Semiconductor-on-diamond cavities for spin optomechanics.

Optomechanical cavities are powerful tools for classical and quantum information processing that can be realized using nanophotonic structures that co-localize optical and mechanical resonances. Typically, phononic localization requires suspended devices that forbid vertical leakage of mechanical energy. Achieving this in some promising quantum photonic materials such as diamond requires non-standard nanofabrication techniques, while hindering integration with other components and exacerbating heating related challenges. As an alternative, we have developed a semiconductor-on-diamond platform that co-localizes phononic and photonic modes without requiring undercutting. We have designed an optomechanical crystal cavity that combines high optomechanical coupling with low dissipation, and we show that this platform will enable optomechanical coupling to spin qubits in the diamond substrate. These properties demonstrate the promise of this platform for realizing quantum information processing devices based on spin, phonon, and photon interactions.

Hexagonal Boron Nitride Cavity Optomechanics.

Hexagonal boron nitride (hBN) is an emerging layered material that plays a key role in a variety of two-dimensional devices, and has potential applications in nanophotonics and nanomechanics. Here, we demonstrate the first cavity optomechanical system incorporating hBN. Nanomechanical resonators consisting of hBN beams with average dimensions of 12 µm × 1.2 µm × 28 nm and minimum predicted thickness of 8 nm were fabricated using electron beam induced etching and positioned in the optical near-field of silicon microdisk cavities. Of the multiple devices studied here a maximum 0.16 pm/[Formula: see text] sensitivity to the hBN nanobeam motion is demonstrated, allowing observation of thermally driven mechanical resonances with frequencies between 1 and 23 MHz, and largest mechanical quality factor of 1100 for a 23 MHz mode, at room temperature in high vacuum. In addition, the role of air damping is studied via pressure dependent measurements. Our results constitute an important step toward realizing integrated optomechanical circuits employing hBN.