量子密鑰分發模擬器之開發

Abstract

量子密鑰分發是量子資訊在加密上最為成功的應用之一，基於量子物理定律，使得通訊雙方理論上能獲得一組無條件安全的共同密鑰，以作為加密通訊的使用，其中如何設計協定使得通訊能獲得更高的密鑰率是量子密鑰分發的重要研究。本論文將會介紹我們對於量子密鑰分發的模擬研究，我們開發了一種模擬框架，以單光子做為系統中的基本單位，並採用混合靜態蒙地卡羅法與離散事件模擬的模型來實現有效率的量子密鑰分發模擬。此外，以相位進行編碼的量子密鑰分發協定是當前的研究重點，所以我們也著重處理干涉、波型、相位調製等光學模組。同時，我們的模擬軟體也採用了模組化的設計，並開發了圖形化介面，允許使用者自行建模光路以比較不同協定的效率，或是對參數的最佳化以提高生成密鑰的效率。除此之外，我們以低密度奇偶檢查碼作為協定的糾錯方式，並提供此方法能成功糾錯的錯誤率的上限，以此為標準並決定系統中各元件要採用的參數規格。

Quantum key distribution (QKD) is one of cryptography's most successful applications of quantum information. Based on quantum mechanics, the communication parties can theoretically obtain a set of unconditionally secure and identical keys for encrypted communications. In this paper, we will introduce our simulation study on QKD. We have developed a simulation framework that takes a single photon as the system's basic unit and uses the hybrid model to achieve efficient simulation, including static Monte Carlo simulation and discrete event simulation. In addition, the phase-encoded QKD protocol is a popular research topic, so we also focus on developing optical modules such as interference, arbitrary waveform, and phase modulation. Meanwhile, our simulation software is modular design. We also developed a graphical user interface (GUI) that allows users to model customized optical paths to compare the efficiency of different protocols and optimize the parameters to improve the key generation rate. In addition, we use low-density parity check (LDPC) codes for error correction during the reconciliation stage. This study provides an upper bound of the error rate that can be successfully corrected in this way. The protocol will be subject to this quantum bit error rate (QBER) to determine the specifications of each components in the system.