Search for optimum labeling schemes in qubit systems for quantum-information processing by nuclear magnetic resonance

Optimal labeling schemes lead to efficient experimental protocols for quantum-information processing by nuclear magnetic resonance (NMR). A systematic approach to finding optimal labeling schemes for a given computation is described here. The scheme is described for both quadrupolar systems and spin-1/2 systems. Using the technique of transition selective pulses, one of the optimal labeling schemes has been applied to experimentally implement a quantum full adder in a four-qubit system by NMR