Quantum-Inspired Kernel Learning for Sparse Data
Jincheng Zhang
Abstract
Kernel methods have demonstrated remarkable success in various machine learning tasks, including classification and regression. However, a significant limitation of traditional kernel methods lies in their computational complexity, particularly when dealing with sparse datasets. The need to construct and invert dense kernel matrices, denoted as $K$, where $K_{ij} = k(s_i, s_j)$ with kernel function $k$, leads to a quadratic scaling problem, rendering these methods impractical for datasets with a large number of features or data points. This paper introduces a novel kernel learning algorithm, termed Quantum-Inspired Kernel Learning (QIKL), which addresses this challenge by mimicking quantum interference. QIKL leverages the inherent correlations within sparse datasets to efficiently learn kernel functions without explicitly constructing dense kernel matrices. The algorithm employs a probabilistic approach, represented by a set of quantum-inspired amplitudes, $(a_1, a_2, ..., a_K)$, where $K \approx \sum_{i=1}^{K} a_i^2$, to approximate the kernel matrix. The core idea is to utilize the interference patterns generated by these amplitudes to capture the relationships between data points. This approach significantly reduces the computational cost and memory requirements, making kernel methods viable for sparse data scenarios. We demonstrate the effectiveness of QIKL through theoretical analysis and a simplified numerical example, highlighting its potential for scaling to large-scale sparse data problems.