SQUID ADC Polarity Sampling With Josephson Junction Pulse Readout
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Solution Overview
Problem
Existing superconducting analog-to-digital converters (ADCs) face limitations in sensitivity and responsiveness due to the properties of Josephson junctions, which can hinder overall device performance in applications requiring high-speed and low-power operation.
Innovation Solution
A superconducting ADC system utilizing a superconducting quantum interference device (SQUID) with paired Josephson junctions, where an interrogation pulse induces trigger currents based on input current polarity to generate distinct output pulses, indicating the input current polarity through output stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Josephson junctions are used in superconducting ADCs, then the device can operate at low temperature with high speed, but the sensitivity and responsiveness are limited by the properties of the Josephson junctions
Solution Approach 1:
The invention divides the single Josephson junction into multiple parallel Josephson junctions (first, second, third, and fourth junctions) within the SQUID structure. This segmentation allows the input current to be distributed across multiple junctions, enhancing the overall sensitivity and responsiveness of the ADC while maintaining superconducting operation at low temperatures.
Solution Approach 2:
The SQUID structure is designed to perform multiple functions: it serves as both the sensing element for detecting input current polarity and as the switching element for generating output pulses. The parallel Josephson junctions within the SQUID provide universal functionality for handling different input conditions while maintaining consistent performance characteristics.
2Productivity
If superconducting ADCs are designed to operate at high speed, then data rate increases, but power dissipation and device complexity increase
Solution Approach 1:
The invention operates the superconducting ADC at cryogenic temperatures (around 4 Kelvin), which fundamentally changes the operating parameters of the Josephson junctions. This temperature parameter change enables the junctions to switch at extremely high speeds with minimal power dissipation, as the superconducting state allows for lossless current flow and rapid switching transitions.
Solution Approach 2:
The ADC utilizes periodic interrogation pulses to sample the input current and trigger the Josephson junctions. This periodic action synchronizes the high-speed switching events, allowing the system to achieve high data rates through controlled, repetitive operation rather than continuous high-power consumption.
3Measurement precision
If the SQUID uses multiple parallel Josephson junctions to enhance sensitivity, then the device can detect smaller current signals, but the device complexity increases
Solution Approach 1:
The invention merges multiple Josephson junctions into a unified SQUID structure where the junctions are connected in parallel between common nodes. This merging approach allows the individual junctions to work together as a single sensing element, achieving enhanced sensitivity through their combined response to input current while maintaining a compact and manageable device architecture.
Solution Approach 2:
The SQUID structure itself acts as an intermediary that simplifies the complexity of having multiple Josephson junctions. By enclosing the parallel junctions within the superconducting loop of the SQUID, the device provides a unified interface for current input and pulse output, masking the internal complexity of multiple junctions with a simple external 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 efficiently converts input current polarity to output pulses, enhancing sensitivity and responsiveness, enabling high-speed, low-power operation with improved device performance.
Implementation Method 1
superconducting Josephson junctions... The first Josephson junction can be configured to trigger to provide a first pulse in response to the interrogation pulse and a first polarity of the input current and the second Josephson junction can be configured to trigger to generate a second pulse
Implementation Method 2
a control line configured to propagate an interrogation pulse
Data Source
AI summary
One example includes a superconducting analog-to-digital converter (ADC) system. The system includes a control line configured to propagate an interrogation pulse and a superconducting quantum interference device (SQUID) comprising a first Josephson junction and a second Josephson junction. The SQUID can be configured to receive an input current. The first Josephson junction can be configured to trigger to provide a first pulse in response to the interrogation pulse and a first polarity of the input current and the second Josephson junction can be configured to trigger to generate a second pulse in response to the interrogation pulse and a second polarity of the input current. The system further includes an output stage configured to propagate the first pulse to an output to indicate the first polarity of the input current.