Collaborative Research: HAYSTAC Sub-Quantum

现在，所有的天体物理学和宇宙学数据都令人信服地指出，宇宙中存在着大量的冷暗物质，而我们只能通过引力来推断它的存在。暗物质的一个很好的候选者是光轴子。在描述强作用力作用的量子色动力学中，轴子被引入来解释电荷宇称（CP）对称性被破坏的微小性。暗物质轴子可以通过在磁场渗透的微波腔谐振器中转换成狭窄的射频（RF）信号来检测。耶鲁大学-伯克利大学-科罗拉多大学合作设计、建造和运行了一个先进的技术实验，HAYSTAC，作为一个创新试验台，开发新的腔设计和量子限制光子探测方案，作为一个探路者，在10 - 50微电子电子ev质量范围内获取第一个数据，远远超过所有以前的轴子搜索。在超导薄膜和亚量子限制光子探测方面的研发肯定会产生意想不到的副产品，就像nsf支持的轴子微带SQUID放大器的开发在量子信息领域所做的那样。HAYSTAC已经被证明是一个非常吸引年轻人才的地方，其中一半以上是女性；这个奖项只会延续这一记录。此外，计划在旧金山探索博物馆建立一个关于暗区科学的轮转展览，利用许多历史上的暗区和宇宙微波背景实验的原型和文物。除了没有找到轴子，HAYSTAC已经非常成功了。在过去的三年里，这个实验基本上实现了量子限制的操作（没有其他实验达到一个数量级）。在第二阶段的准备工作中，伯克利设计并建造了一个具有6 - 12 GHz范围（~ 25 - 50 micro-eV）高品质系数的微波腔。科罗拉多设计、建造并描述了一个压缩真空状态接收器，现在正在HAYSTAC投入使用——它将成为暗物质实验的第一个亚量子接收器，并且与LIGO一起成为基础物理世界中第一个用于数据生产的压缩状态接收器。此外，该小组将生产第一个包含NbTiN（一种ii型超导体）平面薄膜的腔原型，以实现质量因子Q的一个数量级提升，这一增益将直接映射到质量扫描速率。每一项创新都极大地提高了HAYSTAC的发现潜力。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。

All astrophysical and cosmological data now point convincingly to a large component of Cold Dark Matter in the Universe, whose presence we only infer gravitationally. A well-motivated candidate for Dark Matter is a light axion. Axions have been introduced to explain the smallness of the violation of the Charge-Parity (CP) symmetry in Quantum ChromoDynamics, the theory describing the action of the strong force. Dark matter axions may be detected through their conversion into a narrow Radio Frequency (RF) signal in a microwave-cavity resonator permeated by a magnetic field. This Yale-Berkeley-Colorado collaboration came together 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 - 50 micro-eV mass range, well above all previous such searches for axions. R&D on superconducting thin-films, and sub-quantum-limited photon detection will certainly produce unanticipated spin-offs, just as the NSF-supported development of the Microstrip SQUID Amplifier for axions did in the quantum information world. HAYSTAC has already proven to be a great attractor for young talent, more than half being women; this award can only be expected to extend this record. In addition, it is planned to establish a rotating exhibit on dark-sector science at the San Francisco Exploratorium utilizing prototypes and artifacts from many of the historic dark sector and cosmic microwave background experiments.Short of finding the axion, HAYSTAC has been extraordinarily successful. During the past three-year period, the experiment has achieved essentially quantum-limited operation (no other experiment has come within an order of magnitude). In preparation for Phase II, Berkeley has designed and built a microwave cavity with a high figure of merit for the 6 - 12 GHz range (~ 25 - 50 micro-eV). Colorado has designed, built and characterized a squeezed-vacuum state receiver, now being commissioned in HAYSTAC - it will be the first-ever sub-quantum receiver for a dark-matter experiment, and with LIGO the first squeezed-state receivers for data production in the world of fundamental physics. Furthermore, the group will produce a first cavity prototype incorporating planar thin-films of NbTiN, a Type-II superconductor, to achieve a boost in quality factor Q by an order of magnitude, a gain that would map directly into mass scan rate. Each of these innovations dramatically enhances the discovery potential of HAYSTAC.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.