Quantum Circuit Simulator With Bidirectional Gate-Matrix Reuse

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing quantum circuit simulators, including DD-based ones, require recalculating the entire simulation from scratch when even slight changes occur in quantum gate types or parameters, leading to increased simulation time.

Innovation Solution

A method involving merging quantum gates in both forward and backward directions to create matrices, comparing circuits for differences, and reusing these matrices for unchanged portions during simulation, reducing the need for full recalculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum circuit simulator performs all calculations from the beginning when gate type or parameter changes slightly, then simulation accuracy is maintained, but simulation time increases significantly

Engineering Contradiction:

Improvesimulation accuracyVSAvoidsimulation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the quantum circuit into multiple parts and pre-calculates matrix products for different gate types and parameters. When a gate changes, only the affected segment needs recalculation while other segments can be reused, resolving the contradiction between maintaining accuracy and reducing time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary calculations by pre-computing matrix products for various gate configurations and storing them in advance. This allows the simulator to reuse pre-computed results when gates change, avoiding full recalculation and reducing simulation time while maintaining accuracy.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If DD-based quantum circuit simulator integrates multiple quantum gates into a single matrix, then memory amount is reduced, but simulation time increases when gate changes occur

Engineering Contradiction:

Improvememory amountVSAvoidsimulation time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The patent makes the matrix integration dynamic by maintaining multiple matrices corresponding to different gate types and parameters. When a gate changes, the system dynamically switches between pre-computed matrices or performs only local updates, combining memory efficiency with fast simulation time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent exploits parameter changes in quantum gates by pre-computing matrices for different parameter values. When parameters change slightly, the system can reuse pre-computed matrices or perform minimal updates rather than full recalculation, reducing simulation time while maintaining the memory benefits of matrix integration.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250299087A1Computer-readable recording medium storing simulation program, information processing device, and simulation method

Publication Date: 2025.09.25 FUJITSU LTD

AI summary

A medium storing a program for causing a computer to execute: performing, in order from a gate in a first direction among gates in a first quantum circuit, a merging of each gate in the first direction to store first matrices obtained by the merging in the first direction; performing, in order from a gate in a second direction among the gates, a merging of each gate in the second direction to store second matrices obtained by the merging in the second direction; and performing simulation of a second quantum circuit by using the first or second matrices, for a second gate that is a gate in the second quantum circuit, has no difference from the first quantum circuit, and is arranged in the first or second direction than a first gate that is a gate in the second quantum circuit and has a difference from the first quantum circuit.