Surface-Code Logical Qubit Layout With Shared Ancilla Connectivity
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Solution Overview
Problem
Quantum computing devices face challenges in accurately correcting errors in computations due to high error rates associated with the structural properties and connectivity of physical qubits, which complicates the implementation of efficient error correction methods.
Innovation Solution
A quantum computing device is designed with a logical qubit encoding surface comprising a plurality of plaquettes, each including four measurement-based qubits and a first ancilla qubit electrically connected to the data qubits and a second ancilla qubit, allowing for efficient error correction without increasing the number of ancilla qubits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of physical qubits is increased to implement a logical qubit, then the error rate increases
Solution Approach 1:
The patent divides the logical qubit implementation into distinct segments: data qubits for information storage and ancilla qubits for error correction operations. This segmentation allows the system to use measurement-based qubits in a structured manner that reduces the overall error rate while maintaining a manageable number of physical qubits through efficient surface code encoding.
Solution Approach 2:
The patent introduces ancilla qubits as intermediary elements that facilitate error correction without requiring excessive data qubits. These ancilla qubits act as mediators between the data qubits and the measurement apparatus, enabling syndrome measurements that detect errors without directly measuring the data qubits, thereby preserving quantum information while reducing error accumulation.
2Reliability
If the connectivity degree of physical qubits is increased, then the error rate increases
Solution Approach 1:
The patent implements local quality by assigning different roles to different qubits within the surface code structure. Data qubits have specific connectivity patterns optimized for information storage, while ancilla qubits have connectivity optimized for error syndrome measurements. This localized optimization of connectivity reduces the maximum connectivity degree required while maintaining effective error correction capabilities.
Solution Approach 2:
The patent segments the quantum computing device into distinct functional regions with different connectivity requirements. The surface code architecture separates qubits into data regions and ancilla regions, each with optimized connectivity patterns. This segmentation allows the system to achieve effective error correction with lower overall connectivity degree compared to fully connected architectures.
3Productivity
If measurement-based qubits are used, then error correction efficiency is improved, but the number of ancilla qubits must be increased
Solution Approach 1:
The patent applies universality by designing ancilla qubits that serve multiple functions within the surface code architecture. Each ancilla qubit can participate in multiple stabilizer measurements and error correction cycles, reducing the total number of ancilla qubits needed compared to architectures where each ancilla is dedicated to a single measurement function. This multi-functionality is achieved through the repeated use of ancilla qubits in sequential error correction operations.
Solution Approach 2:
The patent implements periodic action through repeated error correction cycles where ancilla qubits are prepared, measured, and reset in a periodic sequence. This periodic operation allows the same ancilla qubits to be reused across multiple error correction cycles, reducing the total ancilla qubit count while maintaining continuous error correction capability through systematic repetition of the correction protocol.
Data Source
AI summary
A quantum computing device is provided, including a logical qubit encoding surface including a plurality of plaquettes. Each plaquette of the plurality of plaquettes may include a plurality of measurement-based qubits. The plurality of measurement-based qubits may include four data qubits and a first ancilla qubit. The first ancilla qubit may be electrically connected to the four data qubits and a second ancilla qubit included in the logical qubit encoding surface.