Photon Emission and Quantum State Transfer between Distant Transmons using Orthogonal Temporal Modes

The strong interaction between light and matter allows for the encoding of stationary quantum information into itinerant photons, a central requirement for quantum networking. The ability to tune this interaction can be used to shape the envelope of the photon wavepackets into a symmetric temporal mode, enabling quantum state transfer between devices at meter-scale distances. Here, with the aim of exploring the use of alternative mode functions and their applications, we realize the generation of photons in an orthogonal set of temporal modes [Peñas et al, arXiv.2403.12222] and demonstrate their selective absorption by a receiver at a distance of 30 meters, using a network of two superconducting quantum devices [Storz et al, Nature 617, 265-270 (2023)]. We first track the population of the source qubit while shaping the photon into three orthogonal modes to benchmark the fidelity of the emission process. As a direct application, we further show that, at the receiver device, we can choose to absorb or reflect the incoming photon with a high selectivity, by virtue of the mode orthogonality. This experimental capability extends the quantum communication toolbox, with potential uses ranging from multi-rail photonic encodings, multiplexing and all-photonic quantum computing to the tomography and correction of wavepacket distortions in closed channels for quantum communication.