Ancilla State Error Detection for Reliable Phase Rotation Gates

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The STAR architecture, which uses phase rotation gates to reduce the number of physical qubits, suffers from incomplete error correction, necessitating a reduction in the occurrence of errors in these gates to achieve accurate quantum computations.

Innovation Solution

A computer program that performs gate operations using an ancilla state generation circuit and error detection circuit to generate and verify the state of a gauge qubit, allowing for the detection and correction of errors in phase rotation gates, specifically through the use of a [[4,1,1,2]] code to minimize errors in the ancilla state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the STAR architecture uses phase rotation gates to reduce the number of physical qubits, then the number of physical qubits is reduced and gate operation speed is improved, but error correction becomes incomplete and error occurrence increases

Engineering Contradiction:
Improvenumber of physical qubitsVSAvoiderror correction completeness
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent segments the quantum error correction process into distinct measurement circuits that separately measure different stabilizer operators (e.g., Z-type and X-type stabilizers). This segmentation allows the system to maintain reduced physical qubit usage while systematically addressing different error types through dedicated measurement protocols, thereby improving reliability without increasing qubit count.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediary measurement circuits and ancilla qubits that act as mediators between the phase rotation gates and the error correction process. These intermediaries enable indirect error detection and correction mechanisms that compensate for the incomplete error correction inherent in the STAR architecture, allowing accurate quantum computation with fewer physical qubits.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Speed

If the STAR architecture uses phase rotation gates instead of T gates, then gate operation speed is improved, but error occurrence in phase rotation gates increases

Engineering Contradiction:
Improvegate operation speedVSAvoiderror occurrence rate
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent applies preliminary error mitigation techniques by preparing corrected ancilla states before they are used in phase rotation gate operations. By pre-correcting potential errors in the ancilla states through measurement and verification circuits, the system maintains high gate operation speeds while reducing error propagation, thus improving reliability without sacrificing speed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where measurement results from error detection circuits are used to adjust and correct subsequent gate operations. The system continuously monitors error syndromes and applies corrective operations based on measurement outcomes, creating a closed-loop control system that maintains high-speed phase rotation gates while actively suppressing error occurrence through real-time feedback.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4675513A1Computer program, quantum computation support method, and information processing apparatus
Publication Date: 2026.01.07 FUJITSU LTD
  • EP4675513A1 patent drawingFigure 1
  • EP4675513A1 patent drawingFigure 2
  • EP4675513A1 patent drawingFigure 3

AI summary

An information processing apparatus causes a quantum computer to perform a first gate operation in accordance with an ancilla state generation circuit representing a procedure of generating a code including a logical qubit representing an ancilla state and a gauge qubit representing a redundant degree of freedom other than the ancilla state. Next, the information processing apparatus causes the quantum computer to perform a second gate operation in accordance with an error detection circuit representing a procedure of detecting an error occurring in a plurality of physical qubits constituting the code generated by the first gate operation. Then, the information processing apparatus determines the presence or absence of the error on the basis of a measurement value obtained by the second gate operation, the measurement value indicating the state of the gauge qubit.