Temporal-Mode Engineering for Multiplexed Microwave Photons and Mode-Selective Absorption

Quantum communication using itinerant microwave photons between distant superconducting qubits on separate chips has been studied to realize distributed quantum computing. To enhance information capacity and fault tolerance in quantum networks, it is an effective approach to encode a larger quantity of quantum information using temporal modes of these photons, which can provide a basis for constructing a higher-dimensional orthogonal mode space, as experimentally demonstrated in the optical domain [1]. In recent years, this approach has also been theoretically proposed in microwave domain [2] and experimentally investigated using the first four modes [3].



In this work, we generate single microwave photons in multiple (up to eight) orthogonal temporal modes propagating along a waveguide through the photon-shaping techniques with a fixed frequency transmon qubit [4]. We further demonstrate mode-selective absorption across these orthogonal modes via the time-reversed process of emission. Finally, we compare the experimental results with theoretical simulations and discuss the practical limits on the number of accessible modes and the optimal set of temporal modes for multiplexed quantum communication.



[1] B. Brecht et al., Phys. Rev. A 90, 030302 (2014).

[2] G. F. Peñas et al., Phys. Rev. Res. 6,, 033294 (2024).

[3] K. Sunada et al., 2025 APS March meeting, M53.00012 (2025).

[4] T. Miyamura et al., PRX Quantum 6, 020347 (2025).