Encoding multiple quantum coherences in non-commuting bases

Multiple quantum (MQ) coherences are characterized by their coherence number and the number of spins that make up the state, though only the coherence number is normally measured. We present a simple set of measurements that extend our knowledge of the MQ state by recording the coherences in two non-commuting bases-the x and the z bases (related by a similarity transformation). The measurement of coherences in a basis other than the usual z basis also permits the study of spin dynamics under Hamiltonians that conserve z basis coherence number. (C) 2003 Elsevier Science B.V. All rights reserved.