Superconducting Latch Bi-Stable Loop SFQ State Control
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Solution Overview
Problem
Current digital logic technologies, such as CMOS, face limitations in performance metrics like speed, power dissipation, and computational density, prompting the need for alternative solutions like superconducting Josephson junction-based circuits, which require efficient state retention and control mechanisms.
Innovation Solution
A superconducting latch system utilizing bi-stable loops with inductive coupling and DC biasing to generate and manage single flux quantum (SFQ) currents, allowing for state setting and resetting with minimal power dissipation, and non-destructive readout capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMOS technology is used for digital logic, then manufacturing maturity and ease of manufacture are improved, but speed, power dissipation, and computational density performance deteriorate
Solution Approach 1:
The patent replaces conventional CMOS electronic switching mechanisms with superconducting Josephson junction-based single flux quantum (SFQ) circuits. This substitution enables higher computational density and speed by utilizing quantum mechanical effects in superconducting materials, achieving up to 1000 times higher switching speeds while reducing power dissipation per operation.
Solution Approach 2:
The invention changes the fundamental operating parameters by transitioning from resistive CMOS switching to superconducting Josephson junction switching. This involves changing the material state from normal conducting to superconducting, enabling operation at cryogenic temperatures with dramatically improved performance metrics including higher switching speeds and lower power consumption.
2Speed
If superconducting Josephson junction circuits are used, then speed and computational density are improved, but power dissipation control and state retention mechanisms worsen
Solution Approach 1:
The patent employs periodic clocking signals to control the timing and synchronization of SFQ pulses in the latch circuit. This periodic action enables precise control of state transitions while allowing the circuit to enter low-power idle states between clock cycles, thereby managing power dissipation effectively while maintaining high-speed operation during active periods.
Solution Approach 2:
The superconducting latch circuit utilizes the inherent persistence of superconducting currents to maintain state information without continuous power input. The bi-stable loop structure allows the circuit to retain its state through persistent current circulation in the superconducting loop, eliminating the need for continuous refreshing or power input to maintain state, thus significantly reducing power dissipation.
3Loss of energy
If bi-stable loops with inductive coupling are used for state retention, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The patent merges the set and reset control functions into a unified bi-stable loop structure with inductive coupling. By combining multiple functions (state setting, state resetting, and state retention) into a single integrated superconducting loop architecture, the design achieves low power consumption while managing complexity through functional integration rather than separate discrete components.
Solution Approach 2:
The bi-stable loop structure serves multiple functions simultaneously: it acts as the state retention element, the switching mechanism, and the memory element. This multi-functionality reduces the overall device complexity by eliminating the need for separate components for each function, achieving power-efficient operation with a compact unified structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively retains and switches states with low power consumption, enhancing performance by utilizing bi-stable currents and SFQ pulses to manage the latch's state, thereby addressing the limitations of traditional digital logic technologies.
Implementation Method 1
the set superconducting loop and the reset superconducting loop are both inductively coupled and DC biased to produce a first bi-stable current in the set superconducting loop and a second bi-stable current in the reset superconducting loop
Implementation Method 2
A superconducting latch system utilizing bi-stable loops with inductive coupling and DC biasing to generate and manage single flux quantum (SFQ) currents
Implementation Method 3
superconducting Josephson junctions, with typical signal power of around 4 nW (nanowatts), at a typical data rate of 20 Gb/s (gigabytes/second), or greater, and operating temperatures of around 4° Kelvin
Data Source
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AI summary
A reciprocal quantum logic (RQL) latch system is provided. The latch system comprises an output portion that retains a state of the latch system, and a bi-stable loop that comprises a set input, a reset input and an output coupled to the output portion. A positive single flux quantum (SFQ) pulse on the set input when the latch system is in a reset state results in providing a SFQ current in the output portion representative of the latch system being in a set state.