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Energy and topological-state properties of the one-dimensional non-Hermitian spin-orbit-coupled Su–Schrieffer–Heeger lattice are theoretically investigated by introducing spin-dependent onsite imaginary potentials with gain and loss. It is found that imaginary potentials lead to the appearance of imaginary energies in the topologically nontrivial phase region, and ${\cal {PT}}$ phase transition occurs in the topologically trivial region. In addition, the imaginary potentials and spin–orbit coupling act together to make the topological phase transition occur in the topologically trivial region, and the topologically nontrivial region becomes wider. The energy spectrum results show that imaginary potentials and spin–orbit coupling have obvious effects on the zero-energy edge states of this system, which mainly lie in the presence of four types of zero-energy states with different localization and numbers. Furthermore, we discuss diagonal disorder and the transport behavior of system, further characterizing the properties of the individual topological states. The above results indicate the special adjustment effect of imaginary potentials and spin–orbit coupling on the band structure of such a system.

Hepatocellular carcinoma (HCC) is one of the common malignant tumors with poor overall prognosis. As a tumor suppressor, the function of miR‐559 in HCC is not clear. In this study, quantitative real‐time PCR was carried out to measure the expression of miR‐559 in HCC cell lines. The effects of miR‐559 on HCC cell proliferation, migration, and invasion were evaluated through a series of functional assays. The mechanism through which miR‐559 regulates HCC cells was investigated by dual‐luciferase reporter assay and functional experiments. The results revealed that miR‐559 expression was low in HCC cell lines. Upregulation of miR‐559 suppressed HCC cell proliferation, migration, and invasion. Dual‐luciferase reporter assay confirmed Golgi membrane protein 73 (GP73) as a target gene of miR‐559. Moreover, miR‐559 could negatively regulate GP73 expression in HCC cells. These results demonstrated that low‐level expression of miR‐559 was associated with HCC, and overexpression of miR‐559 could inhibit HCC cell growth and invasion via targeting GP73.

We investigate the topological properties of a dimerized Kitaev chain with long-range couplings, including the intercell hopping and superconducting pairing terms. It is found that once the intercell hopping term appears, the size of the energy gap, the proportion of topological phases, and the topological phase transition can be modulated. The notable result is that it leads to a new Kitaev-like phase featured by the twofold-degenerated Majorana zero-energy edge states. Next in the presence of the intercell superconducting pairing term, this Majorana phase can be magnified efficiently. Our findings provide new ideas to realize the twofold degenerated Majorana modes based on the intercell hopping and superconducting pairing terms of the dimerized Kitaev chain.

We investigate the Aharonov-Bohm (AB) effect in the parallel double-quantum-dot structure, by introducing an additional s-wave superconductor to couple to the quantum dots. It is found that the AB oscillation of the electron tunneling is different from the superconductor-absent result. Meawhile, the local and crossed Andreev reflections exhibit their special oscillation behaviors, with the change of the local magnetic flux. This means that the AB effect plays an important role in manipulating the complicated quantum transport through this system. We believe that this work can be helpful for understanding the AB oscillation in the presence of Andreev reflection processes.

Using a three-dimensional classical method, we theoretically explore the frustrated double ionization (FDI) of Ar atoms under few-cycle linearly polarized laser pulses with different carrier-envelope phases (CEPs). Our calculated spectra are similar to the recent experimentally observed two peeks in the electron momentum distribution (Larimian et al 2020 Phys. Rev. Res. 2 013021). The dependence of FDI on laser CEPs is investigated, and the result reveals that the two different pathways of FDI can be controlled by CEPs. The information on which pathway leads to FDI is encoded in the electron-electron energy distribution shortly after recollision and momentum distribution at the ionization time after recollision.

Chromium triiodide (CrI3) monolayers have attracted much attention among the first two-dimensional materials discovered experimentally in both electronics and spintronics due to their potential applications. By means of density functional theory, we perform investigations of the electronic structures and magnetic properties of CrI3 monolayer doped with 3 d transition-metal (TM) atoms, which is also called CrXI6 monolayer with X changed from Sc to Fe. It is shown that the electron properties of the CrXI6 system can be tuned from semiconductor to metal/half-metal, which depend on the types of TM atoms. In addition, the CrXI6 system improves ferromagnetic (FM) stabilities, enhancement of magnetic moments, and FM-to-antiferromagnetic transition. These findings enrich the potential application perspectives of CrI3 monolayer in spintronics.

