Advancements in Optomechanics: from Fundamental Physics to Quantum Sensors

Dear Colleagues,

Optomechanics is nowadays a well-established field of research, studying the interaction between light and mechanical oscillators. The raising interest towards optomechanics is due to its capability to address a wide range of problems: providing a benchmark for fundamental tests of the quantum theory of macroscopic objects; applications in quantum technology, like quantum interfaces for quantum information networks; highly sensitive displacement and force measurements, leading to quantum sensing and to quantum signal transduction in hybrid interfaces. The advancements in the field led to the first ever detection of gravitational waves and set the best to date experimental upper bound of quantum gravity models based on generalized uncertainty principles. Moreover, optomechanical system can be used as quantum sensors, where phase-sensitive schemes offer unprecedented sensitivities for the measurement of tiny signals, outperforming classical schemes.

This special issue aims to collect the latest progress in the field of optomechanics, sweeping from cavity optomechanics to optomechanical crystals, levitated optomechanics, multimode optomechanical systems, hybrid electromechanical devices, electro-optomechanical devices and optomechanical transduction.

Dr. Paolo Piergentili
Dr. Nicola Malossi
Guest Editors

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• cavity optomechanics
• levitated optomechanical systems
• electro-optomechanical systems
• quantum sensors

Title: Strain-Engineered SiN Nanomembranes for Room-Temperature Quantum Optomechanics
Authors: Authors: Serra E.(1,2,3), Borrielli A. (2,1), Morana B. (3), Sarro, P.M. (3), Bonaldi M. (1,2)
Affiliation: 1)Istituto Nazionale di Fisica Nucleare (INFN), Trento Institute for Fundamental Physics and Application, 38123 Povo, Trento,Italy 2)Institute of Materials for Electronics and Magnetism, Nanoscience-Trento-FBK Division, 38123 Povo, Trento,Italy 3)Department of Microelectronics, Delft University of Technology, Feldmannweg 17, 2628 CT Delft,The Netherlands
Abstract: Tensioned dielectric nanomembranes boast mechanical and optical properties that position them at the forefront of technology platforms for optomechanical sensing devices, achieving quantum-level precision in measurement. Commonly employed experimental procedures involve coupling the vibrations of a silicon nitride (SiN) membrane resonator with the optical mode of a Fabry-Perot cavity. To approach the quantum limit effectively, these systems necessitate high optical cooperativity, achieved through enhanced membrane reflectivity, and superior mechanical coherence, quantified by mechanical loss or quality factor. In this study, we present the fabrication of a circular SiN nanomembrane aimed at mitigating edge losses while preserving the original thickness at the centre to maintain adequate reflectivity. We analyse and discuss the loss for axis-symmetric modes and demonstrate how the design can be seamlessly integrated into a microfabrication process. This integration enables the production of stepped circular SiN membranes, resulting in an enhanced Q-factor across a 2 MHz bandwidth.