Quantum Gates for Propagating Microwave Photons

Roope Kokkoniemi, Tuomas Ollikainen, Russell Lake, Sakari Saarenpää, Kuan Tan, Janne Kokkala, Ceren B. Dağ, Joonas Govenius, Mikko Möttönen

Research output: Contribution to journalArticleScientific


We report a generic scheme to implement transmission-type quantum gates for propagating microwave photons, based on a sequence of lumped-element components on transmission lines. By choosing three equidistant superconducting quantum interference devices (SQUIDs) as the components on a single transmission line, we experimentally implement a magnetic-flux-tunable phase shifter and demonstrate that it produces a broad range of phase shifts and full transmission within the experimental uncertainty. Together with previously demonstrated beam splitters, these phase shifters can be utilized to implement arbitrary single-qubit gates. Furthermore, we theoretically show that replacing the SQUIDs by superconducting qubits, the phase shifter can be made strongly nonlinear, thus introducing deterministic photon--photon interactions. These results critically complement the previous demonstrations of on-demand single-photon sources and detectors, and hence pave the way for an all-microwave quantum computer based on propagating photons.
Original languageEnglish
Early online date7 Mar 2017
Publication statusE-pub ahead of print - 7 Mar 2017
MoE publication typeB1 Article in a scientific magazine

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