The problems related to the management of large quantum registers could be
handled in the context of distributed quantum computation: unitary non-local
transformations among spatially separated local processors are realized
performing local unitary transformations and exchanging classical
communication. In this paper, we propose a scheme for the implementation of
universal non-local quantum gates such as a controlled-\gate{NOT} (\cnot)
and a controlled-quantum phase gate (\gate{CQPG}). The system we have chosen
for their physical implementation is a Cavity-Quantum-Electro-Dynamics (CQED)
system formed by two spatially separated microwave cavities and two trapped
Rydberg atoms. We describe the procedures to follow for the realization of each
step necessary to perform a specific non-local operation.Comment: 12 pages, 5 figures, RevTeX; extensively revised versio