Spatial phase effect on quantum resonance ratchet transport of cold atoms

Abstract

We investigate the transport dynamics of a cold atom exposed to a sawthooth-like optical lattice potential subject to periodic δ-kicks. By means of the computed transport current, at Quantum Resonance regimes, interesting phenomenon induced by the potential spatial phase θ have been resolved. From a zero-phase High Order Quantum Resonance case, where current reversal is possible, we show by turning on the spatial phase θ that current enhancement, current rectification and zero current are achieved. Specifically, θ can be used to turn a negative current into a positive one and vice-versa, to enhance current, or to set current to zero. With the help of current landscapes displayed as function of θ and the potential P, optimal currents are generated. Such a picture clearly shows regions of optimal currents, at critical values of θ and P, where prospective experiments can be done with present-day optical lattice set-up.