Ising Hamiltonian Generation with Qubit Reduction

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current quantum optimization methods face challenges in efficiently formulating Ising Hamiltonians for integer optimization problems with polynomial inequality constraints and handling limited qubits, particularly in computer vision applications like image segmentation and texture recognition, due to the complexity of higher-order pseudo-boolean functions and non-submodular reductions.

Innovation Solution

The system generates efficient Ising Hamiltonians by representing integer variables as linear sums of binary variables, introducing slack variables to convert inequality constraints to equality constraints, and applying quadratization techniques, such as roof duality and extended roof duality, to reduce the number of variables and qubits required, facilitating automated qubit reduction for quantum optimization algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If higher-order pseudo-boolean functions are used to represent integer optimization problems, then the problem representation becomes more accurate, but the complexity of the Ising Hamiltonian generation increases

Engineering Contradiction:
Improveproblem representation accuracyVSAvoidIsing Hamiltonian generation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the higher-order pseudo-boolean function into multiple quadratic terms by introducing auxiliary variables. Each higher-order term is decomposed into a series of quadratic interactions, transforming a complex non-quadratic problem into a structured sequence of quadratic sub-problems that can be systematically processed by quantum optimization algorithms.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces auxiliary variables as intermediary elements that mediate between the original higher-order terms and the quadratic form required by Ising Hamiltonians. These auxiliary variables act as bridges, allowing the transformation of complex polynomial terms into quadratic expressions without losing the essential problem structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If non-submodular reductions are applied to handle polynomial inequality constraints, then the problem modeling capability is enhanced, but the computational complexity increases

Engineering Contradiction:
Improveproblem modeling capabilityVSAvoidcomputational efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent changes the parameter representation by transforming polynomial inequality constraints into a standardized quadratic form with modified coefficients. By adjusting the parameters of the quadratic terms to encode inequality relationships, the system maintains modeling versatility while ensuring the problem fits the computational requirements of quantum optimization algorithms.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If the number of variables in QPBF is reduced using roof duality techniques, then the qubit requirements decrease, but the formulation complexity increases

Engineering Contradiction:
Improvenumber of qubitsVSAvoidformulation complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent applies preliminary actions by pre-processing the QPBF through roof duality analysis before quantum optimization. This preliminary step identifies and eliminates redundant variables in advance, reducing the problem size that needs to be handled by the quantum system while maintaining the essential problem structure and solution accuracy.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS11556830B2Efficient quadratic ising hamiltonian generation with qubit reduction
Publication Date: 2023.01.17 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US11556830B2 patent drawing
  • US11556830B2 patent drawing
  • US11556830B2 patent drawing

AI summary

Systems and methods that address an optimized method in the area of optimization by showing how to generate Ising Hamiltonians automatically for a large class of optimization problems specially handling the constraints. The innovation facilitates qubit reduction in connection with an optimization problem by representing respective integer variables as linear sums of binary variables, wherein depending on the representation, additional equality constraints are provided. Additional slack variables are introduced to change inequality constraints to equality constraints. Based on the equality constraints, an unconstrained pseudo-boolean optimization problem is created. The pseudo-boolean optimization problem is quadratized to generate a quadratic pseudo-boolean function (QPBF) and the number of variables in the QPBF is reduced to facilitate qubit reduction. This results in an automated, problem instance dependent qubit reduction procedure. Thus, this innovation provides an effective method to solve such class of optimization problems by formulating efficient Ising Hamiltonians for integer optimization problems followed by an automated qubit reduction procedure to get the final Ising Hamiltonian, which can be solved using a quantum optimization algorithm.