Tunable coupling engineering between superconducting resonators: from sidebands to effective gauge fields

In this work we show that a tunable coupling between microwave resonators can be engineered by means of simple Josephson junctions circuits, such as dc- and rf-SQUIDs. We show that by controlling the time dependence of the coupling it is possible to switch on and off and modulate the cross-talk, boost the interaction towards the ultrastrong regime, as well as to engineer red and blue sideband couplings, nonlinear photon hopping and classical gauge fields. We discuss how these dynamically tunable superconducting circuits enable key applications in the fields of all optical quantum computing, continuous variable quantum information and quantum simulation - all within the reach of state of the art in circuit-QED experiments.Comment: 11 pages, 4 figure

Ultrastrong coupling in two-resonator circuit QED

Under the terms of the Creative Commons Attribution license.-- et al.We report on ultrastrong coupling between a superconducting flux qubit and a resonant mode of a system comprised of two superconducting coplanar stripline resonators coupled galvanically to the qubit. With a coupling strength as high as 17.5% of the mode frequency, exceeding that of previous circuit quantum electrodynamics experiments, we observe a pronounced Bloch-Siegert shift. The spectroscopic response of our multimode system reveals a clear breakdown of the Jaynes-Cummings approximation. In contrast to earlier experiments, the high coupling strength is achieved without making use of an additional inductance provided by a Josephson junction. ©2016 American Physical SocietyThiswork is supported by the German Research Foundation through SFB 631 and FE 1564/1-1; Spanish MINECO FIS2012-36673-03-02, MAT2014-53432-C5-1-R, FIS2014- 55867-P and FIS2012-33022; CAM Research Network QUITEMAD+; UPV/EHU UFI 11/55, UPV/EHU PhD Grant, and Basque Government IT472-10; the Fondo Nacional de Desarrollo Cientifico y Tecnológico (FONDECYT, Chile) under Grant 1150653; the EU projects CCQED, PROMISCE, and SCALEQIT. We further acknowledge GEFENOL.Peer Reviewe

Tunable and switchable coupling between two superconducting resonators

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.We realize a device allowing for tunable and switchable coupling between two frequency-degenerate superconducting resonators mediated by an artificial atom. For the latter, we utilize a persistent current flux qubit. We characterize the tunable and switchable coupling in the frequency and time domains and find that the coupling between the relevant modes can be varied in a controlled way. Specifically, the coupling can be tuned by adjusting the flux through the qubit loop or by controlling the qubit population via a microwave drive. Our measurements allow us to find parameter regimes for optimal coupler performance and quantify the tunability range.This work is supported by the German Research Foundation through SFB 631, Spanish MINECO FIS2012-36673-C03-02; UPV/EHU UFI 11/55; Basque Government IT472-10; CCQED, PROMISCE, and SCALEQIT EU projects. B.P. acknowledges support from the STC Center for Integrated Quantum Materials, NSF Grant No. DMR-1231319.Peer reviewe

Tunable coupling of transmission-line microwave resonators mediated by an rf SQUID

10 pags., 5 figs.We realize tunable coupling between two superconducting transmission line resonators. The coupling is mediated by a non-hysteretic rf SQUID acting as a flux-tunable mutual inductance between the resonators. We present a spectroscopic characterization of the device. In particular, we observe couplings g/2π ranging between –320 MHz and 37 MHz. In the case of g 0, the microwave power cross transmission between the two resonators is reduced by almost four orders of magnitude as compared to the case where the coupling is switched on.The authors acknowledge support from the German Research Foundation through SFB 631 and FE 1564/1-1; the EU projects CCQED, PROMISCE and SCALEQIT; the doctorate program ExQM of the Elite Network of Bavaria; the Spanish MINECO projects FIS2012-33022, FIS2012-36673-C03-02, and FIS2015-69983-P; the CAM Research Network QUITEMAD+; the Basque Government IT472-10 and UPV/EHU UFI 11/55

Kontrollierte Interaktionen in supraleitenden Quantenschaltkreisen

This thesis deals with controlled interactions between superconducting circuit elements for quantum computation and simulation applications. First, the electrical design and measurements of transmon type qubits, which are coupled to superconducting resonators, are presented. Secondly the controllable coupling of superconducting microwave resonators via an rf SQUID is experimentally investigated. Thirdly, a theoretical discussion about interaction and entanglement of a microwave resonator with a nanomechanical beam via an rf SQUID is discussed.Diese Promotionsschrift behandelt die kontrollierte Wechselwirkung zwischen supraleitenden Schaltkreiselementen für Quantencomputer und Quantensimulation. Zuerst werden das Design und die Vermessung von an supraleitende Resonatoren gekoppelten Transmonquantenbits präsentiert. Als Zweites wird die einstellbare Kopplung zweier Mikrowellenresonatoren mittels eines rf SQUIDs experimentell untersucht. Drittens wird die Theorie der Interaktion und Verschränkung eines Mikrowellenresonators mit einem nanomechanischem Balken über ein rf SQUID diskutiert