Single-Flux-Quantum Multiplier Circuits for Synthesizing Gigahertz Waveforms With Quantum-Based Accuracy
Manuel C. Castellanos Beltran, David I. Olaya, Adam J. Sirois, Christine A. Donnelly, Paul Dresselhaus, Samuel Benz, Peter F. Hopkins
We designed, simulated, and experimentally demonstrated components for a microwave frequency digital-to-analog converter (DAC) based on rapid single flux quantum (RSFQ) circuits and a superconducting amplifier based on SQUID stacks. These are key components of a self-calibrated programmable waveform reference for communications metrology capable of synthesizing high-speed signals having output with quantum-based accuracy. The amplifier is an SFQ voltage multiplier circuit that consists of a network of SFQ-splitters and SQUID transformers that provides output signals based on quantized pulses. The circuits were fabricated using our Nb/NbxSi1-x/Nb Josephson junction (JJ) fabrication process that produces self-shunted JJs with Nb-doped silicon barriers. In order to demonstrate the quantum-based reproducibility, stability and performance at 4 K, we synthesized single-tone and multi-tone waveforms at gigahertz frequencies and demonstrated their operation over a range of synthesizer and experimental bias parameters. We also propose future circuit designs for achieving higher power, power accuracy, spectral purity, and higher frequencies and discuss the potential limitations.
, Olaya, D.
, Sirois, A.
, Donnelly, C.
, Dresselhaus, P.
, Benz, S.
and Hopkins, P.
Single-Flux-Quantum Multiplier Circuits for Synthesizing Gigahertz Waveforms With Quantum-Based Accuracy, IEEE Transactions on Applied Superconductivity, [online], https://dx.doi.org/10.1109/TASC.2021.3057013, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930294
(Accessed October 19, 2021)