Abstract
Deterministic photon-photon gates enable the controlled generation of entanglement between mobile carriers of quantum information. Such gates have thus far been exclusively realized in the optical domain and by relying on postselection. Here, we present a nonpostselected, deterministic, photon-photon gate in the microwave frequency range realized using superconducting circuits. We emit photonic qubits from a source chip and route those qubits to a gate chip with which we realize a universal gate set by combining controlled absorption and reemission with single-qubit gates and qubit-photon controlled-phase gates. We measure quantum process fidelities of 75% for single- and of 57% for two-qubit gates, limited mainly by radiation loss and decoherence. This universal gate set has a wide range of potential applications in superconducting quantum networks.7 MoreReceived 15 June 2021Accepted 10 November 2021Corrected 16 February 2022DOI:https://doi.org/10.1103/PhysRevX.12.011008Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasQuantum gatesQuantum networksQuantum optics with artificial atomsQuantum states of lightSingle photon sourcesSuperconducting quantum opticsPhysical SystemsSuperconducting qubitsTechniquesMicrowave techniquesQuantum InformationCondensed Matter, Materials & Applied PhysicsAtomic, Molecular & Optical
Highlights
We measure quantum process fidelities of 75% for single- and of 57% for two-qubit gates, limited mainly by radiation loss and decoherence. This universal gate set has a wide range of potential applications in superconducting quantum networks
Photons are ideal carriers of quantum information, because they do not interact with each other when propagating through linear media
Photon-photon gates enable, for example, the processing of quantum information while photonic qubits are traveling between local quantum processing units, potentially allowing for simpler network structures [7]
Summary
To optimize the absorption efficiency, we generate photonic fields with a near time-symmetric temporal profile by controlling the time evolution of the tunable, effective coupling rate J between the qubit and its converter mode, following the protocol detailed in Refs. [38,39,40]. To optimize the absorption efficiency, we generate photonic fields with a near time-symmetric temporal profile by controlling the time evolution of the tunable, effective coupling rate J between the qubit and its converter mode, following the protocol detailed in Refs. To emit photonic fields with the temporal envelope ξðtÞ, the effective coupling rate is controlled according to [38]. To controllably absorb photonic fields with an envelope ξðtÞ, we apply a time-reversed coupling Jð−tÞ. Since we emit photonic qubits from the source qubit S and absorb them at the gate qubit G, Γ is limited by the smaller coupling rate of the two converter modes Γ ≤ min 1⁄2κS; κG. The effective photon bandwidth Γ is limited by the coupling rate κS of the source qubit converter mode
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