Electron transport through the quantum-dot system with ferromagnetic leads is theoretically investigated, by introducing one Majorana bound state (MBS) to be side-coupled with the dot. It is shown that even for the ferromagnetic leads, the zero-bias conductance is manifested as a peak. However, its magnitude becomes more adjustable, especially when the dot suffers from the external magnetic field and superconducting proximity effect. The other notable result is that the magnetoresistance displays interesting characteristics in this system, which is related to the interplay between the magnetization direction of the MBS and other structural parameters. We believe that this work can be helpful in presenting the MBS-assisted transport behaviors in quantum-dot systems.

We theoretically investigate the Kondo effect of a T-shaped triple-quantum-dot structure, by means of the numerical renormalization group method. It is found that at the point of electron-hole symmetry, the system's entropy has opportunities to exhibit three kinds of transition processes for different interdot couplings, with the decrease of temperature. This leads to the different pictures of the Kondo physics, including the three-stage Kondo effect. Next when the electron-hole symmetry is broken or the structural parameters are changed, the Kondo resonance can also be observed in the conductance spectrum. However, it shows alternative dependence on the relevant quantities, i.e., the Coulomb interaction and interdot couplings. All these phenomena exhibit the abundant and interesting Kondo physics in this system. We believe that this work can be helpful for further understanding the Kondo effect in the triple-quantum-dot structures., To be published in Physical Review B

We theoretically study the transport properties in a one-dimensional photonic lattice influenced by the presence of side-coupled

By introducing the next-nearest-neighboring (NNN) intersite coupling, we investigate the eigenenergies of the [Formula: see text]-symmetric non-Hermitian Su-Schrieffer-Heeger (SSH) model with two conjugated imaginary potentials at the end sites. It is found that with the strengthening of NNN coupling, the particle-hole symmetry is destroyed. As a result, the bonding band is first narrowed and then undergoes the top-bottom reversal followed by the its width's increase, whereas the antibonding band is widened monotonously. In this process, the topological state extends into the topologically-trivial region, and its energy departs from the energy zero point, accompanied by the emergence of one new topological state in this region. All these results give rise to the complication of the topological properties and the manner of [Formula: see text]-symmetry breaking. It can be concluded that the NNN coupling takes important effects to the change of the topological properties of the non-Hermitian SSH system.

We theoretically investigate the electronic transport through a parallel-coupled multi-quantum-dot system, in which the terminal dots of a one-dimensional quantum-dot chain are embodied in the two arms of an Aharonov–Bohm interferometer. It is found that in the structures of odd(even) dots, all their even(odd) molecular states have opportunities to decouple from the leads, and in this process antiresonance occurs which are accordant with the odd(even)-numbered eigenenergies of the sub-molecule without terminal dots. Next when Majorana zero modes are introduced to couple laterally to the terminal dots, the antiresonance and decoupling phenomena still co-exist in the quantum transport process. Such a result can be helpful in understanding the special influence of Majorana zero mode on the electronic transport through quantum-dot systems.

In this work, we investigate the effect of PT -symmetric complex potentials on the transport properties of one non-Hermitian system, which is formed by a parallel coupled double-quantum-dot geometry. It is found that the PT -symmetric complex potentials take pronounced effects to the transport properties of such a system, manifested as the occurrence of antiresonance. In the presence of the interdot Coulomb interaction, such potentials lead to the shift and increase of the antiresonance points, dependent on the Coulomb interaction strength. This study exhibits the special impact of the interplay between the interdot Coulomb interaction and PT -symmetric potentials on the quantum transport behaviors.

We investigate the quantum transmission through the n-p-n heterojunction of massive 8-Pmmn borophene. It is found that the Dirac mass of the electron interacts nontrivially with the anisotropy of the 8-Pmmn borophene, leading to the occurrence of new transmission behaviors in this n-p-n heterojunction. Firstly, the effective energy range of nonzero transmission can be reduced but deviates from the mass amplitude, which induces the further controllability of the transmission property. Secondly, even if the equal-energy surfaces in the p and n parts do not encounter in the k-space, finite transmission is allowed to occur as well. In addition, the existence of Dirac mass can change the reflection manner from the retroreflection to the specular reflection under appropriate conditions. The findings in this work can be helpful in describing the quantum transport properties of the heterojunction based on 8-Pmmn borophene.

In this paper, the physical properties of the graphene/As-F hetero-bilayer are investigated using first-principle calculations on the basis of density functional theory. It is found that the Dirac-cone properties of both graphene and As-F nanosheets are well preserved in this system, and that the two Dirac cones are symmetric about the Fermi level and their positions can be effectively tuned by the strained biaxial stretching. These findings are useful for the design and fabrication of novel nano-electronic devices formed by graphene-based hetero-bilayers. Improved optical properties are also observed in this system, displaying its potential photocatalytic and photovoltaic applications.

