Quantum Computer Shared Control Lines for Scalable Qubit Gates
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Solution Overview
Problem
The scalability of quantum computers is limited by the number of control lines required for qubits, and gate operations on a target qubit can undesirably affect neighboring qubits, leading to decoherence and phase rotation.
Innovation Solution
A quantum computer design with a shared control line for qubit pairs, utilizing PSWAP and iSWAP gates to control multiple qubits simultaneously, allowing for software-based gate operations without affecting non-target qubits, and employing a two-dimensional square lattice arrangement with exchange interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a control line is disposed for each of all qubits, then gate operation can be precisely controlled, but the number of qubits that can be made is limited due to the number of control lines
Solution Approach 1:
The patent merges control lines by sharing them among multiple qubit pairs. Specifically, control lines are shared in units of rows or columns, allowing one control line to control multiple qubit pairs simultaneously. This reduces the total number of control lines needed while maintaining the ability to perform gate operations on individual qubits through software-based selection mechanisms.
2Ease of operation
If gate operation is executed on a target qubit by changing gate voltage or applying DC magnetic field, then the target qubit can be controlled, but an undesirable influence (rotation of phase or decoherence) is caused on other qubits
Solution Approach 1:
The patent implements local quality by enabling selective control of specific qubit pairs through software-based selection while using shared control lines. The qubit control section can identify and control only the designated target qubit pair among multiple qubit pairs sharing the same control line, thereby preventing unwanted phase rotation and decoherence on non-target qubits while maintaining precise control capability.
3Quantity of substance
If control lines are shared among qubit pairs, then scalability is improved, but the two-qubit gate is implemented for all qubit pairs in the same column or row simultaneously
Solution Approach 1:
The patent introduces dynamic control through the qubit control section, which can dynamically select which qubit pairs receive the gate operation based on software instructions. Even though control lines are shared and can simultaneously control multiple qubit pairs, the control section can dynamically direct the operation to specific target qubit pairs only, providing selective control capability that adapts to different computational requirements.
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 and scalable gate operations on target qubits while minimizing interference with neighboring qubits, facilitating the implementation of universal quantum computing.
Implementation Method 1
Interaction operated by the shared control line is exchange interaction or XY interaction
Implementation Method 2
when the gate voltage is changed or a DC magnetic field is applied in order to execute gate operation of a target qubit
Data Source
AI summary
A quantum computer has a qubit control section that controls a qubit array in which a plurality of qubits are disposed in a two-dimensional square lattice manner and a shared control line capable of controlling a plurality of qubit pairs composed of a pair of qubits adjacent. The qubit control section controls part of the qubit pairs among the plurality of qubit pairs by a plurality of two-qubit gates that are given a constraint condition relating to a product of operations and that execute operation processing on a plurality of qubit pairs.