AI 中文总结
该研究针对弱耦合波，指出检测其非经典效应存在两大障碍，证明了非经典效应被弱耦合额外幂次抑制，排除了通过引力波观测建立引力量子化的提议。
AI 中文摘要
精密实验越来越多地针对弱耦合波，包括轴子暗物质和引力辐射。这类波通常被描述为经典场，但也可能存在无经典对应物的量子态。我们发现检测非经典效应存在两个严重障碍，均与模式占据数无关。其一，实际探测器无法分辨场的基模，而是耦合到粗粒化的“有效”模式，这往往会消除非经典效应；其二，所有非经典效应都会被弱耦合的额外幂次抑制，使其比波本身更难检测。我们对此进行了一般性证明，并明确展示了该抑制如何出现在正交分量和数统计、纠缠以及退相干中。原则上，借助合适的量子资源（如高度压缩的探测器态）可克服这种抑制，但所需参数远超当前实验能力。我们以轴子腔 haloscope 为例，尽管结论适用于许多超轻暗物质搜索，并排除了通过引力波观测建立引力量子化的提议。
英文摘要
Precision experiments increasingly target weakly coupled waves, including axion dark matter and gravitational radiation. Such waves are commonly described as classical fields, yet they could exist in quantum states with no classical counterpart. We exhibit two severe obstructions to detecting nonclassical effects, both independent of the mode occupancy. First, realistic detectors cannot resolve the fundamental modes of a field; instead they couple to coarse-grained "effective" modes, which often washes out nonclassical effects. Second, all nonclassical effects are suppressed by extra powers of the weak coupling, making them much harder to detect than the waves themselves. We prove this in general, and explicitly show how the suppression arises for quadrature and number statistics, entanglement, and decoherence. The suppression can in principle be overcome given suitable quantum resources, such as highly squeezed detector states, but the required parameters are far beyond current experimental capabilities. We use the axion cavity haloscope as an explicit example, although our conclusions apply to many ultralight dark matter searches, and rule out proposals to establish the quantization of gravity from observations of gravitational waves.
Comments45+18 pages, 5 figures
