6 ms·

so, uh. What does it actually do? In any applied sense. The article doesn't seem to list what it's "useful" for. and can it factor numbers as high as 35 reliab

so, uh. What does it actually do? In any applied sense. The article doesn't seem to list what it's "useful" for. and can it factor numbers as high as 35 reliably yet?

PopePompus 3y ago
This important milestone in quantum computing allows the production of press releases which prevent quantum computing hype from being completely eclipsed by AI hype.
- tleilaxu 3y ago
  Just wait until they can start executing AI-related tasks with quantum computing in 20 years time. The hype will no doubt be insufferable.
  - staunton 3y ago
    The hype might end by that time. Maybe it will be "self-replicating self-organizing microrobots" by then...
- indymike 3y ago
  I don't think that's enough to get over the bar. Need to add some application to cold fusion and you've got it.
  - sonicanatidae 3y ago
    Only if the announcement page has so many ads, the content is literally unreadable. I think then, we'll have it.
- bee_rider 3y ago
  Surely AI training can be cast as annealing, so we can get double hype.
yorwba 3y ago
Chasing through a bunch of links, their claim to "usefulness" seems to be based on this paper https://www.nature.com/articles/s41586-023-06096-3 https://www.nature.com/articles/s41586-023-06096-3 where "Our benchmark circuit is the Trotterized time evolution of a 2D transverse-field Ising model, sharing the topology of the qubit processor" which sounds like a task picked to be easy for this particular quantum processor to solve, and maybe of interest to some physicists working with Ising models, but not really "useful" in the general sense.
programjames 3y ago
The reason it doesn't list what the computer is "useful" for is because quantum computers currently don't have a lot of uses. Right now, it's mostly: - Fourier transform in log(n)^2 rather than nlog(n) time. Shor's algorithm uses this---the numbers 2^0, 2^1, 2^2, ..., 2^n (modulo n) are periodic for some factor of phi(n) (Euler-totient function). A Fourier transform will have a peak around that period, which you can quickly find on a quantum computer. - Speeding up database queries (e.g. Grover's algorithm). You can also make communications more secure with some quantum stuff, but that isn't computing. In the future, some more interesting computer applications will be: - Physical simulations, e.g. how do proteins fold, or chemical reactions take place. - Bayesian neural networks. After training, there's some distribution the weights could be in based on the initialization. Choosing a fixed set of weights results in overfitting, but if you instead take the expected output given that distribution, you get the most likely answer. That's obviously infeasible on a classical computer (though dropout approximates this), but possible on a quantum one.
- necovek 3y ago
  > You can also make communications more secure with some quantum stuff, but that isn't computing. Care to elaborate? The only thing that I can think of is avoiding the current crop of side channel attacks, but I admit to only giving quantum computers cursory glances: still, I am very curious!
  - kdragon 3y ago
    There was a section of IBM's quantum computing challenge that had you encrypt/decrypt logical qbits by transforming their phase state to a known degree. If the state was altered in-transit, than the inverse transform will not cancel out correctly. the challenge also mentioned that for it to work in practice, the qbits themselves would have to be transported somehow.
  - programjames 3y ago
    You send a photon with the polarization giving the bit: Basis +: | = 0, — = 1, Basis x: / = 0, \ = 1 You randomly choose a basis for each photon, but don't tell the receiver which basis it is until they receive the photon. They randomly choose a basis to decode on, and once learning the correct one discard the bit if they mismatch. The key thing is an eavesdropper wouldn't know the correct basis either. If they try to "pass along the photon" they'll re-encode it in the wrong basis half the time, so the receiver will end up with the wrong bit when it should be correct (25% of the time). The sender can share some of the correct bits, and if the receiver has too many errors it's likely someone is eavesdropping. Now, what bits do you actually send? Probably something like a "Learning With Errors" (LWE) cryptography key (as quantum computers kill RSA). Then you can transfer your actually data over classical communications. The quantum part is just the handshake at the beginning. If you detect eavesdropping you just send a new key over. The current limitations are: 1. It's really slow. It can take seconds to send a 1,000 bit key just 1km (figure 4, 10.1109/PHOTONICS49561.2019.00010). 2. You need a single photon source so the eavesdropper cannot pass along photons while reading the message. It also has to be "heralded", i.e. you need to know when that photon gets sent. Right now these are pretty slow to generate. 3. The error rate has to be really low, otherwise you can't detect eavesdropping. 4. Your detection system can't have backscattering/other side-channel attacks. To detect single photons, people usually use "avalanche detectors", where the photon excites an electron, which goes on to excite many more due to a potential difference in a p-n junction. However this also creates small flashes every time a photon hits it.

so, uh. What does it actually do? In any applied sense. The article doesn't seem to list what it's "useful" for. and can it factor numbers as high as 35 reliably yet?

