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Jian Wang

Publications and source records attributed to Jian Wang.

At least 1,207 records · Page 67Linked to original sources
arXiv2012

Improved resummation prediction on Higgs boson production at hadron colliders

We improve the resummation calculations in the ResBos program for the Higgs boson production via gluon-gluon fusion by including the NNLO Wilson coefficient functions and G-functions. The improvement leads to increasing the total cross section predictions of the new ResBos program, dubbed as ResBos2, for Higgs boson production by about 8% and 6% at the Tevatron and the LHC, respectively, as compared to the old ResBos program. Furthermore, the improved predictions are compared with those from the programs HNNLO and HqT2. We find that they agree well for the total cross sections but differ slightly for the transverse momentum $Q_T$ distributions. With ResBos2, we present the distributions of the two variables $a_T$ and $ϕ^{*}$, which can have better experimental resolutions than $Q_T$, for the process of Higgs boson decaying into a photon pair. Theoretical uncertainties of the ResBos2 predictions are also discussed.

hep-ph↗
arXiv2012

Quantum transport in topological insulator hybrid structures -- A combination of topological insulator and superconductor

In this paper, a brief review of the history of topological insulators is given. After that,electronic transport experiments in topological insulator-superconductor hybrid structures, including experimental methods, physical properties and seemingly contradictory observations are discussed. Additionally, some new topological insulator hybrid structures are proposed.

cond-mat.mes-hall↗
arXiv2012

Observation of Correlation between Route to Formation, Coherence, Noise, and Communication Performance of Kerr Combs

Microresonator optical frequency combs based on cascaded four-wave mixing are potentially attractive as a multi-wavelength source for on-chip optical communications. In this paper we compare time domain coherence, radio-frequency (RF) intensity noise, and individual line optical communications performance for combs generated from two different silicon nitride microresonators. The comb generated by one microresonator forms directly with lines spaced by a single free spectral range (FSR) and exhibits high coherence, low noise, and excellent 10 Gbit/s optical communications results. The comb generated by the second microresonator forms initially with multiple FSR line spacing, with additional lines later filling to reach single FSR spacing. This comb exhibits degraded coherence, increased intensity noise, and severely degraded communications performance. This study is to our knowledge the first to simultaneously investigate and observe a correlation between the route to comb formation, the coherence, noise, and optical communications performance of a Kerr comb.

physics.optics↗
arXiv2012

Noncommutative Residue and sub-Dirac Operators for Foliations

In this paper, we define lower dimensional volumes associated to sub-Dirac operators for foliations. In some cases, we compute these lower dimensional volumes. We also prove the Kastler-Kalau-Walze type theorems for foliations with or without boundary. As a corollary, we give an explanation of the gravitational action for the Robertson-Walker space $[a, b]\times_{f}M^{3}$.

math.DG↗
arXiv2012

Experimental measurement-device-independent quantum key distribution

Throughout history, every advance in encryption has been defeated by advances in hacking with severe consequences. Quantum cryptography holds the promise to end this battle by offering unconditional security when ideal single-photon sources and detectors are employed. Unfortunately, ideal devices never exist in practice and device imperfections have become the targets of various attacks. By developing up-conversion single-photon detectors with high efficiency and low noise, we build up a measurement-device-independent quantum key distribution (MDI-QKD) system, which is immune to all hacking strategies on detection. Meanwhile, we employ the decoy-state method to defeat attacks on non-ideal source. By closing the loopholes in both source and detection, our practical system, which generates more than 25 kbit secure key over a 50-km fiber link, provides an ultimate solution for communication security.

quant-ph↗
arXiv2012

A generalization of classical action of Hamiltonian diffeomorphisms to Hamiltonian homeomorphisms on fixed points

We define boundedness properties on the contractible fixed points set of the time-one map of an identity isotopy on a closed oriented surface with genus $g\geq1$. In symplectic geometry, a classical object is the notion of action function, defined on the set of contractible fixed points of the time-one map of a Hamiltonian isotopy. We give a dynamical interpretation of this function that permits us to generalize it in the case of a homeomorphism isotopic to identity that preserves a Borel finite measure of rotation vector zero, provided that a boundedness condition is satisfied. We give some properties of the generalized action. In particular, we generalize a result of Schwarz [Pacific J. Math.,2000] about the action function being non-constant which has been proved by using Floer homology. As applications, we generalize some results of Polterovich [Invent. Math.,2002] about the symplectic and Hamiltonian diffeomorphisms groups on closed oriented surfaces being distortion free, which permits us to give an alternative proof of the $C^1$-version of the Zimmer conjecture on closed oriented surfaces.

