A distributed quantum computing system requires a quantum communication channel between spatially separated processing units. In superconducting circuits, such a channel can be realized by using propagating microwave photons to encode and transfer quantum information between an emitter and a receiver node. Here we experimentally demonstrate a superconducting circuit that deterministically transfers the state of a data qubit into a propagating microwave mode, with a process fidelity of 94.5%. We use a time-varying parametric drive to shape the temporal profile of the propagating mode to be time-symmetric and with constant phase, so that reabsorption by the receiving processor can be implemented as a time-reversed version of the emission. We demonstrate a self-calibrating routine to correct for time-dependent shifts of the emitted frequencies due to the modulation of the parametric drive. Our work provides a reliable method to implement high-fidelity quantum state transfer and remote entanglement operations in a distributed quantum computing network.
@article{arxiv.2303.02899,
title = {Deterministic generation of shaped single microwave photons using a parametrically driven coupler},
author = {Jiaying Yang and Axel Eriksson and Mohammed Ali Aamir and Ingrid Strandberg and Claudia Castillo Moreno and Daniel Perez Lozano and Per Persson and Simone Gasparinetti},
journal= {arXiv preprint arXiv:2303.02899},
year = {2023}
}