Qubit characterization methodologies
Qubit coherence
In a nutshell, \(T_1\) quantifies the time scale at which the qubit passes from an excited state to a ground state due to decoherence processes (e.g., the amplitude damping channel).
In a nutshell, \(T_2\) quantifies the time scale at which the qubit suffers from phase decoherence. Phase decoherence includes energy relaxation (characterized by \(T_1\)) and pure dephasing, corresponding to a knowledge loss about the phase of the qubit.