Multi-Gate FET Qubit Layout for Stable Quantum Dot Confinement
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Solution Overview
Problem
Current nanowire-based quantum bits (qubits) face challenges in scalability, producibility, and reliability, particularly for high-density three-dimensional integration, due to their fragile nature and interaction with external environmental degrees of freedom.
Innovation Solution
A field-effect transistor element with a multi-gate configuration, featuring at least two primary gate regions with parallel main directions of extension and at least one secondary gate region with a main direction of extension orthogonal to the primary gates, allowing for electrostatic confinement and potential confinement of quantum dots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nanowire-based quantum bits are used, then sufficient energy discrepancy in electron/hole states can be achieved, but variability and manufacturing precision deteriorate
Solution Approach 1:
The device is segmented into multiple gate regions (first gate region, second gate region, third gate region) that independently control different aspects of the quantum dot formation. This segmentation allows precise control over energy levels and spatial confinement separately, enabling energy discrepancy to be optimized without being constrained by manufacturing variability in a single monolithic structure.
Solution Approach 2:
The patent transitions from conventional planar or simple vertical gate structures to a three-dimensional arrangement where gates are positioned at different spatial locations (front surface and back surface, different lateral positions). This dimensional approach allows independent optimization of energy confinement and spatial confinement, decoupling the control parameters to reduce variability effects.
2Reliability
If quantum bits are made more stable against environmental interactions, then reliability improves, but device complexity increases
Solution Approach 1:
The multiple gate regions serve multiple functions simultaneously: they control quantum dot formation, adjust energy levels, provide spatial confinement, and enable independent tuning of different quantum states. This multi-functionality allows the device to achieve high reliability through comprehensive environmental control without requiring separate dedicated structures for each function, thereby managing complexity efficiently.
Solution Approach 2:
The patent employs independent voltage control of multiple gate regions to dynamically adjust energy levels and confinement potentials. By changing electrical parameters (voltages applied to different gates) rather than physically reconfiguring the device, the system achieves high stability and adaptability with relatively simple control circuitry, avoiding excessive complexity.
3Productivity
If high-density three-dimensional integration is achieved, then productivity improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes three-dimensional space by positioning gate regions at different vertical and lateral locations (front and back surfaces, different x-y positions). This 3D arrangement enables high integration density by stacking and distributing quantum dots in multiple layers and positions, while the independent gate control allows each quantum dot to be precisely tuned despite variations from high-density fabrication processes.
Solution Approach 2:
By dividing the device into multiple independently controllable gate regions and quantum dot units, the patent enables modular high-density integration. Each segment can be manufactured with standard precision tolerances, but the independent control of each segment compensates for cumulative errors, allowing high overall integration density without requiring extremely tight manufacturing precision across the entire device.
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 design achieves a high energy difference between the ground state and the first excited state of the quantum dot, enhancing resistance to environmental fluctuations and enabling the creation of a 'hot spin quantum bit' with improved scalability, producibility, and reliability.
Implementation Method 1
The field-effect transistor element allows for forming electrostatically, depending on the number of primary gate regions, at least one zero-dimensional quantum dot in the channel region
Implementation Method 2
the proposed field-effect transistor element with multi-gate configuration allows for using potential confinement instead of using physical confinement for hosting qubits
Implementation Method 3
to leverage the Coulomb Blockade effect
Data Source
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AI summary
A quantum dot device (100) for use as a qubit in a quantum computer is disclosed, comprising a channel region (106), a source region (108), a drain region (110), and at least two primary gate regions (120, 122, 124), wherein the at least two primary gate regions (120, 122, 124) are respectively provided with a main direction of extension (126, 128, 130) and disposed on a first surface of the channel region (106), and wherein the respective main directions of extension of the at least two primary gate regions are arranged substantially parallel to each other, at least one secondary gate region (118) having a main direction of extension (132) and disposed on a second opposite surface of the channel region (106), wherein the main direction of extension (132) of the at least one secondary gate region (118) is arranged substantially orthogonally to the respective main directions of extension (126, 128, 130) of the at least two primary gate regions (120, 122, 124). The device may also be formed in a non-planar semiconductor body, like a fin, see figure 6.