7 ms·

IBM unveils 433 qubit quantum computer

28 points by leecarraher 4y ago

aliswe 4y ago
How do we reconcile between these kinds of news and that Quantum Physicist who says that Quantum computers never will amount to anything? I'm confused ...
- e63f67dd-065b 4y ago
  The claim that quantum computers will never amount to anything is more nuanced than that. There is multiple parts to that claim: - Shor's algorithm is about the only productive thing we've figured out where a quantum computer has an advantage - IBM unveils 433 qbit computer, to factor 4096 RSA we're gonna need 8192 logical qbits - Those 433 qbits are physical qbits, and there's (to the best of my knowledge) no literature on their measurement fidelity, coherence timelines, etc. These are purely experimental machines, it's not like you can plug your laptop into their giant cryogenic machines and run quantum algorithms without a giant team of literal quantum physicists standing by the thing and monitoring it - How those 433 qbits actually translate into any amount of meaningful computation is up in the air - The best we figured out was 5 logical qbits running a specialised Shor's algorithm on the 127qbit computer they unveiled a few years back to factor 21=3*7 - Nobody has, to the best of my knowledge, actually run the full Shor's algorithm on anything of note, even on these systems Not a quantum physicist; I only have vague memories from a quantum computing seminar I took long ago. Feel free to correct if any of the above is incorrect.
desro 4y ago
Why such cynicism in the comments? This is a pretty cool achievement, even if it's incremental or lacks present application (I'm not qualified to say either way). I'm cheering them on!
6nf 4y ago
Can it do anything faster than a traditional supercomputer yet?
derekmcloughlin 4y ago
Sabine Hossenfelder has a good summary of the state of Quantum Computing so far: https://youtu.be/CBLVtCYHVO8 https://youtu.be/CBLVtCYHVO8
DoubleDerper 4y ago
i've lost interest in the qubit race. what can this machine do productively?
- yrgulation 4y ago
  It can drive IBM brand awareness. Pretty sure some people are amazed by what ibm just “achieved”.
- thinkmcfly 4y ago
  I'm still pretty curious. Can this thing do traveling salesman yet?
  - seasox 4y ago
    There is no known polynomial time algorithm for TSP. AFAIK there are quantum algorithms for TSP with quadratic speedup in comparison to the brute force method (still exponential though). The one thing quantum computers are (currently and theoretically) able to solve efficiently is the factorization problem, but are very much limited by low qubit number, i.e. engineering problems.
    - thinkmcfly 4y ago
      Thank you for your informative response!
- seasox 4y ago
  There was a time when people used to say these things about conventional computers, remember the 50s?
- spywaregorilla 4y ago
  Find the prime factorization of some two digit numbers.
  - 6nf 4y ago
    Previous record was 21 = 3 * 7 if I recall correctly
bvrmn 4y ago
Does it calculate generic Shore?
- credit_guy 4y ago
  Do you mean Shor's algorithm [1]? Most likely no, or IBM would have made sure you'll hear about that. But let's say it can, and somehow IBM forgot to mention. Shor's algorithm reduces to a quantum Fourier circuit, with 2N qubit inputs and 2N qubit outputs, where N is the number of digits of the number to be factored. That's 4N qubits only for inputs and outputs. So, in the best case scenario, this computer would be able to factor a 108-binary digit number. My computer (2020 Intel-based iMac) can do that in one minute. Here's the code if you want to try it on your computer: import sympy n_digits = 54 p = sympy.randprime(2**(n_digits-1), 2**n_digits) q = sympy.randprime(2**(n_digits-1), 2**n_digits) sympy.factorint(N) Output: {53882560694857690729: 1, 44658549937294814041: 1} [1] https://en.wikipedia.org/wiki/Shor%27s_algorithm https://en.wikipedia.org/wiki/Shor%27s_algorithm
  - nemoniac 4y ago
    Before the last line you need N = p * q
hdjjhhvvhga 4y ago
There's something unsettling about them calling these "quantum computers." There's too much noise for them to be actually usable. It's as if someone constructed one half of an abacus and started calling it "abacus." It just doesn't feel right. And when we actually build a quantum computer (which, I hope, happens by the end of this century), everybody will be too bored about it.

