John Martinis, Google and UCSB Physics

A key step in the roadmap to build a scientifically or commercially useful quantum computer will be to demonstrate its exponentially growing computing power.   I will explain how a 7 by 7 array of superconducting xmon qubits with nearest-neighbor coupling, and with programmable single- and two-qubit gate with errors of about 0.1%, can execute a modest depth quantum computation that fully entangles the 49 qubits.  Sampling of the resulting output can be checked against a classical simulation to demonstrate proper operation of the quantum computer and compare its system error rate with predictions.  With a computation space of 2^49 = 5 x 10^14 states, the quantum computation can only be checked using the biggest supercomputers.  With modest improvements in qubit performance, we plan to demonstrate this experiment in 2017.