Logical Qubit Rotation Control for Efficient Resource State Generation

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Solution Overview

Problem

The inefficiency in generating resource states for quantum computation due to repeated syndrome measurements and errors in the state preparation protocol, leading to deteriorated resource state generation efficiency.

Innovation Solution

A method to efficiently generate resource states by dividing the physical qubits into a post-selection area and an error correction area, where errors in the post-selection area are corrected before accepting the state as a resource, and errors in the error correction area are corrected separately, thereby reducing the need for repeated resource state generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If syndrome measurement is executed several times in the state preparation protocol to detect errors, then the reliability of resource state generation is improved, but the productivity deteriorates due to repeated generation attempts when errors are detected

Engineering Contradiction:
Improveresource state generation reliabilityVSAvoidresource state generation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent divides the physical qubits into two distinct areas: a post-selection area where errors are corrected before accepting the state as a resource, and an error correction area where errors are corrected separately. This segmentation allows the system to maintain high reliability through thorough error checking while improving productivity by avoiding repeated generation attempts for states that pass the post-selection criteria.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary error correction in the post-selection area before the state is accepted as a resource. By performing error correction in advance for the critical post-selection area, the system ensures that only error-free states are used for computation, thereby maintaining reliability without needing to repeatedly generate resource states.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the resource state generation process is redone many times when errors are detected, then the reliability is maintained, but the loss of time increases due to repeated generation attempts

Engineering Contradiction:
Improveresource state generation reliabilityVSAvoidtime for resource state generation
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

By segmenting the physical qubits into post-selection and error correction areas, the patent enables parallel error correction operations. The post-selection area is corrected beforehand to ensure resource state quality, while the error correction area handles remaining errors separately. This reduces the need for repeated generation attempts and minimizes time loss.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent maintains continuous error correction operation across both areas simultaneously. While the post-selection area undergoes preliminary correction, the error correction area continues error correction operations without interruption. This continuous action ensures reliable resource state generation without stopping for repeated attempts, thereby reducing time loss.

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If all physical qubits are subjected to error correction, then the reliability is improved, but the device complexity increases due to the need to manage errors in all qubits uniformly

Engineering Contradiction:
Improveresource state generation reliabilityVSAvoiderror correction process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the physical qubits into two functional areas with different error correction requirements. The post-selection area receives preliminary error correction to ensure resource state quality, while the error correction area handles remaining errors separately. This segmentation simplifies the overall error correction process by avoiding uniform treatment of all qubits and enabling targeted correction strategies.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by providing different error correction treatments to different parts of the system. The post-selection area receives enhanced preliminary correction since it directly affects resource state quality, while the error correction area receives standard correction. This localized approach maintains reliability without uniformly increasing complexity across all qubits.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4651041A1Computer program and quantum computation control method
Publication Date: 2025.11.19 FUJITSU LTD
  • EP4651041A1 patent drawingFigure 1
  • EP4651041A1 patent drawingFigure 2
  • EP4651041A1 patent drawingFigure 3

AI summary

A computer determines, based on a logical rotation angle for rotating the state of a logical qubit around a predetermined axis, a physical rotation angle around the predetermined axis to be applied to d first physical qubits among a plurality of physical qubits constituting the logical qubit. The computer instructs a quantum computer including the plurality of physical qubits to execute a rotation gate operation of rotating the state of each of the d first physical qubits around the predetermined axis by the physical rotation angle. The computer specifies application of an m-qubit rotation gate to a physical qubit group in which m first physical qubits among the d first physical qubits are collected. The m-qubit rotation gate is to rotate the states of the m first physical qubits by one rotation gate operation.