VHF Josephson Arbitrary Waveform Synthesizer

Published

October 1, 2024

Author(s)

Jeremy Thomas, Nathan Flowers-Jacobs, Anna Fox, Akim Babenko, Samuel Benz, Paul Dresselhaus

Abstract

We report on the design, fabrication, and measurement of a Very High Frequency band Josephson Arbitrary Waveform Synthesizer (VHF-JAWS) at frequencies up to 50.05 MHz. The VHF-JAWS chip is composed of a series array of 12810 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 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 Ω 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 0.7 mA and the amplitude of the bias pulses by at least 10%. We use the large bias pulse quantum-locked range to investigate in detail one source of error: the direct feedthrough of the current bias pulses into the DUT at VHF frequencies. We reduce this error by high-pass filtering the current bias pulses and measure the error as a function of input pulse-amplitude in two regimes: over the quantum-locked range and after passively attenuating the input pulse-amplitude so that the JJs no longer generate voltage pulses.

Citation

IEEE Transactions on Applied Superconductivity

Volume

34

Pub Type

Journals

Download Paper

https://doi.org/10.1109/TASC.2024.3418332

Local Download

Keywords

Josephson junction arrays, digital-analog conversion, signal synthesis, superconducting integrated circuits, superconducting microwave devices, power measurement standards

Citation

Thomas, J. , Flowers-Jacobs, N. , Fox, A. , Babenko, A. , Benz, S. and Dresselhaus, P. (2024), VHF Josephson Arbitrary Waveform Synthesizer, IEEE Transactions on Applied Superconductivity, [online], https://doi.org/10.1109/TASC.2024.3418332, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957323 (Accessed December 13, 2024)