Korsch Alexander Rolf, Fiaschi Niccolò, Gröblacher Simon
Department of Physics, Fudan University, Shanghai 200433, People's Republic of China.
Department of Physics, School of Science, Westlake University, Hangzhou 310030, People's Republic of China.
Rev Sci Instrum. 2025 Aug 1;96(8). doi: 10.1063/5.0249931.
Superfluid helium is a prototypical quantum liquid. As such, it has been a prominent platform for the study of quantum many body physics. More recently, the outstanding mechanical and optical properties of superfluid helium, such as low mechanical dissipation and low optical absorption, have positioned superfluid helium as a promising material platform in applications ranging from dark matter and gravitational wave detection to quantum computation. However, experiments with superfluid helium incur a high barrier to entry, as they require the incorporation of complex optical and electrical setups within a hermetically sealed cryogenic chamber to confine the superfluid. Here, we report on the design and construction of a helium chamber setup for operation inside a dilution refrigerator at millikelvin temperatures, featuring electrical and optical fiber access. By incorporating an automated gas handling system, we can precisely control the amount of helium gas inserted into the chamber, rendering our setup particularly promising for experiments with superfluid helium thin films, such as superfluid thin film optomechanics. Using silicon nanophotonic resonators, we demonstrate precise control and in situ tuning of the thickness of a superfluid helium film on the sub-nanometer level. By making use of the exceptional tunability of the superfluid film thickness, we demonstrate optomechanically induced phonon lasing of phononic crystal cavity third sound modes in the superfluid film and show that the lasing threshold crucially depends on the film thickness. The large internal volume of our chamber (Vchamber ≈ 1 l) is adaptable for the integration of various optical and electrical measurement and control techniques. Therefore, our setup provides a versatile platform for a variety of experiments in fundamental and applied superfluid helium research.
超流氦是一种典型的量子液体。因此，它一直是研究量子多体物理的重要平台。最近，超流氦出色的机械和光学特性，如低机械损耗和低光吸收，使其成为从暗物质和引力波探测到量子计算等一系列应用中颇具前景的材料平台。然而，超流氦实验面临着较高的进入门槛，因为它们需要在密封的低温腔室内集成复杂的光学和电气装置来限制超流体。在此，我们报告了一种用于在毫开尔文温度下在稀释制冷机内运行的氦腔装置的设计与构建，该装置具有电气和光纤接入功能。通过引入自动化气体处理系统，我们能够精确控制注入腔室的氦气量，这使得我们的装置对于超流氦薄膜实验，如超流薄膜光力学实验，特别有前景。利用硅纳米光子谐振器，我们展示了在亚纳米水平上对超流氦膜厚度的精确控制和原位调谐。通过利用超流膜厚度的卓越可调性，我们展示了超流膜中声子晶体腔第三声模式的光机械诱导声子激光，并表明激光阈值关键取决于膜厚度。我们腔室的大内部体积（Vchamber ≈ 1升）适用于集成各种光学和电气测量与控制技术。因此，我们的装置为基础和应用超流氦研究中的各种实验提供了一个通用平台。
