量子效應展示出古典物理學無法解釋的現象，受益於此非古典之特性，因而 進一步利用於量子通訊與量子計算之量子資訊科技中。量子遠程狀態準備(remote state preparation, RSP)在量子資訊任務中扮演著重要角色。Dakic 等人 [N at. P hys. 8, 666 (2012)] 指出，量子不一致性是量子遠程狀態製備不可或缺的資源，而相關研究 對於最佳化後此任務所需的關鍵資源有不同觀點。然而，他們使用最佳化遠程狀態 製備評分的方法，需要量子狀態斷層掃描(quantum state tomography, QST)的能力， 可能無法在實際應用(如量子網絡)中有效評估量子遙態製備的表現。為了解決這 個問題，我們提出了一種新的方法來評估 RSP 任務，它可以應用於任何狀態，並且 僅需要最少的測量設置，無需最佳化遠程狀態製備協議。我們更進一步證明此指標 忠實地描述了資源狀態的特徵，顯示量子同調性在量子遙態製備中充分且必要。在 實驗中，我們使用從偏振-薩格納克干涉儀產生的高保真度不同狀態來實現量子遠程 態製備，顯示我們的指標可以有效評分量子遙態製備任務並描述資源狀態的特性。 我們的方法同時在理論與實驗上證明了實現量子遙態製備所需的量子獲益條件，預 期有助於量子網絡中所需的遠態準備。

Quantum effects often show phenomena that cannot be explained by classical physics, and tasks that can show quantum beneficial effects have been attracting attention. Remote state preparation (RSP) [1,2] plays an important role in quantum information tasks. B. Dakic [et al. Nat. Phys. 8, 666 (2012)] point out that quantum discord is an indispensable resource for RSP. Several related studies have different views on what kind of resource is the key to the optimized RSP. However, their scoring methods for optimizing RSP require the ability of quantum state tomography and may not be able to score RSP effectively in practical applications such as quantum networking. To tackle this problem, we propose a new method to evaluate the RSP task, which can apply to any state with the minimum measurement settings and does not need to optimize the RSP protocol. Our identifier faithfully describes the characteristics of the resource state and shows that coherence plays a necessary and sufficient role in RSP. Experimentally, we implement RSP with high-quality different source states generated from polarization-Sagnac-interferometer, showing our identifier can effectively score RSP and describe the resource state property. Our method reveals the sufficient and necessary characteristics of the quantum beneficial effect for realizing RSP, which helps implement practical quantum information processing such as state preparation over long-distant quantum networks.

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