QUANTUM COMPUTING AND JOSEPHSON JUNCTION CIRCUITS

摘要

Among possible realizations of quantum a computing systems nano-elec-tronic circuits appear very promising as they can be easily scaled up to large numbers of qubits and integrated in electronic circuits. We discuss the proposal to use Josephson junctions in the charge regime as quantum bits. They combine the intrinsic coherence of superconducting systems with control possibilities of single-electron circuits. Elementary quantum logic operations can be performed by means of voltage and current pulses. The system can stay phase coherent for a long time which allows many elementary steps before the coherence is lost. To read out the result of computation a quantum measurement is needed which can be accomplished by coupling a single-electron transistor to the qubit.