本論文研究冷銣原子系綜的高效率通訊波段量子轉頻介面，目標是將適合原子量子記憶與量子節點操作的 795 nm 近紅外光子轉換至適合低損耗光纖傳輸的 1367 nm 通訊波段，同時保留其量子態與非古典關聯特性。本研究以鑽石型四波混頻為核心機制，結合理論模型、實驗最佳化與關聯雙光子轉換實驗，建立原子系綜量子轉頻介面的完整研究架構。在理論方面，本論文建立半古典與全量子模型，分析轉換效率、殘餘穿透率與光學深度、控制場強度及失諧量之間的關係，並以海森堡–朗之萬（Heisenberg–Langevin）方程與約化密度算符方法描述轉頻過程中的量子噪聲、轉換效率與量子態保真度。理論結果顯示，在高轉換效率條件下，鑽石型原子系綜可有效保存光子數、路徑與偏振自由度中所攜帶的量子資訊。實驗上，本研究先以弱同調光輸入實現 795 nm 至 1367 nm 的高效率通訊波段轉頻，並透過分析 Λ 型、階梯型與 V 型電磁誘發透明響應，以及最佳化光學深度、耦合場、驅動場與失諧條件，在光學深度為 75 與 110 時分別達到 66% 與 80% 的轉換效率。進一步地，本研究將此轉頻平台與雙 Λ 型自發四波混頻雙光子源結合，實現觸發式原子雙光子波包的通訊波段轉換；當 2.5 MHz 的窄頻觸發式光子頻譜與轉頻器的高效率響應區域良好匹配時，轉換效率可達 79.4(2.6)% ，並保留強烈的時間關聯、單光子特性與明確的時間波包形狀。對於 17.4 MHz 的較寬輸入頻寬，轉換效率降至約 55%，但主要時間波包仍大致維持，顯示有限轉換頻寬主要造成頻譜邊緣損失，而非嚴重的時間模態變形。綜合而言，本論文建立並實現了冷原子系綜的高效率通訊波段量子轉頻介面，為連接原子相容窄頻量子光源、量子記憶與長距離光纖量子通訊提供重要基礎。

This dissertation investigates a high-efficiency telecom quantum frequency interface in cold rubidium atomic ensembles for converting 795 nm near-infrared photons, which are compatible with atomic quantum memories and quantum nodes, into 1367 nm telecom-band photons suitable for low-loss fiber transmission while preserving their quantum states and nonclassical correlations. The work is based on diamond-type four-wave mixing and combines theoretical modeling, experimental optimization, and telecom conversion of correlated atomic biphotons. Theoretically, this dissertation develops semiclassical and fully quantum models to describe the conversion efficiency, residual transmission, quantum noise, and quantum-state fidelity of the frequency-conversion process. Using the Heisenberg-Langevin approach and the reduced-density-operator method, the theory shows that, under high-efficiency conditions, the diamond-type atomic ensemble can preserve quantum information encoded in photon-number, path, and polarization degrees of freedom. Experimentally, high-efficiency 795 nm to 1367 nm telecom conversion is first realized using weak coherent inputs. By characterizing the Λ-, cascade-, and V-type electromagnetically induced transparency responses and optimizing optical depth, coupling and driving fields, and optical detunings, signal conversion efficiencies of 66% and 80% are achieved at optical depths of 75 and 110, respectively. This converter is further integrated with a double-Λ spontaneous four-wave-mixing biphoton source to realize telecom conversion of heralded atomic biphoton wavepackets. When a 2.5 MHz heralded-photon spectrum is well matched to the high efficiency region of the converter response, a conversion efficiency of 79.4(2.6)% is obtained while preserving strong time-resolved correlations, single-photon characteristics, and well-defined temporal wavepackets. For a broader 17.4 MHz input bandwidth, the efficiency decreases to about 55%, whereas the dominant temporal waveform remains largely preserved, indicating that finite spectral acceptance mainly causes spectral-edge loss rather than severe temporal-mode distortion. These results establish a high-efficiency atom-based telecom quantum frequency interface and provide a foundation for connecting narrowband atomic quantum light sources, quantum memories, and long-distance fiber based quantum networks.

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