# 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 $$1 - \mathrm{average\_gate\_fidelity}$$.