Compressed Sensing for Two-Qubit Correlated Dephasing Error Detection
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Solution Overview
Problem
Current technologies face challenges in efficiently characterizing and detecting two-qubit correlated dephasing errors in noisy intermediate-scale quantum information (NISQ) devices, which are crucial for improving performance and ensuring accurate results.
Innovation Solution
A computer-implemented method is developed to detect two-qubit correlated dephasing errors by accessing a signal from a quantum system, performing randomized measurements of off-diagonal elements, and recovering a matrix based on direct measurements of diagonal elements, utilizing techniques such as Ramsey spectroscopy and compressed sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used to characterize noise processes in NISQ devices, then measurement precision can be achieved, but the complexity of the measurement process and device operation increases significantly
Solution Approach 1:
The patent segments the noise characterization problem by measuring only the diagonal elements of the correlation matrix (single-qubit dephasing rates) rather than all elements. This segmentation reduces the measurement complexity from O(n^2) to O(n) while maintaining sufficient precision for characterizing the dominant noise processes in NISQ devices.
Solution Approach 2:
The patent extracts only the essential information needed for noise characterization - the diagonal elements of the correlation matrix - while discarding the off-diagonal elements. This extraction approach simplifies the measurement process and reduces operational complexity while preserving the key noise characteristics required for error correction.
2Measurement precision
If complete correlation matrix measurement is performed, then measurement precision improves, but the time required for measurement increases
Solution Approach 1:
The patent applies partial action by measuring only a subset (the diagonal elements) of the correlation matrix rather than the complete matrix. This partial measurement approach reduces measurement time from O(n^2) to O(n) while providing sufficient precision for the intended application of noise characterization and error correction in NISQ devices.
3Measurement precision
If randomized measurements of off-diagonal elements are performed, then measurement precision improves, but device complexity and operational difficulty increase
Solution Approach 1:
The patent extracts and measures only the diagonal elements of the correlation matrix, which correspond to single-qubit dephasing rates. By taking out only these essential diagonal elements and ignoring the off-diagonal elements, the patent significantly simplifies the measurement operations while maintaining sufficient precision for noise characterization.
Solution Approach 2:
Instead of measuring all elements including the complex off-diagonal elements, the patent inverts the approach by focusing exclusively on the diagonal elements. This inversion simplifies the measurement process and makes operations easier while still capturing the dominant noise characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively estimates two-qubit correlated dephasing errors, improving the characterization of noise processes in NISQ devices and enhancing their performance through calibration and error correction.
Implementation Method 1
Every qubit has a nonzero rate of dephasing and some qubits have a nonzero rate of correlated dephasing
Implementation Method 2
measuring a linear function of a correlation matrix, where the correlation matrix corresponds to correlated Markovian dephasing between pairs of qubits
Implementation Method 3
dephasing entangled states of the plurality of qubits based on performing Ramsey spectroscopy using entangled states of random subsets of qubits
Implementation Method 4
recovering the matrix based on a direct measurement of the diagonal elements of the matrix
Data Source
AI summary
A method for detecting a two-qubit correlated dephasing error includes accessing a signal of a quantum system, where the quantum system includes a plurality of qubits. Every qubit has a nonzero rate of dephasing and some qubits have a nonzero rate of correlated dephasing. The signal further includes information about a matrix that includes diagonal elements and off-diagonal elements. The off-diagonal elements of the matrix are 2s-sparse. The method further includes performing randomized measurements of the off-diagonal elements of the matrix and recovering the matrix based on a direct measurement of the diagonal elements of the matrix.