Generation of an N -qubit phase gate via atom–cavity nonidentical coupling

作     者：张英俏 张寿 

作者机构：Centre for the Condensed-Matter Science and TechnologyHarbin Institute of Technology Department of PhysicsCollege of ScienceYanbian University 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2009年第18卷第11期

页      面：4683-4689页

核心收录：

学科分类：070207[理学-光学] 07[理学] 08[工学] 070203[理学-原子与分子物理] 0803[工学-光学工程] 0702[理学-物理学] 

基　　金：Project supported by the National Natural Science Foundation of China (Grant No 60667001) the Science Foundation of Yanbian University, China (Grant No 2007-31) 

主　　题：quantum phase gate three-level atom cavity QED 

摘      要：A scheme for approximate generation of an N-qubit phase gate is proposed in cavity QED based on nonidentical coupling between the atoms and the cavity. The atoms interact with a highly detuned cavity-field mode, but quantum information does not transfer between the atoms and cavity field, and thus the cavity decay is negligible. The gate time does not rise with an increase in the number of qubits. With the choice of a smaller odd number l （related to atom-cavity coupling constants）, the phase gate can be generated with a higher fidelity and a higher success probability in a shorter time （the gate time is much shorter than the atomic radiative lifetime and photon lifetime）. When the number of qubits N exceeds certain small values, the fidelity and success probability rise slowly with an increase in the number of qubits N. When N→∞, the fidelity and success probability infinitely approach 1, but never exceed 1.