



01105nas a2200121   4500008004100000245009900041210006900140260001500209520067400224100002300898700001800921856004400939       2005                        eng d00aOn the quantum hardness of solving isomorphism problems as nonabelian  hidden shift problems
0 aquantum hardness of solving isomorphism problems as nonabelian h  c2005/10/253 a  We consider an approach to deciding isomorphism of rigid n-vertex graphs (and
related isomorphism problems) by solving a nonabelian hidden shift problem on a
quantum computer using the standard method. Such an approach is arguably more
natural than viewing the problem as a hidden subgroup problem. We prove that
the hidden shift approach to rigid graph isomorphism is hard in two senses.
First, we prove that Omega(n) copies of the hidden shift states are necessary
to solve the problem (whereas O(n log n) copies are sufficient). Second, we
prove that if one is restricted to single-register measurements, an exponential
number of hidden shift states are required.
1 aChilds, Andrew, M.1 aWocjan, Pawel  uhttp://arxiv.org/abs/quant-ph/0510185v1