郭斯彥臺灣大學：電機工程學研究所王瀚緯Wang, Han-WeiHan-WeiWang2007-11-262018-07-062007-11-262018-07-062005http://ntur.lib.ntu.edu.tw//handle/246246/53200身處於資訊爆炸的時代，資訊交換的安全性與資料的可靠度也越來越受到重視。然而現今所使用一般的傳統加密方式，能使用量子電腦或處理量強大的電腦來破解其加密，因此我們必須尋找更安全的方法，以確保達到資訊安全的目的。 這篇論文提出一套方法，利用量子計算中特殊的物理性質，有別於一般傳統方法所沒有的特性，來建立安全與可靠的量子資訊傳輸系統，並擁有一般傳統裝置難以真正達到的資訊安全。 但量子系統仍然有其在實作上的限制，例如qubit decoherence的問題，在第二章[1]會討論並提出可能的解決方案；另外qubit傳送過程中有可能會受到外界干擾，導致其量子狀態改變，第三章[2]會討論使用quantum error-correcting code來解決；第四章[3]提出在除去這些量子系統實作上的限制後，如何使用量子技術來安全的傳送訊息。Living in an age of information explosion, the security and reliability of information exchange is getting more and more important. However, a quantum computer or a powerful computer can be used to decrypt the classical cryptographic techniques. As a result, we have to find a method with better security and relibility for information exchange. This thesis proposes a flow to build a secure and reliable quantum system for information transmission, using the particular physical properties which are very different from the classical method, and is capable of the information security and reliability that classical world is hard to reach. Quantum system still have its limitation on the physical implementation. For example, the qubit decoherence problem, we talk about it and propose a possible solution in chapter two [1]. And the alteration of quantum state caused by the outside interference of qubits during qubits transmission, the quantum error-correcting code solution is to be discussed in chapter three [2].After removing of these physical implementation limitations, the quantum algorithm of secure and reliable information transmission is proposed in chapter four [3].1 Introduction 10 1.1 Preliminaries on quantum bit 10 1.2 Advantage of quantum device 12 1.3 Structure of the thesis 14 2 Qubit Decoherence Avoidance 16 2.1 Methods of avoiding decoherence 17 2.2 Maintaining the quantum state with our circuit 18 2.3 Circuit design 18 2.3.1 The circuits for eigenstates 18 2.3.2 The circuits for superpositions 20 2.4 Analysis 21 2.5 Applications 21 3 Transmission Interference Elimination 23 3.1 Quantum communication model 24 3.2 Channel coding scheme 25 3.2.1 A simple encoder and decoder 25 3.2.2 Old transmission model and drawbacks 26 3.3 Time-spreading transmission model 27 3.3.1 Encoding and decoding 28 3.3.2 Shifter and delay unit 29 3.3.3 Analysis 30 4 Secure Information Sharing 31 4.1 The protocol 32 4.2 Example 35 4.3 Applications 37 4.3.1 Classical information transmission 37 4.3.2 Quantum information transmission 38 4.4 Analysis 39 4.4.1 Some possible attacks for Eve 39 4.4.2 Enhancement 40 5 Conclusions 42 References 442193475 bytesapplication/pdfen-US量子Quantumthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/53200/1/ntu-94-R92921080-1.pdf