标题： Floquet 工程的去相干鲁棒协议用于超越线性标准量子极限的宽频传感 显示英文标题

标题： Floquet-engineered decoherence-resilient protocols for wideband sensing beyond the linear standard quantum limit

摘要： 量子计量的一个关键优势是能够通过使用非经典态来超越测量精度的标准量子极限。然而，对于持续时间超过底层量子态退相干时间的测量，使用非经典态通常不会带来明显的精度提升。因此，旨在达到可能的最高精度的测量几乎完全依赖于经典态，并受到标准量子极限的约束。 在这里，我们展示了通过利用次谐波激发现象，结合最近实现的拉曼激发谐振子的技术，可以将电场频率的测量分辨率提高到对应线性测量的标准量子极限之下。由于输入态可以是经典的，这种计量增益可以持续到长时间尺度上，并提高可能达到的最终精度。 尽管我们通过单个40Ca⁺离子的运动拉曼次谐波激发，利用工程化的弗洛凯态来演示了这一技术，但预计该技术可以扩展到其他平台，如氮空位中心、固态量子比特和中性原子，从而在射频、微波和光学领域提供传感的计量增益。 显示英文摘要

摘要： A key advantage of quantum metrology is the ability to surpass the standard quantum limit for measurement precision through the use of non-classical states. However, there is typically little to no improvement in precision with the use of non-classical states for measurements whose duration exceeds the decoherence time of the underlying quantum states. Measurements aimed at the ultimate possible precision are thus performed almost exclusively with classical states and, therefore, are constrained by the standard quantum limit. Here, we demonstrate that by using the phenomenon of subharmonic excitation, in combination with a recently demonstrated technique of Raman excitation of a harmonic oscillator, the frequency of an electric field can be measured at a resolution below the standard quantum limit of the corresponding linear measurement. As the input states can be classical, this metrological gain persists to long timescales and improves the ultimate possible precision. While we demonstrate this technique using motional Raman subharmonic excitation of a single 40ca^+ ion through engineered Floquet states, this technique is expected to be extendable to other platforms, such as NV centers, solid-state qubits, and neutral atoms, where it can provide metrological gain for sensing across the radio frequency, microwave, and optical domains.