330 research outputs found
Magnetic field tuning of coplanar waveguide resonators
We describe measurements on microwave coplanar resonators designed for
quantum bit experiments. Resonators have been patterned onto sapphire and
silicon substrates, and quality factors in excess of a million have been
observed. The resonant frequency shows a high sensitivity to magnetic field
applied perpendicular to the plane of the film, with a quadratic dependence for
the fundamental, second and third harmonics. Frequency shift of hundreds of
linewidths can be obtained.Comment: Accepted for publication in AP
On the properties of superconducting planar resonators at mK temperatures
Planar superconducting resonators are now being increasingly used at mK
temperatures in a number of novel applications. They are also interesting
devices in their own right since they allow us to probe the properties of both
the superconductor and its environment. We have experimentally investigated
three types of niobium resonators - including a lumped element design -
fabricated on sapphire and SiO_2/Si substrates. They all exhibit a non-trivial
temperature dependence of their centre frequency and quality factor. Our
results shed new light on the interaction between the electromagnetic waves in
the resonator and two-level fluctuators in the substrate.Comment: V2 includes some minor corrections/changes. Submitted to PR
Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator
We propose a scheme for circuit quantum electrodynamics with a
superconducting flux-qubit coupled to a high-Q coplanar resonator. Assuming
realistic circuit parameters we predict that it is possible to reach the strong
coupling regime. Routes to metrological applications, such as single photon
generation and quantum non-demolition measurements are discussed.Comment: 8 pages, 5 figure
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