Quantum Circuit Gate Fusion Graph Optimization

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Solution Overview

Problem

Simulating quantum circuits with a significant number of qubits requires substantial memory and CPU resources, and existing simulators rely on manual specification of gate fusion, which can be inefficient and difficult to optimize.

Innovation Solution

A system that generates a graph representing a quantum circuit with nodes and edges indicating potential gate fusions, using algorithms like Dijkstra to determine the lowest cost paths for fusion, thereby automating the optimization of gate fusion and reducing resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If gate fusion is manually specified in quantum circuit simulation, then operational intensity can be increased, but the system requires significant user expertise and time to optimize fusion parameters

Engineering Contradiction:
Improvesimulation efficiencyVSAvoiduser configuration complexity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The system automatically performs gate fusion optimization without requiring user intervention. The compiler analyzes the quantum circuit and autonomously determines optimal fusion opportunities, eliminating the need for users to manually specify fusion parameters while maintaining high simulation efficiency

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system dynamically adjusts fusion parameters based on circuit characteristics and resource availability. By automatically modifying fusion depth and scope parameters, the system optimizes simulation performance without requiring users to understand or configure these parameters manually

Inventive Principle:
Principle #35Parameter changes

2Productivity

If gate fusion is applied to increase operational intensity, then simulation speed improves, but futile optimizations can consume significant evaluation time

Engineering Contradiction:
Improvesimulation speedVSAvoidoptimization evaluation time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary analysis of the quantum circuit to identify only viable fusion opportunities before applying fusion. By pre-evaluating circuit structure and gate compatibility, the system avoids wasting time on futile optimization attempts during the actual simulation process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses cost-based evaluation with feedback mechanisms to guide fusion decisions. By assigning costs to different fusion options and selecting lowest-cost paths, the system efficiently identifies productive fusion opportunities while avoiding futile optimizations that would consume unnecessary evaluation time

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If more gate fusion is applied to reduce operations, then memory usage decreases, but determining optimal fusion points becomes more complex

Engineering Contradiction:
Improvememory requirementsVSAvoidfusion optimization complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The system introduces a graph representation as an intermediary structure to manage fusion optimization. The graph models circuit gates and their relationships, enabling systematic analysis of fusion opportunities without directly confronting the full complexity of the quantum circuit, thus reducing memory requirements while managing optimization complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system segments the quantum circuit into discrete gates represented as graph nodes, enabling localized fusion analysis. By breaking down the circuit into manageable segments and analyzing fusion opportunities at the gate level, the system reduces overall memory requirements while keeping the optimization process tractable

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS11586792B2Scheduling fusion for quantum computing simulation
Publication Date: 2023.02.21 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US11586792B2 patent drawing
  • US11586792B2 patent drawing
  • US11586792B2 patent drawing

AI summary

Embodiments are provided to simulate a quantum circuit. A system receives a quantum circuit (or its representation), generates a graph, and adds edges for each n-qubit of fusion to be applied. Costs are estimated or calculated for various paths of gate fusion between endpoints in the graph. One or more paths are selected, for example, the lowest cost path based on a Dijkstra algorithm evaluation. A unitary matrix for each gate fusion is then generated for simulating the quantum circuit. A simulation is performed locally or remotely based on the gate fusions along the selected one or more paths, and thus, improving the memory and processor performance of the simulation.