(i) Optomechanical devices with novel 2D materials
The route towards optomechanics exploiting the unique properties of 2D materials has been explored on many fronts in OMT.
In the optical domain, UKON has achieved promising results in combining 2D membranes with Fabry-Perot microcavities. Through strong collaboration within the consortium, freestanding 2D membranes were transferred onto samples suitable for insertion into the high-finesse optical cavities. A second approach in the optical domain pursued by UGENT is the integration of 2D materials into on-chip photonic cavities. Here, demonstration of transfer onto compatible chips was achieved through knowledge transfer inside the consortium. In the microwave domain, a critical study was performed by TU Delft regarding the benefits and feasibility of superconducting 2D materials for microwave optomechanics. The project direction was adjusted, to ensure the activities keep the consortium at the forefront of microwave optomechanics. A second approach to microwave optomechanics with suspended graphene was also pursued by AALTO, including important advances in developing the challenging fabrication, and the observation of the Josephson inductance of graphene at microwave frequencies.
(ii) Dissipative optomechanical systems for low noise amplification and novel non-reciprocal microwave components
Striving to improve the dissipation properties and coherence of nanomechanical oscillators, EPFL has successfully developed and characterized NEMS systems based on high stress materials. A radically different mechanical system was studied at UNIVIE, which succeeded in the observation of near-field coupling of a levitated nanoparticle to a photonic crystal cavity.
Towards the goal of tomographic reconstruction of the quantum state of a MEMS resonator, UHAM has assembled a squeezed light source and a homodyne detection setup. Finally, in a perspective of tech transfer from fundamental research to industry, BOSCH has modelled optomechanical phase shifters. Fabrication and measurements of the active devices are underway.
(iii) Chip-scale microwave to optical conversion schemes
Towards the development of opto-electro-mechanical systems, UCPH has realized fiber-based cavities with high finesse, developed a flip-chip assembly for membrane electromechanics, and demonstrated an integrated transducer in the classical regime. UPMC explored a similar platform: an electro-mechanical system based on a phononic membrane and a superconducting cavity was fabricated and characterized. Crucial steps towards the demonstration of an optomechanical chip-scale microwave oscillator were undertaken by CNRS. Optomechanical structures were realized with piezoelectric III-V semiconductors and integrated on an optical waveguide chip. III-V semiconductors are also investigated within IBM’s research direction. Towards the achievement of quantum coherent microwave-to-optical conversion, IBM has developed a fabrication process for Gallium Phosphide (GaP) photonic devices, including optomechanical cavities, and successfully tested their performance.
(iv) Theoretical possibilities for optomechanical multi-mode structures
FAU has designed and optimized an optomechanical crystal platform that allows for topologically robust transport of phonons, with optical excitation and readout. The architecture offers a path towards multimode optomechanics, non-reciprocal phonon transport and strong coupling of co-localized modes.
