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Search Publications by: Jason Underwood (Fed)

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Displaying 1 - 14 of 14

A fast negative impedance converter for JAWS load compensation

September 10, 2020
Author(s)
Jason Underwood, Stephen Pfeiffer, Geoffrey Palo
For accurate realization of the ac volt, the Josephson Arbitrary Waveform Synthesizer (JAWS) must not be overly loaded by the electrical network in which it is used. The interaction between the on-chip inductance and the stray capacitance in the network

Josephson-Based Full Digital Bridge for High-Accuracy Impedance Comparisons

July 9, 2016
Author(s)
Frederic Overney, Nathan Flowers-Jacobs, Blaise Jeanneret, Alain Rufenacht, Anna Fox, Jason Underwood, Andrew D. Koffman, Samuel P. Benz
This paper describes a Josephson-based impedance bridge capable of comparing any types of impedance over a large bandwidth. The heart of the bridge is a dual AC Josephson Voltage Standards (ACJVS) source which offers unprecedented flexibility in high

Josephson-Based Full Digital Bridge for High-Accuracy Impedance Comparisons

June 24, 2016
Author(s)
Frederic Overney, Nathan Flowers-Jacobs, Blaise Jeanneret, Alain Rufenacht, Anna Fox, Jason Underwood, Andrew D. Koffman, Samuel P. Benz
This paper describes a Josephson-based full digital impedance bridge capable of comparing any two impedances, regardless of type (R-C, R-L, or L-C), over a large frequency range. At the heart of the bridge are two Josephson arbitrary waveform synthesizer

1 V Josephson arbitrary waveform synthesizer

September 17, 2014
Author(s)
Samuel P. Benz, Steven B. Waltman, Anna E. Fox, Paul D. Dresselhaus, Alain Rufenacht, Jason M. Underwood, Charles J. Burroughs
A quantum-accurate waveform with a root-mean-square (RMS) output amplitude of 1 V has been synthesized for the first time. This four-fold increase in voltage over previous systems was achieved through developments and improvements in bias electronics

Sub-100 mK cooling using normal-metal?insulator?superconductor tunnel junctions

December 15, 2013
Author(s)
Peter J. Lowell, Galen C. O'Neil, Jason M. Underwood, Xiaohang NMN Zhang, Joel N. Ullom
Normal-metal∖insulator∖superconductor (NIS) junctions can be used as solid-state refrigerators since the hottest electrons preferentially tunnel from the normal metal into the superconductor. In this paper, we present NIS junctions optimized to cool

Macroscale refrigeration by nanoscale electron transport

February 26, 2013
Author(s)
Peter J. Lowell, Galen C. O'Neil, Jason M. Underwood, Joel N. Ullom
Nano- and Micro- Electromechanical devices (NEMS & MEMS) have become ubiquitous; examples include automobile accelerometers, inkjet printer heads, infrared viewers, and mirrors for image manipulation and projection. Applications fall broadly in the

Insensitivity of Sub-Kelvin Electron-Phonon Coupling to Substrate Properties

December 16, 2011
Author(s)
Jason M. Underwood, Peter J. Lowell, Galen C. O'Neil, Joel N. Ullom
We have examined the role of the substrate on electron-phonon coupling in normal metal films of Mn-doped Al at temperatures below 1 K. Normal metal-insulator-superconductor junctions were used to measure the electron temperature in thin metal films as a