Zou Zhixing, Gong Jiangbin, Chen Weitao
National University of Singapore, Department of Physics, Singapore.
MajuLab, CNRS-UCA-SU-NUS-NTU International Joint Research Unit, Singapore.
Phys Rev Lett. 2025 Jun 13;134(23):230802. doi: 10.1103/lkrt-lvng.
Quantum effects in metrology can in principle enhance measurement precision from the so-called standard quantum limit to the Heisenberg limit. Further advancements in quantum metrology largely rely on innovative metrology protocols that can avoid a number of known obstacles, including the challenge of preparing entangled states with sufficient fidelity, the readout noise in measuring highly entangled states, and no-go theorems for quantum metrology under noisy environments. In this Letter, exploiting some peculiar but experimentally feasible dynamical features of a collection of spins with all-to-all time-periodic interactions, we propose a metrology protocol that can circumvent all three mentioned obstacles and yet still make good use of time as a resource for metrology. Specifically, by mapping the dynamics of such a periodically driven spin system to that of a paradigm of quantum chaos but tuned to some high-order quantum resonance, it is shown that a simple SU(2) coherent state can, after evolving to highly entangled states in the ensuing dynamics, be dynamically brought back to the same initial coherent state. The associated quantum Fisher information is found to exhibit quadratic scaling with both the number of spins and the duration of the metrology protocol. The achieved Heisenberg scaling can also largely survive in the presence of Markovian noise. Representing a previously unknown strategy for quantum metrology, the protocol proposed here can be tested on available experimental platforms.
计量学中的量子效应原则上可以将测量精度从所谓的标准量子极限提高到海森堡极限。量子计量学的进一步发展在很大程度上依赖于创新的计量协议，这些协议可以避免一些已知的障碍，包括以足够的保真度制备纠缠态的挑战、测量高度纠缠态时的读出噪声以及噪声环境下量子计量学的不可行定理。在本信函中，利用具有全对全时间周期相互作用的自旋集合的一些特殊但在实验上可行的动力学特征，我们提出了一种计量协议，该协议可以规避上述所有三个障碍，同时仍能很好地利用时间作为计量资源。具体而言，通过将这种周期性驱动的自旋系统的动力学映射到量子混沌范式的动力学，但调整到某些高阶量子共振，结果表明，一个简单的SU(2)相干态在随后的动力学中演化为高度纠缠态后，可以动态地恢复到相同的初始相干态。发现相关的量子费希尔信息与自旋数和计量协议的持续时间均呈现二次标度关系。在存在马尔可夫噪声的情况下，所实现的海森堡标度也能在很大程度上得以保留。这里提出的协议代表了一种此前未知的量子计量策略，可以在现有的实验平台上进行测试。
