Multiple QPU Instances for Quantum Error Mitigation

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Solution Overview

Problem

Quantum computing systems face challenges in accurately predicting and reproducing operational errors, as these errors can be difficult to understand and reproduce using classical computing resources, and existing methods like quantum error correcting codes and heuristics may not always provide accurate results due to variable error rates and processes across the system.

Innovation Solution

The approach involves evaluating results from multiple executions of a quantum algorithm across distinct quantum processor unit (QPU) instances to determine the most accurate result, leveraging variability in error rates for computational advantage by distributing computations across subdomains of the processor hardware, and using pre-defined evaluation criteria to compute the most accurate answer with a classical co-processor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum error correcting codes are used to actively correct errors, then error correction capability is improved, but system complexity and computational overhead increase

Engineering Contradiction:
Improveerror correction capabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent executes the same quantum algorithm multiple times on different QPU instances (creating copies of the computational process) and compares results to identify and correct errors, avoiding the need for complex quantum error correcting codes while still achieving reliable error correction through redundant execution and classical comparison

Inventive Principle:
Principle #26Copying

2Measurement precision

If multiple QPU instances are used to execute quantum algorithms, then computational accuracy is improved through error mitigation, but resource requirements and system complexity increase

Engineering Contradiction:
Improvecomputational accuracyVSAvoidresource requirements
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent introduces a classical co-processor as an intermediary that receives results from multiple QPU instances, compares them using pre-defined evaluation criteria, and determines the most accurate result. This intermediary enables accurate error mitigation by leveraging classical computing resources to process and evaluate quantum computational results, achieving high accuracy without requiring all QPU resources to be simultaneously active

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If quantum computations are distributed across subdomains of processor hardware, then computational accuracy is improved by leveraging error rate variability, but device complexity and coordination overhead increase

Engineering Contradiction:
Improvecomputational accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the quantum processor into multiple independent QPU instances (subdomains), each executing the same quantum algorithm independently. By distributing computations across these segmented units and comparing results, the system leverages variability in error rates across different hardware segments to identify and mitigate errors, achieving improved accuracy while managing complexity through independent, modular execution units

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS11521103B1Utilizing multiple quantum processor unit (QPU) instances
Publication Date: 2022.12.06 RIGETTI & CO INC
  • US11521103B1 patent drawing
  • US11521103B1 patent drawing
  • US11521103B1 patent drawing

AI summary

In a general aspect, a plurality of distinct quantum processor unit (QPU) instances are utilized to execute a quantum computation. Hybrid classical-quantum computing methods and systems are described which utilize the plurality of QPU instances in the execution of quantum computations.