# IBM Q calibration parameters

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

• T1
• T2
• frequency (GHz)
• 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.
• 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? – Martin Vesely Mar 4 '20 at 14:38
• - 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 – user47787 Mar 5 '20 at 15:04