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Host: Prof. Chunxiao Liu
Venue: TDLI Meeting Room N400
Tencent meeting link: https://meeting.tencent.com/dm/118ndC4qwd4Y
Meeting ID: 521405370, no password
Abstract:
Cavity optomechanics explores the radiation-pressure coupling between light and macroscopic mechanical resonators, constituting a forefront of light–matter interaction. Benefiting from rapid advances in semiconductor micro- and nano-fabrication, a rich variety of optomechanical devices has emerged, enabling diverse studies now routinely exploited for precision sensing, tests of quantum mechanics, and hybrid quantum-information processing. Yet, among the profusion of designs, only a handful can be stably operated deep in the quantum regime.
This talk focuses on superconducting optomechanical circuits. I will report our recent progress in integrating high-Q silicon-nitride/silicon-carbide membrane resonators with microwave cavities [1,2]. Using cavity sideband cooling, we have prepared a macroscopic mechanical mode in its quantum ground state and performed quantum non-demolition measurements of the resonator’s quantum state[3]. On this basis we demonstrate on-demand writing, storage, and retrieval of microwave photonic states, setting a new record for the storage time of microwave photons [4,5].
Beyond linear optomechanical coupling, I will address nonlinear effects and their role in multimode frequency-comb generation. In a single cavity, two mechanical resonator platforms, we observe and study the interaction and hybridization between two distinct mechanical modes [6]. In two-cavity, one-resonator platform we show how phonon lasing drives Floquet cavity modes to produce thresholdless frequency combs [7]. Moreover, by engineering time-modulated optomechanical coupling, we implement reservoir engineering that reveals collective interference induced coherent perfect absorption and infinite group delay/advance in quantum regime.
References:
1. Yulong Liu, Qichun Liu, Shuaipeng Wang, Zhen Chen, Mika A. Sillanpää*, and Tiefu Li#, Optomechanical Anti-Lasing with Infinite Group Delay at a Phase Singularity, Physic Review Letters 127, 273603 (2021).
2. Sishi Wu, Yulong Liu‡, Qichun Liu, Shuaipeng Wang, Zhen Chen, and Tiefu Li#, Hybridized frequency combs in multimode cavity electromechanical system, Physic Review Letters 128, 153901 (2022).
3. Yulong Liu, Jingwei Zhou, Laure M. de Lépinay, and Mika A. Sillanpää#, Quantum backaction evading measurements of a silicon nitride membrane resonator, New Journal of Physics 24, 083043 (2022).
4. Yulong Liu‡, Qichun Liu, Huanying Sun, Mo Chen, Shuaipeng Wang, and Tiefu Li#, Coherent memory for microwave photons based on long-lived mechanical excitations, Nature: npj Quantum Information 9, 80 (2023).
5. Yulong Liu‡, Huanying Sun, Qichun Liu, Haihua Wu, Mika A. Sillanpää, and Tiefu Li#,Degeneracy-breaking and long-lived multimode microwave electromechanical systems enabled by cubic silicon-carbide membrane crystals, Nature Communications 16, 1207 (2025).
6. Sihan Wang, Cheng Wang, Matthijs H. J. de Jong, Laure Mercier de Lépinay, Jingwei Zhou‡, Mika A. Sillanpää, and Yulong Liu#, Pump-Threshold-Free Frequency Comb via Cavity Floquet Engineering, Nature Communications (2026). https://doi.org/10.1038/s41467-026-72320-z
Biography:
Yulong Liu pursued his direct doctoral degree at the Department of Microelectronics (now School of Integrated Circuits), Tsinghua University in 2012, and paid an academic visit to RIKEN, Japan during his study. He conducted postdoctoral research at the Finnish Quantum Technology Centre and Department of Applied Physics, Aalto University in 2017. He joined Beijing Academy of Quantum Information Sciences in 2020, currently serving as a researcher in the Quantum Computing Research Department and leader of the Quantum Interface Devices and Systems team. His research focuses on cutting-edge cavity optomechanical quantum information devices.