Speaker
Description
Optical control of quantum matter – from trapped atoms and ions to quantum dots and defects, is foundational for quantum information science and technology. Development of integrated photonics opens the possibility for realization of scalable circuits with complex functionalities, advancing both science and technology frontiers and enabling real-world applications in quantum sensing and precision measurements. Here, we present our work on scalable, robust and multifunctional nanophotonic interfaces to trap neutral atoms or address trapped ions. Our nanophotonic platform, combining metasurfaces with integrated photonics, replaces bulk optical elements and promises increased complexity and functionality in a batch-fabricated optical microsystem ultimately fully replacing the laboratory optical table to enable cold atom clocks and quantum computers.
Metasurfaces – ultrathin, planar arrays of subwavelength resonators – engineer the local electromagnetic response to provide precise, spatially-varying control over phase and amplitude within a single lithographic layer. By tailoring resonator geometry across the aperture, complex wavefront transformations such as Gaussian-to-top-hat beam shaping, tight focusing, and arbitrary polarization conversion can be realized in components fully compatible with CMOS fabrication processes. Metasurface optics can additionally be multi-functional within a single layer.
Trapped-ion quantum computing faces a scaling bottleneck: delivering tightly focused, individually addressed beams to ions in extended linear or 2D arrays via free-space optics becomes increasingly untenable as qubit counts grow toward fault-tolerant thresholds. Photonic integrated circuits (PICs) offer a natural solution, routing light to individual sites via on-chip waveguides, with metasurface elements providing final-stage beam shaping, polarization control, and NA-matched focusing directly above the trap electrodes. Metasurface optics can also provide complex beam-conditioning in a compact, robust form factor before final beam delivery to the ion trap. This approach opens the possibility of integrating multi-wavelength functionality – simultaneously handling Doppler cooling, qubit manipulation, and state detection wavelengths – within a single compact layer. We also use metasurfaces when designing fluorescence collection optics to remove the need for large, high-NA objectives. An important area of research is ensuring that metasurface optics and integrated photonics are compatible with ion trap material platforms and electrode trap fabrication techniques.
In atomic clock architectures, metasurface optics offer a direct route to replacing bulk telescopes, waveplates, and beam-shaping elements required for laser cooling and state preparation. Integrated with on-chip photonic waveguides at clock-relevant wavelengths, metasurface outcouplers and beam-forming elements can deliver structured, polarization-controlled fields needed for Zeeman state preparation and narrow-line cooling transitions, collapsing multiple optical functions into a single planar element and dramatically reducing system volume and alignment sensitivity.
Designing metasurfaces that simultaneously satisfy multi-objective constraints – intensity uniformity, low wavefront aberration, polarization purity, and multi-wavelength operation – is a non-trivial inverse design problem. We apply reinforcement learning (RL) to navigate this high-dimensional nanostructure parameter space, demonstrated in designing a metasurface for beam shaping within a miniaturized magneto-optical trap (MOT). The RL framework naturally accommodates discrete, non-differentiable design choices inherent to fabrication-constrained geometries while allowing simultaneous optimization across competing performance metrics relevant to efficient atomic capture and cooling.
References: http://arxiv.org/abs/2411.06026
arXiv:2310.13419
https://www.nature.com/articles/s44310-025-00102-4
https://www.nature.com/articles/s41377-025-02138-9
| Academic level | PhD student |
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