Experimental investigation of performance differences between coherent Ising machines and a quantum annealer.

Hamerly, Ryan; Inagaki, Takahiro; McMahon, Peter L; Venturelli, Davide; Marandi, Alireza; Onodera, Tatsuhiro; Ng, Edwin; Langrock, Carsten et al. · Sci Adv · 2019

basic_science · Level V

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Abstract

Physical annealing systems provide heuristic approaches to solving combinatorial optimization problems. Here, we benchmark two types of annealing machines-a quantum annealer built by D-Wave Systems and measurement-feedback coherent Ising machines (CIMs) based on optical parametric oscillators-on two problem classes, the Sherrington-Kirkpatrick (SK) model and MAX-CUT. The D-Wave quantum annealer outperforms the CIMs on MAX-CUT on cubic graphs. On denser problems, however, we observe an exponential penalty for the quantum annealer [exp(-α<sub>DW</sub> <i>N</i> <sup>2</sup>)] relative to CIMs [exp(-α<sub>CIM</sub> <i>N</i>)] for fixed anneal times, both on the SK model and on 50% edge density MAX-CUT. This leads to a several orders of magnitude time-to-solution difference for instances with over 50 vertices. An optimal-annealing time analysis is also consistent with a substantial projected performance difference. The difference in performance between the sparsely connected D-Wave machine and the fully-connected CIMs provides strong experimental support for efforts to increase the connectivity of quantum annealers.