Better Chemistry Through Quantum

Quantum chemistry on a photonic quantum computer

Benjamin Lanyon
Geoffrey Gillett
Marcelo Almeida
Benjamin Powell
Andrew White
University of Queensland
Brisbane, Queensland, Australia

James Whitfield
Ivan Kassal
Masoud Mohseni
Alán Aspuru-Guzik
Harvard University
Cambridge, Massachusetts, USA

Michael Goggin
Truman State University
Kirksville, Missouri, USA

Jacob Biamonte
Oxford University
Oxford, England

Marco Barbieri
Institut d'Optique
Paris, France

Physicists have a problem.

They have an outstandingly successful theory of nature at the small scale---quantum mechanics---but have been unable to apply it exactly to situations more complicated than, say, 4 or 5 atoms---let alone a caffeine or cholesterol molecule.

Instead, they have developed a host of approximate methods to use quantum mechanics in fields such as biology, chemistry, and materials science, but this approach raises the concern that natural behaviours are being missed, and limits the development of new technologies.

Nearly thirty years ago Nobel Prize winning physicist Richard Feynman proposed a better solution: to use computers that are themselves quantum mechanical, a hypothetical device now known as a quantum computer.

This week a team of scientists based in Australia and the US report doing exactly that: building a small quantum computer and using it to calculate the precise energy of molecular hydrogen.

This groundbreaking approach to molecular simulations could have profound implications not only for chemistry, but for a range of fields from cryptography to materials science.

The work, described last month in Nature Chemistry, comes from a partnership between a group of physicists—led by Professor Andrew White at the University of Queensland in Brisbane, Australia---and a group of chemists---led by Professor Alán Aspuru-Guzik at Harvard University, Cambridge, USA.

"Our results agreed with those calculated using a traditional computer to within six parts to a million", says White, "which we were pretty happy with".

While modern supercomputers can perform approximate simulations, increasing the complexity of these systems results in exponential increase in computational time. Quantum computers promise highly precise calculations using a fraction of the resources of conventional computing: circuits of just a few hundred quantum bits---"qubits"---will surpass the combined computing power of all the traditional computers in the world, each of which uses many billions of bits.

References

Towards Quantum Chemistry on a Quantum Computer,
B. P. Lanyon, J. D. Whitfield, G. G. Gillet, M. E. Goggin, M. P. Almeida, I. Kassal, J. D. Biamonte, M. Mohseni, B. J. Powell, M. Barbieri, A. Aspuru-Guzik and A. G. White,
Nature Chemistry 2, 106 (2010).
doi:10.1038/nchem.483

Quantum computing: Chemistry from photons
Kenneth R. Brown
Nature Chemistry 2, 76 - 77 (2010)
doi:10.1038/nchem.527

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Reporters may freely use this image as long as they include the following credit: "Image courtesy of L. Kaye & A. Aspuru-Guzik/Harvard".

For further information, contact:
Jason Bardi
(301) 209-3091