D-Wave, a company based in British Columbia, has announced a new version of its quantum annealer: the D-Wave 2000Q. As the name suggests, the number of bits has increased from about 1,000 to just over 2,000. This is, for D-Wave, an important step on its roadmap to world domination. D-Wave's approach is to increase the number of qubits come hell, high water, or lack of quantumness.
Luckily, hell has stayed south of the border, winter has prevented flooding, and the associated papers indicate that their new board preserves the quantum behavior of the previous generation. But under the hood, it appears that D-Wave has made some pretty significant changes to scale up.
The D-Wave computer is based on a process called annealing. Annealing involves a series of magnets that are arranged on a grid. The magnetic field of each magnet influences all the other magnets—together, they flip orientation to arrange themselves to minimize the amount of energy stored in the overall magnetic field. You can use the orientation of the magnets to solve problems by controlling how strongly the magnetic field from each magnet affects all the other magnets.
To obtain a solution, you start with lots of energy so the magnets can flip back and forth easily. As you slowly cool, the flipping magnets settle as the overall field reaches lower and lower energetic states, until you freeze the magnets into the lowest energy state. After that, you read the orientation of each magnet, and that is the solution to the problem. You may not believe me, but this works really well—so well that it's modeled using ordinary computers (where it is called simulated annealing) to solve a wide variety of problems.
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