If I download calibration of a quantum processor on IBM Q website I see these parameters:

  • T1
  • T2
  • frequency (GHz)
  • readout error
  • single qubit U2 error rate
  • CNOT error rate

T1 and T2 are relaxation and dephasing times, respectively.

What are the other parameters?

  • frequency (GHz): The frequency(energy) associated with the transition between the qubit's ground state ($|0\rangle$) and first excited state ($|1\rangle$).
  • readout error: The probability of preparing a $|0\rangle$($|1\rangle$) and measuring a $|1\rangle$($|0\rangle$), ie., of having an error in your readout
  • single qubit U2 error rate: The average error per gate of a single qubit gate, this is $1 - \mathrm{average\_gate\_fidelity}$.
  • CNOT error rate: The average error per gate of a two-qubit gate.
  • $\begingroup$ Thanks for the answer. What do you mean by average error? Is it an average readout error? Or a probability that a gate will operate in wrong way? Lastly, I am a little bit lost in frequency - is it a frequency of photon that cause excitation from ground state to excited one? $\endgroup$ Mar 4 '20 at 14:38
  • $\begingroup$ - Average gate fidelity specifically means arxiv.org/abs/quant-ph/0205035 - Yes, this is one way of thinking of the frequency but fundamentally it is related to the energy levels of the quantum system en.wikipedia.org/wiki/Energy_level $\endgroup$
    – user47787
    Mar 5 '20 at 15:04

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