Joey Frey, Quantum Technology

Abstract: 
Nanomechanical resonators based on piezoelectric crystals have enabled novel application in quantum technology. One such application is quantum transduction between microwave and optical domains, leveraging GHz piezo-mechanical modes for strong coupling. Mechanical resonators are typically suspended to reduce radiation loss, but this approach limits thermal anchoring, resulting in increased noise. Our recent proposal, reintroduces the substrate in a release-free quantum transduction scheme to improve cooling. While our group has previously demonstrated release-free optomechanical devices, here we present a release-free lithium niobate on silicon (LNOS) electromechanical crystal (EMC) with strong coupling. The EMC is fabricated using a micro-transfer printing process to preserve the silicon substrate surface and allow further material combinations in the future. The design is optimized in simulation, and fabrication-induced loss channels are analyzed. Fabricated devices are characterized via S11 reflection measurement at room temperature confirming a coupling rates of 56 kHz to a 50 Ohms feedline, in good agreement with simulations. Furthermore, tunable high-impedance microwave resonators are developed for further characterization in a cryogenic environment. The microwave device design and fabrication are optimized to achieve internal quality factors exceeding 100, 000 across the full tuning range of 350 MHz. Finally, we present early work on integrating EMCs with microwave resonators in a single device.

Discussion leader: Per Delsing, Full Professor, Quantum Technology

Main supervisor: Raphaël Van Laer,  Assistant Professor, Quantum Technology
Examiner: Magnus Karlsson, Professor, Photonics
Assistant supervisors:
Witlef Wieczorek, Professor, Quantum Technology
Nils J. Engelsen, Assistant Professor, Quantum Technology