2014/01/15 by T. Lanting, A. J. Przybysz, A. Yu. Smirnov +23 · 1 citation
Physics and Astronomy · #quant-ph #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevx.4.021041
published as Phys. Rev. X 4, 021041 (2014) · 13 pages, 8 figures, contact corresponding author for Supplementary Information
arxiv created 2014/01/15 · arxiv updated 2016/06/09
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 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 that 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.