3 ms·

It seems most of these types of post are about simulated quantum effects which end up being faster to do with quantum computers than with classical computers.

It seems most of these types of post are about simulated quantum effects which end up being faster to do with quantum computers than with classical computers. However, that kind of feels to me like saying my analog computer (which consists of my hand, a floor, and a glass) can simulate a glass falling, hitting the floor, and shattering faster than a classical computer.

Green_man 4y ago
I think that's a fair description of the achievements made so far, but there are some quantum simulations that would be worthwhile or even groundbreaking to simulate (and it's possible that quantum computing is the only way to handle large quantum simulations). My guess is that we're a ways off from them, and even further off from any impressive integer factorizing/cryptography breaking quantum computers (but those predictions are basically worthless). I'm definitely not an expert in the field, but I read lecture notes by Scott Aarsonson that referenced research by Microsoft that looked into nitrogen fixation specifically as a (potentially) achievable simulation with a (potentially) massive impact. https://www.scottaaronson.com/qclec/29.pdf https://www.scottaaronson.com/qclec/29.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/2016/05/1605.03590-2.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/...
wrs 4y ago
At one time, an electronic analog computer would have simulated that faster than an electronic digital computer. Not sure where that falls in this argument — are analog computers “classical”?
- BenjiWiebe 4y ago
  Maybe "pre-classical".
- cwillu 4y ago
  Correct. “A Facebook friend said to me: that’s well and good, but surely we could change Borcherds’s teapot experiment to address this worry? For example: add a computer-controlled lathe (or even a 3D printer), with which you can build a teapot in an arbitrary shape of your choice. Then consider the problem of sampling from the probability distribution over how many pieces that teapot will smash into, when it’s dropped from some standard height onto some standard surface. I replied that this is indeed more interesting—in fact, it already seems more like what engineers do in practice (still, sometimes!) when building wind tunnels, than like a silly reductio ad absurdum of quantum supremacy experiments. On the other hand, if you believe the Extended Church-Turing Thesis, then as long as your analog computer is governed by classical physics, it’s presumably inherently limited to an Avogadro’s number type speedup over a standard digital computer, whereas with a quantum computer, you’re limited only by the exponential dimensionality of Hilbert space, which seems more interesting.” https://scottaaronson.blog/?p=5460 https://scottaaronson.blog/?p=5460 (“Doubts about teapot supremacy: my reply to Richard Borcherds”)
- krastanov 4y ago
  Funny thing is, a "perfect and noiseless" analog computer is actually more powerful than a digital quantum computer. It is just that you can not make a noiseless analog computer -- we know how to perform "error correction" only on digital computers. Basically, in our history we have: - real noisy analog computers which are easiest to build, fast for their restricted small problems, but they are not programmable and they are not scalable (because the moment they become "big", the noise becomes too problematic and swamps the results) - error-corrected digital computers that are programmable and scalable - today we have small, noisy, quantum hardware that is halfway between a quantum analog computer (i.e. a fun physics experiment) and some actual digital quantum computing machine. Great engineering achievement, but not yet what was promised by the field - hopefully, soon enough we will have scalable error-corrected "digital" quantum computers. They will be programmable and error-corrected which is the big distinction between them and a fun single-purpose physics experiment
cwillu 4y ago
https://scottaaronson.blog/?p=5460 https://scottaaronson.blog/?p=5460 addresses this point, although he discusses Richard Borcherds's teapot shattering on the floor, not your glass.

Green_man 4y ago

I think that's a fair description of the achievements made so far, but there are some quantum simulations that would be worthwhile or even groundbreaking to simulate (and it's possible that quantum computing is the only way to handle large quantum simulations). My guess is that we're a ways off from them, and even further off from any impressive integer factorizing/cryptography breaking quantum computers (but those predictions are basically worthless). I'm definitely not an expert in the field, but I read lecture notes by Scott Aarsonson that referenced research by Microsoft that looked into nitrogen fixation specifically as a (potentially) achievable simulation with a (potentially) massive impact. https://www.scottaaronson.com/qclec/29.pdf https://www.scottaaronson.com/qclec/29.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/2016/05/1605.03590-2.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/...

wrs 4y ago

At one time, an electronic analog computer would have simulated that faster than an electronic digital computer. Not sure where that falls in this argument — are analog computers “classical”?

BenjiWiebe 4y ago
Maybe "pre-classical".
cwillu 4y ago
Correct. “A Facebook friend said to me: that’s well and good, but surely we could change Borcherds’s teapot experiment to address this worry? For example: add a computer-controlled lathe (or even a 3D printer), with which you can build a teapot in an arbitrary shape of your choice. Then consider the problem of sampling from the probability distribution over how many pieces that teapot will smash into, when it’s dropped from some standard height onto some standard surface. I replied that this is indeed more interesting—in fact, it already seems more like what engineers do in practice (still, sometimes!) when building wind tunnels, than like a silly reductio ad absurdum of quantum supremacy experiments. On the other hand, if you believe the Extended Church-Turing Thesis, then as long as your analog computer is governed by classical physics, it’s presumably inherently limited to an Avogadro’s number type speedup over a standard digital computer, whereas with a quantum computer, you’re limited only by the exponential dimensionality of Hilbert space, which seems more interesting.” https://scottaaronson.blog/?p=5460 https://scottaaronson.blog/?p=5460 (“Doubts about teapot supremacy: my reply to Richard Borcherds”)
krastanov 4y ago
Funny thing is, a "perfect and noiseless" analog computer is actually more powerful than a digital quantum computer. It is just that you can not make a noiseless analog computer -- we know how to perform "error correction" only on digital computers. Basically, in our history we have: - real noisy analog computers which are easiest to build, fast for their restricted small problems, but they are not programmable and they are not scalable (because the moment they become "big", the noise becomes too problematic and swamps the results) - error-corrected digital computers that are programmable and scalable - today we have small, noisy, quantum hardware that is halfway between a quantum analog computer (i.e. a fun physics experiment) and some actual digital quantum computing machine. Great engineering achievement, but not yet what was promised by the field - hopefully, soon enough we will have scalable error-corrected "digital" quantum computers. They will be programmable and error-corrected which is the big distinction between them and a fun single-purpose physics experiment

cwillu 4y ago

https://scottaaronson.blog/?p=5460 https://scottaaronson.blog/?p=5460 addresses this point, although he discusses Richard Borcherds's teapot shattering on the floor, not your glass.