【摘要】：隨著科學(xué)的不斷發(fā)展,結(jié)合了量子力學(xué)和信息科學(xué)的量子信息學(xué)迅速崛起,并取得了突飛猛進(jìn)的發(fā)展。量子信息學(xué)包含兩個(gè)部分,其一為量子通信,其二為量子計(jì)算機(jī)。量子通信,由于其理論上已被證明是絕對(duì)安全的,因而受到諸多研究機(jī)構(gòu),甚至國(guó)家層面的關(guān)注。量子計(jì)算機(jī),其獨(dú)有的多量子態(tài)并行計(jì)算能力遠(yuǎn)遠(yuǎn)快于經(jīng)典計(jì)算機(jī),對(duì)現(xiàn)行的經(jīng)典加密體系提出了嚴(yán)峻的挑戰(zhàn)。量子糾纏態(tài)作為量子信息中必不可少的資源,在量子通信和量子計(jì)算機(jī)中扮演著至關(guān)重要的角色。因而,人們首先面對(duì)的問(wèn)題就是制備糾纏態(tài)。其次,在量子通信的過(guò)程中,環(huán)境噪聲不可避免地會(huì)對(duì)糾纏態(tài)產(chǎn)生影響,可能導(dǎo)致最大糾纏態(tài)退化為部分糾纏態(tài),這會(huì)嚴(yán)重影響量子通信的質(zhì)量,甚至?xí)䦟?duì)量子通信的安全造成威脅。對(duì)于制備糾纏態(tài)的問(wèn)題,本文針對(duì)于目前熱門的糾纏相干態(tài)和concatenated Greenberger-Horne-Zeilinger(C-GHZ)型糾纏態(tài),綜合分析其優(yōu)缺點(diǎn)后,結(jié)合量子通信的實(shí)際需求,提出了C-GHZ型相干態(tài),并給出了此糾纏態(tài)的制備方案。該方案是基于線性光學(xué)的,可以構(gòu)造任意粒子數(shù)的C-GHZ型相干態(tài),且能夠在現(xiàn)今的實(shí)驗(yàn)條件下實(shí)現(xiàn)。對(duì)于糾纏態(tài)的退相干問(wèn)題,本文針對(duì)于目前熱門的復(fù)合糾纏態(tài)(Hybrid entangled state),分別提出了Bell-type,W-type,Cluster-type復(fù)合糾纏態(tài)的三個(gè)糾纏濃縮方案。這三個(gè)方案是完全基于線性光學(xué)元器件實(shí)現(xiàn)的,可以將退相干的部分糾纏態(tài)恢復(fù)至最大糾纏態(tài),在現(xiàn)有技術(shù)條件下更容易實(shí)現(xiàn),對(duì)長(zhǎng)距離量子通信具有很大的現(xiàn)實(shí)意義。此外,本文還針對(duì)現(xiàn)有量子通信技術(shù)進(jìn)行相關(guān)研究。對(duì)于Bennett提出的糾纏成分的概念做了一些工作:兩步測(cè)量超糾纏態(tài)的concurrence。該方案利用了非線性Kerr介質(zhì)去構(gòu)建量子非破壞性測(cè)量技術(shù),并不需要復(fù)雜的CNOT門,在未來(lái)的實(shí)驗(yàn)技術(shù)下是可行的。
[Abstract]:With the development of science, quantum informatics, which combines quantum mechanics and information science, has developed rapidly. Quantum informatics consists of two parts, one is quantum communication, the other is quantum computer. Quantum communication, which has been proved to be absolutely safe in theory, has attracted much attention from many research institutions, even at the national level. Quantum computer, whose unique parallel computing power of multi-quantum states is much faster than the classical computer, poses a severe challenge to the current classical encryption system. As an indispensable resource in quantum information, quantum entangled states play a crucial role in quantum communication and quantum computers. Therefore, the first problem people face is the preparation of entangled states. Secondly, in the process of quantum communication, environmental noise will inevitably affect the entangled state, which may lead to the degradation of the maximal entangled state to partially entangled state, which will seriously affect the quality of quantum communication. It could even pose a threat to the security of quantum communications. For the problem of preparing entangled states, this paper aims at the popular entangled coherent states and concatenated Greenberger-Horne-Zeilinger (C-GHZ) entangled states. After analyzing their advantages and disadvantages, a C-GHZ coherent state is proposed according to the actual requirements of quantum communication. The preparation scheme of the entangled state is also given. The scheme is based on linear optics and can construct C-GHZ coherent states with arbitrary number of particles and can be implemented under the present experimental conditions. For the decoherence of entangled states, this paper proposes three entanglement concentration schemes for Bell-type,W-type,Cluster-type complex entangled states, aiming at the popular complex entangled states (Hybrid entangled state),. These three schemes are completely based on linear optical components and can restore the decoherence partially entangled state to the maximum entangled state, which is easier to implement under the existing technical conditions, and has great practical significance for long-distance quantum communication. In addition, this paper also studies the existing quantum communication technology. Some work has been done on the concept of entangled components proposed by Bennett: Two-step measurement of concurrence. of hyperentangled states This scheme uses nonlinear Kerr medium to construct quantum nondestructive measurement technology. It does not need complex CNOT gates and is feasible in the future experimental technology.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN918;O413

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本文編號(hào)：2408826