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Jian Wang

Publications and source records attributed to Jian Wang.

At least 1,279 records · Page 71Linked to original sources
arXiv2010

Optimizing transport efficiency on scale-free networks through assortative or dissortative topology

We find that transport on scale-free random networks depends strongly on degree-correlated network topologies whereas transport on Erd$\ddot{o}$s-R$\acute{e}$nyi networks is insensitive to the degree correlation. An approach for the tuning of scale-free network transport efficiency through assortative or dissortative topology is proposed. We elucidate that the unique transport behavior for scale-free networks results from the heterogeneous distribution of degrees.

cond-mat.stat-mech↗
arXiv2009

Controllable Andreev retroreflection and specular Andreev reflection in a four-terminal graphene-superconductor hybrid system

We report the investigation of electron transport through a four-terminal graphene-superconductor hybrid system. Due to the quantum interference of the reflected holes from two graphene-superconductor interfaces with phase difference $θ$, it is found that the specular Andreev reflection vanishes at $θ=0$ while the Andreev retroreflection disappears at $θ=π$. This means that the retroreflection and specular reflection can be easily controlled and separated in this device. In addition, due to the diffraction effect in the narrow graphene nanoribbon, the reflected hole can exit from both graphene terminals. As the width of nanoribbon increases, the diffraction effect gradually disappears and the reflected hole eventually exits from a particular graphene terminal depending on the type of Andreev reflection.

cond-mat.mes-hall↗
arXiv2009

New universal conductance fluctuation of mesoscopic systems in the crossover regime from metal to insulator

We report a theoretical investigation on conductance fluctuation of mesoscopic systems. Extensive numerical simulations on quasi-one dimensional, two dimensional, and quantum dot systems with different symmetries (COE, CUE, and CSE) indicate that the conductance fluctuation can reach a new universal value in the crossover regime for systems with CUE and CSE symmetries. The conductance fluctuation and higher order moments vs average conductance were found to be universal functions from diffusive to localized regimes that depend only on the dimensionality and symmetry. The numerical solution of DMPK equation agrees with our result in quasi-one dimension. Our numerical results in two dimensions suggest that this new universal conductance fluctuation is related to the metal-insulator transition.

cond-mat.dis-nn↗
arXiv2009

Transient dynamics of molecular devices under step-like pulse bias

We report first principles investigation of time-dependent current of molecular devices under a step-like pulse.Our results show that although the switch-on time of the molecular device is comparable to the transit time, much longer time is needed to reach the steady state. In reaching the steady state the current is dominated by resonant states below Fermi level. The contribution of each resonant state to the current shows the damped oscillatory behavior with frequency equal to the bias of the step-like pulse and decay rate determined by the life time of the corresponding resonant state. We found that all the resonant states below Fermi level have to be included for accurate results. This indicates that going beyond wideband limit is essential for a quantitative analysis of transient dynamics of molecular devices.

cond-mat.mes-hall↗
arXiv2009

200km Decoy-state quantum key distribution with photon polarization

We demonstrate the decoy-state quantum key distribution over 200 km with photon polarization through optical fiber, by using super-conducting single photon detector with a repetition rate of 320 Mega Hz and a dark count rate of lower than 1 Hz. Since we have used the polarization coding, the synchronization pulses can be run in a low frequency. The final key rate is 14.1 Hz. The experiment lasts for 3089 seconds with 43555 total final bits.

quant-ph↗
arXiv2009

Discovery Potential of New Boson $W_1^{\pm}$ in the Minimal Higgsless Model at LHC

In this paper, we demonstrate the LHC discovery potential of new charged vector boson $W_1^{\pm}$ predicted by the Minimal Higgsless model in the process $pp\to W_1^{\pm}qq^{\prime}\to W^{\pm}Z^0qq^\prime\to \ell^{\pm}\ell^+\ell^-νqq^{\prime}(\ell=e,μ)$ by analyzing the generator level events of the signal and backgrounds. The generator for the signal $pp \to {W_1}^{\pm}qq^\prime\to W^{\pm}Z^0qq^\prime$ at tree level is developed with the Minimal Higgsless model and then interfaced with PYTHIA for the parton showers and hadronization. The backgrounds are produced with PYTHIA and ACERMC. We give integrated luminosities required to discover 5$σ$ signal as a function of $W_1^{\pm}$ mass.

hep-ex↗
arXiv2009

Field test of a practical secure communication network with decoy-state quantum cryptography

We present a secure network communication system that operated with decoy-state quantum cryptography in a real-world application scenario. The full key exchange and application protocols were performed in real time among three nodes, in which two adjacent nodes were connected by approximate 20 km of commercial telecom optical fiber. The generated quantum keys were immediately employed and demonstrated for communication applications, including unbreakable real-time voice telephone between any two of the three communication nodes, or a broadcast from one node to the other two nodes by using one-time pad encryption.

