FROM: “SCIENCE” magazine, 04 Nov 2016, Reports, pages 614 -617
Unconventional, special-purpose machines (Ising Machines; computers using an entirely new type of computer that blends optical and electrical processing, reported Oct. 20 in the journal Science) may aid in accelerating the solution of some of the hardest problems in computing, such as large-scale combinatorial optimizations (for example, the “traveling salesman” problem, wherein a salesman has to visit a specific set of cities, each only once, and return to the first city, and the salesman wants to take the most efficient route possible, by exploiting different operating mechanisms than those of standard digital computers). The authors/researchers of this article present a scalable optical processor with electronic feedback that can operate at large scale with room-temperature technology. Their prototype machine is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems with up to 100 spins and 10,000 spin-spin connections.
An Ising machine, is named for a mathematical model of magnetism. The machine acts like a reprogrammable network of artificial magnets where each magnet only points up or down and, like a real magnetic system, it is expected to tend toward operating at low energy.
Rather than using magnets on a grid, the Stanford team used a special kind of laser system, known as a degenerate optical parametric oscillator, that, when turned on, will represent an upward- or downward-pointing “spin.”