Search

Your search keyword '"Flowers-Jacobs, Nathan E."' showing total 30 results
Start Over Author "Flowers-Jacobs, Nathan E."
30 results on '"Flowers-Jacobs, Nathan E."'

1. VHF Josephson Arbitrary Waveform Synthesizer

Author

Thomas, Jeremy N., Flowers-Jacobs, Nathan E., Fox, Anna E., Babenko, Akim A., Benz, Samuel P., and Dresselhaus, Paul D.

Abstract

We report on the design, fabrication, and measurement of a very high frequency band Josephson arbitrary waveform synthesizer (VHF-JAWS) at frequencies from 1 kHz to 50.05 MHz. The VHF-JAWS chip is composed of a series array of 12 810 Josephson junctions (JJs) embedded in a superconducting coplanar waveguide. Each JJ responds to a pattern of current pulses by creating a corresponding pattern of voltage pulses, each with a time-integrated area related to fundamental constants as ${{h/2e}}$. The pulse patterns are chosen to produce quantum-based single-tone voltage waveforms with an open-circuit voltage of 50 mV rms (–19.03 dBm output power into 50 $\Omega$ load impedances) at frequencies up to 50.05 MHz, which is more than twice the voltage that has been generated by previous RF-JAWS designs at 1 GHz. The VHF-JAWS is “quantum-locked,” that is, it generates one quantized output voltage pulse per input current pulse per JJ while varying the dc current through the JJ array by at least 0.4 mA and the amplitude of the bias pulses by at least 10 %. We use the large bias pulse quantum-locking range to investigate one source of error in detail: the direct feedthrough of the current bias pulses into the DUT at VHF frequencies, which adds an unwanted, in-band component to the measured voltage. We reduce this error by high-pass filtering the current bias pulses and measure the error as a function of input pulse amplitude using two techniques: 1) by measuring small changes over the quantum-locking range and 2) by passively attenuating the input pulse amplitude so that the nonlinear JJs no longer generate voltage pulses while the error is only linearly scaled.

Published
2024
Full Text
View/download PDF

6. A Microwave Quantum-Defined Millivolt Source

Author

Babenko, Akim A., primary, Flowers-Jacobs, Nathan E., additional, Lasser, Gregor, additional, Brevik, Justus A., additional, Fox, Anna E., additional, Dresselhaus, Paul D., additional, Popovic, Zoya, additional, and Benz, Samuel P., additional

Published
2021
Full Text
View/download PDF

7. The NIST Johnson Noise Thermometry System for the Determination of the Boltzmann Constant

Author

Flowers-Jacobs, Nathan E., Pollarolo, Alessio, Coakley, Kevin J., Weis, Adam C., Fox, Anna E., Rogalla, Horst, Tew, Weston L., and Benz, Samuel P.

Subjects
Chemistry, Physics, Science and technology
Abstract

1. IntroductionFor the forthcoming redefinition of the kelvin in the International System of Units (SI), an exact numerical value for the Boltzmann constant k in units of joules per kelvin [...]

Published
2017
Full Text
View/download PDF

12. Characterization of a Josephson Junction Comb Generator

Author

Babenko, Akim A., primary, Boaventura, Alirio S., additional, Flowers-Jacobs, Nathan E., additional, Brevik, Justus A., additional, Fox, Anna E., additional, Williams, Dylan F., additional, Popovic, Zoya, additional, Dresselhaus, Paul D., additional, and Benz, Samuel P., additional

Published
2020
Full Text
View/download PDF

30. Quantized Pulse Propagation in Josephson Junction Arrays.

Author

Donnelly CA, Brevik JA, Flowers-Jacobs NE, Fox AE, Dresselhaus PD, Hopkins PF, and Benz SP

Abstract

We present time-domain electrical measurements and simulations of the quantized voltage pulses that are generated from series-connected Josephson junction (JJ) arrays. The transmission delay of the JJ array can lead to a broadening of the net output pulse, depending on the direction of the output pulse propagation relative to the input bias pulse. To demonstrate this, we compare time-domain measurements of output pulses from radio-frequency Josephson Arbitrary Waveform Synthesizer (RF-JAWS) circuits fabricated with two different output measurement configurations, so that the backward-propagating and forward-propagating pulses can be measured. Measurements were made on arrays with 1200 and 3600 JJs and show that the net backward-propagating output pulse is broadened by timing delays in the JJ array while the net forward-propagating output pulse is insensitive to delay effects and can theoretically be further scaled to longer JJ array lengths without significant output pulse broadening. These measurements match well with simulations and confirm the expectation that the net output pulses arise from the time-delayed superposition of individual JJ output pulses from the series array of JJs. The measurements and analysis shown here have important implications for the realization of RF-JAWS circuits to be used as quantum-based reference sources for communications metrology.

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results