Collaborative Research: ADMX-HF Extreme Axion Experiment

在这个精密宇宙学的时代，测量表明，普通物质只占宇宙总物质密度的一小部分。其余的，我们只是根据引力推断其存在，其本质是未知的，被称为冷暗物质，一种被称为光轴子的粒子是一个有良好动机的候选者。如果轴子构成我们银河系光晕的暗物质，它们可能会通过在被磁场渗透的微波腔谐振器中转换成窄射频(RF)信号而被探测到。该实验在耶鲁大学进行，ADMX-HF(轴子暗物质实验-高频)，旨在作为开发和过渡新的腔体设计和量子限制光子探测方案的创新试验台，以及作为获取10-100微电子伏特质量范围内的第一批数据的探路者。超导薄膜的研发，以及量子电子学中的压缩态和单光子探测，都将产生意想不到的副产品。事实证明，ADMX-HF对年轻人才有很大的吸引力。这一奖项有望延续这一纪录。此外，计划在查博特空间和科学中心或加利福尼亚州奥克兰博物馆建立一个关于暗部门科学的永久展览，利用许多历史上的暗物质、暗能量和宇宙微波背景实验的原型和文物。加州大学伯克利分校和加州大学科罗拉多分校/JILA正在协助耶鲁大学，分别在腔和放大器的开发方面处于领先地位。这三所大学已经成功地在ADMX-HF上交付了数据，最近进行了第一次数据运行。这是约瑟夫森参数放大器(JPA)首次在微波腔实验中使用，并使用了稀释制冷机。有了这个奖项，伯克利和科罗拉多州计划进行两项研发：(I)伯克利分校将致力于通过将薄膜超导体的多层结构融入到腔设计中来提高腔Q，并探索光子带隙(PBG)结构作为用于更高频率操作的实用谐振器；以及(Ii)科罗拉多/JILA将专注于将放大器噪声降低到标准量子极限(SQL)以下，最初是通过集成基于JPA的压缩真空态接收器。这将是继GEO/LIGO重力波干涉仪之后，压缩态接收器的第二次应用。稍后，将开发和部署基于腔内超导量子比特的光子探测器系统。预计的技术成果是(A)将搜索的质量范围扩大到12 GHz(~50微eV)，以及(B)将功率灵敏度提高一个数量级，从而接近对Dine-Fischler-Sredicki-zhitnitsky(DFSZ)轴子的灵敏度。这将极大地提高轴子搜索在最有希望的质量区域的发现潜力。

In this era of precision cosmology, measurements suggest that ordinary matter represents only a fraction of the total matter density in the Universe. The rest, whose presence we only infer gravitationally, is unknown in its nature, and is termed Cold Dark Matter, for which a particle called a light axion is a well-motivated candidate. Should axions constitute the dark matter of our Milky Way halo, they may be detected through their conversion into a narrow Radio Frequency (RF) signal in a microwave-cavity resonator permeated by a magnetic field. The experiment being performed at Yale, ADMX-HF (Axion Dark Matter eXperiment - High Frequency), was designed to serve both as an innovation test-bed to develop and transition new cavity designs and quantum-limited photon detection schemes, and as a pathfinder to take first data in the 10-100 micro-electron Volt mass range. R&D on superconducting thin-films, and squeezed-state and single-photon detection in quantum electronics will produce unanticipated spin-offs. ADMX-HF has proven to be a great attractor for young talent. This award can be expected to extend this record. In addition, it is planned to establish a permanent exhibit on dark-sector science at the Chabot Space and Science Center, or the Oakland Museum of California, utilizing prototypes and artifacts from many of the historic dark matter, dark energy and cosmic microwave background experiments.UC Berkeley and U. Colorado/JILA are assisting Yale by taking the lead on cavity and amplifier development, respectively. The three universities have successfully delivered on ADMX-HF, which recently performed its first data run. This represented the inaugural use of Josephson Parametric Amplifiers (JPAs) in the microwave cavity experiment, and operation with a dilution refrigerator. With this award, Berkeley and Colorado plan two lines of R&D: (i) Berkeley will pursue boosting the cavity Q by incorporating multilayer structures of thin-film superconductors into the cavity design, as well as exploring Photonic Band Gap (PBG) structures as practical resonators for higher frequency operation; and (ii) Colorado/JILA will focus on reducing amplifier noise below the Standard Quantum Limit (SQL), initially by incorporating a JPA-based squeezed-vacuum state receiver. This would be only the second application of a squeezed-state receiver, beside the GEO/LIGO gravity wave interferometers. Later, photon detector systems based on superconducting qubits inside of a cavity will be developed and deployed. Technical deliverables anticipated are to (a) extend the mass range of the search to 12 GHz (~50 micro-eV), and (b) deliver an improvement in power sensitivity by an order of magnitude, and thus approach sensitivity to Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) axions. This will dramatically improve the discovery potential of the axion search in the most promising mass region.