Sergey K. Tolpygo

Massachusetts Institute of Technology

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Evan Golden

Massachusetts Institute of Technology

Vladimir Bolkhovsky

MIT Lincoln Laboratory

ВС

В.К. Семенов

Stony Brook University

Terence J. Weir

MIT Lincoln Laboratory

M. Gurvitch

Stony Brook University

L. M. Johnson

MIT Lincoln Laboratory

M.A. Gouker

Massachusetts Institute of Technology

Alex Wynn

MIT Lincoln Laboratory

I. G. Mikhaǐlov

Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing

J. E. Lukens

United States Military Academy

Cooperative Institutions

Massachusetts Institute of Technology

MIT Lincoln Laboratory

Stony Brook University

State University of New York

National Academy of Sciences of Ukraine

Hypres (United States)

M.N. Mikheev Institute of Metal Physics

Lomonosov Moscow State University

Quantum Devices (United States)

University of California, Berkeley

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Characterization of Flux Trapping in and Fabrication of Large-Scale Superconductor Circuits Using AC-Biased Shift Registers with 108,500 Josephson Junctions

IEEE Transactions on Applied Superconductivity (2025)

Evan Golden Neel A. Parmar В.К. Семенов Sergey K. Tolpygo

10.1109/tasc.2025.3530390

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Extraction and Simulation of the Impact of Flux Trapping in Moats on AC-Biased Shift Registers

IEEE Transactions on Applied Superconductivity (2025)

Scott Meninger Sergey K. Tolpygo

10.1109/tasc.2025.3527936

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Extending Superconducting Qubits Out of Plane (Part 2): Through-Silicon Vias

Bulletin of the American Physical Society (2020)

Justin Mallek Jonilyn Yoder D. Yost Rabindra Nath Das Alexandra Day

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Wafer-Scale Characterization of a Superconductor Integrated Circuit Fabrication Process, Using a Cryogenic Wafer Prober

IEEE Transactions on Applied Superconductivity (2022)

Joshua T. West A. Kurlej Alex Wynn Chad S. Rogers M.A. Gouker

Using a fully automated cryogenic wafer prober, we measured superconductor fabrication process control monitors and simple integrated circuits on 200-mm wafers at 4.4 K, including SQIF-based magnetic field sensors, SQUID-based circuits for measuring inductors, Nb/Al-AlO _x /Nb Josephson junctions, test structures for measuring critical current of superconducting wires and vias, resistors, etc., to demonstrate the feasibility of using the system for characterizing niobium superconducting devices and integrated circuits on a wafer scale. Data on the wafer-scale distributions of the residual magnetic field, junction tunnel resistance, energy gap, inductance of multiple Nb layers, and critical currents of interlayer vias are presented. A comparison with existing models is made. The wafers were fabricated in the SFQ5ee process, the fully planarized process with eight niobium layers and a layer of kinetic inductors, developed for superconductor electronics at MIT Lincoln Laboratory, Lexington, MA, USA. The cryogenic wafer prober was developed at HPD/FormFactor, Inc., Boulder, CO, USA.

Kinetic inductance

10.1109/tasc.2022.3172660

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Automatic 4 K Cryogenic Probe Station for DC and Microwave Measurements on 150-mm and 200-mm Wafers

2022 IEEE/MTT-S International Microwave Symposium - IMS 2022 (2022)

Joshua T. West A. Kurlej Alex Wynn Chad Rogers M.A. Gouker

Robust maturation of cryogenic electronics has been limited by the lack of high-throughput measurement capabilities, especially for electronics that operate at 4 K. Automated on-wafer probing to characterize the dc and RF performance of components and complete circuits has been a critical element in the development of room temperature electronics. We report here the development of a fully automated wafer prober that operates with the wafer cooled to a temperature of 4 K and has the ability to null the ambient magnetic field to below 100 nT, which is important for measuring superconducting circuits with the wafer prober.

