论文标题
使用连续变量对量子计量学的指数增强
Exponential enhancement of quantum metrology using continuous variables
论文作者
论文摘要
相干时间是生成量子计量学增强功能的重要资源。在这项工作中，基于连续变量模型，我们提出了一种信号探针哈密顿量的新设计，该设计产生了测量灵敏度的指数增强。关键的想法是将不直接与信号搭配的Ancilla包含在系统中。这种设计的直接好处是，可以及时将量子渔民信息（QFI）扩展到功率系列中，从而可以在QFI中实现高阶时间缩放。具体而言，人们可以设计量子振荡器Ramsey干涉仪的相互作用，以实现四分之一的时间缩放，基于该缩放仪，可以进一步设计一系列耦合的谐波振荡器，以实现QFI中的指数时间缩放。我们的结果表明，时间和耦合项的数量都足以获得指数增强。这种指数优势与四二次的特征交换关系密切相关。
Coherence time is an important resource to generate enhancement in quantum metrology. In this work, based on continuous-variable models, we propose a new design of the signal-probe Hamiltonian which generates an exponential enhancement of measurement sensitivity. The key idea is to include into the system an ancilla that does not couple directly to the signal. An immediate benefit of such design is one can expand quantum Fisher information(QFI) into a power series in time, making it possible to achieve a higher-order time scaling in QFI. Specifically, one can design the interaction for a qubit-oscillator Ramsey interferometer to achieve a quartic time scaling, based on which, one can further design a chain of coupled harmonic oscillators to achieve an exponential time scaling in QFI. Our results show that linear scaling in both time and the number of coupling terms is sufficient to obtain exponential enhancement. Such exponential advantage is closely related to the characteristic commutation relations of quadratures.
