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So the big deal about quantum computers is how they're really fast at solving certain very specific problems, but I've never seen numbers about how much better

So the big deal about quantum computers is how they're really fast at solving certain very specific problems, but I've never seen numbers about how much better at solving those problems they are than conventional computers. I realize they work on completely different principles but it should be hypothetically possible to make a normal computer solve the same problem even if it were to take a decade to do what a quantum computer can do in a microsecond. So, how much faster are they? A million times faster? A trillion? A googol times faster?

joak 7y ago
It depends on the problem. Let's take the 2048-RSA integer factorization problem. Back of the envelope calculation: The best classical algorithm takes 10^34 steps. The fastest computer on earth _Summit supercomputer_ runs at 200 petaflops (2.5M cores, ~10^6x faster than your desktop computer) Actual quantum computers perform at 1 million operations/s per qubit for 2048-RSA, Shor's algorithm needs 4096 non-noisy qubits (we are far from that) and run in 10^7 steps So for this particular problem: Best classical computer (as of today): 1 billion years An (hypothetical) quantum computer: ~10 seconds Yeah, a trillion times faster...
- Causality1 7y ago
  Interesting, thank you. It makes me wonder if we'll ever find a way to make quantum computers do "easy" math as well as they do difficult math, if we'll ever have general-purpose computers that do their arithmetic and rendering on a quantum processor instead of a transistorized one. Is it even hypothetically possible for a quantum computer to do something like render a web page using less electricity than a conventional cpu?