We propose a scheme to generate a quantum phase gate based on the interaction of the trapped ions with the laser beams. In this scheme, the ions are excited by two lasers with different frequencies ω+υ-δ and ω-υ+δ, simultaneously.
We propose a scheme to generate a quantum phase gate via an unconventional geometric phase shift in an ion-trap system.Since the gate time is only related to the frequency of the vibrational mode, the present scheme, based on the resonant interaction of the trapped ions with a standing-wave laser beam, requires a much shorter gate time than the scheme based on the resonant interaction of the atoms and the cavity.Also the heating effect of the vibrational mode is negligible under certain conditions.
We propose a scheme for the realization of unconventional geometric two-qubit phase gates with two identical two-level ions. In the present scheme, the two ions are simultaneously illuminated by a standing-wave laser pulse with its pulse frequency being tuned to the ionic transition. The gate operation time can be much shorter, making the system robust against decoherence. In addition, we choose the appropriate experimental parameters to construct the geometric phase gate in one step, and thus avoid implementing the pure geometric single qubit operation.
Based on squeezed operators this paper has implemented an ideal unconventional geometric quantum gate (GQG) in ion trap-optical cavity system by radiating the trapped ions with the cavity field of frequency ω c and an external laser field of frequency ωL. It can ensure that the gate time is shorter than the coherence time for qubits and the decay time of the optical cavity by appropriately tuning the ionic transition frequency ω 0 , the frequencies of the cavity mode ω c and the vibrational mode ν. It has also realized the unconventional GQG under the influence of the cavity decay based on the squeezed-like operators and found that the present scheme works well for the smaller cavity decay by investigating the corresponding fidelity and success probability.
We suggest a fast two-qubit quantum logic gates for trapped ions in thermal motion via geometric phase shifts. In the scheme, several vibrational modes are simultaneously displaced by driving the ions with a single off-resonant standing-wave laser. Under certain conditions, all the vibrational modes simultaneously return to the original points in the phase spaces along corresponding closed paths depending on the electronic states, producing a geometric phase gate. During the gate operation, the ions undergo no electronic transitions and the gate time might be shorter than the period of the center-of-mass vibration.
We study the realization of quantum logic gates in the interacting system of a two-dimensional trapped ion and two laser beams. We simplify the Hamiltonian of the system by Choosing the frequency detuning of laser fields and the transition frequency between the internal states of the ion, and furthermore,we describe the realization of a C-NOT gate, a swap gate and a phase gate. During these processes, the system needs to meet the Lamb-Dicke limit, and the Rabi oscillation frequency should be far smaller than the phonon frequency.