arXiv subjects

David Hambraeus

Publications and source records attributed to David Hambraeus.

4 recordsLinked to original sources

arXiv2026

Inverse-designed release-free optomechanical crystal with high photon-phonon coupling

Interactions between light and mechanics provide a powerful interface between optical and microwave-frequency signals, with applications spanning classical signal processing and quantum technologies. High-performance optomechanical devices require both strong photon-phonon coupling and tolerance to parasitic laser heating. Release-free optomechanical crystals provide improved thermal anchoring compared to suspended nanobeams, but have so far exhibited weaker vacuum optomechanical coupling rates, leaving a trade-off between coupling strength and thermal robustness. Here, we largely close this gap: we design and experimentally demonstrate a release-free silicon optomechanical crystal with a record vacuum optomechanical coupling rate of about $g_\text{OM} / (2 \pi) = 800$ kHz, comparable to suspended state-of-the-art devices. The resulting optomechanical scattering rate $\Gamma_\text{OM}/(2 \pi)= 1.1$ kHz is nearly twice that of previous release-free implementations. This performance is achieved by combining physics-guided human intuition with a multiphysics inverse-design algorithm introduced here for resonant optomechanical structures. Beyond the specific device demonstrated, the inverse-design framework is applicable to co-optimizing optical and mechanical resonances and eigenmodes more broadly. These results strengthen release-free optomechanical crystals as a platform for fast, low-noise classical and quantum optomechanics.

physics.optics↗

arXiv2025

Optomechanical crystal in light-resilient quantum ground state

Interaction between light and high-frequency sound is a key area in integrated photonics, quantum and nonlinear optics, and quantum science. However, typical suspended optomechanical structures suffer from poor thermal anchoring, making them susceptible to thermal noise arising from optical absorption. Here, we demonstrate a chip-scale, release-free silicon optomechanical crystal cavity operating cryogenically with improved resilience to laser light. Relative to a suspended design, we observe 18 dB suppression of the thermo-optic effect, and the device also sustains near-unity phonon occupation at 35 dB higher intracavity optical energy in continuous-wave operation. Non-exponential decay dynamics from an as yet unidentified thermal process limit transfer of this performance to pulsed operation. Resolving this channel would open a clear path to near-term quantum protocols, such as microwave-to-optical quantum transduction. More broadly, the release-free architecture offers a novel platform for studying thermal noise dynamics with results relevant across silicon optomechanical platforms.

quant-ph↗

arXiv2024

Design of a release-free piezo-optomechanical quantum transducer

Quantum transduction between microwave and optical photons could combine the long-range connectivity provided by optical photons with the deterministic quantum operations of superconducting microwave qubits. A promising approach to quantum microwave-optics transduction uses an intermediary mechanical mode along with piezo-optomechanical interactions. So far, such transducers have been released from their underlying substrate to confine mechanical fields -- preventing proper thermal anchoring and creating a noise-efficiency trade-off resulting from optical absorption. Here, we introduce a release-free, i.e. non-suspended, piezo-optomechanical transducer intended to circumvent this noise-efficiency trade-off. We propose and design a silicon-on-sapphire (SOS) release-free transducer with appealing piezo- and optomechanical performance. Our proposal integrates release-free lithium niobate electromechanical crystals with silicon optomechanical crystals on a sapphire substrate meant to improve thermal anchoring along with microwave and mechanical coherence. It leverages high-wavevector mechanical modes firmly guided on the chip surface. Beyond quantum science and engineering, the proposed platform and design principles are attractive for low-power acousto-optic systems in integrated photonics.

quant-ph↗

arXiv2022

A chip-based superconducting magnetic trap for levitating superconducting microparticles

Magnetically-levitated superconducting microparticles have been recently proposed as a promising platform for performing quantum experiments with particles in the picogram regime. Here, we demonstrate the superconducting technology to achieve chip-based magnetic levitation of superconducting microparticles. We simulate and fabricate a chip-based magnetic trap capable of levitating superconducting particles with diameters from 0.5$\,μ$m to 200$\,μ$m. The trap consists of two stacked silicon chips, each patterned with a planar multi-winding superconducting coil made of niobium. The two coils generate a magnetic field resembling a quadrupole near the trap center, in which we demonstrate trapping of a spherical 50\,$μ$m diameter SnPb microparticle at temperatures of 4\,K and 40\,mK.

cond-mat.supr-con↗