Majorana Surface Code Measurement Circuit for Dead Qubit Handling

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Solution Overview

Problem

Current quantum computing technologies face challenges in efficiently implementing quantum error correction, particularly when dealing with dead qubits and connections, which can significantly reduce the code distance and efficiency of error correction codes.

Innovation Solution

A computing system is developed that can identify dead qubits and connections within a quantum computing device's lattice, compute a reduced lattice by omitting these faulty components, and execute a reduced plaquette stabilizer measurement circuit to implement an error correction code, thereby minimizing code distance reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the full lattice including dead qubits is used for error correction, then the code distance is reduced, but implementing error correction on the complete lattice maintains measurement circuit complexity

Engineering Contradiction:
Improvecode distanceVSAvoidmeasurement circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes dead qubits from the lattice structure to form a reduced lattice. By identifying and omitting faulty qubits that cannot perform measurements or participate in stabilizer operations, the system creates a simplified lattice that maintains error correction functionality while eliminating components that would otherwise reduce code distance and complicate measurement circuits.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the lattice into functional and non-functional regions by identifying dead qubits. The reduced lattice is constructed by separating live qubits that participate in error correction from dead qubits that are excluded, allowing the system to maintain proper code distance without including problematic components in the measurement circuits.

Inventive Principle:
Principle #1Segmentation

2Reliability

If dead qubits are omitted from the lattice, then code distance is maintained, but the lattice structure becomes more complex to compute

Engineering Contradiction:
Improvecode distanceVSAvoidlattice computation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by identifying and marking dead qubits before constructing the reduced lattice. The system performs upfront detection of faulty qubits and prepares a mapping between the original and reduced lattices, which simplifies subsequent error correction operations and avoids the need to dynamically handle dead qubits during computation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mapping structure that connects the original lattice coordinates to the reduced lattice coordinates. This mapping acts as a mediator that allows the system to reference and operate on the reduced lattice while maintaining compatibility with the original lattice structure, simplifying the computation of error correction codes on the reduced lattice.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS20250124327A1Measurement circuit for majorana surface code implementation
Publication Date: 2025.04.17 MICROSOFT TECHNOLOGY LICENSING LLC
  • US20250124327A1 patent drawing
  • US20250124327A1 patent drawing
  • US20250124327A1 patent drawing

AI summary

A method for implementing a measurement circuit of a surface code on a plaquette of qubits of a Majorana-tetron lattice comprises: (a) distributing among a sequence of time steps a set of one-qubit projective-measurement loops on each of three auxiliary qubits of the plaquette; (b) distributing among the sequence of time steps a set of two-qubit projective-measurement loops on each of four data qubit of the plaquette together with one of the three auxiliary qubits; (c) distributing among the sequence of time steps a set of two-qubit projective measurement loops on two or more auxiliary-qubit pairs selected from the three auxiliary qubits of the plaquette; and (d) advancing through each of the time steps of the sequence, executing the one- and two-qubit projective measurements distributed therein. In this method the measurement circuit corresponds to a stabilizer of the surface code, and the measurements generate measurement of a stabilizer operator.