FROM GAUGE TRANSFORMATIONS TO TOPOLOGY COMPUTATION IN QUANTUM LATTICE GAS AUTOMATA
Abstract
ABSTRACT The evolution of a quantum lattice gas automaton (LGA) for a single charged particle isinvariant under multiplication of the wave function by a global phase. Requiring invariance under the corresponding local gauge transformations determines the rule for minimalcoupling to an arbitrary external electromagnetic field. We develop the Aharonov-Bohm effect in the resulting model into a constant time algorithm to distinguish a one dimen-sional periodic lattice from one with boundaries; any classical deterministic LGA algorithm distinguishing these two spatial topologies would have expected running time on the orderof the cardinality of the lattice. PACS numbers: 03.65.Lx, 03.65.Vf, 03.65.Pm.KEY WORDS: quantum lattice gas; quantum computation; Aharonov-Bohm effect; spatial topology.