Suchergebnisse

6 pags., 2 figs. -- ERRATUM: Publisher's Note: Simulating superluminal physics with superconducting circuit technology [Phys. Rev. A 96, 032121 (2017)] Carlos Sabín, Borja Peropadre, Lucas Lamata, and Enrique Solano Phys. Rev. A 96, 049904 (2017) ; We provide tools for the quantum simulation of superluminal motion with superconducting circuits. We show that it is possible to simulate the motion of a superconducting qubit at constant velocities that exceed the speed of light in the electromagnetic medium and the subsequent emission of Ginzburg radiation. We also consider possible setups for simulating the superluminal motion of a mirror, finding a link with the super-radiant phase transition of the Dicke model. ; Financial support from the Fundación General CSIC is acknowledged by C.S. We also acknowledge support from Spanish MINECO/FEDER FIS2015-69983-P and FIS2015- 70856-P, Ramón y Cajal Grant No. RYC-2012-11391, CAM PRICYT Project QUITEMAD+ S2013/ICE-2801, Basque Government IT986-16, and UPV/EHU UFI 11/55. ; Peer Reviewed

8 págs.; 2 figs.; 4 apps. ; In this work we study a system that consists of 2M matter qubits that interact through a boson sampling circuit, i.e., an M-port interferometer, embedded in two different architectures. We prove that, under the conditions required to derive a master equation, the qubits evolve according to effective bipartite XY spin Hamiltonians, with or without local and collective dissipation terms. This opens the door to the simulation of any bipartite spin or hard-core boson models and exploring dissipative phase transitions as the competition between coherent and incoherent exchange of excitations. We also show that in the purely dissipative regime this model has a large number of exact and approximate dark states, whose structure and decay rates can be estimated analytically. We finally argue that this system may be used for the adiabatic preparation of boson sampling states encoded in the matter qubits. ©2016 American Physical Society ; The authors acknowledge support from the European Union FP7 project PROMISCE, Spanish MINECO Projects No. FIS2012-33022 and No. FIS2015-70856-P, and CAM Research Network QUITEMAD+. D.G.O. was supported by FPI Grant No. BES-2013-066486. B.P. and A.A.-G. acknowledge the Air Force of Scientific Research for support under Award No. FA9550-12-1-0046. A.A.-G. acknowledges support from the Army Research Office under Award No. W911NF-15-1- 0256. B.P. and A.A.-G. acknowledge the Defense Security Science Engineering Fellowship managed by the Office of Naval Research under Award No. N00014-16-1-2008. ; Peer Reviewed

In order to apply all ideas from quantum optics to the field of quantum circuits, one of the missing ingredients is a high-efficiency single-photon detector. In this work we propose a design for such a device which successfully reaches 100% efficiency with only one absorber. Our photon detector consists of a three-level system (a phase qubit) coupled to a semi-infinite one-dimensional waveguide (a microwave transmission line) which performs highly efficient photodetection in a simplified manner as compared to previous proposals. Using the tools of quantum optics we extensively study the scattering properties of realistic wave packets against this device, thereby computing the efficiency of the detector. We find that the detector has many operating modes, can detect detuned photons, is robust against design imperfections, and can be made broadband by using more than one absorbing element in the design. Many of these ideas could be translated to other single-mode photonic or plasmonic waveguides interacting with three-level atoms or quantum dots. © 2011 American Physical Society. ; This work was supported by Spanish MICINN Project No. FIS2009-10061, and CAM research consortium QUITEMAD Project No. S2009-ESP-1594. B.P. acknowledges funding by a CSIC JAE-PREDOC2009 Grant. G.R. acknowledges funding from the Juan de la Cierva program. G.J. and C.M.W. thank the Swedish Research Council (VR) and European Research Council for funding. E.S. acknowledges funding from Basque Government Grant No. IT472-10, Spanish MICINN Project No. FIS2009-12773-C02-01, the SOLID European project, and the EU CCQED project. ; Peer Reviewed

arXiv:1305.4844v1 ; The scattering through a Josephson junction (JJ) interrupting a superconducting line is revisited including power leakage. We also discuss how to make tunable and broadband resonant mirrors by concatenating junctions. As an application, we show how to construct cavities using these mirrors, thus connecting two research fields: JJ quantum metamaterials and coupled-cavity arrays. We finish by discussing the first nonlinear corrections to the scattering and their measurable effects. © 2013 IOP Publishing Ltd. ; This work was supported by Spanish government projects FIS2009-10061, and FIS2011-25167 conanced by FEDER funds. We thanks Aragon government support to group FENOL, CAM research consortium QUITEMAD and PROMISCE European project. ; Peer Reviewed

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 reviewed

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.