Donor-Quantum Dot Coupling for Scalable Quantum Computing
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Solution Overview
Problem
Current scalable quantum computer architectures face limitations in coupling donor qubits, particularly with nearest neighbor coupling, which restricts the implementation of two and multiqubit logic operations, and require coherent shuttling of electrons between donors for longer range coupling options.
Innovation Solution
A quantum computer architecture that couples donor nuclear spins via donor electron spins to quantum dots, enabling further coupling to high Q resonators and allowing for cluster state quantum computing without the need for donor ionization and recombination, using a substrate with buried oxide, semiconductor layers, and gate-controlled quantum dots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nearest neighbor coupling is used for donor qubits, then fabrication simplicity is improved, but coupling range and multiqubit logic capability deteriorate
Solution Approach 1:
The patent introduces quantum dots as intermediary structures between donor qubits. The quantum dot electron acts as a mediator that couples to multiple donor electrons through exchange interaction, enabling long-range coupling between donor qubits without requiring direct donor-donor proximity. This intermediary mechanism overcomes the limitation of nearest-neighbor coupling while maintaining fabrication simplicity.
Solution Approach 2:
The patent transitions from one-dimensional nearest-neighbor coupling to three-dimensional coupling by introducing vertically stacked quantum dots above donor qubits. This dimensional extension allows coupling between donors that are not adjacent in the lateral plane, enabling long-range interactions through the vertical dimension.
2Adaptability or versatility
If coherent shuttling of electrons between donors is implemented for long range coupling, then coupling range is improved, but system complexity and coherence requirements worsen
Solution Approach 1:
The quantum dot serves as a stationary intermediary that eliminates the need for dynamic electron shuttling. Instead of moving electrons between donors, the quantum dot electron remains localized and mediates coupling through exchange interaction, significantly reducing system complexity and coherence requirements during operation.
Solution Approach 2:
The patent inverts the conventional approach by having the quantum dot mediate coupling rather than directly shuttling electrons between donors. This inversion transforms a dynamic transport problem into a static exchange interaction problem, simplifying the system.
3Adaptability or versatility
If donor ionization and recombination is used for quantum information transfer, then quantum communication capability is improved, but coherence maintenance deteriorates
Solution Approach 1:
The quantum dot electron acts as an intermediary that enables quantum information transfer without requiring donor ionization and recombination cycles. The exchange interaction with the quantum dot provides a coherent pathway for quantum information transfer that maintains donor electron coherence throughout the process.
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
Enables efficient quantum information transfer and implementation of cluster state quantum computing, improving coherence and reducing the need for complex ionization and recombination processes, while maintaining high control over quantum memory and communication channels.
Implementation Method 1
Electrostatic gates facilitate transfer of quantum information from nuclear to electron spins and between electron spins, by modulating the contact hyperfine interaction (A-gates)
Implementation Method 2
Electrostatic gates facilitate transfer of quantum information from nuclear to electron spins and between electron spins, by modulating the contact hyperfine interaction (A-gates), and the Heisenberg exchange coupling (J-gates), respectively
Implementation Method 3
Electrostatic gates facilitate transfer of quantum information from nuclear to electron spins and between electron spins, by modulating the contact hyperfine interaction (A-gates), and the Heisenberg exchange coupling (J-gates), respectively
Data Source
AI summary
A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.