Microwave Quantum Link between Superconducting Circuits Housed in Spatially Separated Cryogenic Systems
Paul Magnard, Simon Storz, Philipp Kurpiers, Josua Schär, Fabian Marxer, Janis Lütolf, T. Walter, Jean-Claude Besse, Mihai Gabureac, Kevin Reuer, Abdulkadir Akın, Baptiste Royer, Alexandre Blais, Andreas Wallraff
Abstract
Superconducting circuits are a strong contender for realizing quantum computing systems and are also successfully used to study quantum optics and hybrid quantum systems. However, their cryogenic operation temperatures and the current lack of coherence-preserving microwave-to-optical conversion solutions have hindered the realization of superconducting quantum networks spanning different cryogenic systems or larger distances. Here, we report the successful operation of a cryogenic waveguide coherently linking transmon qubits located in two dilution refrigerators separated by a physical distance of five meters. We transfer qubit states and generate entanglement on demand with average transfer and target state fidelities of 85.8% and 79.5%, respectively, between the two nodes of this elementary network. Cryogenic microwave links provide an opportunity to scale up systems for quantum computing and create local area superconducting quantum communication networks over length scales of at least tens of meters.