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Do I understand correctly, that largest quantum computer that exists today contains less than 100 qubits? Also it does not seem that there's an exponential gro

Do I understand correctly, that largest quantum computer that exists today contains less than 100 qubits? Also it does not seem that there's an exponential grow in this area: https://www.statista.com/statistics/993634/quantum-computers-by-number-of-qubits/#:~:text=Quantum%20computers%20by%20number%20of%20qubits%20achieved%20up%20to%202019%2C%20by%20organization&text=The%20statistic%20shows%20the%20number,new%20quantum%20computer%20by%20IBM https://www.statista.com/statistics/993634/quantum-computers.... They hit the wall in 2017. We should be safe for now :)

cameronperot 6y ago
IBM has 1000 qubits on their roadmap by 2023 [1]. I'm interested to see how that goes, and what we can learn from it about scaling up these systems into the thousands of qubits. Edit: for anyone interested in learning more about quantum computation, I have a list of resources on my website [2]. [1] https://www.ibm.com/blogs/research/2020/09/ibm-quantum-roadmap/ https://www.ibm.com/blogs/research/2020/09/ibm-quantum-roadm... [2] https://cameronperot.com/resources/#quantum-physics https://cameronperot.com/resources/#quantum-physics
- akvadrako 6y ago
  Since I didn't see it mentioned, I assume those are 1000 noisy qubits, so they'll require error correction. I wonder how many ideal qubits they are equivalent to.
megiddo 6y ago
And the error rate of 10^-3 seems problematic, as well.
CodesInChaos 6y ago
Those quantum computers can't execute Shor's algorithm, which is required to attack RSA. AFAIK the best relevant factoring result is still 21=3*7 from 2012. There are claims of bigger factored numbers, but they exploited special cases (e.g. factors differing by only two bits) and have no hope of being extended to attack cryptography. https://crypto.stackexchange.com/questions/59795/largest-integer-factored-by-shors-algorithm https://crypto.stackexchange.com/questions/59795/largest-int... A 2019 paper manged to factor 21 on a 16 qubit ibmqx5, but failed to go up to 35: > the algorithm fails to factor N=35. This is due to the cumulative errors coming from the increasing number of two-qubits gates necessary to implement the more complex MEF needed for this case https://arxiv.org/abs/1903.00768 https://arxiv.org/abs/1903.00768
- graderjs 6y ago
  Jennifer and Peter Shor wrote a limerick that seems relevant: If computers that you build are quantum, Then spies of all factions will want 'em. Our codes will all fail, And they'll read our email, Till we've crypto that's quantum, and daunt 'em. And Volker Strassen responded at a conference: To read our E-mail, how mean of the spies and their quantum machine; Be comforted though, they do not yet know how to factorize twelve or fifteen. Source: http://www-math.mit.edu/~shor/notapoet.html http://www-math.mit.edu/~shor/notapoet.html
  - CodesInChaos 6y ago
    > Till we've crypto that's quantum, and daunt 'em. Luckily there are asymmetric algorithms which are are secure against quantum computers, so we don't have to resort to quantum-key-exchanges.
    - _hl_ 6y ago
      "Secure against quantum" doesn't really mean much because too little is known to make that claim confidently. AFAIK the term generally refers to algorithms that don't rely on factoring being hard, but instead make some different hardness assumptions that we currently don't have classical or quantum algorithms for.
      - CodesInChaos 6y ago
        For practically all computationally secure crypto we use "secure" for "no known attacks faster than we'd like". QCs just extend the set of efficient algorithms.
        _hl_ 6y ago
        Indeed, but there is a much longer history of people trying and failing to break the schemes, and we have come to understand the hardness assumptions in classical crypto as probably quite reasonable.
DebtDeflation 6y ago
>largest quantum computer that exists today contains less than 100 qubits The numbers reported in the press are physical qubits not logical qubits. You need multiple physical qubits + error correction to create a single logical qubit. The main type of error correction used today is something called "surface codes". With this type of error correction it's estimated that MILLIONS of physical qubits will be required to create a SINGLE fully error corrected logical qubit. https://www.ncbi.nlm.nih.gov/books/NBK538709/ https://www.ncbi.nlm.nih.gov/books/NBK538709/ We do not have actual quantum computers today and we don't seem to be much closer to having them than we were a decade ago. What we have are really interesting quantum science experiments that get misrepresented by the press (and a handful of companies with a commercial interest in doing so).
mikewave 6y ago
The largest production quantum computer that exists today - as in, the largest you personally can get access to - has 5,436 qubits: the D-Wave Advantage system. Admittedly, it's not a gate-model machine that can run Shor's Algorithm, but it is a quantum computer, and at more than double the number of qubits plus far higher inter-qubit connectivity than our previous D-Wave 2000Q, it definitely demonstrates tremendous progress. If you have a moment, you can sign up to use it for free at https://cloud.dwavesys.com https://cloud.dwavesys.com - we have an online IDE, Jupyter notebook training material and tons of docs, a community forum, and of course some shiny demos that submit problems to the live QPU if you want to try them out.

