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Quantum Leap

May 24, 2018

UT’s physicists are part of the scientific team that successfully completed the first-ever quantum computation of an atomic nucleus. The research, selected as an Editors’ Suggestion in Physical Review Letters, is the first step toward scalable nuclear structure computation on a quantum processor via the cloud. It also sheds light on how to map scientific computing applications onto quantum devices, which carry the promise of sophisticated calculations.

Physics Professor Thomas Papenbrock explained that “the accomplishment is simply that we were able to compute the energy that binds a proton and a neutron into a deuteron (the atomic nucleus of heavy hydrogen) on existing quantum chips.”

The toolkit, per se, included quantum chips from IBM and Rigetti Computing, publicly available software, and access to quantum processors via the cloud.

In classic computing information is held in bits—either a 0 or a 1. In quantum computing, those values are entangled into a quantum bit, or qubit. The chips used in this research were “noisy” devices, and because qubits are susceptible to electrical or magnetic noise that can throw off their orientation, the research team made allowances to work around that problem. They used a simple yet realistic model for the deuteron and tailored the calculation to cloud-based computing on noisy chips. In doing so, they computed the binding energy of the lightest nucleus within a few percent—the first quantum computation of an atomic nucleus.

Papenbrock said the work, based at Oak Ridge National Laboratory (, resulted from a collaboration between quantum information scientists (Eugene Dumitrescu, Pavel Lougovski, Alex McCaskey, and Raphael Pooser) and nuclear theorists (David Dean, Gaute Hagen, Gustav Jansen, Titus Morris, and Papenbrock). Several team members have UT Physics ties: McCaskey (physics alumnus, 2010), Hagen (adjunct assistant professor), Morris (former postdoc). Pooser is a joint faculty assistant professor who also works in the UT Physics Quantum Technologies group that grew out of Professor George Siopsis’ interest in quantum computing.

The PRL research also has an impact on the broader scientific community. The possibility of cloud access for quantum computing opens an avenue for scientists working from anywhere to solve more complex problems, such as calculating the structure of molecules, atoms, or heavier nuclei beyond the single neutron/single proton model reported on here. In this vein, the paper (Cloud Quantum Computing of an Atomic Nucleus), was chosen as an Editor’s Suggestion, pointing readers to engaging research that may lie outside their typical interests.

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