Hi Quanta This is of interest! Eddie ----------- How "Quantum" is the D-Wave Machine? Umesh Vazirani (Berkeley) Tuesday, July 22, 2014 from 1:30-3pm, Microsoft Research (Barton room, 1st floor), One Memorial Drive. A special purpose "quantum computer" manufactured by the Canadian company D-Wave has led to intense excitement in the mainstream media and the computer industry, and a lively debate in the academic community. Scientifically it leads to the interesting question of whether it is possible to obtain quantum effects on a large scale with qubits that are not individually well protected from decoherence. We propose a simple and natural classical model for the D-Wave machine - replacing their superconducting qubits with classical magnets, coupled with nearest neighbor interactions whose strength is taken from D-Wave's specifications. The behavior of this classical model agrees remarkably well with posted experimental data about the input-output behavior of the D-Wave machine. Further investigation of our classical model shows that despite its simplicity, it exhibits novel algorithmic properties. Its behavior is fundamentally different from that of its close cousin, classical heuristic simulated annealing. In particular, an argument supporting quantum behavior of the D-Wave machine relied on its ability to tunnel through local minima in the energy landscape, minima that simulated annealing got stuck in. The reproduction of D-Wave's behavior by our classical model demonstrates that tunneling on a large scale is a more subtle phenomenon than was previously understood. The talk is aimed at a general audience. Based on joint work with Seung Woo Shin, Graheme Smith, and John Smolin. *********************************************** Edward Farhi Cecil and Ida Green Professor of Physics Director Center for Theoretical Physics Massachusetts Institute of Technology 6-300 Cambridge MA 02139 617 253 4871 *********************************************** _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip