Replica Interaction in Ising Machine Optimization

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Solution Overview

Problem

Existing optimization methods using multiple replicas in Ising machines often fail to sufficiently explore the state space due to replicas getting trapped in local solutions, leading to inefficient search performance.

Innovation Solution

The optimization method introduces interaction between replicas by calculating the strength of interaction based on distance, using the Metropolis-Hastings method to determine proposal and acceptance probabilities, thereby influencing the state transition process and enhancing the exploration of the state space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple replicas are used to perform MCMC processes independently, then the search speed is improved, but replicas get trapped in local solutions reducing search effectiveness

Engineering Contradiction:
Improvesearch speedVSAvoidsolution accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent introduces interaction terms that create feedback between replicas based on their state variable configurations. Each replica's state transition probability is modified by feedback from other replicas' states, allowing the system to collectively escape local solutions while maintaining independent parallel computation. This feedback mechanism ensures that replicas influence each other's search trajectories without requiring complete synchronization.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent modifies the transition probability parameters by introducing interaction terms that depend on the distance between replica states in the state space. The proposal probability is changed from a uniform distribution to one that incorporates interaction strengths, allowing replicas to explore the state space more effectively. This parameter change enables the system to maintain high productivity while improving solution accuracy through enhanced exploration.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If interaction between replicas is introduced to prevent trapping in local solutions, then solution search capability is improved, but computational complexity increases

Engineering Contradiction:
Improvesolution search capabilityVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by introducing interaction terms that are non-zero only for replicas within a certain distance threshold in the state space. Not all replicas interact with all others; instead, each replica only considers interactions with nearby states, reducing the computational burden. This localized interaction approach maintains solution search capability while significantly lowering computational complexity compared to full pairwise interactions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements partial action by considering only a subset of interaction terms rather than all possible replica combinations. The interaction strength is modulated by distance, automatically reducing the effective number of interactions as replica states diverge. This partial action strategy provides sufficient interaction to prevent local solution trapping while avoiding the excessive computational cost of complete interaction consideration.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS11790130B2Optimization device, optimization method, and non-transitory computer-readable storage medium for storing optimization program
Publication Date: 2023.10.17 FUJITSU LTD
  • US11790130B2 patent drawing
  • US11790130B2 patent drawing
  • US11790130B2 patent drawing

AI summary

An optimization method includes: identifying, for each of a plurality of replicas each of which has a plurality of state variables, an amount of change in strength of interaction that corresponds to a change in a distance between the replica and another replica in a state space in a case where a value of a first state variable among the plurality of state variables of the replica is updated, the state space indicating a space which a combination of values of the plurality of state variables is able to take; and determining whether or not to update the value of the first state variable, based on a proposal probability that corresponds to the amount of change in the strength of interaction in the case where the value of the first state variable is updated and based on an acceptance probability that corresponds to a target probability distribution.