Millimeter-Wave Superconducting Resonators and 2D Heterostructures for Hybrid Quantum-Mechanical Platforms

Superconducting resonators have long been the foundation of microwave quantum circuits, enabling state-of-the-art coherence and coupling to other quantum degrees of freedom. Here, we extend these concepts into the millimeter-wave regime, where shorter wavelengths allow for stronger optomechanical coupling, smaller device footprints, and potentially higher operating temperatures. We present recent results on single-layer superconducting resonators fabricated on sapphire substrates, optimized for optomechanical coupling and mode confinement. Cryogenic measurements demonstrate quality factors exceeding 10⁵, validating the potential of millimeter-wave operation for compact, high-coherence circuit architectures. Building on this platform, we are developing 2D-material-based heterostructures such as niobium diselenide (NbSe₂) and hexagonal boron nitride (hBN), whose low mass and high mechanical frequencies are expected to enhance coupling strength and displacement sensitivity. Together, these efforts advance the realization of hybrid superconducting–mechanical systems that bridge microwave quantum technologies with emerging mechanical platforms in the quantum regime.