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Search Publications by: Anna Fox (Fed)

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Displaying 26 - 50 of 57

DC Comparison of a Programmable Josephson Voltage Standard and a Josephson Arbitrary Waveform Synthesizer

July 7, 2018
Author(s)
Alain Rufenacht, Nathan Flowers-Jacobs, Anna Fox, Steven B. Waltman, Robert E. Schwall, Paul Dresselhaus, Samuel P. Benz, Charles J. Burroughs
We present the first dc comparison of a programmable Josephson voltage standards and a pulse- driven Josephson arbitrary waveform synthesizer (JAWS) at 3 V. Both devices are mounted side- by-side on the cold stage of a cryocooler. The relative agreement

Radiofrequency Waveform Synthesis with the Josephson Arbitrary Waveform Synthesizer

July 7, 2018
Author(s)
Justus Brevik, Christine A. Donnelly, Nathan Flowers-Jacobs, Anna Fox, Pete Hopkins, Paul Dresselhaus, Samuel P. Benz
We have measured the frequency-dependent voltage output up to 100 MHz of a modified version of the Josephson Arbitrary Waveform Synthesizer. An impedance-matching resistor was integrated within the Josephson junction array circuit to match the nominally

Three Volt Pulse-Driven Josephson Arbitrary Waveform Synthesizer

July 7, 2018
Author(s)
Nathan Flowers-Jacobs, Alain Rufenacht, Anna Fox, Steven B. Waltman, Justus Brevik, Paul Dresselhaus, Samuel P. Benz
This paper describes a new generation of Josephson Arbitrary Waveform Synthesizers which generate ac waveforms with a root-mean-squared (rms) amplitude of 3 V over a quantum-accurate operating range greater than 1 mA at 1 kHz. This system is composed of

Automated Direct Comparison of Two Cryocooled 10 Volt Programmable Josephson Voltage Standards

July 6, 2018
Author(s)
Alain Rufenacht, Yi-hua D. Tang, Stephane Solve, Anna E. Fox, Paul D. Dresselhaus, Charles J. Burroughs, Robert E. Schwall, Regis Chayramy, Samuel P. Benz
We have performed direct dc comparisons between two cryocooled 10 V programmable Josephson voltage standards utilizing an automated synchronization scheme for the voltage reversals, which enables the use of a high-sensitivity analog null detector on its 10

The NIST Johnson noise thermometry system for the determination of the Boltzmann constant

December 29, 2017
Author(s)
Nathan Flowers-Jacobs, Alessio Pollarolo, Kevin Coakley, Adam C. Weis, Anna Fox, Horst Rogalla, Weston L. Tew, Samuel Benz
In preparation for the redefinition of the International System of Units (SI), five different electronic measurements of the Boltzmann constant have been performed using different Johnson noise thermometry (JNT) systems over the past seven years. In this

A Boltzmann Constant Determination Based on Johnson Noise Thermometry

August 10, 2017
Author(s)
Nathan E. Flowers-Jacobs, Alessio Pollarolo, Kevin J. Coakley, Anna E. Fox, Horst Rogalla, Weston L. Tew, Samuel P. Benz
A value for the Boltzmann constant was measured electronically using an improved version of the Johnson Noise Thermometry (JNT) system at the National Institute of Standards and Technology (NIST), USA. This system is different from prior ones, including

Advanced Waveform Synthesis with Pulse-driven Josephson Voltage Standards

February 21, 2017
Author(s)
Justus A. Brevik, Nathan E. Flowers-Jacobs, Anna E. Fox, Evan B. Golden, Paul D. Dresselhaus, Samuel P. Benz
We describe the implementation of new commercial pulse-bias electronics that have enabled an improvement in the generation of quantum-accurate waveforms both with and without low-frequency compensation biases. We have used these electronics to apply a

On-Chip Temperature Distribution for Josephson Voltage Standards

November 22, 2016
Author(s)
Anna E. Fox, Evan B. Golden, Paul D. Dresselhaus, Samuel P. Benz
A substrate surface temperature characterization for the National Institute of Standards and technology Josephson voltage standard has been performed by fabricating and measuring Josephson junction arrays with on-chip thermometry. Circuits were designed

2 V Pulse-Driven Josephson Arbitrary Waveform Synthesizer

July 10, 2016
Author(s)
Nathan E. Flowers-Jacobs, Alain Rufenacht, Anna E. Fox, Paul D. Dresselhaus, Samuel P. Benz
We created a Josephson Arbitrary Waveform Synthesizer (JAWS) with a root-mean-square (rms) output magnitude of 2 V. This system is composed of two 1 V chips operating on a cryocooler. By controlling the relative phase of the two chips’ output voltage, we

Direct comparison of a Pulse-driven Josephson Arbitrary Waveform Synthesizer and a Programmable Josephson Voltage Standard at 1 Volt