The Kondo effect in the T-shaped double-quantum-dot structure is theoretically investigated, by considering different adjustments of the quantum dot levels. It is shown that when the quantum dot levels are shifted to the electron–hole symmetry point, the two-stage Kondo effect can be induced at the limit of weak interdot coupling. However, with the increase of interdot coupling, the interdot antiferromagnetic correlation modifies the Kondo effect efficiently, leading to the destruction of the conductance plateau. If the dot levels are detuned, the low-temperature entropy transition will exhibit new results and complicated transport behaviors occur. The reason also arises from the competition between the Kondo effect and the interdot antiferromagnetic correlation. We believe that these results are helpful for the further understanding of the Kondo physics in the T-shaped double-dot structure.

We theoretically study the transport properties in the T-shaped double-quantum-dot structure, by considering the dot in the main channel to be coupled to the Majorana bound state (MBS) at one end of the topological superconducting nanowire. It is found that the side-coupled dot governs the effect of the MBS on the transport behavior. When its level is consistent with the energy zero point, the MBS contributes little to the conductance spectrum. Otherwise, the linear conductance exhibits notable changes according to the inter-MBS coupling manners. In the absence of inter-MBS coupling, the linear conductance value keeps equal to e 2/2h when the level of the side-coupled dot departs from the energy zero point. However, the linear conductance is always analogous to the MBS-absent case once the inter-MBS coupling comes into play. These findings provide new information about the leakage effect of MBSs in quantum-dot structures.

We investigate the effect of quantum interference on the Andreev reflections (ARs) induced by Majorana bound states (MBSs), by considering their additional coupling via a quantum-dot molecule. It is found that due to the direct and indirect couplings of MBSs, a quantum ring is constructed in this system. Consequently, the interference effect makes important contribution to the ARs, especially in the presence of the local magnetic flux. All the results are manifested as the tight dependence of the differential conductance and Fano factors on the magnetic flux phase factor, dot-MBS couplings, and the dot level, respectively. Moreover, at the zero-bias limit, the magnitudes of the Fano factors and their relation can be efficiently altered by the interference properties. We believe that quantum interference is important for manipulating the Andreev reflection behaviors of the MBSs.

The Majorana-induced Andreev reflection is theoretically investigated, by considering the case of ferromagnetic lead to couple to it via one quantum dot. We find that for the ferromagnetic lead, the Majorana zero mode (MZM) still causes the resonant Andreev reflection at the low-bias limit, even when finite Zeeman splitting appears in the quantum dot. However, the magnetoresistance exhibits interesting properties, and its magnitude and sign depend on the magnetization-direction difference between the ferromagnetic lead and the MZM, especially in the presence of Zeeman effect in the dot. We believe that these findings can be helpful in understanding the MZM-driven Andreev reflections modulated by the ferromagnetic lead.

We study the eigenenergies of a one-dimensional quantum-dot chain with its each dot side coupling to two additional dots. It is found that when the $\mathcal{P}T$-symmetric complex potentials are introduced to the side-coupled dots, the eigenlevel degeneracy is broken. However, further increasing the complex potentials induces a kind of two-degree degeneracy of the eigenlevels. This is accompanied by the $\mathcal{P}T$-symmetry breaking, with the appearance of the complex part of the eigenlevels. These changes exactly affect the quantum transport properties of the chain. First, in the case of weak $\mathcal{P}T$-symmetric complex potentials, a group of transmission function peaks arise at the center of the transmission function spectrum. When the eigenlevel degeneracy takes place, the degenerated eigenlevels decouple from the leads and the corresponding peaks disappear in the transmission function spectra. We believe that this work provides helpful information for a better understanding of the eigenenergies and quantum transport properties in non-Hermitian systems.

By introducing the next-nearest-neighboring (NNN) intersite coupling, we investigate the eigenenergies of the $\cal PT$-symmetric non-Hermitian Su-Schrieffer-Heeger (SSH) model with two conjugated imaginary potentials at the end sites. It is found that with the strengthening of NNN coupling, the particle-hole symmetry is destroyed. As a result, the bonding band is first narrowed and then undergoes the top-bottom reversal followed by the its width's increase, whereas the antibonding band is widened monotonously. In this process, the topological state extends into the topologically-trivial region, and its energy departs from the energy zero point, accompanied by the emergence of one new topological state in this region. All these results give rise to the complication of the topological properties and the manner of $\cal PT$-symmetry breaking. It can be concluded that the NNN coupling takes important effects to the change of the topological properties of the non-Hermitian SSH system., Comment: 8 pages and 8 figures

