256 research outputs found
Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography
Quantum state reconstruction involves measurement devices that are usually
described by idealized models, but not known in full detail in experiments. For
weak propagating microwaves, the detection process requires linear amplifiers
which obscure the signal with random noise. Here, we introduce a theory which
nevertheless allows one to use these devices for measuring all quadrature
moments of propagating quantum microwaves based on cross-correlations from a
dual-path amplification setup. Simultaneously, the detector noise properties
are determined, allowing for tomography. We demonstrate the feasibility of our
novel concept by proof-of-principle experiments with classical mixtures of weak
coherent microwaves.Comment: 11 pages, 3 figure
ANDROGEN SUPPLEMENTATION IMPROVES RIGHT VENTRICULAR SYSTOLIC FUNCTION IN A CHRONIC HYPOXIA MODEL
Tunable and Switchable Coupling Between Two Superconducting Resonators
We realize a device allowing for tunable and switchable coupling between two
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 frequency and time domain 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
saturating the qubit. Our time domain measurements allow us to find parameter
regimes for optimal switch performance with respect to qubit drive power and
the dynamic range of the resonator input power
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
Tumor banking for health research in Brazil and Latin America: time to leave the cradle
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
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