This is not Schrödinger's Cat
From Quartz:
For the past several years, a Canadian company called D-Wave Systems has been selling what it says is the largest quantum computer ever built. D-Wave’s clients include Lockheed Martin, NASA, the US National Security Agency, and Google, each of which paid somewhere between $10 million and $15 million for the thing. As a result, D-Wave has won itself millions in funding and vast amounts of press coverage—including, two months ago, the cover of Time (paywall).+These machines are of little use to consumers. They are delicate, easily disturbed, require cooling to just above absolute zero, and are ruinously expensive. But the implications are enormous for heavy number-crunching. In theory, banks could use quantum computers to calculate risk faster than their competitors, giving them an edge in the markets. Tech companies could use them to figure out if their code is bug-free. Spies could use them to crack cryptographic codes, which requires crunching through massive calculations. A fully-fledged version of such a machine could theoretically tear through calculations that the most powerful mainframes would take eons to complete.+The only problem is that scientists have been arguing for years about whether D-Wave’s device is really a quantum computer or not. (D-Wave canceled a scheduled interview and did not reschedule.) And while at some level this doesn’t matter—as far as we know, D-Wave’s clients haven’t asked for their money back—it’s an issue of importance to scientists, to hopeful manufacturers of similar machines, and to anyone curious about the ultimate limits of humankind’s ability to build artificial brains.
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The processor at the heart of the controversy.
D-Wave Systems
Quantum computers: a grossly oversimplified introduction
...MOREThe foundation of all computing is a logic gate—a simple yes/no switch. In modern computers, one position of the switch represents 0; the other represents 1. Your laptop computer contains billions of such gates, each of which switches between 1 and 0 billions of times a second.+Nonetheless, your computer has a handicap, imposed by classical physics. At any given moment it can only be in one state—one particular combination of 1s and 0s across those billions of gates. It has to step through a sequence of such states to complete a calculation. But what if, instead, a vast number of copies of your computer could somehow exist in parallel, each representing one of these possible states, and collectively perform the entire calculation simultaneously?+Essentially, this is what quantum theory says can happen. The key is to shrink the gates small enough that quantum physics, which describes the behavior of extremely small objects, takes over from classical physics. (Some quantum gates consist of a single atom, held in place by electric and magnetic fields.) Such a tiny gate, called a “qubit,” can exist as a kind of combination—called a “superposition”—of 1 and 0. A computer made of qubits would, in some sense, exist in all the possible combinations of 1s and 0s at once.+Physicists differ in how they interpret this. Some literally believe a myriad parallel universes exist, each containing a separate copy of the computer; some have a more minimalist explanation. But the outcome is the same: In principle, it’s possible to reap the fruits of all that parallel processing to arrive at a result faster—so much faster that even the hardest calculation could become pretty much instantaneous.(For more details in something resembling English, see this interview with MIT’s Scott Aaronson—a long-time skeptic of D-Wave—in the Washington Post, this excellent blog post by Michael Nielsen, and, thus prepared, this Reddit thread.)...+
"Baa baa Schrödinger's sheep, have you any wool?
Yes sir, no sir, three bags simultaneously full and empty"
-from last year's birthday celebration of da S-man.
