Symmetry, Reversibility, and Efficiency of Quantum Computation

The reason for the higher efficiency exhibited by some quantum algorithms over their classical counterparts is examined by considering the interplay between the reversible actions required to prepare the computer registers in an entangled state before measurement (the “initial actions”), and the final measurement action – whereas measurement is interepreted in a new way, particularly suited to a problem solving context. This unification shows that the computation process, comprising the measurement outcome, is significantly influenced by both the initial actions and the need to satisfy the constraints set by the final measurement action. Reviewing the existing quantum algorithms in the light of this dual influence, yields new valuable insight in the nature of the quantum computation speed up.