title: Theory of 2 delta-kicked quantum rotors.
abstract: We examine the quantum dynamics of cold atoms subjected to pairs of closely spaced delta kicks from standing waves of light and find behavior quite unlike the well-studied quantum kicked rotor (QKR). We show that the quantum phase space has a periodic, cellular structure arising from a unitary matrix with oscillating bandwidth. The corresponding eigenstates are exponentially localized, but scale with a fractional power L is less similar to h(-0.75), in contrast to the QKR for which L is less similar to h(-1). The effect of intercell (and intracell) transport is investigated by studying the spectral fluctuations with both periodic as well as "open" boundary conditions.
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
authors.forename: C E
authors.initials: CE
authors.lastname: Creffield
authors.forename: S
authors.initials: S
authors.lastname: Fishman
authors.forename: T S
authors.initials: TS
authors.lastname: Monteiro