Amorphous Alloy Nanomagnet for Uniform Quantum-Dot Spin Control
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Solution Overview
Problem
Existing spin-based quantum computing devices face challenges in effectively controlling and manipulating the spins of charge carriers due to limitations in the strength and uniformity of the magnetic fields applied to quantum dots.
Innovation Solution
Incorporating a nanomagnet with an amorphous ferromagnetic alloy, such as a cobalt-iron-boron (CoFeB) alloy, above the quantum dots in the quantum computing device to apply a stronger and more uniform external magnetic field, thereby enhancing the control over the spins of the charge carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional crystalline ferromagnetic material is used for the nanomagnet, then the device structure is simpler to manufacture, but the magnetic field strength and uniformity applied to quantum dots is insufficient
Solution Approach 1:
The patent employs an amorphous ferromagnetic alloy (such as cobalt-iron-boron or cobalt-iron-silicon-boron) for the nanomagnet instead of conventional crystalline materials. This composite material approach provides superior magnetic field strength and uniformity while maintaining compatibility with standard semiconductor fabrication processes, thereby resolving the contradiction between improved spin control reliability and ease of manufacture
Solution Approach 2:
The invention changes the material parameters of the nanomagnet by using amorphous ferromagnetic alloys with specific composition ranges (e.g., CoFeB with 0.2 < y < 1 where composition is Co1-xFexBy). These parameter changes in material composition and structure enable enhanced magnetic field characteristics without requiring fundamentally new manufacturing techniques
2Force
If the magnetic field strength is increased to improve spin control, then the uniformity of the magnetic field across quantum dots deteriorates
Solution Approach 1:
The amorphous ferromagnetic alloy nanomagnet provides both high magnetic field strength and superior uniformity simultaneously. The amorphous structure eliminates grain boundaries and magnetic inhomogeneities present in crystalline materials, while the specific alloy composition ensures strong magnetization, thus resolving the contradiction between field strength and uniformity
Solution Approach 2:
The nanomagnet is designed with specific local properties through the amorphous alloy composition and structure. The material exhibits uniform magnetic characteristics at the local level across the nanomagnet structure, ensuring consistent field distribution over the quantum dot array while maintaining high overall field strength
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 use of an amorphous ferromagnetic alloy nanomagnet increases the strength and uniformity of the magnetic field applied to the quantum dots, leading to improved control over the spins and enhanced reliability in quantum computations.
Implementation Method 1
The nanomagnet is configured to apply an external magnetic field to one or more quantum dots included in a spin-based quantum computing device
Implementation Method 2
The nanomagnet includes an amorphous ferromagnetic alloy
Data Source
Figure 1~2A
Figure 2B
Figure 3
AI summary
A quantum computing device is provided, including a plurality of spin-based quantum-dot qubits that each include one or more quantum dots. The plurality of spin-based quantum-dot qubits also each include a nanomagnet including an amorphous ferromagnetic alloy.