Collaborative Research: ADMX-HF Extreme Axion Experiment

在这个精确宇宙学的时代，测量表明，普通物质只代表宇宙中总物质密度的一小部分。其余的，我们只能通过引力来推断它们的存在，其性质是未知的，被称为冷暗物质，一种被称为轻轴子的粒子是一个很好的候选者。如果轴子构成我们银河系晕的暗物质，它们可以通过在磁场渗透的微波腔谐振器中将其转换为窄射频（RF）信号来检测。在耶鲁大学进行的实验ADMX-HF（Axion Dark Matter eXperiment - High Frequency）旨在作为一个创新的测试平台，以开发和转换新的腔体设计和量子限制光子探测方案，并作为一个探路者，在10-100微电子伏特质量范围内获取第一批数据。超导薄膜的研发，量子电子学中的压缩态和单光子探测将产生意想不到的副产品。ADMX-HF已被证明是吸引年轻人才的绝佳场所。该奖项有望延续这一纪录。此外，计划在Chabot空间和科学中心或加州奥克兰博物馆建立一个关于暗区科学的永久展览，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。科罗拉多/JILA正在协助耶鲁大学分别在腔和放大器的开发方面发挥主导作用。这三所大学已经成功交付了ADMX-HF，最近进行了首次数据运行。这代表了约瑟夫森参量放大器（JPA）在微波谐振腔实验中的首次使用，以及稀释制冷机的操作。有了这个奖项，伯克利和科罗拉多计划两条线的&研发：（i）伯克利将通过将薄膜超导体的多层结构纳入腔体设计，以及探索光子带隙（PBG）结构作为更高频率操作的实用谐振器来提高腔体Q;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，最初通过结合基于JPA的挤压真空状态接收器。这将是除了GEO/LIGO重力波干涉仪之外，压缩态接收器的第二个应用。之后，将开发和部署基于腔内超导量子位的光子探测器系统。预期的技术交付成果是（a）将搜索的质量范围扩展到12 GHz（~50微电子伏特），以及（B）将功率灵敏度提高一个数量级，从而接近Dine-Fischler-Srednicki-Zhitnitsky（DFSZ）轴子的灵敏度。这将极大地提高在最有希望的质量区域中搜索轴子的发现潜力。

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.