We report on a method to certify a unitary operation with the help of source and measurement apparatuses whose calibration throughout the certification process needs not be trusted. As in the device-independent paradigm our certification method relies on a Bell test and requires no assumption on the underlying Hilbert space dimension, but it removes the need for high detection efficiencies by including the single additional assumption that non-detected events are independent of the measurement settings. The relevance of the proposed method is demonstrated experimentally by bounding the unitarity of a quantum frequency converter. The experiment starts with the heralded creation of a maximally entangled two-qubit state between a single ⁴⁰Ca⁺ ion and a 854 nm photon. Entanglement preserving frequency conversion to the telecom band is then realized with a non-linear waveguide embedded in a Sagnac interferometer. The resulting ion-telecom photon entangled state is assessed by means of a Bell-CHSH test from which the quality of the frequency conversion is quantified. We demonstrate frequency conversion with an average certified fidelity of ≥84% and an efficiency ≥3.1 × 10⁻⁶ at a confidence level of 99%. This ensures the suitability of the converter for integration in quantum networks from a trustful characterization procedure.

我们报告了一种在源和测量设备的帮助下认证单一操作的方法，在整个认证过程中其校准不需要被信任。与设备无关范式一样，我们的认证方法依赖于贝尔测试，并且不需要对底层希尔伯特空间维度进行假设，但它通过包含未检测事件独立于事件的单个附加假设，消除了对高检测效率的需求。测量设置。通过限制量子频率转换器的幺正性，通过实验证明了所提出方法的相关性。该实验首先预示着在单个 ⁴⁰ Ca ⁺ 离子和 854 nm 光子之间创建最大纠缠的双量子位态。然后通过嵌入萨格纳克干涉仪中的非线性波导实现电信频段的纠缠保留频率转换。由此产生的离子电信光子纠缠态通过 Bell-CHSH 测试进行评估，由此量化频率转换的质量。我们展示了频率转换，平均认证保真度≥84%，效率≥3.1 × 10 ⁻⁶ ，置信度为 99%。这确保了转换器通过可靠的表征程序集成到量子网络中的适用性。