Coherent Ising Machine for L0 Compressed Sensing Support Vector Estimation

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Solution Overview

Problem

Current methods for L0 regularization-based compressed sensing face challenges in estimating the support vector, making it difficult to reconstruct sparse signals efficiently, especially when the number of non-zero elements exceeds a critical value.

Innovation Solution

A quantum-classical hybrid system composed of a coherent Ising machine and classical digital processors is used to alternately optimize parameters, minimizing the Hamiltonian cost function, where the quantum machine estimates the support vector and the classical machine solves for the signal values, effectively addressing the difficulty of support vector estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If L0 regularization-based compressed sensing is used to reconstruct sparse signals, then reconstruction accuracy is improved, but the difficulty of estimating the support vector increases

Engineering Contradiction:
Improvesignal reconstruction accuracyVSAvoidsupport vector estimation difficulty
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the L0 regularization problem into two separate optimization tasks: (1) estimating the support vector σ using a quantum machine (coherent Ising machine), and (2) solving for the signal values r using a classical machine. This segmentation allows each component to specialize in one aspect of the problem, making the overall estimation process more tractable while maintaining high reconstruction accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a quantum machine as an intermediary device between the observation signal and the final signal reconstruction. The quantum machine acts as a mediator that efficiently estimates the support vector by mapping the combinatorial optimization problem to an Ising Hamiltonian, thereby reducing the classical computational burden and improving the overall estimation process.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the number of non-zero elements exceeds the critical value, then LASSO techniques fail to reconstruct signals efficiently, but quantum-classical hybrid system maintains performance

Engineering Contradiction:
Improvesignal reconstruction efficiencyVSAvoidreconstruction reliability at high sparseness
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the optimization approach by transforming the L0 regularization problem into an Ising Hamiltonian formulation with specific parameter mappings: the support vector elements σi become Ising spins, the regularization parameter λ becomes part of the Hamiltonian coefficients, and the objective function is reformulated to match the quantum machine's optimization capabilities. This parameter transformation enables the system to handle higher sparseness ratios that would otherwise be intractable.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If L1 regularization is used instead of L0 regularization, then the optimization problem becomes convex and easier to solve, but reconstruction performance deteriorates due to soft-thresholding

Engineering Contradiction:
Improveoptimization problem solvabilityVSAvoidsignal reconstruction accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the classical convex optimization mechanism (L1 regularization with soft-thresholding) with a quantum-inspired mechanism (coherent Ising machine) that can efficiently solve the non-convex L0 regularization problem. The quantum machine's ability to explore the solution space through quantum effects allows it to achieve hard-thresholding behavior without getting trapped in local minima, thereby maintaining both ease of operation and high reconstruction accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20240133987A1L0 regularization-based compressed sensing system and method with coherent ising machines
Publication Date: 2024.04.25 NTT RESEARCH INC
  • US20240133987A1 patent drawing
  • US20240133987A1 patent drawing
  • US20240133987A1 patent drawing

AI summary

A system and method for L0 regularization-based compressed sensing (CS) may use a quantum-classical hybrid system consisting of coherent Ising machines (CIM) and classical digital processors CDP). The CIM and CDP each performs alternating minimization for L0 regularization-based compressed sensing (CS). A truncated Wigner stochastic differential equation (W-SDE) is obtained from the master equation for the density operator of the network of degenerate optical parametric oscillators.