with bits cast as either a 1 or a 0, as standard computers do, quantum computing bits, or qubits, use electrons’ quantum properties to represent 1, 0 or both simultaneously, a state called superposition. Superposition allows quantum computers to perform two calculations simultaneously on the same bit, greatly accelerating processing speed.

Quantum computing could make a number of long-sought applications possible, a Harvard press release says, but a key use is computing material properties at the atomic level, particularly electron interactions in complex molecules. Such calculations are beyond the reach of standard computers.

The capacity to calculate electronic properties would let researchers accurately predict which compounds have desired properties so they can synthesize and test only the most promising ones.

The team ran its algorithm on a set of programmable superconducting qubits chilled to near absolute zero and computed the potential energy curve of molecular hydrogen. Although the hydrogen molecule is small, the algorithm is scalable, so it would work just as well on a larger, more complex compound, Aspuru-Guzik said.

Besides Berkeley Lab and Harvard, the team included collaborators from Google, Tufts University, University College London and the University of California, Santa Barbara.

McClean was a fellow from 2011-2015. He served a practicum at Los Alamos National Laboratory in 2012 and graduated from Harvard in 2015. His quantum computing research was featured recently in the DOE Office of Science webzine ASCR Discovery.