Quantum Dot Nanowire Layout for Multi-Dot Charge Sensing
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Solution Overview
Problem
Existing charge sensing technologies for large-scale quantum processing systems face limitations in sensing multiple quantum dots due to decreased capacitive coupling and increased chip size, particularly when using single electron transistors (SETs), which restricts the number of quantum dots that can be sensed effectively.
Innovation Solution
A quantum processing device architecture utilizing functional and sensing nanowires with floating couplers and gate electrodes to form quantum dots electrostatically, allowing a remote SET to sense charge transitions in multiple quantum dots through capacitive coupling, thereby increasing the number of quantum dots sensed without increasing chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If single electron transistors are used to sense charge transitions in quantum dots, then charge sensing capability is achieved, but the number of quantum dots that can be sensed effectively is limited due to decreased capacitive coupling and increased chip size
Solution Approach 1:
The patent transitions from planar charge sensing to three-dimensional quantum dot arrays with vertical stacking. Multiple quantum dots are arranged in vertical columns along the nanowire axis, enabling a single SET to sense multiple quantum dots through capacitive coupling along the wire length rather than requiring lateral expansion of the chip area.
Solution Approach 2:
The patent implements a hierarchical sensing architecture where a single SET is nested within a structure that can sense multiple quantum dots through intermediate coupling. The SET is positioned to sense charge transitions in multiple quantum dots arranged along the nanowire, creating a nested sensing capability where one sensor serves multiple quantum systems.
2Measurement precision
If quantum dots are spaced further apart to reduce interaction, then individual quantum dot control is improved, but capacitive coupling between sensing SET and quantum dots decreases
Solution Approach 1:
The patent introduces intermediate coupling structures and gate electrodes that mediate the capacitive coupling between the SET and distant quantum dots. These intermediate elements enhance the sensing capability without requiring the SET to be in direct close proximity to all quantum dots, allowing precise sensing while maintaining coupling strength through the intermediate coupling mechanism.
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 solution enables efficient sensing of charge transitions in multiple quantum dots, maintaining strong capacitive coupling and reducing the footprint of quantum processing elements by using a single SET to detect changes in electric charges across a larger number of quantum dots.
Implementation Method 1
one or more gate electrodes capacitively coupled to each of the one or more functional nanowires; one or more gate electrodes capacitively coupled to the sensing nanowire; a floating coupler positioned between and electrostatically coupling the one or more functional nanowires and the sensing nanowire
Implementation Method 2
A confining arrangement is utilized for confining one or more electrons in the silicon substrate to form the quantum dot and a control arrangement (e.g., a gate) is formed on the dielectric material to control the confined electron
Data Source
AI summary
The present disclosure provides a quantum processing device comprising: one or more functional nanowires, each functional nanowire connected to at least one of a source and a drain; a sensing nanowire spaced from the one or more functional nanowires and connected to at least one of a source and a drain; one or more gate electrodes capacitively coupled with each of the one or more functional nanowires; one or more electrodes capacitively coupled with the sensing nanowire; and a floating coupler positioned between and electrostatically coupling the one or more functional nanowires and the sensing nanowire; and a controller connected to the one or more gates of the sensing nanowire and the one or more gates of the one or more functional nanowires.