Quantum Optical Physics with Neutral-Atom Waveguide-QED

Project Information

NanoAtom

Grant agreement ID: 101097755

DOI

10.3030/101097755

EC signature date 4 October 2023

Start date 1 October 2023

End date 30 September 2028

Funded under

• European Research Council (ERC)

Total cost

€ 2 498 750,00

EU contribution

€ 2 498 750,00

Coordinated by

SORBONNE UNIVERSITE
France

Periodic Reporting for period 1 - NanoAtom (Quantum Optical Physics with Neutral-Atom Waveguide-QED)

Reporting period: 2023-10-01 to 2026-03-31

Summary of the context and overall objectives of the project

The interaction between cold atoms and nanophotonic devices offers a powerful way to control how light and matter interact – essential for advancing quantum technologies. These systems can create strong connections between atoms and light, allow atoms to interact over long distances and produce unique effects that classical methods cannot achieve. However, while this area has been extensively studied theoretically, experimental progress has lagged behind. The ERC-funded NanoAtom project will work to develop a state-of-the-art platform where cold atoms are precisely trapped near photonic-crystal waveguides. Researchers will leverage specific materials, advanced waveguide designs and novel atom delivery techniques to develop the full potential of this emerging field.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The NanoAtom project aims at harnessing the new paradigm offered by the coupling of cold atoms to nanoscopic photonic-crystal (PhC) waveguides. Tailored dispersion relations offer regimes for light-matter interaction beyond conventional settings. Over the reporting period, a dedicated team has been assembled, and progresses along the two main experimental building blocks were obtained: a dedicated cold-atom setup has been upgraded to enable versatile single-atom tweezers and atom transport, including via spatially-structured beams, while structure design and nanofabrication has enabled to obtained a variety of PhC waveguides that can now be integrated to the main setup.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

To facilitate the robustness and scalability of the waveguides, NanoAtom relies on a relatively new material for the field, Gallium Indium Phosphide (GaInP). This material, which is grown and routinely processed at C2N, provides a strong advantage relative to the existing SiN-based devices. The project has developed so-called half-W1 waveguides, characterized by extremely flat dispersion relations. By adding inverse design, injection and mode matching are now optimized. The structures are succesfuly fabricated and being integrated in the atomic platform.

A second result of the reporting period is the demonstration of single-atom trapping in higher-order spatial modes and in superpositions of higher-order Laguerre-Gaussian modes. Such tweezers provide improved localization with narrowed axial intensity distribution and potentially enable to suppress interference fringes from reflection, thanks to a rapid change of the Gouy phase of this superposition. This technique can potentially be a game changer to integrate atom transport and nanostructures, with applications to other systems.