In-situ Quantum Error Correction via Closed-Loop Feedback

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Solution Overview

Problem

Existing methods for optimizing physical gate parameters in quantum computers are complex and require interruption of error detection operations, which can lead to suboptimal performance and reliability in error correction circuits.

Innovation Solution

A method for continuous and parallel optimization of qubit performance in-situ during error correction operations, where error detection outputs are used as feedback to calibrate quantum gates, allowing for independent optimization of each hardware pattern without interrupting computations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional characterization methods (randomized benchmarking or tomography) are used to optimize physical gate parameters, then optimization can be performed, but error detection operations must be interrupted and the process becomes complex requiring multiple steps

Engineering Contradiction:
Improvegate parameter optimizationVSAvoidinterruption of error detection operations
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent implements continuous optimization by performing gate parameter calibration concurrently with error detection operations. The system continuously monitors syndrome measurements and adjusts gate parameters in real-time without interrupting the quantum computation or error correction cycle, thereby maintaining continuous useful action throughout the operation.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent merges the optimization process with the error detection operation by combining gate parameter calibration with syndrome measurement. Instead of separating these operations into distinct phases, the system integrates them so that optimization occurs within the same temporal and operational framework, eliminating the need for interruption.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If error model optimization methods are used to optimize physical gate parameters, then parameters can be optimized using measured physical errors, but the process complexity increases due to training requirements and linking errors to control parameters

Engineering Contradiction:
Improvegate parameter optimizationVSAvoidoptimization process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential information needed for optimization directly from syndrome measurements without requiring complex error models. By focusing on the measurable syndrome outcomes and their direct relationship to gate parameters, the system eliminates the need for extensive error modeling, training processes, and complex parameter linking that characterize traditional error model optimization methods.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If qubits are not measured during computation to maintain quantum state integrity, then quantum computation can proceed, but optimization of qubit performance becomes difficult

Engineering Contradiction:
Improvequantum state integrityVSAvoidqubit performance optimization
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces syndrome measurements as an intermediary that enables optimization without directly measuring data qubits. The syndrome measurements serve as a mediator that provides information about qubit performance and gate parameters while maintaining the quantum state integrity of the computational qubits, allowing optimization to proceed concurrently with computation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3371752B1In-situ quantum error correction
Publication Date: 2025.04.16 GOOGLE LLC
  • EP3371752B1 patent drawingFigure 1A~1B
  • EP3371752B1 patent drawingFigure 2A~2B
  • EP3371752B1 patent drawingFigure 3

AI summary

Methods, systems, and apparatus for parallel optimization of continuously running quantum error correction by closed-loop feedback. In one aspect, a method includes continuously and effectively optimizing qubit performance in-situ whilst an error correction operation on the quantum system is running. The method directly monitors the output from error detection and provides this information as feedback to calibrate the quantum gates associated with the quantum system. In some implementations, the physical qubits are spatially partitioned into one or more independent hardware patterns, where the errors attributable to each hardware pattern are non-overlapping. The one or more different sets of hardware patterns are then temporarily interleaved such that all physical qubits and operations are optimized. The method allows for the optimization of each section of a hardware pattern to be performed individually and in parallel, and can result is O(1) scaling.