Bai Si-Yuan, An Jun-Hong
Key Laboratory of Quantum Theory and Applications of MoE, Lanzhou Center for Theoretical Physics, and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, China.
Phys Rev Lett. 2023 Aug 4;131(5):050801. doi: 10.1103/PhysRevLett.131.050801.
Permitting a more precise measurement to physical quantities than the classical limit by using quantum resources, quantum metrology holds a promise in developing many revolutionary technologies. However, the noise-induced decoherence forces its superiority to disappear, which is called no-go theorem of noisy quantum metrology and constrains its application. We propose a scheme to overcome the no-go theorem by Floquet engineering. It is found that, by applying a periodic driving on the atoms of the Ramsey spectroscopy, the ultimate sensitivity to measure their frequency characterized by quantum Fisher information returns to the ideal t^{2} scaling with the encoding time whenever a Floquet bound state is formed by the system consisting of each driven atom and its local noise. Combining with the optimal control, this mechanism also allows us to retrieve the ideal Heisenberg-limit scaling with the atom number N. Our result gives an efficient way to avoid the no-go theorem of noisy quantum metrology and to realize high-precision measurements.
通过使用量子资源，量子计量学能够实现比经典极限更精确的物理量测量，有望开发许多革命性技术。然而，噪声诱导的退相干使得其优势消失，这被称为有噪声量子计量学的不可行定理，限制了其应用。我们提出了一种通过弗洛凯工程克服不可行定理的方案。研究发现，通过对拉姆齐光谱中的原子施加周期性驱动，每当由每个被驱动原子及其局部噪声组成的系统形成一个弗洛凯束缚态时，以量子费希尔信息表征的测量其频率的最终灵敏度就会恢复到与编码时间成理想的t²比例关系。结合最优控制，这种机制还使我们能够恢复与原子数N成理想的海森堡极限比例关系。我们的结果给出了一种有效方法，可避免有噪声量子计量学的不可行定理并实现高精度测量。
