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Physics

Condensed matter

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Displaying 901 - 925 of 1253

Radiation-suppressed superconducting quantum bit in a planar geometry

February 19, 2013
Author(s)
Martin O. Sandberg, Tomas A. Ohki, Jose A. Aumentado, Martin P. Weides, David P. Pappas
We present a superconducting transmon qubit circuit design based on large, coplanar capacitor plates and a microstrip resonator. The microstrip geometry, with the ground plane on the back, enhances access to the circuit for state preparation and

Improvements in silicon oxide dielectric loss for superconducting microwave detector circuits

January 24, 2013
Author(s)
Dale Li, Jason Austermann, James A. Beall, Daniel T. Becker, Hsiao-Mei Cho, Anna E. Fox, Nils Halverson, Jason Henning, Gene C. Hilton, Johannes Hubmayr, Jeffrey L. Van Lanen, John P. Nibarger, Michael D. Niemack, Kent D. Irwin
Dielectric loss in low-temperature superconducting integrated circuits can cause lower overall efficiency, particularly in the 90 to 220 GHz regime. We present a method to tune the dielectric loss for silicon oxide deposited by plasma-enhanced chemical

Spin-Transfer Nano-Oscillators

January 7, 2013
Author(s)
Stephen E. Russek, Ranko R. Heindl, Thomas Cecil, William H. Rippard
Spin transfer nano-oscillators are small multilayer magnetic devices that undergo microwave oscillations and output a microwave voltage when a bias current is applied. The oscillation frequency is tunable, over a range of 0.5 GHz to 225 GHz, by varying the

Ultrafast element-specific magnetization Dynamics of complex magnetic materials on a table-top

December 21, 2012
Author(s)
Thomas J. Silva, Justin M. Shaw, Hans T. Nembach, Chan La-O-Vorakiat, Henry C. Kapteyn, Margaret M. Murnane, Stefan Mathias, Roman Adam, Patrik Grychtol, Martin Aeschlimann, Claus M. Schneider, Emrah Turgut, Dennis Rudolf
We review recent progress in femtosecond magnetization dynamics probed by extreme ultraviolet pulses from high-harmonic generation. In a transverse magneto-optical Kerr geometry, we establish an ultrafast, element-specific experimental capability - on a

Current Distribution and Transition Width in Superconducting Transition-Edge Sensors

December 13, 2012
Author(s)
Daniel S. Swetz, Douglas A. Bennett, Daniel R. Schmidt, Joel N. Ullom
Present models of the superconducting-to-normal transition in transition-edge sensors (TESs)do not describe the current distribution within a biased TES. This distribution is complicated by normal-metal features that are integral to TES design. We present

Silicon Micromachines for Fun and Profit

December 12, 2012
Author(s)
David Bishop, Flavio Pardo, Cris Bolle, Randy Giles, Vladimir Aksyuk
Over the last decade or so a group of us, while working at Bell Labs, have been able to develop a large number of silicon micromachines for a wide range of applications. In this article, which is part of a special volume to celebrate the career of

Observation of bias-specific telegraph noise in large transition-edge sensors

December 11, 2012
Author(s)
Vincent Y. Kotsubo, Douglas A. Bennett, Mark Croce, Michael W. Rabin, Daniel R. Schmidt, Joel N. Ullom
We have observed anomalous random telegraph noise in discrete regions of voltage bias throughout the superconducting transition in larger transition-edge sensors (TESs). The bimodal nature of these noise features is consistent with thermally activated

Superconductivity in Nb-Sn thin films of stoichiometric and off-stoichiometric compositions

December 7, 2012
Author(s)
Matthijs Mentink, John E. Bonevich, Marc Dhalle, Daniel Dietderich, Arno Godeke, Frances Hellman, Herman Ten Kate
Binary Nb-Sn thin film samples are fabricated and characterized in terms of their composition, morphology and superconducting properties. Nb-Sn is magnetron-sputtered onto heated R-plane sapphire substrates at 700 C, 800 C, and 900 C, using a custom-built

First-principles modeling of gold adsorption on BeO (0001)

