2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91124In quant-ph/0303042, Poulin, Laflamme, Milburn and Paz consider the problem of distinguishing quantum chaos from quantum integrability for dynamics in an $N$-dimensional Hilbert space. They claim that this can be done by deterministic quantum computing with a single bit using $O(\sqrt{N})$ physical resources, compared to O(N) physical resources classically. I point out what seems to be a fatal flaw with their proposal.1/2 page, no equationsQuantum Physicstext