Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEICE Technical Report; IEICE Tech. Rep.

Improvement of double oscillator type SFQ time-to-digital converter and realization of high temporal resolution

Yuma Tomitsuka, Yutaka Abe, Nobuyuki Zen, Yuki Yamanashi, Nobuyuki Yoshikawa

Published Aug 2, 2017• 0 citations
OpenAlex

Related papers

Improvement of spatial resolution of superconducting imaging systems using single-flux-quantum double-oscillator time-to-digital converters

Yuma Tomitsuka, Yutaka Abe, Nobuyuki Zen +2 more

The Japan Society of Applied Physics•Feb 8, 2018•0 citations

Design and implementation of double oscillator time-to-digital converter using SFQ logic circuits

T. Nishigai, M. Ito, Nobuyuki Yoshikawa +3 more

Physica C Superconductivity•Jul 19, 2005•6 citations

Demonstration of Picosecond Time Resolution in Double-Oscillator Time-to-Digital Converter Using Single-Flux-Quantum Circuits

Yuma Tomitsuka, Yuki Yamanashi, Nobuyuki Zen +2 more

We have been developing a time-to-digital converter (TDC) using single-flux-quantum (SFQ) circuits in order to realize an imaging system based on a superconducting strip single-photon detector (SSPD). In this system, the absorption position of a single photon in a meander-shaped SSPD is determined by measuring the delay time of the detected signal propagating through an SSPD delay line. Increasing the time resolution of the TDC is the primary concern for improving the spatial resolution of the system. Here we focused on the double-oscillator SFQ TDC, where the difference of oscillation periods between two SFQ ring oscillators determines the time resolution. In the previous study, a time resolution of about 4 ps was demonstrated by using the Nb standard Josephson integrated circuit (IC) process with a critical current density of 2.5 kA/cm2. In this study, we improved the time resolution by adopting the Nb advanced Josephson IC process with a critical current density of 10 kA/cm2and by optimizing the circuit parameters of the coincidence detector. The histogram and the linearity of the delay measurements show that the time resolution is improved to up to 2 ps.

IEEE Transactions on Applied Superconductivity•Mar 1, 2019•6 citations

Improvement of SFQ pulse frequency in an SFQ-D/A converter

Yuma Arai, Tomoki Watanabe, Kazunao Sawada +2 more

The Japan Society of Applied Physics•Jul 22, 2016•1 citation

Direct measurements of propagation delay of single-flux-quantum circuits by time-to-digital converters

Kazunori Nakamiya, Nobuyuki Yoshikawa, Akira Fujimaki +2 more

Direct measurements of propagation delay of single-flux-quantum (SFQ) circuits were performed using SFQ double-oscillator time-to-digital converters. The propagation delay of several SFQ logic gates in our cell library named CONNECT were measured in picosecond resolution. Small discrepancy in the propagation delay of picosecond level was observed between measurement and circuit simulation results. The discrepancy is well explained assuming the parasitic inductance around shunt resistors of Josephson junctions.

IEICE Electronics Express•Jan 1, 2008•5 citations

Challenges in the Realization of SFQ Digital Circuits

T. Van Duzer

Springer eBooks•Jan 1, 1999•0 citations
We have been developing a time-to-digital converter (TDC) using single-flux-quantum (SFQ) circuits in order to realize an imaging system based on a superconducting strip single-photon detector (SSPD). In this system, the absorption position of a single photon in a meander-shaped SSPD is determined by measuring the delay time of the detected signal propagating through an SSPD delay line. Increasing the time resolution of the TDC is the primary concern for improving the spatial resolution of the system. Here we focused on the double-oscillator SFQ TDC, where the difference of oscillation periods between two SFQ ring oscillators determines the time resolution. In the previous study, a time resolution of about 4 ps was demonstrated by using the Nb standard Josephson integrated circuit (IC) process with a critical current density of 2.5 kA/cm2. In this study, we improved the time resolution by adopting the Nb advanced Josephson IC process with a critical current density of 10 kA/cm2and by optimizing the circuit parameters of the coincidence detector. The histogram and the linearity of the delay measurements show that the time resolution is improved to up to 2 ps.
Direct measurements of propagation delay of single-flux-quantum (SFQ) circuits were performed using SFQ double-oscillator time-to-digital converters. The propagation delay of several SFQ logic gates in our cell library named CONNECT were measured in picosecond resolution. Small discrepancy in the propagation delay of picosecond level was observed between measurement and circuit simulation results. The discrepancy is well explained assuming the parasitic inductance around shunt resistors of Josephson junctions.