Session J3: Invited Session: Quantum Computing with Superconducting Circuits

11:15 AM–2:15 PM, Tuesday, February 28, 2012
Room: 205AB

Sponsoring Units: GQI DCMP
Chair: John Martinis, University of California, Santa Barbara

Abstract ID: BAPS.2012.MAR.J3.4

Abstract: J3.00004 : The Photon Shell Game and the Quantum von Neumann Architecture with Superconducting Circuits

1:03 PM–1:39 PM

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  Matteo Mariantoni
    (Department of Physics and California NanoSystems Institute, University of California, Santa Barbara, CA 93106-9530, USA)

Superconducting quantum circuits have made significant advances over the past decade, allowing more complex and integrated circuits that perform with good fidelity. We have recently implemented a machine comprising seven quantum channels, with three superconducting resonators, two phase qubits, and two zeroing registers. I will explain the design and operation of this machine, first showing how a single microwave photon $| 1 \rangle$ can be prepared in one resonator and coherently transferred between the three resonators. I will also show how more exotic states such as double photon states $| 2 \rangle$ and superposition states $| 0 \rangle + | 1 \rangle$ can be shuffled among the resonators as well [1]. I will then demonstrate how this machine can be used as the quantum-mechanical analog of the von Neumann computer architecture, which for a classical computer comprises a central processing unit and a memory holding both instructions and data. The quantum version comprises a quantum central processing unit (quCPU) that exchanges data with a quantum random-access memory (quRAM) integrated on one chip, with instructions stored on a classical computer. I will also present a proof-of-concept demonstration of a code that involves all seven quantum elements: (1), Preparing an entangled state in the quCPU, (2), writing it to the quRAM, (3), preparing a second state in the quCPU, (4), zeroing it, and, (5), reading out the first state stored in the quRAM [2]. Finally, I will demonstrate that the quantum von Neumann machine provides one unit cell of a two-dimensional qubit-resonator array that can be used for surface code quantum computing. This will allow the realization of a scalable, fault-tolerant quantum processor with the most forgiving error rates to date. \\[4pt] [1] M. Mariantoni \textit{et al.}, Nature Physics \textbf{7}, 287-293 (2011.)\\[0pt] [2] M. Mariantoni \textit{et al.}, Science \textbf{334}, 61-65 (2011).

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