Scalable quantum computing using persistent current qubits with Josephson junctions

We study quantum logic gates using two persistent current states as a qubit in the superconducting ring with Josephson junction. We use an RF SQUID as a single persistent current qubit. An effective double-well potential, where quantum tunneling is possible, exists in the single qubit. The degeneracy of the two persistent current states is lifted by tunneling. The coupling between qubits is performed by the inductive current connecting qubits. A scalable qubit is constructed by making quantum circuit connecting many qubits in a topologically the same way. Switching each qubit is possible by inserting DC SQUID into the line coming out of qubit. (C) 2003 Elsevier Science B.V. All rights reserved.