Abstract

Entanglement lies at the core of quantum algorithms designed to solve problems that are intractable by classical approaches. One such algorithm, quantum annealing (QA), provides a promising path to a practical quantum processor. We have built a series of architecturally scalable QA processors consisting of networks of manufactured interacting spins (qubits). Here, we use qubit tunneling spectroscopy to measure the energy eigenspectrum of two- and eight-qubit systems within one such processor, demonstrating quantum coherence in these systems. We present experimental evidence that, during a critical portion of QA, the qubits become entangled and entanglement persists even as these systems reach equilibrium with a thermal environment. Our results provide an encouraging sign that QA is a viable technology for large-scale quantum computing.

Date

2014

Authors

Trevor Lanting, Anthony J Przybysz, A Yu Smirnov, Federico M Spedalieri, Mohammad H Amin, Andrew J Berkley, Richard Harris, Fabio Altomare, Sergio Boixo, Paul Bunyk, Neil Dickson, C Enderud, Jeremy P Hilton, Emile Hoskinson, Mark W Johnson, Eric Ladizinsky, Nicholas Ladizinsky, Richard Neufeld, Travis Oh, Ilya Perminov, Chris Rich, Murray C Thom, E Tolkacheva, Sergey Uchaikin, AB Wilson, Geordie Rose

Journal

Physical Review X

Volume

4

Issue

2

Pages

021041

Publisher

American Physical Society