July 9, 2016
Author(s)
Alain Rufenacht, Nathan Flowers-Jacobs, Anna Fox, Charles J. Burroughs, Paul Dresselhaus, Samuel P. Benz
We have performed direct ac comparisons between two types of quantum voltage standards, a pulse- driven Josephson arbitrary waveform synthesizer and a programmable Josephson voltage standard, at 1 V rms amplitude and a frequency of 100 Hz. The system

Improved spectra aberration in the Johnson Noise Thermometry

July 9, 2016
Author(s)
Alessio Pollarolo, Horst Rogalla, Anna Fox, Kevin J. Coakley, Weston L. Tew, Samuel P. Benz
SPECTRAL ABERRATION HAS BEEN FOR A LONG TIME THE MAIN SOURCE OF UNCERTAINTY IN THE JOHNSON NOISE THERMOMETRY APPROACH TO MEASURING THE BOLTZMANN CONSTANT. RECENTLY, WITH NEWLY DEVELOPED HARDWARE AND THE INTRODUCTION OF A NOVEL FITTING ALGORITHM FOR

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

Simultaneous Double Waveform Synthesis with a Single Programmable Josephson Voltage Standard

July 9, 2016
Author(s)
Alain Rufenacht, Anna Fox, Paul Dresselhaus, Charles J. Burroughs, Samuel P. Benz, Bryan C. Waltrip, Thomas L. Nelson
We have recently demonstrated new 2 V PJVS devices configured with two voltage outputs and two sets of least significant bits in order to simultaneously generate two independent stepwise output waveforms. This development improves upon our previous

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

Two Volt Josephson Arbitrary Waveform Synthesizer Using Wilkinson Dividers

February 19, 2016
Author(s)
Nathan E. Flowers-Jacobs, Anna E. Fox, Paul D. Dresselhaus, Robert E. Schwall, Samuel P. Benz
The root-mean-square (rms) output voltage of the NIST Josephson arbitrary waveform synthesizer (JAWS) has been doubled from 1 V to a record 2 V by combining two new 1 V chips on a cryocooler. This higher voltage will improve calibrations of ac thermal

Cryocooled 10 V Programmable Josephson Voltage Standard

December 11, 2014
Author(s)
Alain Rufenacht, Logan A. Howe, Anna E. Fox, Robert E. Schwall, Paul D. Dresselhaus, Charles J. Burroughs, Samuel P. Benz
Improvements in fabrication and packaging of our 10 V Programmable Josephson Voltage Standard circuits have enabled the successful operation of these devices on a cryocooler. Limited cooling power and temperature oscillations at the chip must not

Cryocooled 10 V Programmable Josephson Voltage Standard

December 11, 2014
Author(s)
Alain Rufenacht, Logan A. Howe, Anna Fox, Robert E. Schwall, Paul Dresselhaus, Charles J. Burroughs, Samuel Benz
Implementation of programmable Josephson voltage standard (PJVS) circuits on cryocooler at 4 K is a challenge. The limited cooling power of the cryocoolers has to balance the heat dissipated by the PJVS circuit in order to maintain a stable temperature

Junction Yield Analysis for 10 V Programmable Josephson Voltage Standard Devices

December 5, 2014
Author(s)
Anna E. Fox, Paul D. Dresselhaus, Alain Rufenacht, Aric W. Sanders, Samuel P. Benz
Analysis of the Josephson junction yield in the National Institute of Standards and Technology 10 V Programmable Josephson Voltage Standard (PJVS) has been performed by fabricating and measuring over 25 million Nb/NbxSi1-x/Nb junctions. Using the 265,116

Performance Improvements for the NIST 1 V Josephson arbitrary waveform synthesizer

November 10, 2014
Author(s)
Samuel P. Benz, Steven B. Waltman, Anna E. Fox, Paul D. Dresselhaus, Alain Rufenacht, Logan A. Howe, Robert E. Schwall, Nathan E. Flowers-Jacobs
The performance of the NIST Josephson arbitrary waveform synthesizer has been improved such that it generates a root-mean-square (RMS) output voltage of 1 V with an operating current range greater than 2 mA. Our previous 1 V JAWS circuit achieved this same

NIST 10 V Programmable Josephson Voltage Standard System Using a Low Capacity Cryocooler

November 6, 2014
Author(s)
Logan A. Howe, Anna Fox, Alain Rufenacht, Charles J. Burroughs, Paul Dresselhaus, Samuel Benz, Robert E. Schwall
Rising costs of and difficulty in obtaining liquid helium in many areas of the world provides strong motivation for cryogen-free operation of superconducting devices such as NIST Programmable Josephson Voltage Standard (PJVS) systems. However, operation on

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

Optimization of Focused Ion Beam-Tomography for Superconducting Electronics

August 27, 2014
Author(s)
Aric W. Sanders, Anna E. Fox, Paul D. Dresselhaus, Alexandra Curtin
Superconducting electronics play an important role in quantum computation, ultra-low power electronics, voltage standards and magnetic sensors. Many of these applications rely on the microfabrication of superconducting circuits with multiple wiring layers

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