arXiv subjects

Yi Xu

Publications and source records attributed to Yi Xu.

440 records · Page 25Linked to original sources

arXiv2012

Nonlinear Mach-Zehnder-Fano interferometer

We demonstrate that the interaction of loop and nonlinear Fano resonances results in a formation of hybrid resonant states in Mach-Zehnder type interferometers, providing with opportunities for an advanced phase manipulation. The nonlinear response of such structures can be greatly enhanced, leading to a low threshold 100% switching operation. We further propose one of the possible realizations based on nonlinear photonic crystal circuits, suitable for optimal all-optical switching.

physics.optics↗

arXiv2011

Polarization manipulation holographic lithography by single refracting prism

We propose a simple but effective strategy for polarization manipulation holographic lithography by single refractive prism. By tuning the polarization of single laser beam, we simply obtain a pill shape interference pattern where multiple modulated beams are needed in conventional holography lithography. Fabrication of large area pill shape two-dimensional polymer photonic crystals template using one beam and one shoot holography lithography is shown as an example. This integrated fabrication technique, for example, can release the crucial stability restrictions imposed on the multiple beams holography lithography.

physics.optics↗

arXiv2011

Three-dimensional Orientation Sensors by Defocused Imaging of Gold Nanorods through an Ordinary Wide-Field Microscope

Gold (Au) nanoparticles particularly nanorods are actively exploited as imaging probes because of their special nonblinking and nonbleaching absorption, scattering and emitting properties that arise from the excitation of surface plasmons. Herein, we report a novel orientation sensor at nanoscale by defocused imaging of single Au nanorods (AuNRs) through an ordinary wide-field optical microscope. By simultaneously recording defocused images and two-photon luminescence intensities for a large number of single AuNRs, we correlate their defocused images with their three-dimensional spatial orientations. As many AuNRs can be monitored in parallel, defocused imaging of single AuNRs is a high throughput sensing technique that allows us to obtain their spatial orientations within one frame in situ and real-time. The probe size can be down to several nanometers, which is highly desirable in order to minimize any potential interference from the probe itself. Furthermore, the sensing property is insensitive to the excitation polarization and the distribution of the probe aspect ratio, which allows AuNRs of any length in a proper regime to be used as orientation sensors without changing the laser frequency and polarization. These unique features make the orientation probes proposed here outstanding candidates for optical imaging and sensing in material science and biology.

physics.optics↗

arXiv2011

Standard Big-Bang Nucleosynthesis up to CNO with an improved extended nuclear network

Primordial or Big Bang nucleosynthesis (BBN) is one of the three strong evidences for the Big- Bang model together with the expansion of the Universe and the Cosmic Microwave Background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and we enlarge the nuclear network until Sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including \approx 270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial Beryllium, Boron, Carbon, Nitrogen and Oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, 9Be and Boron nucleosynthesis. We reevaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial Beryllium abundance increase by a factor of 4 compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 \times 10-15. On the other hand, the extension of the nuclear network has not changed the 7Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.

astro-ph.CO↗

arXiv2010

Enhanced surface acceleration of fast electrons by using sub-wavelength grating targets

Surface acceleration of fast electrons in intense laser-plasma interaction is improved by using sub-wavelength grating targets. The fast electron beam emitted along the target surface was enhanced by more than three times relative to that by using planar target. The total number of the fast electrons ejected from the front side of target was also increased by about one time. The method to enhance the surface acceleration of fast electron is effective for various targets with sub-wavelength structured surface, and can be applied widely in the cone-guided fast ignition, energetic ion acceleration, plasma device, and other high energy density physics experiments.

physics.plasm-ph↗

arXiv2006

A quantum secret sharing scheme among three parties ultilizing four-qubit Smolin bound entangled state

Four-qubit Smolin bound entangled state has a distinct feature: the state is not distillable when every qubit is seperated from each other; but it makes two separated qubit entangled if the other qubits group together. Here the feature is applied to quantum secret sharing, a QSS protocol similar to Ekert 91 protocol of QKD is proposed. The security problem, disadvantage and advantageof this protocol are disscused.

quant-ph↗

arXiv2004

Proton incorporations and superconductivity in a cobalt oxyhydrate

We report the evidence of proton incorporations in a newly-discovered cobalt oxyhydrate superconductor. During the hydration process for Na$_{0.32}$CoO$_{2}$ by the direct reaction with water liquid, it was shown that substantial NaOH was gradually liberated, indicating that H$^{+}$ is incorporated into the hydrated compound. Combined with the thermogravimetric analysis, the chemical composition of the typical sample is Na$_{0.22}$H$_{0.1}$CoO$_{2}\cdot 0.85$H$_{2}$O, which shows bulk superconductivity at 4.4 K.

cond-mat.supr-con↗

arXiv2003

Superconductivity in a layered cobalt oxyhydrate Na$_{0.31}$CoO$_{2}\cdot$1.3H$_{2}$O

We report the electrical, magnetic and thermal measurements on a layered cobalt oxyhydrate Na$_{0.31}$CoO$_{2}\cdot$1.3H$_{2}$O. Bulk superconductivity at 4.3 K has been confirmed, however, the measured superconducting fraction is relatively low probably due to the sample's intrinsic two-dimensional characteristic. The compound exhibits weak-coupled and extreme type-II superconductivity with the average energy gap $Δ_{a}(0)$ and the Ginzburg-Landau parameter $κ$ of $\sim$ 0.50 meV and $\sim$ 140, respectively. The normalized electronic specific heat data in the superconducting state well fit the $T^{3}$ dependence, suggesting point nodes for the superconducting gap structure.

cond-mat.supr-con↗