论文标题
如何使用任意测量设备执行几乎完美的测量
How to use arbitrary measuring devices to perform almost perfect measurements
论文作者
论文摘要
考虑到执行另一种量子的能力,我们考虑重现一个量子测量的问题。我们为此问题提供了一般框架和特定协议。例如,我们显示如何使用可用的“不完美”设备进行少量次数来实现目标测量,并以平均误差为准,而所使用的不完美测量值则呈指数级别。我们希望这在近期应用中可以用作测量设备的一种轻量级误差。除了对实际应用的观点外,我们还从一般理论的角度考虑了一个问题,在最通用的环境中,可用的和目标测量都是任意的广义量子测量。我们表明,这个总体问题实际上降低了重现(完整)von Neumann测量的统计数据的能力,并且在无限多次使用可用测量的渐近限制中,基于“经典克隆”的简单协议可以完美地完成此任务。我们表明,渐近的所有(非平凡)量子测量都是等效的。我们还研究了可用测量的固定用途的最佳协议。这包括但不限于改善嘈杂和有损量子测量值。此外,我们表明,在同时进行多个测量的环境中,我们可以使用经典信息理论中的块编码技术实现有限速率测量复制。最后,我们表明,也可以利用概率协议来获得优势。
We consider the problem of reproducing one quantum measurement given the ability to perform another. We give a general framework and specific protocols for this problem. For example, we show how to use available "imperfect" devices a small number of times to implement a target measurement with average error that drops off exponentially with the number of imperfect measurements used. We hope that could be useful in near-term applications as a type of lightweight error mitigation of the measuring devices. As well as the view to practical applications, we consider the question from a general theoretical perspective in the most general setting where both the available and target measurements are arbitrary generalised quantum measurements. We show that this general problem in fact reduces to the ability to reproduce the statistics of (complete) von Neumann measurements, and that in the asymptotic limit of infinitely many uses of the available measurement, a simple protocol based upon `classical cloning' can perfectly achieve this task. We show that asymptotically all (non-trivial) quantum measurements are equivalent. We also study optimal protocols for a fixed number of uses of the available measurement. This includes, but is not limited to, improving both noisy and lossy quantum measurements. Furthermore, we show that, in a setting where we perform multiple measurements in parallel, we can achieve finite-rate measurement reproduction, by using block-coding techniques from classical information theory. Finally, we show that advantages can also be gained by making use of probabilistic protocols.