Quantum Spin Qubit Device Electrostatic Grid Addressing

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Solution Overview

Problem

The existing quantum device architectures for spin qubits face challenges in addressing qubits efficiently due to the large number of electrical interconnection levels required, especially as matrix size increases, and in producing detection elements with the necessary precision for small qubit dimensions.

Innovation Solution

The proposed quantum device uses electrostatic grids formed by electrically conductive vias to address qubits, reducing the number of electrical interconnection levels needed and allowing for individual control of qubits using two metallization levels, regardless of matrix size, and incorporates charge detectors within a semiconductor layer to facilitate charge detection and exchange.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If direct electrical connections are used to address each qubit in a two-dimensional matrix, then individual qubit addressing is achieved, but the number of electrical interconnection levels increases significantly with matrix size

Engineering Contradiction:
Improvequbit addressing capabilityVSAvoidnumber of electrical interconnection levels
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces electrostatic grids as intermediary structures that control the conduction of tunnel barriers between qubits. Instead of directly connecting each qubit to external control lines, the grids act as mediators that can control multiple tunnel barriers simultaneously through electrostatic fields, thereby reducing the number of direct electrical connections needed

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrostatic grids serve multiple functions: they control the conduction of tunnel barriers, enable qubit addressing, and facilitate charge detection. By making the grids multi-functional, the patent reduces the overall number of separate control mechanisms needed in the system

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Productivity

If qubit dimensions are reduced to increase matrix density, then more qubits can be integrated, but the realization of detection elements becomes difficult

Engineering Contradiction:
Improvequbit integration densityVSAvoiddetection element fabrication
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent positions the electrostatic grids in a third dimension above the qubit plane, rather than confining all elements to a single two-dimensional layer. This vertical arrangement allows detection elements to be realized above the qubits without interfering with the tight lateral spacing between qubits, thus maintaining high integration density while enabling detection element fabrication

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Device complexity

If the number of electrical connections is reduced for scalability, then device complexity decreases, but addressing and detection precision may be compromised

Engineering Contradiction:
Improvenumber of electrical connectionsVSAvoidqubit detection precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the control and detection function into multiple electrostatic grids, each controlling specific tunnel barriers. This segmentation allows precise local control of individual qubit connections while using fewer overall electrical connections, as each grid can be independently controlled to address specific qubits with high precision

Inventive Principle:
Principle #1Segmentation

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 approach enables efficient addressing of qubits with reduced electrical connections and precise production of qubits and detection elements, overcoming the limitations of previous technologies by allowing for smaller qubit dimensions and fewer charge detectors, thus enhancing the scalability and production feasibility of quantum devices.

Implementation Method 1

qubit addressing means configured to control the conduction of tunnel barriers by field effect

Methodology Applied
Scientific EffectField effect: Electric Field

Data Source

PatentEP3401848B1Quantum device with spin qubits
Publication Date: 2021.07.28 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3401848B1 patent drawingFigure 1~2
  • EP3401848B1 patent drawingFigure 3~4
  • EP3401848B1 patent drawingFigure 5~6

AI summary

A quantum device (100) with spin qubits, comprising: - a first semiconductor layer (102) comprising a first matrix of data qubits (104) and measurement qubits (106) connected together by tunnel barriers (108); - qubit addressing means configured to control by field effect the conduction of each of the tunnel barriers and comprising: • first and second conductive portions (116, 124) arranged respectively in a first and second superimposed metallization levels (112, 114); • first and second conductive vias (118, 126) each comprising a first end (120, 128) connected respectively to one of the first and second conductive portions, and a second end (122, 130) arranged opposite one of the tunnel barriers; - a first dielectric layer interposed between the tunnel barriers and the second ends of the first and second conductive vias.