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Do we have an example of a real quantum computer doing some kind of a computation that is not easily accessible by the regular computer? I keep hearing about "

Do we have an example of a real quantum computer doing some kind of a computation that is not easily accessible by the regular computer? I keep hearing about "the promise" and "achieving quantum supremacy" (again!), but is there a real example of a quantum machine doing something useful in real life?

ion_trapper 7mo ago
The Venn diagram of "useful" and "not possible on a classical computer" has demonstrations on both disjoint ends but is currently empty in the intersection. For now. I fully sympathize with the hype-fatigue though.
- moi2388 7mo ago
  What about Schor’s algorithm?
  - scheme271 7mo ago
    That's on the useful end but I don't think any QC has gone beyond being able to factor 14 or something in that neighborhood. Realistically we'd need a few thousand qubits to factor anything that's reasonable and current QCs have a dozen or so qubits that work.
    - vrighter 7mo ago
      no QC has gone beyond being able to factor 1. The "factorization" done with quantum computers involved cherry picking special numbers so that a special "compiled" circuit (knowledge of the answer is required in order to do this) can be used instead of the full thing. That makes the semantics of the executed program "slightly" different. What the claims say: factor(a,b) What the implementation does: println("3").
      - scheme271 7mo ago
        Oh, I didn't realize that. I knew it was limited but not that limited. That's pretty misleading.
  - mapt 7mo ago
    On the one hand you have strong and persistent claims about quantum factoring of large numbers On the other hand you have https://algassert.com/post/2500 https://algassert.com/post/2500
    - moi2388 7mo ago
      Thank you for that. I had no idea, very interesting read!
cwillu 7mo ago
No, there are none; the closest we currently have are various special purpose and more or less hard-coded machines that demonstrate that scaling exists; various general-purpose machines operating on handfuls of qubits demonstrating the various gates; and various snake oil scams that may or may not have semi-respectable research divisions associated with them.
- jgilias 7mo ago
  Interesting, do you work in that field?
CamperBob2 7mo ago
No. It's as if there's a "No computing with this shit" theorem, enforced by nature alongside "No FTL communications," "No hidden variables," "No, you can't build a transporter, not yours," and "No cloning."
deleted 7mo ago
[deleted]
ottah 7mo ago
https://www.newscientist.com/article/mg26735582-700-how-a-well-trained-new-zealand-dog-took-on-quantum-computers-and-won/ https://www.newscientist.com/article/mg26735582-700-how-a-we...
EvgeniyZh 7mo ago
> Do we have an example of a real quantum computer doing some kind of a computation that is not easily accessible by the regular computer? Simulations of condensed matter simulations performed on QCs (google's OTOCs, quantinuum's HUbbard model) are not easily accessible by the regular computer. There are people working hard on simulating these results classically so it's quite likely they'll be simulated eventually. We're at point where classical computers are still in the race thanks to immense scale and algorithmic progress, but I think it won't be the case soon. > something useful in real life? usefulness is subjective. There are results that are potentially interesting to some people on Earth (as opposed to RCS).

ion_trapper 7mo ago

The Venn diagram of "useful" and "not possible on a classical computer" has demonstrations on both disjoint ends but is currently empty in the intersection. For now. I fully sympathize with the hype-fatigue though.

moi2388 7mo ago
What about Schor’s algorithm?
- scheme271 7mo ago
  That's on the useful end but I don't think any QC has gone beyond being able to factor 14 or something in that neighborhood. Realistically we'd need a few thousand qubits to factor anything that's reasonable and current QCs have a dozen or so qubits that work.
  - vrighter 7mo ago
    no QC has gone beyond being able to factor 1. The "factorization" done with quantum computers involved cherry picking special numbers so that a special "compiled" circuit (knowledge of the answer is required in order to do this) can be used instead of the full thing. That makes the semantics of the executed program "slightly" different. What the claims say: factor(a,b) What the implementation does: println("3").
    - scheme271 7mo ago
      Oh, I didn't realize that. I knew it was limited but not that limited. That's pretty misleading.
- mapt 7mo ago
  On the one hand you have strong and persistent claims about quantum factoring of large numbers On the other hand you have https://algassert.com/post/2500 https://algassert.com/post/2500
  - moi2388 7mo ago
    Thank you for that. I had no idea, very interesting read!

cwillu 7mo ago

No, there are none; the closest we currently have are various special purpose and more or less hard-coded machines that demonstrate that scaling exists; various general-purpose machines operating on handfuls of qubits demonstrating the various gates; and various snake oil scams that may or may not have semi-respectable research divisions associated with them.

jgilias 7mo ago
Interesting, do you work in that field?

CamperBob2 7mo ago

No. It's as if there's a "No computing with this shit" theorem, enforced by nature alongside "No FTL communications," "No hidden variables," "No, you can't build a transporter, not yours," and "No cloning."

deleted 7mo ago

[deleted]

ottah 7mo ago

https://www.newscientist.com/article/mg26735582-700-how-a-well-trained-new-zealand-dog-took-on-quantum-computers-and-won/ https://www.newscientist.com/article/mg26735582-700-how-a-we...

EvgeniyZh 7mo ago

> Do we have an example of a real quantum computer doing some kind of a computation that is not easily accessible by the regular computer? Simulations of condensed matter simulations performed on QCs (google's OTOCs, quantinuum's HUbbard model) are not easily accessible by the regular computer. There are people working hard on simulating these results classically so it's quite likely they'll be simulated eventually. We're at point where classical computers are still in the race thanks to immense scale and algorithmic progress, but I think it won't be the case soon. > something useful in real life? usefulness is subjective. There are results that are potentially interesting to some people on Earth (as opposed to RCS).