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Displaying 126 - 150 of 204

Dependence of noise in magnetic tunnel junction sensors on annealing field and temperature

March 7, 2008
Author(s)
Stephen E. Russek, David P. Pappas, Sean Halloran, Lu Yuan, Sy-Hwang Liou, Rui Zhang
The minimum detectable field of magnetoresistive sensors is limited by their intrinsic noise. Magnetization fluctuations are one of the crucial noise sources and are related to the magnetization alignment at the antiferromagnetic – ferromagnetic interface

256-Channel Magnetic Imaging System

January 18, 2008
Author(s)
Fabio C. da Silva, Sean Halloran, Anthony B. Kos, David P. Pappas
We present the design and fabrication of a magentoresistive imaging system capable of measuring 256 channels simultaneously along linear ranges of 4 mm and 13 mm. The channels are interfaced by custom electronics and the images are displayed in real time

256-channel magnetic imaging system

January 15, 2008
Author(s)
Fabio C. Da Silva, Sean Halloran, Anthony B. Kos, David P. Pappas
We present the design and fabrication of a magnetoresistive imaging system capable of scanning 256 channels simultaneously along linear ranges of either 4 or 13 mm. High speed electronics read the channels and transfer the data to a computer that builds

Development of a thin film magnetic moment reference material

January 1, 2008
Author(s)
Robert R. Owings, Fabio C. Da Silva, David P. Pappas
This paper presents the results of an interlaboratory comparison and development of a magnetic moment reference material. The comparison was between the National Institute of Standards and Technology, magnetometer manufacturers, industrial, academic, and

Elimination of two level fluctuators in superconducting quantum bits by an epitaxial tunnel barrier

September 7, 2006
Author(s)
Seongshik Oh, Katarina Cicak, Jeffrey S. Kline, Mika Sillanpaa, Jed D. Whittaker, Raymond W. Simmonds, David P. Pappas, Kevin Osborn
Quantum computing based on Josephson junction technology is considered promising due to its scalable architecture. However, decoherence is a major obstacle. Here, we report evidence for improved Josephson quantum bits qubits using a single-crystal Al2O3

Josephson Junction Materials Research Using Phase Qubits

May 30, 2006
Author(s)
Raymond Simmonds, Dustin P. Hite, Robert McDermott, Matthias Steffen, Ken B. Cooper, Kristine Lang, John M. Martinis, David P. Pappas
At present, the performance of superconducting qubits is limited by decoherence. Strong decoherence of phase qubits is associated with spurious microwave resonators residing within the Josephson junction tunnel barrier [1]. In this work, we investigate

Erbium-doped Gold Sensor Films for Magnetic Microcalorimeter X-ray Detectors*

April 17, 2006
Author(s)
Barry L. Zink, Kent D. Irwin, Gene C. Hilton, Joel Ullom, David P. Pappas
We briefly review the principles of a magnetic microcalorimeter x-ray detector and the requirements for fabricating an array of these sensors, which include a paramagnetic sensor fabricated with thin-film techniques. We discuss two methods for depositing

Decoherence in Josephson Qubits from Dielectric Loss

November 16, 2005
Author(s)
John M. Martinis, Ken B. Cooper, Robert Mcdermott, Matthias Steffen, Markus Ansmann, Kevin Osborn, Katarina Cicak, Seongshik Oh, David P. Pappas, Raymond Simmonds, Clare Yu
Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the tunnel junction can lead to short coherence times. We show

Epitaxial growth of rhenium with sputtering

October 6, 2005
Author(s)
Seongshik Oh, Dustin P. Hite, Katarina Cicak, Kevin Osborn, Raymond W. Simmonds, Robert Mcdermott, Ken B. Cooper, Matthias Steffen, John M. Martinis, David P. Pappas
We have grown epitaxial renium (0001) films on α-Al 2O 3(0001) substrates using sputter deposition in an ultra high vacuum system. We find that better epitaxy is achieved with DC rather than with RF sputtering. With DC sputtering, epitaxy is obtained with

Low-Leakage Superconducting Tunnel Junctions with a Single-Crystal Al2O3 Barrier

September 5, 2005
Author(s)
Seongshik Oh, Katarina Cicak, Kevin Osborn, Raymond Simmonds, David P. Pappas, Robert Mcdermott, Ken B. Cooper, Matthias Steffen, John M. Martinis
We have developed a two-step growth scheme for single-crystal Al2O3 tunnel barriers. The barriers are epitaxially grown on single-crystal rhenium (Re) base electrodes that are grown epitaxially on a sapphire substrate, while polycrystalline Al is used as

Low-frequency noise measurements on commercial magnetoresistive magnetic field sensors

May 17, 2005
Author(s)
Nathan Stutzke, Stephen E. Russek, David P. Pappas, Mark Tondra
Low frequency noise was measured in the frequency range from 0.1 Hz to 10 kHz on a variety of commercially available magnetic sensors. The types of sensors investigated include anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), and tunnel