The Preparation And Measurement Of Quantum States Via Trapped-Ion System

Quantum information is the combination of quantum theory and information science. Quantum information technique is expected to be one of the most important high and new technologies in the 21st century and will bring information science to a new era. In order to deal with quantum information, the device manufacture for manipulating quantum states is necessary. Since Cirac and Zoller proposed the scheme of quantum computation in ion trap in 1995 year, the theory and experimentation of quantum information in ion trap have been developed. In this dissertation, we study the preparation and storage of entangled states for multiple trapped ions and scheme for direct measurement of Wigner characteristic function for motion of single trapped ion. The main contents are as follows:(1) The theory of the ion's trapping system. We introduce the ion's trapping and cooling first. In the part of the ion's trapping, the Paul trap and Penning trap are presented. In the part of the ion's cooling, the Doppler cooling and Webbing cooling are given. Then we show the development of quantum information in ion's trapping system.(2) Preparation and storage of the entangled states of multiple trapped ions. We propose a scheme of the entangled states'preparation of multiple trapped ions by using two laser beams excite the ions. Utilizing that method, we realize the storage of entangled states and numerical analyse the influence of the coupling of this model with the surroundings.(3) Direct measurement of Wigner characteristic function for motion of single trapped ion. In our scheme of direct measurement, the trapped ion is driven by two laser beams with different frequencies tuned to the first lower and upper vibrational sidebands. This model can also be extended to the two-dimension case.