Mechanically tunable nanophotonic cavities for scalable quantum network nodes

Ziel

This project aims to establish a novel nanophotonic platform that enables scalable quantum network nodes based on mechanically tunable photonic crystal (PhC) cavities coupled to trapped cold atoms. Future quantum computers will require modular architectures, where multiple atomic processors are linked via photonic channels at telecom wavelengths. PhC cavities are promising atom–photon interfaces, yet fabrication-induced disorder prevents large-scale deterministic resonance with atomic transitions, while existing thermal tuning techniques are limited in range, stability, and scalability.
We propose a new approach using electromechanical “zipper” PhC cavities, in which the optical resonance can be tuned over a large range by controlling the separation between parallel nanobeams with applied voltages. This mechanism offers an order-of-magnitude improvement in tuning range compared to thermal methods, while providing stable, reproducible, and fast electrical control compatible with simultaneous operation of many devices. Integrated fibre arrays will enable multiplexed readout of multiple cavities, paving the way for chip-scale, fibre-coupled quantum interfaces. On this platform, we will generate time-bin entanglement between atomic qubits and emitted telecom photons, and demonstrate heralded entanglement between two distant atoms. This will constitute the first realization of long-distance atom–atom entanglement mediated by PhC cavities.
Beyond its immediate impact on neutral atom quantum computing, the project will open the toolbox of on-chip nanophotonics to atomic quantum systems, advancing quantum networking and engineered many-body physics. The researcher Alexander Korsch is in a unique position to realise this project given his background in nanophotonics, optomechanics, and nanofabrication, which matches perfectly with the cold atom expertise of the host group of Prof. Hannes Bernien at the Austrian Academy of Sciences.