Separating Quantum and Classical Learning

Abstract

We consider a model of learning Boolean functions from quantum membership queries. This model was studied in [26], where it was shown that any class of Boolean functions which is information-theoretically learnable from polynomially many quantum membership queries is also information-theoretically learnable from polynomially many classical membership queries. In this paper we establish a strong computational separation between quantum and classical learning. We prove that if any cryptographic one-way function exists, then there is a class of Boolean functions which is polynomial-time learnable from quantum membership queries but not polynomial-time learnable from classical membership queries. A novel consequence of our result is a quantum algorithm that breaks a general cryptographic construction which is secure in the classical setting.