Quantum Memory Timing Control via Flux Pump Scheduling
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Solution Overview
Problem
Superconducting digital technology lacks adequate capacity and speed for random-access memory (RAM) relative to logic circuits, limiting its integration density and application in high-speed and quantum computing, due to fundamental limitations in magnetic flux quanta and timing attributes differing from other memory systems.
Innovation Solution
A quantum memory system with an array of Josephson junction superconducting memory cells, controlled by an array controller that manages access through flux pumps and a timing controller to prevent collisions and optimize access timing, allowing efficient read and write operations by queuing requests and utilizing low-amplitude currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If magnetic flux quanta are used for superconducting memory, then superconducting operation is achieved, but integration density is limited due to fundamental size limitations of inductive loops
Solution Approach 1:
The patent replaces the mechanical/physical constraint of large inductive loops with a different physical mechanism - using Josephson junctions and magnetic coupling to achieve memory functionality. This substitution allows memory cells to be implemented without the fundamental size limitations of traditional superconducting inductive loops, thereby improving integration density while maintaining superconducting operation
Solution Approach 2:
The patent changes the fundamental operating parameters from relying on large magnetic flux quanta in inductive loops to using quantum tunneling effects in Josephson junctions. By changing the physical mechanism from classical magnetic flux storage to quantum-based Josephson effects, the system achieves both superconducting operation and higher integration density
2Speed
If traditional superconducting memory is used, then superconducting speed is achieved, but timing collisions occur due to fundamentally different timing attributes
Solution Approach 1:
The patent introduces timing controller circuits that monitor and control the timing of read and write operations. These controllers use feedback mechanisms to detect potential timing collisions and adjust operation timing accordingly, ensuring reliable operation while maintaining superconducting speed performance
Solution Approach 2:
The patent implements preliminary timing control by pre-scheduling and coordinating read and write operations before they execute. The timing controller circuits prepare and manage operation sequences in advance, preventing timing collisions before they can occur while maintaining high-speed superconducting operation
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 enhances memory access efficiency by preventing collisions and optimizing timing, thereby improving the integration density and performance of quantum memory systems, enabling more effective integration with high-speed and quantum computing applications.
Implementation Method 1
a hysteretic magnetic Josephson junction (HMJJ). The HMJJ can store a binary value and convert superconducting pairs associated with the read current flowing through the HMJJ from a singlet-state to a triplet-state
Implementation Method 2
The system further includes a write circuit magnetically coupled to the HMJJ and configured to write the binary value into the at HMJJ
Data Source
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AI summary
One embodiment describes a quantum memory system. The system includes a plurality of quantum memory cells arranged in an array of rows and columns. Each of the plurality of quantum memory cells can be configured to store a binary logic state in response to write currents in a write operation and configured to provide an indication of the binary logic state in response to read currents in a read operation. The system also includes an array controller comprising a plurality of flux pumps configured to provide the write currents and the read currents with respect to the rows and columns. The array controller can be configured to control timing associated with the write operation and the read operation in response to memory request signals based on application of the write currents and the read currents and based on recharging flux associated with the plurality of flux pumps.