Table 1: Representation and significance of one-spin and two-spin operators [28, 37].

Product OperatorCoherence name

, Longitudinal -spin (-spin) magnetization
, , , Transverse -spin (-spin) magnetization
Nonequilibrium longitudinal two-spin magnetization
, Transverse -spin magnetization antiphase with respect to the coupling to -spin
, Transverse -spin magnetization antiphase with respect to the coupling to -spin
, , , Multiple-Quantum Coherence