  The enormous theoretical potential of Quantum Information Processing (QIP) is
driving the pursuit for its practical realization by various physical
techniques. Currently Nuclear Magnetic Resonance (NMR) has been the forerunner
by demonstrating a majority of quantum algorithms. In NMR, spin systems
consisting of coupled nuclear spins are utilized as qubits. In order to carry
out QIP, a spin system has to meet two major requirements: (i) qubit
addressability and (ii) mutual coupling among the qubits. It has been
demonstrated that the magnitude of the mutual coupling among qubits can be
increased by orienting the spin-systems in a liquid crystal matrix and
utilizing the residual dipolar couplings. While utilizing residual dipolar
couplings may be useful to increase the number of qubits, nuclei of same
species (homonuclei) might become strongly coupled. In strongly coupled
spin-systems, spins loose their individual identity of being qubits. We propose
that even such strongly coupled spin-systems can be used for QIP and the
qubit-manipulation can be achieved by transition-selective pulses. We
demonstrate experimental preparation of pseudopure states, creation of
maximally entangled states, implementation logic gates and implementation of
Deutsch-Jozsa (DJ) algorithm in strongly coupled 2,3 and 4 spin systems. The
energy levels of the strongly coupled 3 and 4 spin systems were obtained by
using a Z-COSY experiment.
