由於量子電腦和量子演算法的迅速發展，使得許多安全性基於數學難題的傳統密碼協定被證明可在多項式時間內破解。有鑑於此，量子密碼學利用量子物理的特性設計通訊協定，且可達到無條件安全。量子通訊協定具有兩項優點：(1) 協定之安全性係植基於量子物理的特性，故不受量子電腦的威脅；(2) 可偵測通訊過程中是否存在竊聽者。然而，現存的量子通訊協定必須假設量子傳輸過程中無雜訊干擾的影響，即假設量子通道為理想通道。若無此假設，於偵測竊聽者的過程中發現錯誤時，將無法分辨此錯誤是竊聽或雜訊干擾所造成。因此，攻擊者可藉此發動攻擊，利用雜訊干擾所造成的錯誤隱藏其攻擊所產生的錯誤。讓通訊雙方在檢查竊聽者存在的討論中，誤以為錯誤的量測結果是通道雜訊所造成，而非竊聽者干擾造成。因此，如何在雜訊干擾的環境中建立安全的通訊協定將是未來量子密碼學研究的重點議題。
本論文利用量子物理的特性與可抗雜訊干擾的量子態設計可抗集合雜訊之量子安全通訊協定。本論文專注於研究可抗雜訊干擾的量子糾結態與其編碼方法。首先，針對二種量子糾結態，包括：GHZ糾結態（GHZ state）與GHZ-like糾結態 (GHZ-like state)，提出編碼方法，且利用提出的編碼方法建置量子金鑰分配協定、量子直接通訊協定與確定式量子通訊協定。最後，本論文利用貝爾糾結態（Bell state）提出一量子對話通訊協定。

Recently, due to the rapid development of quantum computers and quantum computings, it is believed that many difficult mathematical problems can easily be resolved in near future with the presence of quantum computers. Accordingly, the various well known cryptosystems whose security is based on these mathematical problems can easily be broken and then they become insecure. Eventually, that makes the researches of the quantum computation as well as quantum cryptography busy in order to resolve the aforesaid issues. By using the quantum phenomena, e.g., the no-cloning theorem and the measurement uncertainty principle, many quantum security protocols have been proposed. Compared to the classical communication protocols, the quantum security protocols have the following advantages: (1) Its security is based on quantum phenomena. Therefore it is secure against quantum computers; and (2) The existence of eavesdroppers can also be detected. However, the existing quantum security protocols assumed that the quantum channels are ideal. That is, the quantum channel is assumed to be free from any kind of noise. In reality, however, with the existence of noises, an eavesdropper can disguise his/her attack in noises in order to avoid being detected in eavesdropping check process. Hence, in real applications, quantum security protocols have to be designed to combat the noises, which is an important research direction.
In view of this fact, this thesis attempts to employ the properties of the quantum mechanics as well as decoherece-free states to develop fault tolerant quantum secure communication protocols in quantum environments. This thesis investigates the properties of decoherece-free entangled states and its coding functions. Firstly, two entangled states, GHZ states and GHZ-like states, are considered. Three coding functions are developed using these entangled states, and these are used to establish the fault tolerant quantum key distribution protocol, the fault tolerant quantum direct communication protocol, and the fault tolerant deterministic quantum communication protocol, respectively. Finally, this thesis proposes a fault tolerant quantum dialogue protocol based on Bell states.

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