Public-key Cryptography: Theory and Practice

8.1. Introduction

So far, we studied algorithms in the area of cryptology, that can be implemented on classical computers (Turing machines or von Neumann’s stored-program computers). Now, we shift our attention to a different paradigm of computation, known as quantum computation. The working of a quantum computer is specified by the laws of quantum mechanics, a branch of physics developed in the 20^th century. However counterintuitive, contrived or artificial these laws initially sound, they have been accepted by the physics community as robust models of certain natural phenomena. A bit, modelled as a quantum mechanical system, appears to be a more powerful unit than a classical bit to build a computing device.

This enhanced power of a computing ...