Influence Of The Virtual Photon Process On The Trapped Ion In Trapped Ion Quantum Computer

The trapped ion scheme is very promising among all the proposal forconstructing practical quantum computer. In it, the crucial problems are cooling thetrapped ion to quantum ground state and controlling the ion by maneuvering laserbeam from external, so the interaction of the ion and the laser field play a decisiverole in the quantum computing process. Generally, when discuss the ion interactingwith electromagnetic field, the Jaynes-cumming model is fundamental in which anon-relative two-level atom and a single mode laser field interacts and two kinds ofapproximations are adopted in order that the problem is exactly solvable, one is dipoleapproximation and the other is rotating wave approximation ,that is, the size of theatom must be extremely small in comparison to the wavelength of the laser field andthe non-rotating wave terms can be neglected. In the case of trapped ion quantumcomputer, very high fidelity is required so we must consider the full couple of the ionand the laser field. In this paper, I have investigate the contribution and the effect ofnon-rotating wave terms in the process of the interaction of the ion and the laser field,namely, the influence of the virtual photon process on the state of trapped ion.Computational result show that virtual photon process does has its own effect on theion;it increase the Rabi frequency of the trapped ion and the damping speed ofthe population probability of the ground state;but in the acceptable limit, thisinfluence can be neglected. So we have solve a new problem about the accuracy andstability of the trapped ion quantum computer and make a progress towards therealization of the practical quantum computer.