cameronperot 6y ago

IBM has 1000 qubits on their roadmap by 2023 [1]. I'm interested to see how that goes, and what we can learn from it about scaling up these systems into the thousands of qubits. Edit: for anyone interested in learning more about quantum computation, I have a list of resources on my website [2]. [1] https://www.ibm.com/blogs/research/2020/09/ibm-quantum-roadmap/ https://www.ibm.com/blogs/research/2020/09/ibm-quantum-roadm... [2] https://cameronperot.com/resources/#quantum-physics https://cameronperot.com/resources/#quantum-physics

akvadrako 6y ago
Since I didn't see it mentioned, I assume those are 1000 noisy qubits, so they'll require error correction. I wonder how many ideal qubits they are equivalent to.

megiddo 6y ago

And the error rate of 10^-3 seems problematic, as well.

CodesInChaos 6y ago

Those quantum computers can't execute Shor's algorithm, which is required to attack RSA. AFAIK the best relevant factoring result is still 21=3*7 from 2012. There are claims of bigger factored numbers, but they exploited special cases (e.g. factors differing by only two bits) and have no hope of being extended to attack cryptography. https://crypto.stackexchange.com/questions/59795/largest-integer-factored-by-shors-algorithm https://crypto.stackexchange.com/questions/59795/largest-int... A 2019 paper manged to factor 21 on a 16 qubit ibmqx5, but failed to go up to 35: > the algorithm fails to factor N=35. This is due to the cumulative errors coming from the increasing number of two-qubits gates necessary to implement the more complex MEF needed for this case https://arxiv.org/abs/1903.00768 https://arxiv.org/abs/1903.00768

graderjs 6y ago
Jennifer and Peter Shor wrote a limerick that seems relevant: If computers that you build are quantum, Then spies of all factions will want 'em. Our codes will all fail, And they'll read our email, Till we've crypto that's quantum, and daunt 'em. And Volker Strassen responded at a conference: To read our E-mail, how mean of the spies and their quantum machine; Be comforted though, they do not yet know how to factorize twelve or fifteen. Source: http://www-math.mit.edu/~shor/notapoet.html http://www-math.mit.edu/~shor/notapoet.html
- CodesInChaos 6y ago
  > Till we've crypto that's quantum, and daunt 'em. Luckily there are asymmetric algorithms which are are secure against quantum computers, so we don't have to resort to quantum-key-exchanges.
  - _hl_ 6y ago
    "Secure against quantum" doesn't really mean much because too little is known to make that claim confidently. AFAIK the term generally refers to algorithms that don't rely on factoring being hard, but instead make some different hardness assumptions that we currently don't have classical or quantum algorithms for.
    - CodesInChaos 6y ago
      For practically all computationally secure crypto we use "secure" for "no known attacks faster than we'd like". QCs just extend the set of efficient algorithms.
      - _hl_ 6y ago
        Indeed, but there is a much longer history of people trying and failing to break the schemes, and we have come to understand the hardness assumptions in classical crypto as probably quite reasonable.

DebtDeflation 6y ago

>largest quantum computer that exists today contains less than 100 qubits The numbers reported in the press are physical qubits not logical qubits. You need multiple physical qubits + error correction to create a single logical qubit. The main type of error correction used today is something called "surface codes". With this type of error correction it's estimated that MILLIONS of physical qubits will be required to create a SINGLE fully error corrected logical qubit. https://www.ncbi.nlm.nih.gov/books/NBK538709/ https://www.ncbi.nlm.nih.gov/books/NBK538709/ We do not have actual quantum computers today and we don't seem to be much closer to having them than we were a decade ago. What we have are really interesting quantum science experiments that get misrepresented by the press (and a handful of companies with a commercial interest in doing so).

mikewave 6y ago

The largest production quantum computer that exists today - as in, the largest you personally can get access to - has 5,436 qubits: the D-Wave Advantage system. Admittedly, it's not a gate-model machine that can run Shor's Algorithm, but it is a quantum computer, and at more than double the number of qubits plus far higher inter-qubit connectivity than our previous D-Wave 2000Q, it definitely demonstrates tremendous progress. If you have a moment, you can sign up to use it for free at https://cloud.dwavesys.com https://cloud.dwavesys.com - we have an online IDE, Jupyter notebook training material and tons of docs, a community forum, and of course some shiny demos that submit problems to the live QPU if you want to try them out.