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Displaying 51 - 75 of 204

Origin and Reduction of 1=f Magnetic Flux Noise in Superconducting Devices

October 18, 2016
Author(s)
P Kumar, David P. Pappas, Robert Mcdermott, J.W. Freeland, Clare Yu, M Beck, Hui Wang, Ruqian Wu
Magnetic flux noise is a dominant source of dephasing and energy relaxation in superconducting qubits. The noise power spectral density varies with frequency as 1=f^α, with α ≲ 1, and spans 13 orders of magnitude. Recent work indicates that the noise is

Hotspot Relaxation Dynamics in a Current Carrying Superconductor

March 17, 2016
Author(s)
Francesco Marsili, Martin Stevens, Alex Kozorezov, Varun Verma, Colin Lambert, Jeffrey A. Stern, Rob Horansky, Shellee D. Dyer, Shannon Duff, David P. Pappas, Matthew Shaw, Richard Mirin, Sae Woo Nam
When a photon is absorbed in a superconductor it creates a region of nonequilibrium superconductivity referred to as a hotspot [1]. The operation of most superconducting single photon detectors (microwave kinetic inductance detectors, MKIDs [2,3]

Concentric transmon qubit featuring fast tunability and an anisotropic magnetic dipole moment

January 21, 2016
Author(s)
Jochen Braumuller, Martin O. Sandberg, Michael Vissers, Andre Schneider, Steffen Schlor, Lukas Grunhaupt, Hannes Rotzinger, Michael Marthaler, Alexander Lukashenko, Amadeus Dieter, Alexey V. Ustinov, Martin Weides, David P. Pappas
We present a planar qubit design based on a superconducting circuit that we call concentric transmon. While employing a straightforward fabrication process using Al evaporation and lift-off lithography, we observe qubit lifetimes and coherence times in the

Low noise kinetic inductance traveling-wave amplifier using three-wave mixing

October 1, 2015
Author(s)
Michael R. Vissers, Robert P. Erickson, Leila R. Vale, Xian Wu, Gene C. Hilton, David P. Pappas
We have fabricated a wide-bandwidth, high dynamic range, low noise cryogenic amplifier based on a superconducting kinetic inductance traveling-wave device. The device was made from NbTiN and consisted of a long, coplanar waveguide on a silicon chip. By

Efficient Quantum State Transfer in an Engineered Chain of Quantum Bits

September 15, 2015
Author(s)
Emanuel Knill, Michael Vissers, David P. Pappas, Martin Sandberg
Here we present a method of performing quantum state transfer in a chain of superconducting quantum bits. Our protocol is based on the engineerability of the energy levels of superconducting quantum systems. This, together with the tunability of the

Quasiparticle recombination in hotspots in superconducting current-carrying nanowires

August 6, 2015
Author(s)
Alex Kozorezov, Colin Lambert, Francesco Marsili, Martin Stevens, Varun Verma, Jeffrey A. Stern, Rob Horansky, Shellee D. Dyer, Shannon Duff, David P. Pappas, Adriana Lita, Matthew D. Shaw, Richard Mirin, Sae Woo Nam
We describe a kinetic model of recombination of nonequilibrium quasiparticles generated by single photon absorption in superconducting current-carrying nanowires. The model is developed to interpret two-photon detection experiments in which a single photon

Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors

February 20, 2015
Author(s)
Johannes Hubmayr, James A. Beall, Daniel T. Becker, Hsiao-Mei Cho, Gene C. Hilton, Dale Li, David P. Pappas, Jeffrey L. Van Lanen, Mark Devlin, Kent D. Irwin, Chris Groppi, Phillip Mauskopf
We demonstrate photon-noise limited performance at sub-millimeter wavelengths in microwave kinetic inductance detectors (MKIDs) made of a new superconducting material, a TiN/Ti/TiN trilayer film. Optical coupling is achieved by use of feedhorns, a standard

Frequency Comb Generation in Superconducting Resonators

October 30, 2014
Author(s)
Robert P. Erickson, Michael Vissers, Martin O. Sandberg, Steven R. Jefferts, David P. Pappas
We have generated frequency combs spanning 0.5 to 20 GHz in superconducting λ=2 resonators at T ¼ 3 K. Thin films of niobium-titanium nitride enabled this development due to their low loss, high nonlinearity, low frequency dispersion, and high critical

Superconducting nanowire single photon detectors fabricated from an amorphous Mo0.75Ge0.25 thin-film

July 15, 2014
Author(s)
Varun B. Verma, Adriana E. Lita, Michael R. Vissers, Francesco Marsili, David P. Pappas, Richard P. Mirin, Sae Woo Nam
We present the characteristics of superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous Mo0.75Ge0.25 thin -films. Fabricated devices show a saturation of the internal detection efficiency at temperatures below 1 K, with system

Dual-polarization-sensitive kinetic inductance detectors for balloon-borne, sub-millimeter polarimetry

March 20, 2014
Author(s)
James A. Beall, Dan Becker, Justus Brevik, Hsiao-Mei Cho, Gene C. Hilton, Kent D. Irwin, Dale Li, David P. Pappas, Jeffrey L. Van Lanen, Johannes Hubmayr
We are developing arrays of kinetic inductance detectors for sub-millimeter polarimetry that will be deployed on the BLAST balloon-borne instrument. The array is feedhorn-coupled, and each pixel contains two lumped-element kinetic inductance detectors

Properties of TiN for Detector and Amplifier Applications

February 8, 2014
Author(s)
Jiansong Gao, Michael R. Vissers, Martin O. Sandberg, Dale Li, Hsiao-Mei Cho, Clint Bockstiegel, Ben Mazin, Henry G. Leduc, Saptarshi Chaudhuri, David P. Pappas, K D. Irwin
We have experimentally explored and carefully characterized the important properties of TiN, including the resistivity, nonlinear kinetic inductance, the anomalous electro-dynamical response, and the two-level-system induced frequency shift and noise. We

Surface science for improved ion traps

October 1, 2013
Author(s)
David P. Pappas, Dustin A. Hite, Andrew C. Wilson, David T. Allcock, David J. Wineland, Dietrich G. Leibfried, Yves Colombe
Trapped ions are sensitive to electric-field noise from trap-electrode surfaces. This noise has been an obstacle to progress in trapped-ion quantum information processing (QIP) experiments for more than a decade. It causes motional heating of the ions, and