Quantum Phase Rotation with Parallel Ancilla State Generation

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Solution Overview

Problem

The execution time of phase rotation gates in quantum computation is prolonged due to high failure probabilities in generating ancilla states, especially when the physical error rate of qubits is high or the code distance of logical qubits is large.

Innovation Solution

A method is implemented to generate ancilla states in parallel using multiple partial areas within an available area, and utilize a phase rotation circuit that stochastically determines the rotation direction, with ancilla states being generated in advance to handle potential failures, and dynamically update the available area during the gate operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the code distance of the logical qubit is increased to improve error correction capability, then the reliability of quantum computation is improved, but the failure probability of ancilla state generation increases and the execution time of phase rotation gates is prolonged

Engineering Contradiction:
Improveerror correction capabilityVSAvoidexecution time of phase rotation gate
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The available area is divided into multiple partial areas, and ancilla states are generated in parallel across these partial areas. This segmentation allows simultaneous generation of multiple ancilla states, reducing the total time required while maintaining the code distance necessary for error correction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Ancilla states are generated in advance in parallel before the phase rotation operation is needed. By preparing multiple ancilla states beforehand in different partial areas, the system avoids repeated failure attempts and reduces the overall execution time while maintaining the required error correction capability through appropriate code distance.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the physical error rate of qubits is high, then the reliability of quantum computation deteriorates, but the failure probability of ancilla state generation increases and the execution time is prolonged

Engineering Contradiction:
Improvequantum computation reliabilityVSAvoidexecution time of phase rotation gate
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system divides the available area into multiple partial areas and generates ancilla states in parallel across these segments. This allows the system to compensate for high physical error rates by having multiple independent generation attempts simultaneously, increasing the likelihood of successful ancilla state generation without proportionally increasing execution time.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple ancilla states are generated in advance in parallel before the phase rotation operation. This preliminary action ensures that even with high physical error rates, there is a high probability that at least one ancilla state will be successfully generated, reducing the overall execution time by avoiding repeated failure attempts.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If multiple ancilla states are generated in parallel to reduce execution time, then the productivity of quantum computation is improved, but the device complexity increases

Engineering Contradiction:
Improveexecution speed of phase rotation gateVSAvoidquantum circuit complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The available area is segmented into multiple partial areas that can independently generate ancilla states in parallel. This segmentation enables concurrent operations that reduce execution time while keeping each individual partial area's circuit complexity manageable, as each area operates independently with similar circuit structures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The same basic ancilla state generation circuit structure is reused across multiple partial areas. This universal approach allows parallel generation of multiple ancilla states without proportionally increasing overall circuit complexity, as each partial area uses the same standardized circuit design that can be independently instantiated.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4685710A1Computer program, quantum computation support method, and information processing apparatus
Publication Date: 2026.01.28 FUJITSU LTD
  • EP4685710A1 patent drawingFigure 1
  • EP4685710A1 patent drawingFigure 2
  • EP4685710A1 patent drawingFigure 3

AI summary

An information processing apparatus uses, as an operation target, each of a plurality of partial areas in an available area in which physical qubits available for the phase rotation of a first rotation angle of a state of a logical qubit are arranged. The information processing apparatus instructs a quantum computer to execute an operation of generating a first ancilla state used for the phase rotation of the first rotation angle on each of the plurality of partial areas. The information processing apparatus instructs the quantum computer to execute a phase rotation operation using the first ancilla state indicated in a first partial area in which the first ancilla state has been successfully generated, by using the logical qubit as an operation target.