Quantum Gate Noise Simulation for Coherent Error Modeling

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Solution Overview

Problem

Conventional noise simulation methods for quantum circuits face challenges such as increased computation cost and difficulty in enhancing accuracy due to exponential dimension growth and the inability to accurately model coherent errors arising from interference with quantum gates.

Innovation Solution

A noise simulation approach that applies quantum gates in reverse and forward directions with intermediate time evolution from residual interactions, using Pauli channels to model noise processes individually for each quantum gate, incorporating device characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If analysis using quantum master equation is performed, then noise simulation can be conducted, but computation cost increases exponentially with the number of quantum bits

Engineering Contradiction:
Improvenoise simulation accuracyVSAvoidcomputation cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The quantum circuit is divided into individual quantum gates, and noise processes are extracted and applied separately for each gate. This segmentation allows the noise simulation to be performed gate-by-gate rather than requiring full quantum master equation analysis of the entire system, thereby reducing computation cost while maintaining accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the continuous noise processes described by quantum master equation into discrete noise processes that can be represented as quantum gates. By parameterizing the noise processes (e.g., using Pauli error rates, depolarizing noise parameters), the simulation can use efficient gate-based computation instead of expensive matrix operations.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If noise is categorized into common types (N1Q, N2Q), then noise simulation can be performed, but accuracy is reduced due to inability to model coherent errors with changing nature

Engineering Contradiction:
Improvenoise simulation efficiencyVSAvoidnoise simulation accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent makes the noise process dynamic by extracting and applying specific noise processes individually for each quantum gate based on its characteristics. Instead of using static common noise categories, the noise model adapts to each gate's specific error characteristics, enabling accurate modeling of coherent errors whose nature changes depending on the simultaneous quantum gate action.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If conventional noise processes are applied after quantum gates, then noise simulation can be performed, but the simultaneous action of noise and quantum gate cannot be accurately modeled

Engineering Contradiction:
Improvenoise simulation simplicityVSAvoidnoise simulation accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent extracts the noise process from each quantum gate operation in advance, capturing the simultaneous action characteristics. By pre-characterizing the noise process for each gate type and applying it immediately after the gate operation, the method models the simultaneous action of noise and quantum gate more accurately than conventional sequential approaches.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4682780A1Noise simulation program, information processing apparatus, and noise simulation method
Publication Date: 2026.01.21 FUJITSU LTD
  • EP4682780A1 patent drawingFigure 1~2
  • EP4682780A1 patent drawingFigure 3
  • EP4682780A1 patent drawingFigure 4A~4B

AI summary

An information processing apparatus (1) performs noise simulation using a noise process of a quantum gate included in a quantum circuit. For example, after the processing by the quantum gate, the information processing apparatus (1) performs noise simulation by performing application, as the noise process, including applying the quantum gate by half in a reverse direction, adding time evolution derived from residual interaction, and applying the quantum gate by another half in a forward direction.