HAYSTAC Phase II: Quantum Detection Technology Enhanced Axion Dark Matter Search

天体物理观测和宇宙学数据令人信服地指出，宇宙中存在大量冷暗物质。弱相互作用大质量粒子（wimp）和轴子在理论上被认为是暗物质的首选候选者。尽管有强有力的证据证明暗物质的存在，但wimp和轴子都没有被最终探测到。暗物质轴子可以在磁场渗透的微波腔谐振器中转化为窄带射频（RF）信号来探测。在美国国家科学基金会的资助下，耶鲁大学-加州大学伯克利分校-科罗拉多大学博尔德分校于2011年合作，共同设计，建造和运营一个先进的技术实验，HAYSTAC，作为创新试验台，开发新的腔设计和量子限制光子探测方案，并作为探路者，在10到50微电子伏特的质量范围内获取第一批数据，远远超过以往所有此类搜索。该奖项将为继续轴子研究提供资金。HAYSTAC的广泛合作正在导致许多技术创新。在超导薄膜和亚量子受限光子探测方面的研发将产生意想不到的副产品。正在开发的实验技术，特别是磁屏蔽和数据分析，将对使用类似量子传感技术的其他实验有用。集团将继续以包容的方式成功招聘和培训新人才。HAYSTAC非常成功地吸引了许多聪明的年轻人进入这个领域。警务专员积极举办受欢迎的公开讲座和参与教育外展活动。赖特实验室已经开始与耶鲁大学皮博迪自然历史博物馆进行谈判，准备举办一个展览，突出实验室本身的历史和研究，以暗物质研究为特色。HAYSTAC是第一个成功结合压缩真空态量子有限接收器的暗物质搜索，与LIGO一起，是第一个使用压缩态接收器进行数据生产的基础物理实验。实际的系统噪声温度是标准量子极限（SQL）的两倍，加上传输损耗带来的额外噪声量子。在第一阶段，HAYSTAC在23.15 ~ 24.0微ev范围内建立了2.3倍KSVZ耦合的排除极限。HAYSTAC正在接近其目标，即与第一阶段相比，将质量扫描率提高至少2倍，灵敏度约为KSVZ轴子耦合的两倍。计划进行更多的创新改进，包括新的对称调谐器设计腔和改进的压缩状态接收器，消除了当前接收器设计中环行器和其他元素的损耗。然后，长期运行将开始覆盖由Klaer和Moore预测的轴子质量范围，这是基于第一次也是唯一一次轴子产生的计算，以自一致的方式结合真空重新排列和弦辐射机制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Astrophysical observations and cosmological data point convincingly to a large component of Cold Dark Matter in the Universe. Weakly interacting massive particles (WIMPs) and axions have been proposed as theoretically favored candidates for dark matter. Despite the strong evidence for the existence of dark matter, neither WIMPs nor axions have been conclusively detected. Dark matter axions may be detected through their conversion into a narrow band Radio Frequency (RF) signal in a microwave-cavity resonator permeated by a magnetic field. Under NSF funding, a Yale-UC Berkeley-University of Colorado Boulder collaboration came together in 2011 to design, build and operate an advanced technology experiment, HAYSTAC, to serve both as an innovation test-bed to develop new cavity designs and quantum-limited photon detection schemes, and as a pathfinder to take first data in the 10 to 50 micro-eV mass range, well above all previous such searches. This award will provide funding to continue this axion search. The collaboration-wide efforts of HAYSTAC are leading to many technical innovations. R&D on superconducting thin-films and sub-quantum-limited photon detection will produce unanticipated spin-offs. The experimental techniques being developed, in particular magnetic shielding and data analysis, will be useful to other experiments that use similar quantum sensing techniques. The group will continue their successful recruiting and training of new talent inclusively. HAYSTAC has been very successful in attracting many bright young people to the field. The PIs are active in giving popular public lectures and participating in educational outreach. Wright Laboratory has begun negotiations with the Peabody Natural History Museum at Yale to prepare an exhibit highlighting the history and research of the Laboratory itself, featuring dark matter studies.HAYSTAC is the first dark matter search to successfully incorporate a squeezed-vacuum-state quantum limited receiver, and along with LIGO, is among the first fundamental physics experiments to use squeezed-state receivers for data production. The actual system noise temperature is twice the standard quantum limit (SQL), with the additional quantum of noise from transmission losses. During Phase I, HAYSTAC established an exclusion limit of 2.3 times the KSVZ coupling at 23.15 to 24.0 micro-eV. HAYSTAC is nearing its goal of increasing the mass scan rate by at least a factor of 2 compared to Phase I, with sensitivity at the level of about twice the KSVZ axion coupling. Additional innovative improvements are planned, including a new symmetrized-tuner design cavity and an improved squeezed state receiver that eliminates losses from circulators and other elements in the present receiver design. A long run will then commence to cover the axion mass range predicted by Klaer and Moore, based on the first and only calculation of axion production incorporating in a self-consistent way both the vacuum realignment and string radiation mechanisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.