Josephson Transmission Line With Inductive Loop For Unidirectional Pulse Propagation
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Solution Overview
Problem
CMOS technology-based digital circuits face limitations in device size and high power consumption, particularly due to static power dissipation and current leakage even when inactive, leading to inefficiencies in high-performance systems like data center servers.
Innovation Solution
The use of Josephson transmission lines (JTLs) with inductive loops and Josephson junctions, powered by alternating current (AC), which propagate quantum pulses in one direction only, eliminating backward propagation and reducing static power dissipation by using AC power as a stable clock reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If CMOS technology is used for digital circuits, then device functionality and integration are achieved, but power consumption increases and device size reaches limits
Solution Approach 1:
The patent transitions from CMOS technology operating at room temperature with DC voltage to superconducting logic operating at cryogenic temperatures with AC voltage. This fundamental parameter change enables zero static power dissipation while maintaining computational functionality, directly resolving the contradiction between power consumption and device functionality
Solution Approach 2:
The patent replaces the electronic switching mechanism of CMOS transistors with quantum mechanical Josephson junctions that utilize quantum tunneling effects. This substitution enables logic operations with dramatically reduced power consumption while maintaining computational capabilities, addressing the power consumption vs. functionality trade-off
2Loss of energy
If CMOS circuits are kept inactive to save power, then dynamic power consumption decreases, but static power dissipation and current leakage continue
Solution Approach 1:
The patent employs AC voltage biasing with periodic clock signals to control Josephson junctions instead of continuous DC voltage. This periodic action allows circuits to be in a low-power state between clock cycles while maintaining readiness, eliminating static power dissipation that plagues CMOS circuits in idle states
Solution Approach 2:
The transition from DC voltage biasing in CMOS to AC voltage biasing in superconducting logic fundamentally changes the power consumption characteristics. The AC bias enables the circuit to dissipate zero power when inactive, while the clocked operation ensures reliable state transitions when active, resolving the contradiction between energy loss and reliability
3Adaptability or versatility
If Josephson transmission line allows bidirectional pulse propagation, then signal flexibility increases, but unintentional backward pulse propagation causes errors
Solution Approach 1:
The patent introduces asymmetry into the Josephson transmission line by configuring the inductive loop with specific inductance values and Josephson junction parameters that create directional bias. This asymmetric configuration allows pulses to propagate freely in the forward direction while blocking backward propagation, resolving the contradiction between signal flexibility and directional control reliability
Solution Approach 2:
The inductive loop serves as an intermediary element that mediates pulse propagation direction. By carefully designing the loop's inductance and coupling with Josephson junctions, it enables forward pulse propagation while preventing backward propagation, thus maintaining signal flexibility while ensuring reliable unidirectional control
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
This approach enables low-power superconducting logic circuits with zero static power dissipation, preventing unintentional backward pulse propagation and allowing for efficient propagation of digital data through RQL circuits, thus reducing power consumption and improving performance.
Implementation Method 1
at least one Josephson transmission line (JTL) for propagating quantum pulses in a first direction in response to an application of a clock signal having a plurality of phases
Implementation Method 2
a second inductive element coupled between the second terminal and a third terminal... the inductive loop is configured to operate in a mode such that a quantum pulse cannot travel in a second direction
Data Source
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AI summary
Josephson transmission lines (JTLs) for superconducting devices and related methods are provided. In one example, a device comprising a JTL for propagating quantum pulses in a first direction in response to an application of a clock signal having a plurality of phases is provided. The JTL may include a first inductive element coupled between a first terminal and a second terminal, a first Josephson junction (JJ) coupled between the second terminal and a ground terminal, a second inductive element coupled between the second terminal and a third terminal, and a second JJ coupled between the third terminal and the ground terminal. The second inductive element is configured to form an inductive loop, and the inductive loop may be configured to operate in a mode such that a quantum pulse cannot travel in a second direction opposite from the first direction regardless of a phase of the clock signal.