PopePompus 3y ago

This important milestone in quantum computing allows the production of press releases which prevent quantum computing hype from being completely eclipsed by AI hype.

tleilaxu 3y ago
Just wait until they can start executing AI-related tasks with quantum computing in 20 years time. The hype will no doubt be insufferable.
- staunton 3y ago
  The hype might end by that time. Maybe it will be "self-replicating self-organizing microrobots" by then...
indymike 3y ago
I don't think that's enough to get over the bar. Need to add some application to cold fusion and you've got it.
- sonicanatidae 3y ago
  Only if the announcement page has so many ads, the content is literally unreadable. I think then, we'll have it.
bee_rider 3y ago
Surely AI training can be cast as annealing, so we can get double hype.

yorwba 3y ago

Chasing through a bunch of links, their claim to "usefulness" seems to be based on this paper https://www.nature.com/articles/s41586-023-06096-3 https://www.nature.com/articles/s41586-023-06096-3 where "Our benchmark circuit is the Trotterized time evolution of a 2D transverse-field Ising model, sharing the topology of the qubit processor" which sounds like a task picked to be easy for this particular quantum processor to solve, and maybe of interest to some physicists working with Ising models, but not really "useful" in the general sense.

programjames 3y ago

The reason it doesn't list what the computer is "useful" for is because quantum computers currently don't have a lot of uses. Right now, it's mostly: - Fourier transform in log(n)^2 rather than nlog(n) time. Shor's algorithm uses this---the numbers 2^0, 2^1, 2^2, ..., 2^n (modulo n) are periodic for some factor of phi(n) (Euler-totient function). A Fourier transform will have a peak around that period, which you can quickly find on a quantum computer. - Speeding up database queries (e.g. Grover's algorithm). You can also make communications more secure with some quantum stuff, but that isn't computing. In the future, some more interesting computer applications will be: - Physical simulations, e.g. how do proteins fold, or chemical reactions take place. - Bayesian neural networks. After training, there's some distribution the weights could be in based on the initialization. Choosing a fixed set of weights results in overfitting, but if you instead take the expected output given that distribution, you get the most likely answer. That's obviously infeasible on a classical computer (though dropout approximates this), but possible on a quantum one.

necovek 3y ago
> You can also make communications more secure with some quantum stuff, but that isn't computing. Care to elaborate? The only thing that I can think of is avoiding the current crop of side channel attacks, but I admit to only giving quantum computers cursory glances: still, I am very curious!
- kdragon 3y ago
  There was a section of IBM's quantum computing challenge that had you encrypt/decrypt logical qbits by transforming their phase state to a known degree. If the state was altered in-transit, than the inverse transform will not cancel out correctly. the challenge also mentioned that for it to work in practice, the qbits themselves would have to be transported somehow.
- programjames 3y ago
  You send a photon with the polarization giving the bit: Basis +: | = 0, — = 1, Basis x: / = 0, \ = 1 You randomly choose a basis for each photon, but don't tell the receiver which basis it is until they receive the photon. They randomly choose a basis to decode on, and once learning the correct one discard the bit if they mismatch. The key thing is an eavesdropper wouldn't know the correct basis either. If they try to "pass along the photon" they'll re-encode it in the wrong basis half the time, so the receiver will end up with the wrong bit when it should be correct (25% of the time). The sender can share some of the correct bits, and if the receiver has too many errors it's likely someone is eavesdropping. Now, what bits do you actually send? Probably something like a "Learning With Errors" (LWE) cryptography key (as quantum computers kill RSA). Then you can transfer your actually data over classical communications. The quantum part is just the handshake at the beginning. If you detect eavesdropping you just send a new key over. The current limitations are: 1. It's really slow. It can take seconds to send a 1,000 bit key just 1km (figure 4, 10.1109/PHOTONICS49561.2019.00010). 2. You need a single photon source so the eavesdropper cannot pass along photons while reading the message. It also has to be "heralded", i.e. you need to know when that photon gets sent. Right now these are pretty slow to generate. 3. The error rate has to be really low, otherwise you can't detect eavesdropping. 4. Your detection system can't have backscattering/other side-channel attacks. To detect single photons, people usually use "avalanche detectors", where the photon excites an electron, which goes on to excite many more due to a potential difference in a p-n junction. However this also creates small flashes every time a photon hits it.