Electron-Hole Spin Qubit Transistor with 3D Islands for Low Crosstalk

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional spin qubits based on heterostructures like Si(1-x)Ge(x)/Ge or AlGaAs/GaAs suffer from limitations in scalability and require improvements for realizing efficient quantum computers.

Innovation Solution

The development of an electron-hole spin qubit transistor with 3-dimensional semiconductor islands that utilize electron-hole pairs for quantum information encoding, featuring unique resonance frequencies and microwave modulation, enabling scalable quantum computers with improved fidelity and reduced cross-talk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional spin qubits based on heterostructures like Si(1-x)Ge(x)/Ge or AlGaAs/GaAs are used, then quantum computing can be realized, but scalability is limited

Engineering Contradiction:
ImprovescalabilityVSAvoidqubit performance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention divides the qubit into separate semiconductor islands (first computing semiconductor island, second computing semiconductor island, first readout semiconductor island, second readout semiconductor island) that can be independently fabricated and scaled. This segmentation enables modular assembly and improved scalability while maintaining qubit functionality through defined tunnel junctions between islands.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from conventional 2D heterostructure confinement to 3D quantum confinement by forming semiconductor islands with height comparable to their lateral dimensions. This three-dimensional confinement provides enhanced quantum confinement effects, improved charge stability, and better scalability for quantum computing applications.

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

2Object-affected harmful factors

If 2-dimensional electron gas is used to create potential energy landscape, then quantum confinement is achieved, but cross-talk between qubits increases

Engineering Contradiction:
Improvecross-talkVSAvoidqubit structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention extracts the electron-hole pairs from the continuous 2D electron gas and confines them in discrete semiconductor islands. This extraction isolates the quantum states spatially, reducing interactions and cross-talk between neighboring qubits while maintaining the necessary quantum confinement for coherent operations.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces tunnel junctions as intermediaries between the computing and readout semiconductor islands. These tunnel junctions provide controlled coupling for quantum state transfer and measurement while isolating the qubits from each other, thereby reducing cross-talk without compromising quantum operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Length of moving object

If semiconductor islands are placed closer together to reduce distance, then quantum operations improve, but fabrication precision requirements increase

Engineering Contradiction:
Improvedistance between islandsVSAvoidisland positioning accuracy
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The invention optimizes the size and spacing parameters of the semiconductor islands to achieve effective quantum coupling at distances of 3-10 nm while maintaining manufacturability. By carefully selecting island dimensions and separation distances, the invention balances quantum operational effectiveness with fabrication precision requirements.

Inventive Principle:
Principle #35Parameter changes

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 electron-hole spin qubit transistor achieves high-fidelity quantum computations with scalable qubits, allowing for entangled states and efficient quantum operations, such as Rabi oscillations, with reduced error rates and longer decoherence times.

Implementation Method 1

each of said semiconductor islands has a size causing each of said semiconductor islands to exhibit 3-dimensional quantum confinement of a single electron-hole

Methodology Applied
Scientific EffectQuantum confinement: Potential Well

Implementation Method 2

each of said semiconductor islands forms a heterojunction with the base layer

Methodology Applied
Scientific EffectHeterojunction:

Implementation Method 3

a first gate terminal arranged over the first computing semiconductor island, the first gate terminal being configured for microwave modulation of the spin state of the first computing semiconductor island

Methodology Applied
Scientific EffectMicrowave modulation: Microwave Radiation

Implementation Method 4

a first qubit comprising: a first computing semiconductor island and a first readout semiconductor island arranged with a distance in the range of 3-10 nm therebetween

Methodology Applied
Scientific EffectQuantum tunneling:

Data Source

PatentEP4487380B1Electron hole spin qubit transistor, and methods for forming a electron hole spin qubit transistor
Publication Date: 2025.09.03 EPINOVATECH AB
  • EP4487380B1 patent drawingFigure 1~3b
  • EP4487380B1 patent drawingFigure 4a~5
  • EP4487380B1 patent drawingFigure 6

AI summary

The present inventive concept relates to a spin qubit transistor (100) comprising a base layer (102), a first qubit comprising, a first computing semiconductor island (106) and a first readout semiconductor island (108) arranged with a distance in the range of 3-10 nm therebetween, a second qubit comprising, a second computing semiconductor island (110) and a second readout semiconductor island (112) arranged with a distance in the range of 3-10 nm therebetween, wherein each of said semiconductor islands has a size causing each of said semiconductor islands to exhibit 3-dimensional quantum confinement of a single electron hole, and wherein each of said semiconductor islands forms a semiconductor heterojunction with the base layer. Each of the semiconductor islands has a corresponding gate (G1-G4), for modulation of the computing islands or readout of the readout islands. Said first computing semiconductor island and said second computing semiconductor island are configured to have a unique resonance frequency respectively. A control electrode arrangement (B) between the computing and the readout islands controls the coupling between the qubits. The present inventive concept further comprises a method for forming a spin qubit transistor and a quantum computer comprising at least one spin qubit transistor.