Weighted Alternating Paths in Graphs for Quantum Error Detection

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Solution Overview

Problem

Existing algorithms for computing the cost of weighted alternating paths in graphs are inefficient for error detection in quantum computing systems, particularly in expanding matched nodes and optimizing cost functions in partially-matched graphs.

Innovation Solution

A computer-implemented method that expands a set of matched nodes in a partially-matched graph by determining an alternating path between unmatched nodes, inverting the matching labels of edges along this path, and repeating this process to include unmatched nodes in the matching set while minimizing the overall cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If existing algorithms are used to compute weighted alternating paths in graphs, then the error detection process can be performed, but the computational efficiency is insufficient and the cost optimization is suboptimal

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidcomputation time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The algorithm segments the graph traversal process into distinct phases: identifying unmatched nodes, finding alternating paths, and updating matching labels. This segmentation allows for more efficient processing by focusing computational resources on specific subtasks rather than treating the entire error detection process as a monolithic operation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The algorithm performs preliminary actions by pre-identifying all unmatched nodes and pre-computing potential alternating paths before the actual error detection begins. This preliminary preparation reduces the computational burden during the main execution phase, thereby improving overall efficiency and reducing computation time.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the matching set is expanded to include more nodes, then the error detection coverage is improved, but the computational complexity increases

Engineering Contradiction:
Improveerror detection coverageVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The algorithm inverts the traditional approach by starting with unmatched nodes and working backward to find alternating paths that lead to matched nodes, rather than starting from matched nodes and expanding forward. This inversion simplifies the complexity management while expanding error detection coverage, as it allows the algorithm to focus on the minimal set of nodes that need to be included in the matching set.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The algorithm applies local quality by treating different nodes differently based on their matching status. Matched nodes receive one type of processing while unmatched nodes receive another, allowing the algorithm to optimize computational resources locally rather than applying a uniform complex process to all nodes. This local differentiation improves reliability without proportionally increasing overall complexity.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If the cost function is optimized by minimizing the sum of edge weights, then the error source identification is improved, but the algorithm complexity increases

Engineering Contradiction:
Improveerror source identification accuracyVSAvoidalgorithm complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The algorithm changes the parameter being optimized from a generic matching criterion to a specific cost function based on edge weights. By parameterizing the optimization around minimizing the sum of edge weights, the algorithm achieves more precise error source identification. The parameter change is managed through systematic updates to the matching labels along alternating paths, which keeps the implementation complexity controlled despite the enhanced precision.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12204406B2Weighted alternating paths in graphs for quantum computing
Publication Date: 2025.01.21 GOOGLE LLC
  • US12204406B2 patent drawing
  • US12204406B2 patent drawing
  • US12204406B2 patent drawing

AI summary

A computer-implemented method for expanding a set of matched nodes in a partially-matched graph can include obtaining, by a computing system, a partially-matched graph having a matching set, the partially-matched graph including one or more edges and a plurality of nodes, the one or more edges having a matching label. The method can include obtaining at least two unmatched nodes. The method can include determining an alternating path from a first unmatched node of the at least two unmatched nodes to a second unmatched node of the at least two unmatched nodes, the alternating path including at least one edge of the one or more edges. The method can include inverting the matching label of the at least one edge of the alternating path such that the at least two unmatched nodes are included in the matching set of the partially-matched graph.