Implementation of a two-qubit controlled-U gate based on unconventional geometric phase with a constant gating time

We propose an alternative scheme to implement a two-qubits Controlled-U gate in the hybrid system atom-$CCA$ (coupled cavities array). Our scheme results in a constant gating time and, with an adjustable qubit-bus coupling (atom-resonator), one can specify a particular transformation $U$ on the target qubit. We believe that this proposal may open promising perspectives for networking quantum information processors and implementing distributed and scalable quantum computation.Comment: 4 pages, 1 figure, APS format, an extended version is in progress with some improvement

Generation Of States Maximally Entanglement (epr States) By Passing Two Atoms Through Two Coupled Cavities

We present the results of the interaction of identical two-level atoms with a system formed by two identical coupled cavities via evanescent field. With new bosonic operators (normal nodes), the interaction Hamiltonian between the cavities can be diagonalized. In a particular case, we can eliminate the interaction of the atoms with the nonresonant normal modes reducing the system to the interaction of the atom with a single-mode (like JCM). As an application of this interaction, we analyze the entanglement between distant atoms. We present two related simple procedures to generate two atoms maximally entangled state (EPR pair) interacting (i)successively (atoms passing through the cavities at different moments) and (ii) simultaneously (at the same time) with the coupled cavities system. Moreover, in contrast with other schemes, we can use identical atoms which simplifies in a experiment point of view. © 2008 American Institute of Physics.992472477Ashcroft, N.W., Mermin, N.D., (1976) Solid State Physics, , Saunders: PhiladelphiaJaynes, E.T., Cummings, F.W., (1963) Proc. IEEE, 51, p. 89Skarja, M., Borstnik, N.M., Löffler, M., Walther, H., (1999) Phys. Rev. A, 60, p. 3229Zoubi, H., Orenstein, M., Ron, A., (2000) Phys. Rev. A, 62, p. 033801Luis, A., Sánchez-Soto, L.L., (1999) Phys. Lett. A, 252, p. 130de Ponte, M.A., de Oliveira, M.C., Moussa, M.H.Y., (2003), quant-ph/0309082Cirac, J.I., Zoller, P., (1994) Phys. Rev. A, 50, pp. R2799Hagley, E., Maître, X., Nogues, G., Wunderlich, C., Brune, M., Raimond, J.M., Haroche, S., (1997) Phys. Rev. Lett, 79, p. 1Zheng, S.-B., Guo, G.-C., (2000) Phys. Rev. Lett, 85, p. 2392Guo, G.-P., Li, C.-F., Li, J., Guo, G.-C., (2002) Phys. Rev. A, 65, p. 042102Gerry, C.C., (1996) Phys. Rev. A, 53, p. 4583Pellizzari, T., (1997) Phys. Rev. Lett, 79, p. 5242Serafini, A., Mancini, S., Bose, S., (2006) Phys. Rev. Lett, 96, p. 010503B. F. C. Yabu-uti, F. K. Nohama, and J. A. Roversi, to be submitted to J. Mod. OptYin, Z.-Q., Li, F.-L., (2007) Phys. Rev. A, 75, p. 012324Peng, P., Li, F.-L., (2007) Phys. Rev. A, 75, p. 06232