Photonics Breakthroughs 2024: Scalable Quantum Computing on a Single Photon Using Spatial Modes

High-dimensional quantum gates based on spatial mode of photons hold promise for advancing quantum computation. We demonstrate high-fidelity spatial mode quantum gates with fidelities up to 99.6%, using diffractive neural networks (DNNs). These gates are experimentally implemented with programmable phase layers in a compact and scalable device, enabling demonstrations like the Deutsch algorithm. Our approach showcases high reliability, adaptability, and potential for integration in quantum computation.