October 29, 2012
Author(s)
Shmuel Barzilai, Francesca M. Tavazza, Lyle E. Levine
Gold nanowire chains are considered a good candidate for nanoelectronics devices since they exhibit remarkable structural and electrical properties. For practical engineering devices, -wurtzite BeO may be a useful platform for supporting these nanowires

Dynamics of the non-classical light from a single solid-state quantum emitter

October 18, 2012
Author(s)
Edward B. Flagg, Sergey Polyakov, Tim O. Thomay, Glenn S. Solomon
We measure the dynamics of a non-classical optical field using two-time second-order correlations in conjunction with pulsed excitation. The technique quantifies single-photon purity and coherence during the excitation-relaxation cycle of an emitter, which

Toward a Probe-Based Method for Determining Exfoliation Energies of Lamellar Materials

October 4, 2012
Author(s)
Zhao Z. Deng, Alexander Smolyanitsky, Qunyang Li, Xi-Qiao Feng, Rachel J. Cannara
We discuss a potential new measurement application based on nanotribological measurements and simulations of the model lamellar material graphite. While frictional forces always oppose motion, we have observed that friction increases with decreasing load

A 4:1 transmission-line impedance transformer for broadband superconducting circuits

October 1, 2012
Author(s)
Leonardo M. Ranzani, Lafe F. Spietz, Jose A. Aumentado, Zoya Popovic
We present a 4 : 1 superconducting transmission-line impedance transformer for cryogenic applications. The device transforms 25 {Ω} in the coplanar waveguide to 6.25 {Ω} in the microstrip and is designed to operate at 20 mK. Calibrated measurements in a

A high resolution gamma-ray spectrometer based on superconducting microcalorimeters

September 28, 2012
Author(s)
Douglas A. Bennett, Robert D. Horansky, Daniel R. Schmidt, Andrew Hoover, Ryan Winkler, Bradley K. Alpert, James A. Beall, William B. Doriese, Joseph W. Fowler, Gene C. Hilton, Kent D. Irwin, Nathan J. Hoteling, Vincent Y. Kotsubo, John A. Mates, Galen C. O'Neil, Michael W. Rabin, Carl D. Reintsema, Francis J. Schima, Daniel S. Swetz, Leila R. Vale, Joel N. Ullom
Improvements in superconductor device fabrication, detector hybridization techniques, and superconducting quantum interference device readout have made square-centimeter-sized arrays of gammaray microcalorimeters, based on transition-edge sensors (TESs)

Characterization and In-situ Monitoring of Sub-stoichiometric Adjustable TC Titanium Nitride Growth

September 21, 2012
Author(s)
Michael R. Vissers, Jiansong Gao, Jeffrey S. Kline, Martin O. Sandberg, Martin P. Weides, David S. Wisbey, David P. Pappas
The structural and electrical properties of Ti-N films deposited by reactive sputtering depend on their growth parameters, in particular the Ar:N2 gas ratio. We show that the nitrogen percentage changes the crystallographic phase of the film progressively

Anomalous Friction in Suspended Graphene

September 20, 2012
Author(s)
Alexander Y. Smolyanitsky, Jason P. Killgore
Since the discovery of the Amonton's law and with support of modern tribological models, friction between surfaces of three-dimensional materials is known to generally increase when the surfaces are in closer contact. Here, using molecular dynamics

Spin Dynamics in the Time and Frequency Domain

September 15, 2012
Author(s)
Thomas J. Silva
The current status of experimental approaches to analyze the spin wave dynamics in ferromagnetic nanoscale structures is reviewed. Recent developments in frequency- and field swept spectroscopy to determine the resonant response of nanoscale ferromagnets

Zero-energy modes and gate-tunable gap in graphene on hexagonal boron nitride

September 13, 2012
Author(s)
Markus Kindermann, Bruno Uchoa, David L. Miller
In this article, we derive an effective theory of graphene on a hexagonal boron nitride (h-BN) substrate. We show that the h-BN substrate generically opens a spectral gap in graphene despite the lattice mismatch. The origin of that gap is particularly
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