  We present a scheme to achieve maximally entangled states, controlled
phase-shift gate, and SWAP gate for two
superconducting-quantum-interference-device (SQUID) qubits, by placing SQUIDs
in a microwave cavity. We also show how to transfer quantum information from
one SQUID qubit to another. In this scheme, no transfer of quantum information
between the SQUIDs and the cavity is required, the cavity field is only
virtually excited and thus the requirement on the quality factor of the cavity
is greatly relaxed.