quant-ph↗
arXiv2009

Superconductivity and quantum oscillations in crystalline Bi nanowires

While bulk bismuth (Bi) is a semimetal, we have found clear evidence of superconductivity in a crystalline 72 nm diameter Bi nanowire below 1.3 K. In a parallel magnetic field (H), the residual resistance of the nanowire below Tc displays periodic oscillations with H, and the period corresponds to the superconducting flux quantum. This result provides evidence that the superconductivity comes from the interface shell between Bi and the surface oxide. In a perpendicular H, the resistance in the superconducting state shows Shubnikov-de Haas (SdH) oscillations, a signature of a normal metal. These results indicate a novel coexistence of Bosonic and Fermionic states in the surface shell of nanowires.

cond-mat.mes-hall↗
arXiv2009

Proximity-induced superconductivity in nanowires: Mini-gap state and differential magnetoresistance oscillations

We study proximity-induced superconductivity in gold nanowires as a function of the length of the nanowire, magnetic field, and excitation current. Short nanowires exhibit a sharp superconducting transition, whereas long nanowires show nonzero resistance. At intermediate lengths, however, we observe two sharp transitions; the normal and superconducting regions are separated by what we call the mini-gap phase. Additionally, we detect periodic oscillations in the differential magnetoresistance. We provide a theoretical model for the mini-gap phase as well as the periodic oscillations in terms of the coexistence of proximity-induced superconductivity with a normal region near the center of the wire, created either by temperature or application of a magnetic field.

cond-mat.supr-con↗
arXiv2009

Different mechanisms for efficient optical transmission through bilayered subwavelength patterned metal films

Light transmission through bilayered thin metal films perforated with subwavelength hole arrays are numerically studied based on a full-vector finite-difference time-domain approach. A variety of transmission peaks originating from different physical mechanisms are observed. In addition to the direct tunnelling and Fabry-Pèrot resonances, generally possessed by idealized bilayered dielectric slabs, the near-field localized plasmon polaritons also play important roles. They not only influence the direct tunnelling in a destructive or constructive way, the interactions between these localized plasmon polaritons on different metal films also result in additional channels which transfer optical energy effectively.

physics.optics↗
arXiv2008

Spin Bias Measurement Based on a Quantum Point Contact

Electron charge transport through a quantum point contact (QPC) driven by an asymmetric spin bias is studied. A large charge current is induced when the transmission coefficient of the QPC jumps from one integer plateau to the next. Furthermore, for an open external circuit, the induced charge bias instead of the charge current is found to be quite large. It provides an efficient and practical way to detect spin bias by using a very simple device, a QPC or a STM tip. In addition, with the aid of magnetic field, polarization direction of the spin bias can also be determined.

cond-mat.mes-hall↗
arXiv2008

EtabFDC: an $η_b$ event generator in hadroproduction at LHC

The EtabFDC is a matrix-element event generator package for $η_b$ hadroproduction at LHC. It generates $pp\toη_b X$ events for all possible parton-level $2\to2$ leading-order processes with three commonly used $η_b$ decay channels being implemented. The \pythia interface is used for parton-shower and hadronization to obtain the hadronic events. The FORTRAN codes of this package are generated by FDC (Feynman Diagram Calculation) system automatically.

hep-ph↗
arXiv2008

Single-mode phonon transmission in symmetry broken carbon nanotubes

Normal mode phonon transmissions are studied in carbon nanotubes with the presence of Stone-Wales (SW) defect, using a mode-matching method and through the analysis of symmetry. The calculation shows that the transmission for low group velocity acoustic phonons is evidently reduced at high frequency range, and that this SW defect induced symmetry breaking strongly inhibits the transmission of long wave optical phonons in carbon nanotubes. The characteristic features of transmission for each phonon mode depend on the symmetry. These findings suggest that the local heating in the defective nanotubes may be contributed mainly from the low group velocity acoustic phonons and optical phonons near the $Γ$-point.

cond-mat.mes-hall↗
arXiv2008

Conductance spectra of metallic nanotube bundles

We report a first principles analysis of electronic transport characteristics for (n,n) carbon nanotube bundles. When n is not a multiple of 3, inter-tube coupling causes universal conductance suppression near Fermi level regardless of the rotational arrangement of individual tubes. However, when n is a multiple of 3, the bundles exhibit a diversified conductance dependence on the orientation details of the constituent tubes. The total energy of the bundle is also sensitive to the orientation arrangement only when n is a multiple of 3. All the transport properties and band structures can be well understood from the symmetry consideration of whether the rotational symmetry of the individual tubes is commensurate with that of the bundle.

cond-mat.mes-hall↗
arXiv2008

Disorder-induced enhancement of transport through graphene p-n junctions

We investigate the electron transport through a graphene p-n junction under a perpendicular magnetic field. By using Landauar-Buttiker formalism combining with the non-equilibrium Green function method, the conductance is studied for the clean and disordered samples. For the clean p-n junction, the conductance is quite small. In the presence of disorders, it is strongly enhanced and exhibits plateau structure at suitable range of disorders. Our numerical results show that the lowest plateau can survive for a very broad range of disorder strength, but the existence of high plateaus depends on system parameters and sometimes can not be formed at all. When the disorder is slightly outside of this disorder range, some conductance plateaus can still emerge with its value lower than the ideal value. These results are in excellent agreement with the recent experiment.

cond-mat.mes-hall↗