用悬浮铁磁扭转振荡器搜索超轻轴子暗物质
Search for Ultralight Axion Dark Matter with a Levitated Ferromagnetic Torsional Oscillator
AI总结：
利用悬浮铁磁扭转振荡器探测超轻轴子暗物质，通过高真空和磁屏蔽获得18000秒数据，设定90%置信度限，未来计划通过优化提升灵敏度。
摘要：
我们提出了一种利用悬浮铁磁扭转振荡器（FMTO）搜索与电子自旋耦合的超轻轴子暗物质的方法。该平台直接测量轴子诱导的扭矩作用在宏观自旋极化的物体上，结合大自旋密度和强机械隔离，以探测低于10Hz的磁波动，同时抑制梯度场噪声。在首次实现中，实验在室温下高真空环境下，通过光学读出和三层磁屏蔽，获得了18000秒可分析数据。采用基于似然的统计框架，结合轴子场幅度的随机波动，用于评估数据。在约2e-14 eV附近未观察到与轴子诱导伪磁场一致的过剩。为了考虑可能的屏蔽引起的信号衰减，我们量化其影响，并报告了未校正（g_aee < 1e-7）和衰减校正（g_aee < 6e-5）的90%置信度限。未来，通过噪声预算分析和屏蔽衰减考虑的改进，包括优化悬浮几何形状、低温操作和超导屏蔽，预计可使灵敏度提高多个数量级。
英文摘要：
We present a search for ultralight axion dark matter coupled to electron spins using a levitated ferromagnetic torsional oscillator (FMTO). This platform directly measures axion-induced torques on a macroscopic spin-polarized body, combining large spin density with strong mechanical isolation to probe magnetic fluctuations below 10 Hz while suppressing gradient-field noise. In a first implementation, the experiment yielded 18000 s of analyzable data at room temperature under high vacuum with optical readout and triple-layer magnetic shielding. A likelihood-based statistical framework, incorporating stochastic fluctuations in the axion-field amplitude, was used to evaluate the data. No excess consistent with an axion-induced pseudo-magnetic field was observed near 2e-14 eV. To account for possible shielding-induced signal attenuation, we quantify its effect and report both the uncorrected (g_aee < 1e-7) and attenuation-corrected (g_aee < 6e-5) 90% CL limits on the axion-electron coupling. Looking ahead, improvements guided by both noise-budget analysis and shielding-attenuation considerations, including optimized levitation geometry, cryogenic operation, and superconducting shielding, are expected to boost sensitivity by multiple orders of magnitude.
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