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I’ve never understood how D-Wave is more than a “bathtub accelerator”: - fill your tub with water - sit a computer at the edge that: - plays music, vibrating

I’ve never understood how D-Wave is more than a “bathtub accelerator”: - fill your tub with water - sit a computer at the edge that: - plays music, vibrating the walls - shines a light at the surface - records the surface in HD What does D-Wave actually do that I don’t, with my accelerator which solves the Bath Tub Problem faster than any classical computer? At least mine is demonstrably faster: a bathtub can in real time solve diffraction problems that would take minutes to hours on a high end cluster using ray-tracing.

dekhn 4y ago
Are you intentionally referring to the use of vibrating water baths to emulate quantum behavior? https://news.mit.edu/2014/fluid-systems-quantum-mechanics-0912 https://news.mit.edu/2014/fluid-systems-quantum-mechanics-09... because if so that's a pretty funny joke. Mentally I picture a quantum annealer being a lot more like spontaneously finding the ising model that optimizes the objective function through the use of quantum fluctuations.
krastanov 4y ago
I mostly agree, but I think there is a risk for a reader of your comment to completely confuse analog computers and scalable digital quantum computers. Analog computers, like your bathtub accelerator, wind tunnels, ballistic aiming computers, scale models of flood plains, etc, are amazing at one single task (or maybe a few very related tasks), are not Turing complete, and, *by far most importantly*, can not scale as there is a hard insurmountable upper bound on the number of variables they can deal with before noise completely ruins the simulation. Digital computers might be slower (they used to be in the vast majority of cases), but they can scale arbitrarily large, because digital computation permits error correction. That is true about classical digital computers (which have existed for 60ish years after being conceptually predicted 200 years ago) and about digital quantum computers (which do not exist just yet after being predicted 30 years ago). Digital quantum computers also happen to be able to solve efficiently a few important but idiosyncratic problems that classical digital computers can not solve efficiently. I am writing all of this because your complaint, while fairly reasonable when made against any analog computer, is not correct when made against the (proposed) digital quantum computers (like the ones still in development at IBM, Google, PsiQuantum, or many research universities). Lastly, it seems there is some limited resurgence in analog computation lately (classical or quantum, that does not matter), thanks to new technologies (mainly photonics) which provide a significant constant factor improvements in suppressing noise.

dekhn 4y ago

Are you intentionally referring to the use of vibrating water baths to emulate quantum behavior? https://news.mit.edu/2014/fluid-systems-quantum-mechanics-0912 https://news.mit.edu/2014/fluid-systems-quantum-mechanics-09... because if so that's a pretty funny joke. Mentally I picture a quantum annealer being a lot more like spontaneously finding the ising model that optimizes the objective function through the use of quantum fluctuations.

krastanov 4y ago

I mostly agree, but I think there is a risk for a reader of your comment to completely confuse analog computers and scalable digital quantum computers. Analog computers, like your bathtub accelerator, wind tunnels, ballistic aiming computers, scale models of flood plains, etc, are amazing at one single task (or maybe a few very related tasks), are not Turing complete, and, *by far most importantly*, can not scale as there is a hard insurmountable upper bound on the number of variables they can deal with before noise completely ruins the simulation. Digital computers might be slower (they used to be in the vast majority of cases), but they can scale arbitrarily large, because digital computation permits error correction. That is true about classical digital computers (which have existed for 60ish years after being conceptually predicted 200 years ago) and about digital quantum computers (which do not exist just yet after being predicted 30 years ago). Digital quantum computers also happen to be able to solve efficiently a few important but idiosyncratic problems that classical digital computers can not solve efficiently. I am writing all of this because your complaint, while fairly reasonable when made against any analog computer, is not correct when made against the (proposed) digital quantum computers (like the ones still in development at IBM, Google, PsiQuantum, or many research universities). Lastly, it seems there is some limited resurgence in analog computation lately (classical or quantum, that does not matter), thanks to new technologies (mainly photonics) which provide a significant constant factor improvements in suppressing noise.