| 摘要: | 光子數解析 偵測 器（ Photon Number Resolving Detector, PNRD）在光量子技術應用中 扮演著重要的角色。例如，將 PNRD應用於量子密鑰分發(Quantum Key Distribution, QKD）中可以防止光子數分裂 (Photon Number Splitting, PNS）攻擊，提升通信的安全性。通過對子系統進行光子數檢測並後選擇特定光子數模式，有助於生成非高斯態，促進容錯量子計算。在近紅外光通信中，常選擇基於InGaAs或Ge的單光子雪崩二極體（ Single-Photon Avalanche Diode, SPAD），以實現單光子 靈敏 度。本論文研究了InGaAs/InAlAs SPAD和 InGaAs/InP SPAD作為 PNRD的 特性， 這兩種 SPAD的主要區別在於放大層所使用的材料。然而，每種材料都有其優點和缺點，如 InAlAs元件中較高的暗計數和InP元件 中較低 的崩潰機率， 這些因素可能 交 互 影響光子數解析能力。因此，本論文旨在分析這兩種元件的特性並進一步 探 討 它們的光子數解析能力。
本論文使用了我們自製的 InGaAs/InAlAs SPAD和 Princeton Lightwave的 InGaAs/InP SPAD。這些 元 件在閘 控 模式下運行， 所使用的 閘 控 頻率為104.7 MHz，脈衝寬度為 1.5 ns。為了 能分辨出 早期 觸發 微弱的崩潰訊號更採用了自差 分 (self-differencing)電路以消除電容 耦合訊 號 使用重複頻率為 26.2 MHz（閘 控 頻率的四分之一）的 1550 nm脈衝 雷射 作為光子源。我們證明了兩種 SPAD的光子數解析性能隨著單光子檢測效 率 Single Photon Detection Efficiency SPDE）的增加而提高。在各自最佳的 SPDE值下，Princeton Lightwave的 InGaAs/InP SPAD能夠解析 4個光子，而我們自製的InAlAs SPAD能夠解析 5個光子， 結果 表明我們自製的 InGaAs/InAlAs SPAD的光子數解析能力優於商用 SPAD。;Photon number resolving detector (PNRD) plays a crucial role in photonic quantum technology applications. For example, implementing PNRD to the applications of quantum key distribution (QKD) could prevent the photon number splitting (PNS) attack, enhancing the security of communication. By performing photon-number detection on a subsystem and postselecting a particular photon-number pattern are instrumental to the generation of non-Guassian states, facilitating fault-tolerant quantum computing. InGaAs-based or Ge-based single-photon avalanche diodes (SPADs) are commonly chosen for optical communication in the near infrared that demands single photon sensitivity. In this thesis, we study the performance of InGaAs/InAlAs SPAD and InGaAs/InP SPAD when they are served as PNRDs. For these two SPADs, the main difference is the material used for the multiplication layer. However, each material has its own advantages and drawbacks, such as higher dark counts in InAlAs-based devices and lower breakdown probability in InP-based devices. These factors might interactively affect the photon number resolving capability. Hence, the purpose of this thesis is to analyze the characteristics of these two devices and explore their photon number resolving capabilities.
The devices used in this thesis are our homemade InGaAs/InAlAs SPAD and a Princeton Lightwave InGaAs/InP SPAD. The devices are operated under gated mode with a gate frequency of 104.7 MHz and a pulse width of 1.5 ns. To sense the early onset of avalanche signal, a self-differencing circuit is further incorporated to eliminate capacitive signals. A 1550 nm pulsed laser with repetition rate of 26.2 MHz, 1/4th the gate frequency, is used as the photon source. We demonstrate that the PNR performance is elevated with increasing single photon detection efficiency (SPDE) for both SPADs. At their respective optimum SPDE, Princeton Lightwave InGaAs/InP SPAD is capable of resolving 4 photons, while our homemade InAlAs SPAD resolves 5 photons, indicating that the PNR capability of our homemade InGaAs/InAlAs SPAD outperforms that of a commercial SPAD. |
