Bacon-Shor Syndrome Decoding for Fault-Tolerant Quantum Error Correction

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Solution Overview

Problem

Current quantum computing systems face challenges in implementing high-density, fault-tolerant syndrome extraction and decoding for quantum error correction, particularly in superconducting qubits, where bulky room temperature equipment is required for controlling transmon qubits with limited coherence times and process fidelities.

Innovation Solution

The system employs a Bacon-Shor quantum error correction code implemented in reciprocal quantum logic (RQL) circuits, using a grid arrangement of qubits for syndrome extraction and decoding, with measurement qubits detecting X and Z errors, and an integrated circuit for processing syndromes, ensuring fault-tolerant operation and reducing power consumption by only active components during error corrections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Bacon-Shor quantum error correction code is implemented with grid arrangement of qubits for syndrome extraction, then error correction reliability is improved, but device complexity increases

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

Solution Approach 1:

The quantum system is divided into a grid arrangement of data qubits and measurement qubits, where measurement qubits are segmented to detect errors in specific rows or columns. This segmentation allows independent syndrome extraction for different error types (X errors in columns, Z errors in rows) while maintaining overall system reliability through distributed error detection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Measurement qubits serve as intermediary elements between data qubits and the classical control system. These intermediary qubits extract syndrome information by interacting with data qubits without directly processing the encoded quantum information, thereby enabling error detection while preserving the integrity of the logical qubits.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If integrated circuit processes syndromes continuously for error correction, then error correction speed is improved, but power consumption increases

Engineering Contradiction:
Improveerror correction speedVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The integrated circuit processes syndromes periodically rather than continuously, activating components only when error correction is needed. The system extracts syndromes at specific intervals and processes them through the integrated circuit only when measurement qubits indicate errors, thereby maintaining error correction speed while significantly reducing power consumption during idle periods.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system incorporates on-chip syndrome processing capability within the quantum circuit itself, allowing the quantum system to self-diagnose and self-correct errors without requiring external classical processing equipment. This self-service approach enables rapid error correction while minimizing the need for continuous external intervention and reducing overall power consumption.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3298548B1Fault tolerant syndrome extraction and decoding in bacon-shor quantum error correction
Publication Date: 2023.12.06 NORTHROP GRUMMAN SYSTEMS CORP
  • EP3298548B1 patent drawingFigure 1~2
  • EP3298548B1 patent drawingFigure 3
  • EP3298548B1 patent drawingFigure 4

AI summary

Systems and methods are provided for quantum error correction. A quantum system includes an array of qubits configured to store an item of quantum information. The array of qubits includes a plurality of data qubits and a plurality of measurement qubits configured to extract a syndrome representing agreement among the plurality of data qubits. The quantum system further includes an integrated circuit comprising validation logic configured to determine if the syndrome is valid, decoding logic configured to determine evaluate the syndrome to determine location of errors within the plurality of data qubits, and an error register configured to store locations of the determined errors.