Quantum Error Correction with Linear Codes and Fewer Parity Checks

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Solution Overview

Problem

Current quantum error correction methods, such as Shor's method, require a large number of parity check measurements, leading to significant time overhead and noise introduction during error correction processes in quantum computers, which limits their practical application.

Innovation Solution

A fault-tolerant error correction scheme that reduces the number of parity measurements required by using a look-up-table-based decoder and implementing a sequence of measurements optimized for specific linear codes, such as Hamming and Golay codes, to achieve efficient error correction with reduced noise and increased qubit lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Shor's method is used for quantum error correction, then fault tolerance is achieved, but the number of parity measurements required is large, leading to significant time overhead and noise introduction

Engineering Contradiction:
Improvefault toleranceVSAvoidtime overhead
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the measurement parameters by using optimized measurement sequences and cat state preparations that require fewer measurements than Shor's method. This reduces the time overhead while maintaining fault tolerance through careful parameter selection in the error correction protocol

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The error correction process is segmented into distinct phases: cat state preparation, parity measurement, and correction application. This segmentation allows for optimization of each phase independently, reducing overall time overhead while maintaining reliability

Inventive Principle:
Principle #1Segmentation

2Reliability

If Shor's method is used for quantum error correction, then fault tolerance is achieved, but the number of parity measurements required is large, leading to significant noise introduction

Engineering Contradiction:
Improvefault toleranceVSAvoidnoise
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

By optimizing the measurement sequence parameters and using cat states with specific properties, the patent reduces the total number of measurements required. This parameter optimization directly reduces noise accumulation while preserving fault tolerance through carefully chosen measurement configurations

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses cat states as copies of quantum information that can be measured without directly measuring the data qubits. This copying approach allows error detection while minimizing noise propagation to the actual computational qubits

Inventive Principle:
Principle #26Copying

3Productivity

If a look-up-table-based decoder is used, then decoding speed is improved, but memory requirements increase

Engineering Contradiction:
Improvedecoding speedVSAvoidmemory requirements
Core Design Contradiction:
ProductivityVSVolume of stationary object

Solution Approach 1:

The look-up table is segmented into smaller sub-tables that can be stored in limited memory. The decoding process is divided into multiple steps, each using a portion of the table, which reduces peak memory requirements while maintaining overall decoding speed through systematic processing

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS11700020B2Fault tolerant quantum error correction with linear codes
Publication Date: 2023.07.11 MICROSOFT TECHNOLOGY LICENSING LLC
  • US11700020B2 patent drawing
  • US11700020B2 patent drawing
  • US11700020B2 patent drawing

AI summary

This disclosure focuses on example embodiments of a classical approach to the problem of quantum error correction in the presence of faults. Linear codes equipped with faulty parity measurements are disclosed. Example definitions of fault tolerance are introduced and embodiments of a fault tolerant scheme are disclosed that reduce the number of parity measurements required compared with Shor method. Such schemes are well suited to be implemented in the classical control device of a quantum computer in order to ensure quantum fault tolerance.