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

作　　者：张英俏 张寿 

机构地区：[1]Centre for the Condensed-Matter Science and Technology,Harbin Institute of Technology [2]Department of Physics,College of Science,Yanbian University

出　　处：《Chinese Physics B》2009年第11期4683-4689,共7页中国物理B（英文版）

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)

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.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.

关 键 词：quantum phase gate three-level atom cavity QED 

分 类 号：O431.2[机械工程—光学工程] O562[理学—光学]