Differential Coupled-Line Qubit Layout for Low-Crosstalk Coupling
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Solution Overview
Problem
Existing quantum bit devices face challenges in enhancing electromagnetic field extraction efficiency while minimizing crosstalk between quantum bits, particularly when multiple quantum bits are connected via capacitive coupling.
Innovation Solution
The quantum bit device employs a coupled line formed by differential wiring, where one wiring is provided on a separate connection substrate, allowing capacitive coupling between quantum bits, thereby improving electromagnetic field extraction efficiency and reducing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitance of the capacitor in the coupled line is increased to improve electromagnetic field extraction efficiency, then the extraction efficiency improves, but the crosstalk between quantum bits increases
Solution Approach 1:
The patent transitions from a planar coupled line configuration to a three-dimensional stacked configuration where quantum bits are arranged on different substrates (first substrate and second substrate). The coupled line connects quantum bits across these substrates, utilizing the vertical dimension to reduce in-plane crosstalk while maintaining extraction efficiency through optimized capacitive coupling between substrates.
Solution Approach 2:
The patent divides the quantum bit device into separate modular units (quantum bits on different substrates) connected by coupled lines. This segmentation allows independent optimization of each quantum bit's ground capacitance while controlling inter-bit coupling through the coupled line design, thereby reducing unwanted crosstalk.
2Adaptability or versatility
If multiple quantum bits are connected via capacitive coupling using a coupled line, then quantum operations can be performed between bits, but crosstalk between adjacent quantum bits occurs
Solution Approach 1:
By arranging quantum bits on stacked substrates and connecting them via coupled lines that extend between substrates, the patent enables controlled quantum operations between bits while spatially separating them in the vertical dimension to minimize parasitic coupling and crosstalk.
Solution Approach 2:
The coupled line acts as an intermediary element that mediates the interaction between quantum bits. It provides a controlled capacitive coupling path that enables desired quantum operations while its specific design (including grounding structures) suppresses unwanted crosstalk, effectively filtering harmful interactions.
3Quantity of substance
If a concentric pattern with circular inner electrode and annular outer electrode is used, then ground capacitance increases, but electromagnetic field extraction efficiency decreases
Solution Approach 1:
The patent applies different structural characteristics to different parts of the quantum bit system. The ground electrode structure is optimized locally at each quantum bit to provide sufficient ground capacitance, while the coupled line structure is optimized to enable efficient electromagnetic field extraction. This local optimization allows both requirements to be satisfied simultaneously without compromise.
Solution Approach 2:
The patent moves the coupled line configuration into the vertical dimension by placing quantum bits on stacked substrates. This allows the ground capacitance to be optimized in the planar direction (through substrate grounding) while electromagnetic field extraction is optimized through the vertical coupled line connection, separating the two functions spatially.
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 configuration enhances signal transmission efficiency and reduces the risk of crosstalk by using differential wiring, allowing for improved electromagnetic field extraction and increased resistance to noise.
Implementation Method 1
a coupled line including a first wiring and a second wiring forming a differential pair and forming capacitive coupling between the first quantum bit and the second quantum bit
Data Source
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AI summary
A quantum bit device includes a quantum bit substrate having a first quantum bit and a second quantum bit, a connection substrate provided to face the quantum bit substrate, and a coupled line including a first wiring and a second wiring forming a differential pair and forming capacitive coupling between the first quantum bit and the second quantum bit. At least one of the first wiring or the second wiring is provided on the connection substrate.