论文标题
通过光子量子步行进行的两倍纠缠测量的通用设备
Universal device for two-qubit entangled measurements via photonic quantum walks
论文作者
论文摘要
复杂的量子测量是在许多信息问题中获得量子优势的基础。在这里，我们考虑了猜测以两分纯状态编码的方向的任务。我们在实验上证明，即使是从非理想状态中，也可以使用弃权来恢复最佳方向猜测（根据忠诚度和最大似然得分来衡量）。我们的协议使用九步光子量子步道来实现最佳的五分之二Quition集体测量，其保真度高于0.9850。得益于弃权，我们获得了方向猜测得分的10倍以上（就最佳猜测分数而言）。我们的工作证明了光子量子步道的多功能性，以实现多个Quition的复杂测量。
Sophisticated quantum measurements are fundamental to obtain a quantum advantage in many informational problems. Here, we consider the task of guessing a direction encoded in a two-qubit pure state. We experimentally demonstrate that abstention can be used to recover optimal direction guessing (measured in terms of the fidelity and maximum likelihood scores) even from non ideal states. Our protocol uses nine-step photonic quantum walks to implement the optimal five-output two-qubit collective measurements with fidelities above 0.9850. Thanks to abstention, we obtain more than a 10-fold improvement of the direction guessing scores (in terms of deviation to the optimal guessing scores). Our work demonstrates the versatility of photonic quantum walks for implementing many-qubit sophisticated measurements.
