Quantum transport of bosonic cold atoms in double-well optical lattices

Abstract

We numerically investigate, using the time evolving block decimation algorithm, the quantum transport of ultracold bosonic atoms in a double-well optical lattice through slow and periodic modulation of the lattice parameters (intra-and inter-well tunneling, chemical potential, etc.). The transport of atoms does not depend on the rate of change of the parameters (as along as the change is slow) and can distribute atoms in optical lattices at the quantized level without involving external forces. The transport of atoms depends on the atom filling in each double well and the interaction between atoms. In the strongly interacting region, the bosonic atoms share the same transport properties as noninteracting fermions with quantized transport at the half filling and no atom transport at the integer filling. In the weakly interacting region, the number of the transported atoms is proportional to the atom filling. We show the signature of the quantum transport from the momentum distribution of atoms that can be measured in the time-of-flight image. A semiclassical transport model is developed to explain the numerically observed transport of bosonic atoms in the noninteracting and strongly interacting limits. The scheme may serve as an quantized battery for atomtronics applications.

Simulation and measurement of the fractional particle number in one-dimensional optical lattices

“…(10), which corresponding to the mimicked FPN in this system. In addition, the particle transport can be directly measured from the shift of the center of mass of an atomic cloud in a finite lattice system [33,35,40]. In our system, the center of mass of an atomic cloud in the lattice with L sites x com (t) is given by…”

“…This is an analog of the adiabatic charge pumping proposed by Thouless [32]; however, the parametric driving in our case does not form a closed cycle but only a half one. The topological pumping in cold atom systems and photonic quasi-crystals has been discussed in the contexts of SSH model [33][34][35] and 1D quasi-periodic Harper model [36][37][38][39][40], where the pumping particle is shown to be quantized one over one period and can be fractional over a fraction of one period [40].…”

Total Current Blockade in an Ultracold Dipolar Quantum Wire

“…What makes these systems particularly interesting is that one essentially can freely engineer their properties, and even control the shape and strength of the interparticle interactions. More recently this sparked great interest in making (quantum-)logical devices with ultracold atoms and molecules analogous to those in electronics and spintronics [10][11][12][13][14][15].…”

Anomalous charge pumping in a one-dimensional optical superlattice

“…While recent studies have focused on the tight-binding limit (the Aubry-Andre model) [4-21], we study the continuous limit of the 1D superlattice, where, because of the weak potential, the single-particle spectra can be calculated perturbatively. Related cold atom proposals on quantized transport [22][23][24][25][26] have focused on the simplest superlattice where one sub-lattice constant is half of the other, and are therefore not in the anomalous regime which interests us.The 1D superlattice can be mapped onto the HarperHofstadter model [2,27]. The topological numbers (Chern numbers) associated with charge pumping can be mapped onto quantized Hall conductances [28,29].…”

“…While recent studies have focused on the tight-binding limit (the Aubry-Andre model) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], we study the continuous limit of the 1D superlattice, where, because of the weak potential, the single-particle spectra can be calculated perturbatively. Related cold atom proposals on quantized transport [22][23][24][25][26] have focused on the simplest superlattice where one sub-lattice constant is half of the other, and are therefore not in the anomalous regime which interests us.…”