Quantum Manipulations of Small Josephson Junctions

Low-capacitance Josephson junction arrays in the parameter range where single charges can be controlled are suggested as possible physical realizations of the elements which have been considered in the context of quantum computers. We discuss single and multiple quantum-bit systems. The systems are controlled by applied gate voltages, which also allow the necessary manipulation of the quantum states. We estimate that the phase-coherence time is sufficiently long for experimental demonstration of the principles of quantum computation.