  The recent progress in quantum computing and space exploration led to a surge
in interest in cryogenic electronics. Superconducting devices such as Josephson
junction, Josephson field effect transistor, cryotron, and superconducting
quantum interference device (SQUID) are traditionally used to build cryogenic
logic gates. However, due to the superconducting nature, gate-voltage-based
control of these devices is extremely difficult. Even more challenging is to
cascade the logic gates because most of these devices require current bias for
their operation. Therefore, these devices are not as convenient as the
semiconducting transistors to design logic gates. Here, to overcome these
challenges, we propose a ferroelectric SQUID (FeSQUID) based voltage-controlled
logic gates. FeSQUID exhibits two different critical current levels for two
different voltage-switchable polarization states of the ferroelectric. We
utilize the polarization-dependent (hence, voltage-controllable)
superconducting to resistive switching of FeSQUID to design Boolean logic gates
such as Copy, NOT, AND, and OR gates. The operations of these gates are
verified using a Verilog-A-based compact model of FeSQUID. Finally, to
demonstrate the fanning out capability of FeSQUID-based logic family, we
simulate a 2-input XOR gate using FeSQUID-based NOT, AND, and OR gates.
Together with the ongoing progress on FeSQUID-based non-volatile memory, our
designed FeSQUID-based logic family will enable all-FeSQUID based cryogenic
computer, ensure minimum mismatch between logic and memory blocks in terms of
speed, power consumption, and fabrication process.
