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，宇宙中有很大一部分冷暗物质。弱相互作用大质量粒子(WIMP)和轴子被认为是暗物质理论上最受欢迎的候选者。尽管有强有力的证据证明暗物质的存在，但WIMP和轴子都没有被确凿地探测到。暗物质轴子可以通过在被磁场渗透的微波腔谐振器中转换成窄带射频(RF)信号来探测。在NSF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大学在2011年合作设计、建造和运营了一个先进技术实验Haystac，既作为一个创新试验台来开发新的腔体设计和量子限制光子探测方案，又作为一个探索者在10到50微EV质量范围内获取第一批数据，远远超过以前的所有此类搜索。这项奖励将为继续进行AXION搜索提供资金。Haystac在整个协作范围内的努力带来了许多技术创新。超导薄膜和亚量子极限光子探测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，将对其他使用类似量子传感技术的实验有用。该集团将继续成功地招聘和培训新的人才。Haystac非常成功地吸引了许多聪明的年轻人进入这一领域。督导人员积极举办广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的皮博迪自然历史博物馆谈判，准备一个展览，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，是第一批使用压缩态接收器产生数据的基础物理实验之一。实际系统噪声温度是标准量子极限(SQL)的两倍，外加传输损耗产生的噪声。在第一阶段，Haystac确定了23.15至24.0微电子伏特的排除极限为KSVZ耦合的2.3倍。Haystac正在接近其目标，即与第一阶段相比，质量扫描速度至少提高2倍，灵敏度约为KSVZ轴子耦合的两倍。还计划进行其他创新改进，包括新的对称调谐器设计腔和改进的压缩态接收器，该接收器消除了当前接收器设计中的环行器和其他元件的损耗。然后，将开始覆盖Klaer和Moore预测的轴子质量范围，基于第一次也是唯一一次以自洽的方式结合真空重排和弦辐射机制的轴子产生计算。该奖项反映了NSF的法定使命，并已通过使用基金会的智力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.