Fusion-Based Quantum Computing with Joint Measurements for Fault Tolerance

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Solution Overview

Problem

Existing quantum computing systems face challenges in generating and maintaining large entangled states of qubits, which are necessary for fault-tolerant quantum computation, particularly due to the probabilistic nature of entanglement generation and the requirement of long-range entanglement across thousands of qubits.

Innovation Solution

A fusion-based quantum computing approach that performs destructive joint measurements on smaller, independent entangled quantum sub-systems to generate joint measurement outcome data, allowing for fault-tolerant determination of logical qubit states without relying on large cluster states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large cluster states of qubits are used for quantum error correction, then fault tolerance is achieved, but the complexity of generating and maintaining entangled states increases significantly

Engineering Contradiction:
Improvefault toleranceVSAvoidentanglement generation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the large cluster state into multiple smaller, independent entangled quantum sub-systems. Each sub-system can be generated and maintained separately, reducing the complexity of entanglement generation while still achieving the necessary fault tolerance through their collective operation in the lattice structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from requiring all qubits to be entangled in a single large cluster state to organizing qubits in a lattice structure where smaller sub-systems are arranged spatially. This dimensional reorganization allows independent sub-systems to contribute to overall fault tolerance without requiring global entanglement

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If photonic architectures are used for generating entangled states, then quantum computation is enabled, but the probabilistic nature of entanglement generation reduces success probability

Engineering Contradiction:
Improvequantum computation capabilityVSAvoidentanglement generation success probability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent combines multiple independent entangled quantum sub-systems through destructive joint measurements to achieve the desired logical qubit state. By merging results from multiple independent attempts at generating entangled sub-systems, the overall success probability improves while maintaining the advantages of photonic architectures

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If destructive joint measurements are performed on quantum sub-systems, then logical qubit states can be determined, but the quantum sub-systems are destroyed in the process

Engineering Contradiction:
Improvelogical qubit state determinationVSAvoidquantum sub-system loss
Core Design Contradiction:
Measurement precisionVSLoss of substance

Solution Approach 1:

The patent employs a strategy where quantum sub-systems are prepared in advance as independent entangled states, then selectively measured and discarded after contributing to the logical qubit state determination. The system recovers by preparing new sub-systems to replace those that have been measured, maintaining a continuous supply of quantum resources for computation

Inventive Principle:
Principle #34Discarding and recovering

Data Source

PatentEP4097651B1Fusion based quantum computing
Publication Date: 2025.12.10 PSIQUANTUM CORP
  • EP4097651B1 patent drawingFigure 1A~1B
  • EP4097651B1 patent drawingFigure 1C
  • EP4097651B1 patent drawingFigure 2

AI summary

A method includes receiving a plurality of quantum systems, wherein each quantum system of the plurality of quantum system includes a plurality of quantum sub-systems in an entangled state, and wherein respective quantum systems of the plurality of quantum systems are independent quantum systems that are not entangled with one another. The method further includes performing a plurality of joint measurements on different quantum sub-systems from respective ones of the plurality of quantum systems, wherein the joint measurements generate joint measurement outcome data and determining, by a decoder, a plurality of syndrome graph values based on the joint measurement outcome data.