math.DS↗
arXiv2012

Lower bounded semi-Dirichlet forms associated with Lévy type operators

Let $k:E\times E\to [0,\infty)$ be a non-negative measurable function on some locally compact separable metric space $E$. We provide some simple conditions such that the quadratic form with jump kernel $k$ becomes a regular lower bounded (non-local, non-symmetric) semi-Dirichlet form. If $E=\R^n$ we identify the generator of the semi-Dirichlet form and its (formal) adjoint. In particular, we obtain a closed expression of the adjoint of the stable-like generator $-(-Δ)^{α(x)}$ in the sense of Bass. Our results complement a recent paper by Fukushima and Uemura (2012) and establishes the relation of these results with the symmetric principal value (SPV) approach due to Zhi-ming Ma and co-authors (2006).

math.PR↗
arXiv2012

Search for the signal of monotop production at the early LHC

We investigate the potential of the early LHC to discover the signal of monotops, which can be decay products of some resonances in models such as R-parity violating SUSY or SU(5), etc. We show how to constrain the parameter space of the models by the present data of $Z$ boson hadronic decay branching ratio, $K^0-\bar{K^0}$ mixing and dijet productions at the LHC. Then, we study the various cuts imposed on the events, reconstructed from the hadronic final states, to suppress backgrounds and increase the significance in detail. And we find that in the hadronic mode the information from the missing transverse energy and reconstructed resonance mass distributions can be used to specify the masses of the resonance and the missing particle. Finally, we study the sensitivities to the parameters at the LHC with $\sqrt{s}$=7 TeV and an integrated luminosity of $1 {\rm fb}^{-1}$ in detail. Our results show that the early LHC may detect this signal at 5$σ$ level for some regions of the parameter space allowed by the current data.

hep-ph↗
arXiv2012

Weighted Poincaré Inequalities for Nonlocal Dirichlet Forms

Let $V$ be a locally bounded measurable function such that $e^{-V}$ is bounded and belongs to $L^1(dx)$, and let $μ_V(dx):=C_V e^{-V(x)} dx$ be a probability measure. We present the criterion for the weighted Poincaré inequality of the non-local Dirichlet form $$ D_{ρ,V}(f,f):=\iint(f(y)-f(x))^2ρ(|x-y|) dy μ_V(dx) $$ on $L^2(μ_V)$. Taking $ρ(r)={e^{-δr}}{r^{-(d+α)}}$ with $0<α<2$ and $δ\geqslant 0$, we get some conclusions for general fractional Dirichlet forms, which can be regarded as a complement of our recent work Wang and Wang (2012), and an improvement of the main result in Mouhot, Russ, and Sire (2011). In this especial setting, concentration of measure for the standard Poincaré inequality is also derived. Our technique is based on the Lyapunov conditions for the associated truncated Dirichlet form, and it is considerably efficient for the weighted Poincaré inequality of the following non-local Dirichlet form $$ D_{ψ,V}(f,f):=\iint(f(y)-f(x))^2ψ(|x-y|) e^{-V(y)} dy e^{-V(x)} dx $$ on $L^2(μ_{2V})$, which is associated with symmetric Markov processes under Girsanov transform of pure jump type.

math.PR↗
arXiv2012

On the conservativeness and the recurrence of symmetric jump-diffusions

Sufficient conditions for a symmetric jump-diffusion process to be conservative and recurrent are given in terms of the volume of the state space and the jump kernel of the process. A number of examples are presented to illustrate the optimality of these conditions; in particular, the situation is allowed to be that the state space is topologically disconnected but the particles can jump from a connected component to the other components.

math.PR↗
arXiv2012

A Silicon Optical Transistor

A fundamental road block for all-optical information processing is the difficulty in realizing a silicon optical transistor with the ability to provide optical gain, input output isolation and buffer action. In this work, we demonstrate an all-optical transistor using optical nonlinearity in microrings. By using weak light to control strong light, we observed an On/Off ratio up to 20 dB. It can compensate losses in other optical devices and provide fan-out capability. The device is ultra compact and is compatible with current complementary metal-oxide-semiconductor (CMOS) processing.

physics.optics↗
arXiv2012

Conditional Fault Diagnosis of Bubble Sort Graphs under the PMC Model

As the size of a multiprocessor system increases, processor failure is inevitable, and fault identification in such a system is crucial for reliable computing. The fault diagnosis is the process of identifying faulty processors in a multiprocessor system through testing. For the practical fault diagnosis systems, the probability that all neighboring processors of a processor are faulty simultaneously is very small, and the conditional diagnosability, which is a new metric for evaluating fault tolerance of such systems, assumes that every faulty set does not contain all neighbors of any processor in the systems. This paper shows that the conditional diagnosability of bubble sort graphs $B_n$ under the PMC model is $4n-11$ for $n \geq 4$, which is about four times its ordinary diagnosability under the PMC model.

