Solid State Charge Qubit Device Using Dopant Atoms
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Solution Overview
Problem
Existing quantum computing proposals face challenges in scalability and error correction due to decoherence, requiring hundreds of gates for useful tasks and increased qubits, with real spin qubits offering longer decoherence times but restricted clock speed and complex measurement processes.
Innovation Solution
A quantum device using a pair of dopant atoms in a solid semiconductor or insulator substrate, creating a double-well potential for charge qubits with external gate control, allowing for scalable and faster logic operations and easier measurement, while minimizing environmental coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If real spin qubits are used, then decoherence time is extended, but clock speed is restricted and measurement complexity increases
Solution Approach 1:
The patent transitions from spin-based qubits to charge-based qubits, fundamentally changing the physical parameter used for quantum state encoding. This parameter change enables faster clock speeds while maintaining acceptable decoherence times through the use of dopant atoms in solid-state substrates with carefully controlled environmental coupling.
Solution Approach 2:
The patent replaces the magnetic moment-based spin system with an electric charge-based system. This substitution allows for faster manipulation and readout of quantum states through electrical fields and voltages, significantly improving clock speed while enabling simpler measurement processes through charge detection.
2Speed
If charge qubits are used, then clock speed increases and measurement becomes easier, but scalability and error correction are challenged by decoherence
Solution Approach 1:
The patent introduces gate electrodes as intermediary elements that mediate between the external control environment and the quantum dot system. These gates allow precise electrical control of the quantum states while the quantum dots remain isolated in the semiconductor substrate, protecting against environmental decoherence while enabling fast manipulation and easy readout.
Solution Approach 2:
The patent creates localized quantum states within individual quantum dots formed by dopant atoms in the semiconductor lattice. Each quantum dot provides a confined potential well that traps charge carriers, creating isolated quantum systems with distinct local properties that can be independently controlled and measured, enhancing both reliability and scalability.
3Adaptability or versatility
If hundreds of gates are required for useful tasks, then computational capability increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the quantum computing system into modular units consisting of individual quantum dots, each capable of hosting qubits. Multiple quantum dots can be arranged in arrays on a single semiconductor substrate, with gate electrodes providing control over each dot. This segmentation enables scalable construction of complex quantum circuits while maintaining manageable device complexity through standardized building blocks.
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 solution enables scalable quantum computing with faster clock speeds and reduced decoherence errors, facilitating the implementation of quantum logic operations and readout processes, thus addressing the limitations of existing technologies.
Implementation Method 1
The two dopants produce a double-well electric potential and a charge qubit is realised by the location of one or more electrons or holes within this potential
Implementation Method 2
The logical states of the charge qubit is formed by either the location of a single electron in one or other well of the double-well potential
Data Source
AI summary
Ionisation of one of a pair of dopant atoms in a substrate creates a double well potential, and a charge qubit is realised by the location of one or more electrons or holes within this potential. The dopant atoms may comprise phosphorous atoms, located in a silicon substrate. A solid state quantum computer may be formed using a plurality of pairs of dopant atoms, corresponding gate electrodes, and read-out devices comprising single electron transistors.