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While most of the recent popular coverage has been full of hype, Aaronson provides a concise summary of what's been going on before taking on the hype which appears to have left the poor man at his wit's end. Honestly I was rather confused also as the skepticism D-wave was met with at the beginning appears to have been replaced with a lot of hype without any mention of the actual physics of what's happening.

The position of most of the scientific community at the outset regarding D-Wave quantum computers was that it was uncertain what was going on at all. Nobody knew for sure if the D-Wave computers were really using quantum entanglement when they ran or not. Obviously a computer that does computations without doing at least some of the weird things allowed by quantum mechanics wouldn't be much of a quantum computer.

It appears that the D-Wave computers could indeed be taking advantage of entanglement. However since the D-Wave computers are not very isolated from their environment, the delicate effects they attempt to harness are sometimes disrupted when the computer interacts with its environment (aka decoherence to use the Quantum Mechanics term).

Overall it looks like D-Wave is making some progress on demonstrating their computer does really harness what's allowed by quantum mechanics. This is exciting, though ironically they have not caught up to their own overstated claims of what their machine does. Perhaps with more work they can better isolate their computer from it's environment and graduate from quantum annealing to reversible adiabatic quantum computing. Or maybe someone else working with some other physical system which has an intrinsically lower coupling to it's environment might beat them to it. An exciting time for the field nonetheless.

Getting a speed up on a particular class of problem could have a great deal of practical importance, but building a scalable computer that fully takes advantage of everything allowed by the laws of physics is the holy grail of quantum computing, and it doesn't look like D-Wave is there quite yet. Still an exciting time for the field nonetheless.