Hybrid Quantum-Classical Simulation Using RBM Ansatz

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Solution Overview

Problem

Simulating complex quantum systems with classical computers is challenging due to exponential resource scaling, and near-term quantum computers face limitations in qubits and error-prone operations, making existing methods impractical for accurate simulations.

Innovation Solution

A hybrid quantum-classical method combining quantum imaginary time evolution with Restricted Boltzmann Machine (RBM) ansatz, utilizing a device with both quantum and classical computing portions to optimize variational parameters for wavefunctions, allowing for efficient simulation of quantum systems without requiring quantum error correction or high-dimensional noisy classical optimization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If classical computers are used to simulate quantum systems, then simulation capability is available, but resource requirements scale exponentially with system size

Engineering Contradiction:
Improvesimulation accuracyVSAvoidcomputational resources
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent combines quantum computing resources with classical computing resources in a hybrid quantum-classical system. The quantum processor handles specific quantum mechanical calculations while the classical processor manages optimization and control, allowing the system to simulate quantum systems with polynomial resource scaling rather than exponential scaling.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs variational parameters that can be optimized to represent quantum states. By changing the parameterization approach using neural network-inspired variational forms, the system can accurately represent complex quantum wavefunctions with a manageable number of parameters, reducing the computational resources needed.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If near-term quantum computers are used for simulation, then quantum computing capability is available, but qubit limits and error-prone operations constrain accuracy

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidqubit requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a variational approach where the quantum processor performs partial quantum calculations with limited qubits, while the classical processor compensates by optimizing variational parameters through multiple measurements and iterations. This partial quantum computation approach achieves accurate results without requiring fault-tolerant quantum computers with many qubits.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent implements a feedback loop where measurement results from the quantum processor are fed back to the classical processor, which updates the variational parameters. This iterative feedback process allows the system to converge to accurate solutions even with noisy intermediate-scale quantum devices, overcoming the limitation of error-prone operations.

Inventive Principle:
Principle #23Feedback

3Productivity

If existing quantum simulation methods are used, then quantum systems can be simulated, but high-dimensional noisy classical optimization is required

Engineering Contradiction:
Improvesimulation efficiencyVSAvoidoptimization complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the optimization problem by separating quantum circuit parameter optimization from wavefunction ansatz structure optimization. The variational neural network approach divides the high-dimensional optimization space into manageable segments that can be optimized independently, reducing the complexity of classical optimization while maintaining simulation productivity.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS11314536B2Quantum variational method, apparatus, and storage medium for simulating quantum systems
Publication Date: 2022.04.26 TENCENT AMERICA LLC
  • US11314536B2 patent drawing
  • US11314536B2 patent drawing
  • US11314536B2 patent drawing

AI summary

The present disclosure discloses a method for obtaining optimal variational parameters of a ground state wavefunction for a Hamiltonian system. The method includes initializing a plurality of variational parameters and sending the variational parameters to a quantum computing portion to output a plurality of measurement results. The method includes transmitting the measurement results to a classical computing portion to update the plurality of variational parameters based on the plurality of measurement results and an update rule, and determining whether a measured energy satisfies a convergence rule. When the measured energy does not satisfy the convergence rule, the method includes sending the plurality of updated variational parameters to the quantum computing portion for a next iteration; and when the measured energy satisfies the convergence rule, the method includes obtaining a plurality of optimal variational parameters for the Hamiltonian system.