Superconducting Digital Logic Families Using Quantum Phase-slip Junctions

Juan José García‐Ripoll, E. Torrontegui, Andrés Ruiz-Chamorro

Uday S. Goteti, Michael C. Hamilton

Superconducting digital computing systems, primarily involving Josephson junctions are actively being pursued as high performance and low energy dissipating alternatives to CMOS-based technologies for petascale and exascale computers, although several challenges still exist in overcoming barriers to practically implement these technologies. In this paper, we present an alternative superconducting logic structure: quantized charge-based logic circuits using quantum phase-slip junctions, which have been identified as dual devices to Josephson junctions. Basic principles of logic implementation using quantum phase-slips are presented in simulations with the help of a SPICE model that has been developed for the quantum phase-slip structures. Circuit elements that form the building blocks for complex logic circuit design are introduced. Two different logic gate designs: or gate and xor gate are presented to demonstrate the usage of the building blocks introduced.

Azam Malekpoor, Seyed Amir Hashemi, Satyabrata Jit

In this article, the quantum phase slip junction (QPSJ) based full adder, multiplexer, and demultiplexer memoryless circuits for superconducting digital applications are designed for the first time. Generally, the memoryless circuits are implemented by interconnection of the basic gates (i.e., AND, OR, NOT). So in this article, the structures of the QPSJ-based AND and OR gates are also modified in order to reduce the complexity of their connections to the other gates by removing or changing the location of the clock pulse from their output branches. When a gate is connected to the next one, the elements of the second gate are loaded to the circuit of the first gate. The output current of the first gate will be affected due to this loading and no Cooper pair may be produced at its output and the next connected gate will not be switched. Therefore, the main tip in designing of these circuits is that each constituent gate must provide the necessary output current to drive the next connected gates, since each gate is driven by one Cooper pair. In this article, providing sufficient output current for each gate has been observed by 1) selecting proper critical voltages of the QPSJs and 2) by adding extra elements to or removing some elements from the connected gates in the proposed memoryless circuits.

U. Las Heras, Laura García-Álvarez, Lucas Lamata +1 more

Babak Dastbarjan Boroujeni, Seyed Amir Hashemi, Satyabrata Jit

Quantum phase slip (QPS) junction can act as a superconductor switch when a voltage pulse larger than its critical voltage is applied to it. As a result, a current pulse with an area equal to 2e(or multiples of 2e) flows across the junction, and the junction switches from zero to one in the charge-base logic. For having a proper operation simulation of the QPS junction, it should be overdamped, and the damping factor should be less than one. Physical parameters of the QPS junction, namely, the normal resistance, the kinetic inductance, and the critical voltage, can affect the overdamping condition and switching behavior of the junction, as well as the damping factor. The basic block for designing the QPS logic gates is the charge island. By different and proper connections of the charge islands, basic QPSand, or, andxorlogic gates are designed. Generally, each of these gates has its own circuit and junction parameters for proper operation. In this manuscript, a universal QPS logic gate is proposed that can perform basicand, or, andxorBoolean functions by proper selection of parameters for QPS junctions in the case of each Boolean function. This universal QPS logic gate can simplify the design the complicated QPS logic circuits, since only the parameters of each junction have to be properly selected for achieving the desired Boolean function, and the gate circuit topology remains unchanged.

Mutuso Hidaka