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The argument here is nonsensical. For example, "With what exactitude must, say, the square root of 2 (an irrational number that enters into many of the relevan

The argument here is nonsensical. For example, "With what exactitude must, say, the square root of 2 (an irrational number that enters into many of the relevant quantum operations) be experimentally realized? Should it be approximated as 1.41 or as 1.41421356237? Or is even more precision needed? Amazingly, not only are there no clear answers to these crucial questions, but they were never even discussed!" This is completely wrong. Of course the field has studied this problem; people aren't idiots. But your concern is also wrong. Preparing the initial state is easy; quantum algorithms generally start in the all-0s state. Even quantum devices like the D-Wave machine, for which there is considerable skepticism about its workings and power, can easily be initialized in the all-0s state. (With error correction, one needs to prepare the encoded all-0s state, which is indeed difficult to prepare. But in principle it is doable.)

resource0x 8y ago
Doable in principle? My impression was that the author doesn't argue against this. He claims it's unlikely to be doable in practice. That's the whole point of the article.
- danishcrows 8y ago
  His argument is pretty poor. He refers to the threshold theorem which does rely on certain assumptions, and then claims that these assumptions cannot be satisfied in practice. This is apparently because "continuous quantities can be neither measured nor manipulated exactly", however this ISN'T an assumption of the threshold theorem. In fact the whole premise of the threshold theorem is that they can't. It's a straw man argument, the same one he's been making since the 1990s.