Quantum supremacy: checking a quantum computer with a classical supercomputer

Condensed Matter Seminars

Speaker: John Martinis, University of California at Santa Barbara
Date & Time: Thu, 2017-11-30 14:00 - 15:00
Location: HENNINGS #211
Local Contact: Josh Folk
Intended Audience: Graduate

As microelectronics technology nears the end of exponential growth over time, known as Moore’s law, there is a renewed interest in new computing paradigms such as quantum computing.   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 0.2%, 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.  I will show experimental data towards this demonstration from a 9 qubit adjustable-coupler “gmon” device, which implements the basic sampling algorithm of quantum supremacy for a computational (Hilbert) space of about 500.  We plan to begin testing a 49 qubit device by the end of 2017.