math.CO↗
arXiv2012

Enhancement of Secrecy of Block Ciphered Systems by Deliberate Noise

This paper considers the problem of end-end security enhancement by resorting to deliberate noise injected in ciphertexts. The main goal is to generate a degraded wiretap channel in application layer over which Wyner-type secrecy encoding is invoked to deliver additional secure information. More specifically, we study secrecy enhancement of DES block cipher working in cipher feedback model (CFB) when adjustable and intentional noise is introduced into encrypted data in application layer. A verification strategy in exhaustive search step of linear attack is designed to allow Eve to mount a successful attack in the noisy environment. Thus, a controllable wiretap channel is created over multiple frames by taking advantage of errors in Eve's cryptanalysis, whose secrecy capacity is found for the case of known channel states at receivers. As a result, additional secure information can be delivered by performing Wyner type secrecy encoding over super-frames ahead of encryption, namely, our proposed secrecy encoding-then-encryption scheme. These secrecy bits could be taken as symmetric keys for upcoming frames. Numerical results indicate that a sufficiently large secrecy rate can be achieved by selective noise addition.

cs.CR↗
arXiv2012

Tuning thermal transport in nanotubes with topological defects

Using the atomistic nonequilibrium Green's function, we find that thermal conductance of carbon nanotubes with presence of topological lattice imperfects is remarkably reduced, due to the strong Rayleigh scattering of high-frequency phonons. Phonon transmission across multiple defects behaves as a cascade scattering based with the random phase approximation. We elucidate that phonon scattering by structural defects is related to the spatial fluctuations of local vibrational density of states (LVDOS). An effective method of tuning thermal transport in low-dimensional systems through the modulation of LVDOS has been proposed. Our findings provide insights into experimentally controlling thermal transport in nanoscale devices

cond-mat.mes-hall↗
arXiv2012

Dimensional crossover of thermal conductance in graphene nanoribbons: A first-principles approach

First-principles density-functional calculations are performed to investigate the thermal transport properties in graphene nanoribbons (GNRs). The dimensional crossover of thermal conductance from one to two dimensions (2D) is clearly demonstrated with increasing ribbon width. The thermal conductance of GNRs in a few nanometer width already exhibits an approximate low-temperature dependence of $T^{1.5}$, like that of 2D graphene sheet which is attributed to the quadratic nature of dispersion relation for the out-of-plane acoustic phonon modes. Using a zone-folding method, we heuristically derive the dimensional crossover of thermal conductance with the increase of ribbon width. Combining our calculations with the experimental phonon mean-free path, some typical values of thermal conductivity at room temperature are estimated for GNRs and for 2D graphene sheet, respectively. Our findings clarify the issue of low-temperature dependence of thermal transport in GNRs and suggest a calibration range of thermal conductivity for experimental measurements in graphene-based materials.

cond-mat.mes-hall↗
arXiv2012

Superconductivity in single crystalline Pb nanowires contacted by normal metal electrodes

The transport properties of superconducting single crystal Pb nanowires of 55 nm and 70 nm diameter are studied by standard four electrodes method. Resistance-temperature (R-T) scans and magneto-resistance (R-H) measurements show a series of resistance steps with increasing temperature and magnetic field as the wires are brought toward the normal state. The resistance-current (R-I) scans at different temperature and magnetic field show that the increase in R with I is punctuated with sharp steps at specific current values. We interpret these steps as consequence of phase slip centers (PSCs) in the superconducting wires enhanced by the presence of the normal Pt electrodes.

cond-mat.mes-hall↗
arXiv2012

Covalent Hybrid of Spinel Manganese-Cobalt Oxide and Gra-phene as Advanced Oxygen Reduction Electrocatalysts

Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co3O4 nanoparticles, a manganese-cobalt spinel MnCo2O4/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic-nanocarbon hybrid results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge and nitrogen K-edge XANES showed strongly perturbed C-O and C-N bonding in the N-rmGO sheet, suggesting the formation of C-O-metal and C-N-metal bonds between N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge XANES suggested substitu-tion of Co3+ sites by Mn3+, which increased the activity of the catalytic sites in the hybrid materials, further boosting the ORR activity compared to the pure cobalt oxide hybrid. The covalently bonded hybrid afforded much greater activity and durability than the physi-cal mixture of nanoparticles and carbon materials including N-rmGO. At the same mass loading, the MnCo2O4/N-graphene hybrid can outperform Pt/C in ORR current density at medium overpotentials with superior stability to Pt/C in alkaline solutions.

cond-mat.mtrl-sci↗