2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89668An efficient quantum algorithm is proposed to solve in polynomial time the parity problem, one of the hardest problems both in conventional quantum computation and in classical computation, on NMR quantum computers. It is based on the quantum parallelism principle in a quantum ensemble, the selective decoherence manipulation, and the NMR phase-sensitive measurement. The quantum circuit for the quantum algorithm is designed explicitly.18 pages, no figure. Some small errors are corrected, but conclusion is not changedQuantum Physicstext