2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/94150Realistic physical implementations of quantum computers can entail tradeoffs which depart from the ideal model of quantum computation. Although these tradeoffs have allowed successful demonstration of certain quantum algorithms, a crucial question is whether they fundamentally limit the computational capacity of such machines. We study the limitations of a quantum computation model in which only ensemble averages of measurement observables are accessible. Furthermore, we stipulate that input qubits may only be prepared in highly random, ``hot'' mixed states. In general, these limitations are believed to dramatically detract from the computational power of the system. However, we construct a class of algorithms for this limited model, which, surprisingly, are polynomially equivalent to the ideal case. This class includes the well known Deutsch-Jozsa algorithm.4 pages, revtex, submitted June 29, 1999Quantum Physicstext