Brillouin systems operating in the quantum regime have recently been identified as a valuable tool for quantum information technologies and fundamental science. However, reaching the quantum regime is extraordinarily challenging, owing to the stringent requirements of combining low thermal occupation with low optical and mechanical dissipation, and large coherent phonon-photon interactions. Here, we propose an on-chip liquid based Brillouin system that is predicted to exhibit ultra-high coherent phonon-photon coupling with exceptionally low acoustic dissipation. The system is comprised of a silicon-based "slot" waveguide filled with superfluid helium. This type of waveguide supports optical and acoustical traveling waves, strongly confining both fields into a subwavelength-scale mode volume. It serves as the foundation of an on-chip traveling wave Brillouin resonator with a single photon optomechanical coupling rate exceeding $240$kHz. Such devices may enable applications ranging from ultra-sensitive superfluid-based gyroscopes, to non-reciprocal optical circuits. Furthermore, this platform opens up new possibilities to explore quantum fluid dynamics in a strongly interacting condensate.
Brillouin-Mandelstam Scattering-based Cooling of Traveling Acoustic Waves from Cryogenic Temperatures
Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；Friedrich-Alexander Universität Erlangen-Nürnberg（埃尔朗根-纽伦堡大学）；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；Institut des Sciences Chimiques de Rennes（雷恩化学科学研究所）；University of Rennes（雷恩大学）
Optical coprocessor based on spontaneous Brillouin scattering
Moscow Institute of Physics and Technology（莫斯科物理技术学院）；Institute for Theoretical and Applied Electrodynamics（理论与应用电动力学研究所）；Dukhov Research Institute of Automatics (VNIIA)（杜霍夫自动技术研究院）
A solid-state quantum memory based on a continuous optoacoustic system
Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；Institute of Photonics, Leibniz University Hannover（汉诺威莱布尼茨大学光子学研究所）；TU Darmstadt, Institute for Applied Physics（达姆施塔特工业大学应用物理研究所）；Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg（埃尔朗根-纽伦堡弗里德里希-阿历山大大学物理系）
Optomechanical disk resonator in the quantum ground state of motion
Université Paris Cité, CNRS, Matériaux et Phénomènes Quantiques（巴黎西岱大学，法国国家科学研究中心，物质与量子现象研究所）；Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies（巴黎萨克雷大学，法国国家科学研究中心，纳米科学与工程中心）
Investigating the performance of RPM JTWPAs by optimizing LC-resonator elements
National Institute of Advanced Industrial Science and Technology (AIST)（先进产业科学技术研究所）；Global Research and Development Center for Business by Quantum-AI technology (G-QuAT)（量子AI技术商业全球研发中心）
Quantum-limited traveling-wave parametric amplifier based on DUV-defined planar structures
Swiss Federal Institute of Technology Lausanne (EPFL)（洛桑联邦理工学院）；Institute of Electrical and Micro Engineering (IEM)（电气与微电子工程研究所）；Center for Quantum Science and Engineering（量子科学与工程中心）；WithWave Co., Ltd.（WithWave有限公司）
