Implementing the Quantum von Neumann Architecture with Superconducting   Circuits
  The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two superconducting qubits coupled through a quantum bus, two quantum memories, and two zeroing registers. Two vital algorithms for quantum computing are demonstrated, the quantum Fourier transform, with 66% process fidelity, and the three-qubit Toffoli OR phase gate, with 98% phase fidelity. Our results, in combination especially with longer qubit coherence, illustrate a potentially viable approach to factoring numbers and implementing simple quantum error correction codes. 
Matteo Mariantoni, H. Wang, T. Yamamoto, M. Neeley, Radoslaw C.   Bialczak, Y. Chen, M. Lenander, Erik Lucero, A. D. O'Conne...
cond-mat.mes-hall physics.atom-ph quant-ph