We theoretically study the quantum transmission through a one-dimensional photonic lattice that couples laterally to the one parity-time ( P T )-symmetric non-Hermitian Su–Schrieffer–Heeger (SSH) chain. It is found that the SSH chain plays important roles in modifying the transmission properties of this system. In the case of weak coupling, the effect of the SSH chain is manifested mainly as the antiresonance caused by the edge states when it is in a topologically nontrivial region. And when the P T -symmetric complex potentials are introduced at the ends of the SSH chain, the edge states undergo P T -symmetry breaking accompanied by a notable change in transmission function spectra. On the other hand, few changes can be observed in the topologically trivial region of the SSH chain. For the strong coupling case, the antiresonance effect of the non-Hermitian SSH chain is apparently modified. Our findings provide helpful content for describing the physics properties of the P T -symmetric non-Hermitian SSH chain.

The Majorana-induced Andreev reflection is theoretically investigated, by considering an additional quantum dot coupled to the normal metallic lead. We find that the quantum dot takes variable effect on the zero-bias conductance induced by the Majorana zero mode. The non-superconducting dot with zero-energy level can suppress the Andreev reflection. Otherwise, the quantum dot only changes the width of the Andreev reflection peak around the zero-bias point with its magnitude equal to 2 e 2 h . Alternatively for the Majorana nonzero mode, the effect of quantum dot becomes dominant, including the zero-bias result. Our findings provide new insights for understanding the Andreev reflection driven by the Majorana modes in experiment.

We theoretically investigate the frustrated double ionization (FDI) of Ar atoms with counter-rotating two-color circular (CRTC) laser fields using the three-dimensional (3D) classical ensemble method. Our results show that the FDI probability depends upon the intensity ratio of the CRTC laser fields. The FDI event accompanied with the recollision excitation with subsequent ionization is prevalent and three pathways exist in FDI processes driven by CRTC laser fields. The momentum distribution of a recaptured electron at the ionization time after recollision indicates that the momentum being close to the vector potential is a necessary condition for FDI events to occur. In addition, the recaptured electron most probably transitions to a Rydberg state of which the quantum number is ten in the CRTC fields.

We theoretically investigate the band structure of the parity-time ( P T )-symmetric non-Hermitian bilayer honeycomb photonic lattice by considering the co-existence of onsite energy detuning and P T -symmetric imaginary potentials. It is found that P T symmetry causes the system’s energy spectra to display salient features, which include various energy-band degeneracies and deformation of the band structure in the vicinity of the Dirac point. Also, the P T -symmetry breaking can be modulated by introducing strain to the system. The findings in this work can help in understanding the band structures of P T -symmetric bilayer honeycomb photonic-lattice systems.

With the semiclassical ensemble model, we explore the relative phase-dependent nonsequential double ionization (NSDI) of Mg by counter-rotating two-color circularly polarized (TCCP) laser pulses. The yield of Mg2+ sensitively depends on the relative phase Δφ and the intensity of TCCP laser fields. At Δφ = 1.5π, the yield of Mg2+ exhibits a pronounced peak in the 0.05 PW/cm2 laser field. This behavior results from the increase of the initial transverse velocity compensating for the drift velocity with the decreasing angle by analyzing the angular distributions of the electron pairs in four relative phases. By changing the relative phases, we find that the recollision excitation with subsequent ionization and the recollision-impact ionization mechanisms can be controlled with TCCP laser fields.

We consider one system in which the terminal dots of a one-dimensional quantum-dot chain couple equally to the left and right leads and study the influence of PT -symmetric complex potentials on the quantum transport process. It is found that in the absence of the complex potentials, remarkable decoupling and antiresonance phenomena are able to co-occur in the transport process. For the chains with odd(even) dots, their even(odd)-numbered molecular states decouple from the leads. Meanwhile, antiresonance occurs at the positions of the even(odd)-numbered eigenenergies of the sub-chains without terminal dots. When the PT -symmetric complex potentials are applied on the terminal dots, the decoupling phenomenon is found to transform into the Fano antiresonance. These results can helpful in understanding the quantum transport modified by the PT symmetry in non-Hermitian discrete systems.

We present a comprehensive analysis about the effect of $\mathcal{PT}$-symmetric complex potentials on quantum transport through one parallel coupled double-quantum-dot structure. It is found that such potentials are able to eliminate the decoupling phenomenon while inducing the Fano effect, even under the situation of uniform dot-lead coupling. Moreover, the Fano line shape in the transmission function spectrum is opposite to that that arises from the detuning of the dot levels. We ascertain that this work can be helpful in understanding the quantum transport properties in the quantum systems with $\mathcal{PT}$ symmetry.