Effect of disorders on topological phases in one-dimensional optical superlattices

In a recent paper, Lang et al. proposed that edge states and topological phases can be observed in one-dimensional optical superlattices. They showed that the topological phases can be revealed by observing the density profile of a trapped fermion system, which displays plateaus with their positions. However, disorders are not considered in their model. To study the effect of disorders on the topological phases, we introduce random potentials to the model for optical superlattcies.Our calculations show that edge states are robust against the disorders. We find the edge states are very sensitive to the number of the sites in the optical superlattice and we propose a simple rule to describe the relationship between the edge states and the number of sites. The density plateaus are also robust against weak disorders provided that the average density is calculated over a long interval. The widths of the plateaus are proportional to the widths of the bulk energy gaps when there are disorders. The disorders can diminish the bulk energy gaps. So the widths of the plateaus decrease with the increase of disorders and the density plateaus disappear when disorders are too strong. The results in our paper can be used to guide the experimental detection of topological phases in one-dimensional systems.

Topologically protected edge gap solitons of interacting Bosons in one-dimensional superlattices

We comprehensively investigate the nontrivial states of an interacting Bose system in a cosine potential under the open boundary condition. Our results show that there exists a kind of stable localized state： edge gap solitons. We argue that the states originate from the eigenstates of independent edge parabolas. In particular, the edge gap solitons exhibit a nonzero topological-invariant behavior. The topological nature is due to the connection of the present model to the quantized adiabatic particle transport problem. In addition, the composition relations between the gap solitons and the extended states are also discussed.

Optical and fast nondestructive identification of the ages of leaded ancient pottery

In this paper,based on the one-dimensional（1D） optical superlattice model,we calculate the average reflectivities（ARs） of leaded ancient pottery（AP） made within the last 2000 years,and find that for incident light with a suitable wavelength,the AR of the leaded AP increases monotonously with the increase in the layer number of the silvery glaze（SG） media.Based on this property,we propose an optical nondestructive method for identifying the age of leaded AP by detecting the AR.By using the exhaust algorithm and the discriminant function of variance,we obtain the optimal wavelength range of the incident light to identify the ages of the leaded AP.It is found that in the visible light band,if we choose green light with a wavelength range of 540-540.1 nm as the incident light,leaded AP made within the last 2000 years can be identified swiftly and precisely by detecting the ARs.This will be useful for designing optical instruments for the fast nondestructive identification of the ages of leaded AP.

Generation of tripartite Einstein-Podolsky-Rosen steering by cascaded nonlinear process

A scheme is proposed to generate genuine tripartite Einstein-Podolsky-Rosen(EPR)steering in cascaded nonlinear process of the fourth-harmonic generation.The second-harmonic is generated by the first double-frequency process in an optical superlattice.Then,the fourth-harmonic is produced by the second cascaded double-frequency process through quasi-phase-matching technique in the same optical superlattice.The genuine tripartite EPR steering among the pump,the second-harmonic,and the fourth-harmonic beams can be obtained by this cascaded nonlinear process according to a criterion for genuine multipartite quantum steering.The quantum steering properties are discussed by adjusting the parameters related to the cascaded nonlinear system.The present research provides a reference scheme and data for obtaining good multipartite EPR steering in experiment and can advance the applications of quantum steering in the quantum information processing.

Isolated structures in two-dimensional optical superlattice

Overlaying commensurate optical lattices with various configurations called superlattices can lead to exotic lattice topologies and, in turn, a discovery of novel physics. In this study, by overlapping the maxima of lattices, a new isolated structure is created, while the interference of minima can generate various ＂sublattice＂ patterns. Three different kinds of primitive lattices are used to demonstrate isolated square, triangular, and hexagonal ＂sublattice＂ structures in a two-dimensional optical superlattice, the patterns of which can be manipulated dynamically by tuning the polarization, frequency, and intensity of laser beams. In addition, we propose the method of altering the relative phase to adjust the tunneling amplitudes in ＂sublattices＇. Our configurations provide unique opportunities to study particle entanglement in ＂lattices＂ formed by intersecting wells and to implement special quantum logic gates in exotic lattice geometries.