Two models of computer, a quantum and a classical "chemical machine" designed to compute the relevant part of Shor's factoring algorithm are discussed. The comparison shows that the basic quantum features believed to be responsible for the exponential speed-up of quantum computations possess their classical counterparts for the hybrid digital-analog computer. It is argued that the measurement errors which cannot be fully corrected make the computation not efficient for both models.
A precise estimation of the computational complexity in Shor's factoring algorithm
Shor's Factoring Algorithm and Modular Exponentiation Operators: A Pedagogical Presentation with Examples
Effects of dynamical phases in Shor's factoring algorithm with operational delays
