2025-07-23 –, Main Room 6
Waveguide quantum electrodynamics (WQED) describes how propagating photons interact with localized quantum systems. Their multimode nature leads to entanglement and feedback effects, making analytical solutions impractical beyond simple cases. WaveguideQED.jl is a Julia package that efficiently simulates WQED using a time-bin discretization approach, enabling intuitive modeling of traveling photon states to treat photon scattering, non-Markovian feedback, and multi-photon interactions.
WaveguideQED.jl leverages Julia’s multiple dispatch and lazy evaluation of operator products to efficiently handle time-dependent quantum mechanical operators, significantly improving computational performance. Unlike traditional methods that rely on sparse matrices, this framework employs matrix-free operator applications through non-allocating kernel functions, exploiting the structured nature of time-dependent waveguide operators. This enables high-performance simulation of up to two propagating photons, facilitating studies of non-Markovian feedback and multiphoton entanglement. By seamlessly integrating with QuantumOptics.jl, the package provides a flexible interface for researchers familiar with other quantum optics toolkits, such as QuTiP in Python and Quantum Toolbox in Matlab. This flexible interface and generality allow users to construct arbitrary local quantum systems, making it possible to study complex interactions.
In the talk, the framework’s capabilities will be demonstrated through examples, including photon scattering calculations, quantum feedback simulations, and multi-photon dynamics in waveguides. The use of lazy operator application to efficiently implement time-dependent waveguide operators, significantly reducing memory overhead and computational complexity, will also be introduced in the talk and highlighted through benchmarks.
WaveguideQED.jl provides an efficient and flexible framework for studying quantum systems coupled to waveguides. Its combination of performance, conceptual simplicity, and modular design enables simulations of a broad range of quantum optical phenomena. Future work will focus on exploring losses in systems through Monte Carlo trajectories and potentially increasing the maximum number of propagating photons.
