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Towards the end, the article suddenly states: > That is where the real power of annealing lies From context, it seems he means 'quantum annealing'. Nowhere in

by rocqua 8y ago

Towards the end, the article suddenly states: > That is where the real power of annealing lies From context, it seems he means 'quantum annealing'. Nowhere in the article is it explained what this is. I vaguely recall hearing something about D-wave not building the kind of quantum computer we've heard about (i.e. the kind that can factor numbers). Is this 'quantum annealing', and what makes it different? Is it better, worse, or plain different from the usual quantum computer?

SargeZT 8y ago
Different, and worse, and better. Quantum annealing is basically taking a function and using quantum trickery to find a minimum of that function. Annealing is useful for a certain subset of problems, but in theory a classical quantum computer should be able to solve any problems that a quantum annealing computer can solve. As a matter of practicality though, a proper quantum computer is much harder to build, so while it may be more powerful, as a cost-benefit analysis it makes sense to specialize.
ToFab123 8y ago
I have seen it explain as D-wave is comparable to an analog computer that is good at specific problems. A topological quantum computer is comparable to a general purpose digital computer.
- klyrs 8y ago
  > A topological quantum computer is comparable to a general purpose digital computer. Bold claim. Has anybody made one?
hannob 8y ago
From what I understood, yeah, it's a different kind of quantum computer, and it's a cause of lots of confusion. I.e. when d-wave says "we already have a xxx bit quantum computer", it sounds impressive, but it really is meaningless compared to qbits in a "real" (and until now hypothetical) quantum computer. Also until now D-Wave has been unable to show that their QC can do anything at all faster than a classical computer. Which really puts this into perspective: This is all early research. Something interesting may come out of it some day. Or not.
- klyrs 8y ago
  > I.e. when d-wave says "we already have a xxx bit quantum computer", it sounds impressive, but it really is meaningless compared to qbits in a "real" (and until now hypothetical) quantum computer. Only, gate model quantum computers require error correction. Which doesn't sound bad except that thousands of qubits are required to implement a single error corrected qubit. I.e. when IBM says "we already have a 5 qubit quantum computer", it sounds impressive, but it really is meaningless compared to qubits in the theoretical framework that promises a speedup. If we're willing to accept unimplemented theory in favor of scalable architecture, then adiabatic and gate model are known to be polynomially equivalent. So far, no quantum computing effort has shown superiority over classical computers, but you don't see this kind of skepticism over IBM and Rigetti's breathless headlines...
  - ianai 8y ago
    Do you mean error correcting a single qubit requires thousands of separate qubits? As a paradox?
    - klyrs 8y ago
      Not at all. We have a similar situation with classical computing, where a "bit" of error-corrected memory is comprised of 3 or more bits of physical memory.
- scottlocklin 8y ago
  > This is all early research. D-wave was founded in 1999...

by rocqua 8y ago

SargeZT 8y ago

Different, and worse, and better. Quantum annealing is basically taking a function and using quantum trickery to find a minimum of that function. Annealing is useful for a certain subset of problems, but in theory a classical quantum computer should be able to solve any problems that a quantum annealing computer can solve. As a matter of practicality though, a proper quantum computer is much harder to build, so while it may be more powerful, as a cost-benefit analysis it makes sense to specialize.

ToFab123 8y ago

I have seen it explain as D-wave is comparable to an analog computer that is good at specific problems. A topological quantum computer is comparable to a general purpose digital computer.

klyrs 8y ago
> A topological quantum computer is comparable to a general purpose digital computer. Bold claim. Has anybody made one?

hannob 8y ago

From what I understood, yeah, it's a different kind of quantum computer, and it's a cause of lots of confusion. I.e. when d-wave says "we already have a xxx bit quantum computer", it sounds impressive, but it really is meaningless compared to qbits in a "real" (and until now hypothetical) quantum computer. Also until now D-Wave has been unable to show that their QC can do anything at all faster than a classical computer. Which really puts this into perspective: This is all early research. Something interesting may come out of it some day. Or not.

klyrs 8y ago
> I.e. when d-wave says "we already have a xxx bit quantum computer", it sounds impressive, but it really is meaningless compared to qbits in a "real" (and until now hypothetical) quantum computer. Only, gate model quantum computers require error correction. Which doesn't sound bad except that thousands of qubits are required to implement a single error corrected qubit. I.e. when IBM says "we already have a 5 qubit quantum computer", it sounds impressive, but it really is meaningless compared to qubits in the theoretical framework that promises a speedup. If we're willing to accept unimplemented theory in favor of scalable architecture, then adiabatic and gate model are known to be polynomially equivalent. So far, no quantum computing effort has shown superiority over classical computers, but you don't see this kind of skepticism over IBM and Rigetti's breathless headlines...
- ianai 8y ago
  Do you mean error correcting a single qubit requires thousands of separate qubits? As a paradox?
  - klyrs 8y ago
    Not at all. We have a similar situation with classical computing, where a "bit" of error-corrected memory is comprised of 3 or more bits of physical memory.
scottlocklin 8y ago
> This is all early research. D-wave was founded in 1999...