Surface polarization and edge charges

Abstract

The term "surface polarization" is introduced to describe the in-plane polarization existing at the surface of an insulating crystal when the in-plane surface inversion symmetry is broken. Here, the surface polarization is formulated in terms of a Berry phase, with the hybrid Wannier representation providing a natural basis for study of this effect. Tight binding models are used to demonstrate how the surface polarization reveals itself via the accumulation of charges at the corners/edges for a two dimensional rectangular lattice and for GaAs.

Activating remote entanglement in a quantum network by local counting of identical particles

“…Besides its conceptual novelty, the key advantage of this process is that it simplifies the task of distributing entanglement, overcoming the drawbacks encountered in the usual entanglement transfer procedures during the initial preparation stage and the final measurement phase. In fact, it skips the use of sources of entangled particle pairs, which are for instance generated by SPDC at the very low rate of about 10 −2 for single laser pulse [38], and also avoids the experimental inefficiency associated to performing Bell measurements [23,28,[40][41][42][43][44][45].…”

“…4 (orange points and blue triangles, respectively). From the experimental viewpoint, one has to take into account that the requirement of Bell measurements further hinders the protocol efficiency [23,28,[40][41][42][43][44][45]. Therefore, the fermionic process results in being not only qualitatively different, but also more advantageous from a practical viewpoint than the other procedures that necessarily require Bell measurements.…”

“…Multiple ES has been theoretically proposed and experimentally realized by extension of the standard protocol [33][34][35][36]. The overall success of the process is influenced by the low creation rate of photon pairs in SPDC [37][38][39] and by the inefficiency in the realization of Bell measurements [23,28,[40][41][42][43][44][45].…”

Topological edge states in the Su-Schrieffer-Heeger model

“…24 Integration of the Berry connection over momentum space (also called the Zak phase 25 ) results in an electric dipole moment that generates robust fractional surface charges. [26][27][28] Such a dipole field related to the Zak phase is used to design topological materials, i.e., topological electrides 29,30 and A 3 B atomic sheet such as C 3 N. 31,32 Recently, this idea is extended to an electric quadrapole moment which induces topological corner states. [33][34][35][36][37][38][39][40] In addition, since topological design on the basis of Zak phase does not demand the spin-orbit couplings, this approach is useful to apply to nonelectronic systems such as topological photonic, [41][42][43][44][45] accoustic crystals [46][47][48][49] and topological circuit.…”

Bloch oscillations of spin-orbit-coupled cold atoms in an optical lattice and spin-current generation

“…Before concluding the paper, we need to note that in the presence of SO interaction one should be very careful while using the above lowest energy band truncation. As was pointed out by Zhou and Cui [44], in this case tightbinding models have limitations in predicting the correct single-particle physics due to the missed high-band contributions. Physically the Raman lasers inducing SO interaction also inevitably couple atoms to high-lying bands which will significantly affect the single-particle physics [24].…”