Quantum transport with cold atoms in time-dependent optical potentials: the role of quasi-momentum in the resonant dynamics of the atom–optics kicked rotor

We examine the effect of the initial atomic momentum distribution on the dynamics of the atom–optical realisation of the quantum kicked rotor. The atoms are kicked by a pulsed optical lattice, the periodicity of which implies that quasi–momentum is conserved in the transport problem. We study and compare experimentally and theoretically two resonant limits of the kicked rotor: in the vicinity of the quantum resonances and in the semiclassical limit of vanishing kicking period. It is found that the same experimental distribution of quasi–momenta induces significant deviations from the kicked rotor model close to quantum resonance while its impact close to the classical resonance (i.e. for small kicking period) vanishes. PACS numbers: 42.50.Vk,32.80.Qk,05.45.Mt,05.60.-k Submitted to: J. Phys. A: Math. Gen. § Corresponding author’s e-mail: [email protected] Quantum transport . . . the role of quasi–momentum. 2