Dzyaloshinskii-Moriya相互作用和内禀消相干对基于两量子比特Heisenberg自旋系统的量子密集编码的影响  

Effects of Dzyaloshinskii-Moriya interaction and intrinsic decoherence on quantum dense coding via a two-qubit Heisenberg spin system

作　　者：邹琴[1] 胡小勉 刘金明[1] 

机构地区：[1]华东师范大学,精密光谱科学与技术国家重点实验室,上海200062

出　　处：《物理学报》2015年第8期39-48,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11174081,11034002,11134003,11104075);国家重点基础研究发展计划(批准号:2011CB921602,2012CB821302)资助的课题~~

摘　　要：通过求解Milburn方程,研究了内禀消相干条件下包含Dzyaloshinskii-Moriya(DM)相互作用的两量子比特Heisenberg自旋系统实现的量子密集编码最佳传输容量的演化特性,分析了不同方向DM相互作用、不同初态、各向异性以及内禀消相干因子等参数对最佳编码容量的影响.研究表明:初态的选择对系统密集编码最佳传输容量的影响很大,不同类型初态下密集编码容量的依赖参数不完全相同;当系统初态处于c|01〉+d|10〉形式的非最大纠缠时,引入较弱的DM相互作用z分量可提高最佳编码容量;相位消相干可抑制最佳编码容量的涨落并使其在长时间演化下趋于稳定.研究还发现:内禀消相干下,通过选取合适的最大纠缠初态,系统密集编码的最佳传输容量能够保持理想极大值2;而且无论引入哪个方向的DM相互作用,基于两量子比特Heisenberg自旋系统的最佳编码容量总可优于经典通信的传输容量.By solving the Milburn equation, we investigate the properties of optimal channel capacity for the quantum dense coding via a two-qubit Heisenberg spin system with Dzyaloshinskii-Moriya （DM） interaction in the presence of intrinsic decoherence. The influences of different DM interactions, different initial states, anisotropic coupling parameters, and intrinsic decoherence on optimal coding capacity are analyzed in detail. It is found that the initial state of the system affects optimal coding capacity greatly, whose dependent parameters are not identical for different types of initial states. When the system is initially in the form of the nonmaximally entangled state c 101） ＋ d I10）, a weak z-component DM interaction can enhance the value of optimal coding capacity as compared with the value without DM interaction, and the phase decoherence effect can suppress the oscillation of optimal coding capacity and make the capacity decrease to a stable value for the long-time evolution. It is also found that under the influence of intrinsic decoherence, the optimal transmission capacity of dense coding can keep an ideal maximal value of 2 by choosing the proper initial maximally entangled state. Moreover, no matter from which direction the DM interaction is introduced, the optimal coding capacity via the two-qubit Heisenberg spin system is always larger than the transmission capacity of any classical communication.

关 键 词：Heisenberg模型 Dzyaloshinskii-Moriya 相互作用 内禀消相干 最佳编码容量 

分 类 号：O413[理学—理论物理]