近日，北京师范大学的艾清及其研究小组与重庆邮电大学的张娜娜合作并取得一项新进展。经过不懈努力，他们实现了束缚态增强量子计量的量子模拟。相关研究成果已于2024年4月26日在国际知名学术期刊《物理评论A》上发表。

本文提出了一种利用N个量子比特来模拟包含一个原子，和耦合谐振器的混合系统开放量子动力学方法。研究人员发现由于束缚态的存在，测量误差可以随着时间的增加而减小。通过分析和数值模拟证明，当混合系统存在束缚态时，测量误差的t^-1标度是可以恢复的。

有趣的是，研究人员观察到有规则的振荡可以用来评估原子跃迁频率。在有限的N值下，每当增加一个量子比特，规则振荡的持续时间便会实现翻倍。

据悉，量子计量学通过探索量子效应来提高超出经典极限的物理量的测量精度。然而，由于系统与环境的相互作用，退相干会显著降低测量的精度。为了在长时间范围内恢复测量的精度，人们提出了许多方法。最近，人们发现束缚态有助于提高测量精度和恢复t^-1标度。

附：英文原文

Title: Quantum simulation of bound-state-enhanced quantum metrology

Author: Cheng-Ge Liu, Cong-Wei Lu, Na-Na Zhang, Qing Ai

Issue&Volume: 2024/04/26

Abstract: Quantum metrology explores quantum effects to improve the measurement accuracy of some physical quantities beyond the classical limit. However, due to the interaction between the system and the environment, the decoherence can significantly reduce the accuracy of the measurement. Many methods have been proposed to restore the accuracy of the measurement in the long-time limit. Recently, it was found that the bound state can help improve measurement accuracy and recover the t^-1 scaling [Bai et al., Phys. Rev. Lett. 123, 040402 (2019)]. Here, by using N qubits, we propose a method to simulate the open quantum dynamics of a hybrid system including one atom and coupled resonators. We find that the error of the measurement can decrease as the time increases due to the existence of the bound state. With both analytical and numerical simulations, we prove the t^-1 scaling of the measurement error can be recovered when there is a bound state in the hybrid system. Interestingly, we observe that there are regular oscillations which can be used for the evaluation of the atomic transition frequency. For a finite N, the duration of the regular oscillations doubles as one more qubit is involved.

DOI: 10.1103/PhysRevA.109.042623

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.042623