Deterministic Quantum State Transfer and Remote Entanglement using Microwave Photons
Paul Magnard1*, Philipp Kurpiers1*, Theo Walter1, Baptiste Royer2, Marek Pechal1, Johannes Heinsoo1, Yves Salathé1, Abdulkadir Akin1, Simon Storz1, Jean-Claude Besse1, Simone Gasparinetti1, Alexandre Blais2,3 and Andreas Wallraff1
1Department of Physics, ETH Zürich, Zürich, Switzerland.
2Institut Quantique and Départment de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada.
3Canadian Institute for Advanced Research, Toronto, Ontario, Canada.
*These authors contributed equally: P. Magnard, P. Kurpiers.
Sharing information over computer networks for private, business or science-related communication is part of our everyday lives. In the future, we may use protocols based on quantum physics to realize secure communication or to perform distributed quantum information processing exceeding the capabilities of classical computers and communication networks. Establishing a deterministic quantum channel between spatially separated nodes is a key element for these ambitious goals. In this work, we present the realization of a fully deterministic quantum communication protocol between two remote superconducting qubits fabricated on separate chips. Our implementation is based on an all-microwave cavity-assisted Raman process which entangles or transfers the qubit state of a transmon-type artificial atom with a time-symmetric itinerant single photon. By deterministically absorbing these itinerant photons at the receiving node, we transfer qubit states and generate remote entanglement on-demand with fidelities as high as 80% in a protocol duration of only 180 ns. This deterministic protocol has the potential to be used for quantum computing distributed across different nodes of a cryogenic network.