Cryogenics

10.1109/ims37962.2022.9865525

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Electrical stress effect on Josephson tunneling through ultrathin AlOx barrier in Nb/Al/AlOx/Nb junctions

Journal of Applied Physics (2008)

Sergey K. Tolpygo Denis Amparo

The effect of dc electrical stress and breakdown on Josephson and quasiparticle tunneling in Nb/Al/AlOx/Nb junctions with ultrathin AlOx barriers typical for applications in superconductor digital electronics has been investigated. The junctions' conductance at room temperature and current-voltage (I-V) characteristics at 4.2 K have been measured after the consecutive stressing of the tunnel barrier at room temperature. Electrical stress was applied using current ramps with increasing amplitude ranging from 0 to ~1000 Ic corresponding to voltages across the barrier up to 0.65 V where Ic is the Josephson critical current. A very soft breakdown has been observed with polarity-dependent breakdown current (voltage). A dramatic increase in subgap conductance of the junctions, the appearance of subharmonic current steps, and gradual increase in both the critical and the excess currents as well as a decrease in the normal-state resistance have been observed. The observed changes in superconducting tunneling suggest a model in which a progressively increasing number of defects and associated additional conduction channels (superconducting quantum point contacts (SQPCs)) are induced by electric field in the tunnel barrier. By comparing the I-V characteristics of these conduction channels with the nonstationary theory of current transport in SQPCs based on multiple Andreev reflections by Averin and Bardas, the typical transparency D of the induced SQPCs was estimated as D ~ 0.7. The number of induced SQPCs was found to grow with voltage across the barrier as sinh(V/V_0) with V_0 = 0.045 V, in good agreement with the proposed model of defect formation by ion electromigration. The observed polarity dependence of the breakdown current (voltage) is also consistent with the model.

Tunnel effect

Tunnel junction

10.1063/1.2977725

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Development of a Neuromorphic Network Using BioSFQ Circuits

arXiv (Cornell University) (2024)

Evan Golden В.К. Семенов Sergey K. Tolpygo

Superconductor electronics (SCE) appear promising for low energy applications. However, the achieved and projected circuit densities are insufficient for direct competition with CMOS technology. Original algorithms and nontraditional architectures are required for realizing SCE energy advantages for computing. Neuromorphic computing (NMC) is a commonly discussed deviation from conventional CMOS digital solutions. Instead of mimicking a conventional network of artificial neurons, we compose a network from the previously demonstrated single flux quantum (SFQ) electronics components which we termed bioSFQ. We present a design and operation of a new neuromorphic circuit containing a 3x3 array of bioSFQ cells - superconductor artificial neurons - capable of performing various analog functions and based on Josephson junction comparators with complementary outputs. The resultant asynchronous network closely resembles a three-layer perceptron. We also present superconductor analog memory and the memory Read/Write interface implemented with the neural network. The circuits were fabricated in the SFQ5ee process at MIT Lincoln Laboratory.

Neuromorphic engineering

10.48550/arxiv.2412.16804

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High quality YBa2Cu3O7 Josephson junctions made by direct electron beam writing

Applied Physics Letters (1993)

Sergey K. Tolpygo S. Shokhor B. Nadgorny J.-Y. Lin M. Gurvitch

High-Tc Josephson junctions have been fabricated by direct electron beam writing over YBa2Cu3O7 thin-film microbridges, using scanning transmission electron microscope (STEM) with an accelerating voltage of 80–120 kV. Annealing at 330–380 K increases Tc and Ic of the junctions and makes them more stable. In the operating range of a few degrees below Tc, the junctions show 100% magnetic field modulation of the critical current, microwave-induced Shapiro steps oscillating according to the resistively shunted junction (RSJ) model, and RSJ current-voltage characteristics with IcRn product up to 0.5–0.6 mV at 75 K and 0.3 mV at 77 K.

10.1063/1.110688

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Citations (54)

Response to ‘‘Comment on ‘High quality YBa2Cu3O7 Josephson junctions made by direct electron beam writing’ ’’ [Appl. Phys. Lett. 64, 3190 (1994)]

Applied Physics Letters (1994)

Sergey K. Tolpygo S. Shokhor B. Nadgorny J.‐Y. Lin M. Gurvitch

First Page

10.1063/1.111336

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Superconductivity at 227 K in the system La-Ca-Co-O?

PZETF (1990)

Sergey K. Tolpygo A. E. Morozovskiǐ

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