近日，美国普林斯顿大学Theodoros Ilias团队发现了偏置量子轨迹增强传感。相关论文于2025年4月29日发表在《物理评论A》杂志上。

量子连续测量策略是许多现代传感技术中的一个基本要素，可以潜在地增强对未知物理参数的估计。在这种方案中，对编码感兴趣参数的量子系统的连续监测会产生不同的量子轨迹，这些轨迹取决于携带参数本身信息的测量结果。重要的是，不同的轨迹携带不同数量的信息，即它们对未知的感兴趣参数或多或少敏感。

在这项工作中，研究组提出了一种如何系统地设计量子开放系统动力学的方法，以提高获得高灵敏度轨迹的概率。他们关注的是单个两级系统与辅助系统相互作用的最简单情况，这反过来又使用连续监测的离散版本进行测量。研究组分析了该协议的性能，并证明它可能会导致灵敏度的显著提高，正如经典Fisher信息所量化的那样，即使应用于如此小的系统规模，也有望在最先进的实验平台和大型复杂的多体系统中直接实现。

附：英文原文

Title: Biasing quantum trajectories for enhanced sensing

Author: Theodoros Ilias

Issue&Volume: 2025/04/29

Abstract: Quantum continuous measurement strategies are an essential element in many modern sensing technologies, leading to potentially enhanced estimation of unknown physical parameters. In such schemes, continuous monitoring of the quantum system, which encodes the parameters of interest, gives rise to different quantum trajectories conditioned on the measurement outcomes which carry information on the parameters themselves. Importantly, different trajectories carry different amounts of information, i.e., they are more or less sensitive to the unknown parameters of interest. In this work, we propose an approach on how to systematically engineer the quantum open-system dynamics in order to increase the probability of obtaining trajectories of high sensitivity. We focus on the simplest case scenario of a single two-level system interacting with ancillas, which are in turn measured using the discretized version of continuous monitoring. We analyze the performance of our protocol and demonstrate that it may lead to a substantial enhancement of sensitivity, as quantified by the classical Fisher information, even when applied to such small system sizes, holding the promise of direct implementation in state-of-the-art experimental platforms and large, complex many-body systems.

DOI: 10.1103/PhysRevA.111.042432

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.042432