AI 中文总结
研究GHz频率下固态引力波探测器，用于寻找原初随机引力波背景和轻原初黑洞双星合并。提出用超纯蓝宝石单晶模块化阵列，对比候选材料，阐述针对不同目标的搜索方法，该探测器可积分连续GW信号，为相关研究提供新途径。
AI 中文摘要
暴胀后的再加热是引力波（GW）的最强来源之一，产生了一个非热谱的随机背景（SGWB），其峰值频率在几GHz左右。检测它很困难：基于强磁场中逆格特申斯坦效应的实验能达到MHz频段，但达不到GHz频段，该频段典型应变约为\(10^{-30}\)。同一频段还包含轻原初黑洞（PBH）双星的合并，其合并频率\(f\simeq4.4\ \mathrm{kHz}\,(M_\odot/M)\)对于行星到亚行星质量落在MHz - GHz范围内；由于此类物体必然是次太阳质量的，其探测将是PBHs作为暗物质组成部分的有力证据。我们提出一种GHz频率的固态探测器，它可以对来自大爆炸的连续GW进行数月到数年的积分，并搜索轻PBH双星合并。作为具体实现，我们考虑一个由约\(10^3\)个\((10\ \mathrm{cm})^3\)超纯蓝宝石单晶组成的模块化阵列，形成一个立方米探测器，由低温单声子传感器读出，其分段提供热隔离、良好的计数统计和基于符合的背景抑制。我们还比较了候选材料，发现金刚石单位体积性能优越，但受限于大单晶的不可得性。最后，我们对比了两个目标。静止背景是散粒噪声限制的计数问题，最好通过窄带、共振增强、长积分搜索来解决；附近合并的响亮瞬态啁啾最好通过具有符合标记的快速宽带搜索来捕捉。由于声子谱是连续的，模块化固态阵列可以通过在整个频段交错共振单元并运行一个宽带子集进行啁啾跟踪来同时服务于两者。
英文摘要
Reheating after inflation is one of the strongest sources of gravitational waves (GW), producing a stochastic background (SGWB) with a non-thermal spectrum peaked at frequencies of order a few GHz. Detecting it is difficult: experiments based on the inverse Gertsenshtein effect in intense magnetic fields reach the MHz but not the GHz band, where the typical strain is around $10^{-30}$. The same window contains the coalescence of light primordial black hole (PBH) binaries, whose merger frequency $f\simeq4.4\ \mathrm{kHz}\,(M_\odot/M)$ falls in the MHz--GHz range for planetary to sub-planetary masses; since such objects are necessarily sub-solar, their detection would be strong evidence for PBHs as a component of the dark matter. We propose a solid-state detector at GHz frequencies that could integrate over months to years the GW continuously arriving from the Big Bang and search for light PBH binary coalescence. As a concrete realization we consider a modular array of $\sim10^3$ ultra-pure sapphire $(10\ \mathrm{cm})^3$ monocrystals forming a cubic-metre detector read out by cryogenic single-phonon sensors, whose segmentation provides thermal isolation, favourable counting statistics and coincidence-based background rejection. We also compare candidate materials, finding diamond superior per unit volume but limited by the unavailability of large single crystals. Finally, we contrast the two targets. The stationary background is a shot-noise-limited counting problem, best served by a narrow, resonance-enhanced, long-integration search; the loud transient chirp of a nearby merger is better caught by a fast, broad-band search with coincidence tagging. Because the phonon spectrum is continuous, a modular solid-state array can serve both, by staggering resonant cells across the band while running a broad-band subset for chirp tracking.
Comments17 pages, 2 figures
