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A new physical scheme for implementing an N-bit discrete quantum Fourier transform (DQFT) is proposed via superconducting (SC) qubits coupled to a single-mode SC cavity. Two-qubit and one-qubit gates as well as a new two-qubit gate are realized. Such gates are used for implementing the algorithm of N-bit DQFT. We propose and analyze a detailed experimental procedure for implementing the algorithm and compute the fidelity measure to quantify the success of this algorithm. Estimates show that the protocol can be successfully implemented within the present experimental limits.

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The nondegenerate bimodal multiquanta Jaynes-Cummings model (JCM) governed by the Milburn equation is studied. An exact solution of this equation is obtained and applied to investigate the influence of the intrinsic decoherence on nonclassical effects (population inversion, oscillations of the number distribution, squeezing of the field modes), for the resonant and the off-resonant cases.

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We study the effect of phase damping in the two-mode Jaynes–Cummings model (JCM) using a master equation describing phase damping under the Markovian approximation. An analytic solution of the master equation for the nondegenerate bimodal multiquanta JCM with phase damping is obtained. We show that phase damping has a less detrimental effect on nonclassical properties of the field than energy damping. In contrast to energy damping the strong nonclassical coherences of a Schrödinger’s cat superposition state of two well separated coherent states decay with a similar time constant, independent of the separation of the two states.