Title: Atomic Quantum Sensors for High-Frequency Gravitational Wave Searches Show Chinese title

Title: 原子量子传感器在高频引力波搜索中的应用

Abstract: High-frequency gravitational waves represent an unexplored frontier of gravitational physics. While pulsar timing arrays reach nHz frequencies and ground-based interferometers probe the audio band, the regime above the MHz scale remains essentially untested. We propose a hybrid detection framework in which gravitons convert to photons via the Gertsenshtein effect in strong magnetic fields; the resulting electromagnetic signal is resonantly enhanced in a cavity and read out by atomic quantum sensors. Our approach combines multiple channels, including long-coherence Raman interferometry in alkali atoms, microwave Rydberg transitions, photoionization-based detection, and inner-shell electronic resonances. We derive the graviton-photon conversion probability, compute the induced photon flux, and estimate the shot-noise-limited spectral strain noise density. Depending on configuration, the projected shot-noise-limited sensitivity ranges from $\sqrt{S_{h, {\rm min}}} \sim 10^{-22}{\rm\,Hz^{-1/2}}$ in conservative microwave implementations to $\sqrt{S_{h, {\rm min}}} \sim 10^{-37}{\rm\,Hz^{-1/2}}$ in aggressive optical Raman schemes, potentially surpassing the cosmological bound from Big Bang Nucleosynthesis for stochastic backgrounds, while coherent bursts remain unconstrained and detectable. Such reach allows to test scenarios involving primordial black holes, topological defects, violent phase transitions, and (p)reheating, motivating advances in high-$Q$ cavities, strong-field magnets, and quantum-limited atomic sensors, with broad impact across quantum metrology and fundamental physics. Show Chinese abstract

Abstract: 高频引力波代表了引力物理中一个未被探索的前沿领域。 虽然脉冲星计时阵列可以达到纳赫兹频率，地面干涉仪探测音频频段，但兆赫兹以上的频段基本上尚未被测试。 我们提出了一种混合检测框架，其中在强磁场中，引力子通过Gertsenshtein效应转换为光子；产生的电磁信号在腔体中被共振增强，并由原子量子传感器读取。 我们的方法结合了多个通道，包括碱金属原子中的长相干拉曼干涉测量、微波里德伯跃迁、基于光电离的检测以及内壳层电子共振。 我们推导了引力子-光子转换概率，计算了感应光子通量，并估计了 shot-noise-limited 光谱应变噪声密度。 根据配置不同，预期的 shot-noise-limited 灵敏度范围从保守的微波实现中的$\sqrt{S_{h, {\rm min}}} \sim 10^{-22}{\rm\,Hz^{-1/2}}$到激进的光学拉曼方案中的$\sqrt{S_{h, {\rm min}}} \sim 10^{-37}{\rm\,Hz^{-1/2}}$，可能超过来自宇宙大爆炸核合成的宇宙背景的约束，而相干脉冲仍然未被约束且可检测。 这种探测范围允许测试涉及原初黑洞、拓扑缺陷、剧烈相变以及 (p)reheating 的情景，推动高-$Q$腔体、强磁场和量子极限原子传感器的发展，在量子计量学和基础物理领域产生广泛影响。