2025/05/28 by Dominic Lowe, M. S. Kim, Lowe, Dominic +3 · 1 citation
Computer Science · #FOS: Computer and information sciences #FOS: Physical sciences #Gaussian Processes and Bayesian Inference #Machine Learning (cs.LG) #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.2505.22502
openalex publication_date 2025/05/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Gaussian Process Regression is a well-known machine learning technique for which several quantum algorithms have been proposed. We show here that in a wide range of scenarios these algorithms show no exponential speedup. We achieve this by rigorously proving that the condition number of a kernel matrix scales at least linearly with the matrix size under general assumptions on the data and kernel. We additionally prove that the sparsity and Frobenius norm of a kernel matrix scale linearly under similar assumptions. The implications for the quantum algorithms runtime are independent of the complexity of loading classical data on a quantum computer and also apply to dequantised algorithms. We supplement our theoretical analysis with numerical verification for popular kernels in machine learning.