A classical computer performs processor cycles at around 3GHz.

What kind of speed should we expect (now, but also more long-term) from a quantum computer operating on superconducting qubits, such as the ones developed by Google, IBM, or Rigetti?

Any measure of speed would be interesting, such as CNOT gates per second, T gate per second, or related metrics.


1 Answer 1


Google's Sycamore processor for which they claimed quantum supremacy (https://doi.org/10.1038/s41586-019-1666-5) performs two-qubit operations in 12 ns, so that would be some 80 MHz. Of course comparing that to the clock frequency of a classical computer is meaningless though.

Their two-qubit gates are a somewhat exotic combination of an iSWAP gate and a controlled-phase gate about 1/6th of a full CZ operation.

  • $\begingroup$ Thanks for the quick reply! Is it known how much faster such a processor could potentially get? Maybe by roadmaps (I am not aware of anything), due to fundamental limits, or known engineering challenges? $\endgroup$
    – Peter
    Jun 7 at 18:09
  • $\begingroup$ I don't think that will change significantly any time soon. It is largely dictated by the physical design of the processor and the operating parameters, which actually require a lot of work to optimize over the whole processor. It is also not that important either though, as the real speed up will come from scaling up to larger numbers of qubits. $\endgroup$
    – Johan
    Jun 7 at 18:46

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