28 points by leecarraher 4y ago

How do we reconcile between these kinds of news and that Quantum Physicist who says that Quantum computers never will amount to anything? I'm confused ...

e63f67dd-065b 4y ago
The claim that quantum computers will never amount to anything is more nuanced than that. There is multiple parts to that claim: - Shor's algorithm is about the only productive thing we've figured out where a quantum computer has an advantage - IBM unveils 433 qbit computer, to factor 4096 RSA we're gonna need 8192 logical qbits - Those 433 qbits are physical qbits, and there's (to the best of my knowledge) no literature on their measurement fidelity, coherence timelines, etc. These are purely experimental machines, it's not like you can plug your laptop into their giant cryogenic machines and run quantum algorithms without a giant team of literal quantum physicists standing by the thing and monitoring it - How those 433 qbits actually translate into any amount of meaningful computation is up in the air - The best we figured out was 5 logical qbits running a specialised Shor's algorithm on the 127qbit computer they unveiled a few years back to factor 21=3*7 - Nobody has, to the best of my knowledge, actually run the full Shor's algorithm on anything of note, even on these systems Not a quantum physicist; I only have vague memories from a quantum computing seminar I took long ago. Feel free to correct if any of the above is incorrect.

desro 4y ago

Why such cynicism in the comments? This is a pretty cool achievement, even if it's incremental or lacks present application (I'm not qualified to say either way). I'm cheering them on!

6nf 4y ago

Can it do anything faster than a traditional supercomputer yet?

derekmcloughlin 4y ago

Sabine Hossenfelder has a good summary of the state of Quantum Computing so far: https://youtu.be/CBLVtCYHVO8 https://youtu.be/CBLVtCYHVO8

DoubleDerper 4y ago

i've lost interest in the qubit race. what can this machine do productively?

yrgulation 4y ago
It can drive IBM brand awareness. Pretty sure some people are amazed by what ibm just “achieved”.
thinkmcfly 4y ago
I'm still pretty curious. Can this thing do traveling salesman yet?
- seasox 4y ago
  There is no known polynomial time algorithm for TSP. AFAIK there are quantum algorithms for TSP with quadratic speedup in comparison to the brute force method (still exponential though). The one thing quantum computers are (currently and theoretically) able to solve efficiently is the factorization problem, but are very much limited by low qubit number, i.e. engineering problems.
  - thinkmcfly 4y ago
    Thank you for your informative response!
seasox 4y ago
There was a time when people used to say these things about conventional computers, remember the 50s?
spywaregorilla 4y ago
Find the prime factorization of some two digit numbers.
- 6nf 4y ago
  Previous record was 21 = 3 * 7 if I recall correctly

bvrmn 4y ago

Does it calculate generic Shore?

credit_guy 4y ago
Do you mean Shor's algorithm [1]? Most likely no, or IBM would have made sure you'll hear about that. But let's say it can, and somehow IBM forgot to mention. Shor's algorithm reduces to a quantum Fourier circuit, with 2N qubit inputs and 2N qubit outputs, where N is the number of digits of the number to be factored. That's 4N qubits only for inputs and outputs. So, in the best case scenario, this computer would be able to factor a 108-binary digit number. My computer (2020 Intel-based iMac) can do that in one minute. Here's the code if you want to try it on your computer: import sympy n_digits = 54 p = sympy.randprime(2**(n_digits-1), 2**n_digits) q = sympy.randprime(2**(n_digits-1), 2**n_digits) sympy.factorint(N) Output: {53882560694857690729: 1, 44658549937294814041: 1} [1] https://en.wikipedia.org/wiki/Shor%27s_algorithm https://en.wikipedia.org/wiki/Shor%27s_algorithm
- nemoniac 4y ago
  Before the last line you need N = p * q

hdjjhhvvhga 4y ago

There's something unsettling about them calling these "quantum computers." There's too much noise for them to be actually usable. It's as if someone constructed one half of an abacus and started calling it "abacus." It just doesn't feel right. And when we actually build a quantum computer (which, I hope, happens by the end of this century), everybody will be too bored about it.