通过触发计数和外差探测对光子减法设备的原位表征
In situ characterization of a photon-subtraction device via heralding counts and homodyne detection
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- Dipartimento di Fisica dell’Università di Milano（米兰大学物理系）
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中文总结 AI 辅助
本文提出一种利用触发计数和外差探测原位同时估计光子减法设备分束器透射率与触发探测器量子效率的方案，证明适当选择正交分量可减少参数简并，且联合估计优于顺序估计。
中文摘要 AI 辅助
光子减法是产生非高斯光学态的最重要技术之一，并构成量子信息处理和量子计量学的关键资源。光子减法设备的实际性能主要由分束器的透射率和触发探测器的量子效率决定。因此，准确了解这些参数对于评估所生成非经典态的质量至关重要。在本工作中，我们提出了一种实验上可行的原位方案，仅利用设备运行期间产生的测量数据即可同时估计这两个参数。我们的协议将开关型触发探测器的点击统计与在位移压缩态输入下对分束器透射模式进行的外差测量相结合。在经典多参数估计理论的框架内，我们推导了相应的Fisher信息矩阵，并研究了联合估计和顺序估计两种策略。对于参数的同时测量，我们评估了底层统计模型的迟钝性，并分析了其对所测正交分量、探针光子数、压缩分数、分束器透射率和探测器效率的依赖性。我们的分析证明，适当选择外差正交分量可显著减少参数简并，并实现高效的同时估计。此外，我们表明，在广泛的实验相关参数范围内，联合估计策略始终提供比顺序估计方法更低的估计界限。
英文摘要
Photon subtraction is one of the most important techniques for generating non-Gaussian optical states and constitutes a key resource for quantum information processing and quantum metrology. The practical performance of a photon-subtraction device is primarily determined by the transmissivity of the beam splitter and the quantum efficiency of the heralding detector. Accurate knowledge of these parameters is therefore essential for assessing the quality of the generated non-classical states. In this work, we propose an experimentally feasible in situ scheme for the simultaneous estimation of these two parameters using only the measurement data produced during the operation of the device. Our protocol combines the click statistics of an on/off heralding detector with homodyne measurements performed on the transmitted mode of the beam splitter when fed by a displaced squeezed state. Within the framework of classical multi-parameter estimation theory, we derive the corresponding Fisher information matrix and investigate both joint and sequential estimation strategies. For simultaneous measurement of parameters, we evaluate the sloppiness of the underlying statistical model and analyze its dependence on the measured quadrature, probe photon number, squeezing fraction, beam splitter transmissivity, and detector efficiency. Our analysis proves that an appropriate choice of the homodyne quadrature substantially reduces parameter degeneracy and enables efficient simultaneous estimation. Furthermore, we show that the joint estimation strategy consistently provides a lower estimation bound than the sequential estimation approach over a broad range of experimentally relevant parameters.
