1,548 research outputs found
An optical fiber tip micrograting thermometer
An ~12 µm long Bragg grating was engraved in an ~5 µm diameter optical fiber tip by focused ion beam (FIB) milling. An ~10-dB extinction was achieved at 1570 nm with only 11 indentations. The grating was used for temperature sensing, and it exhibited a temperature sensitivity of ~22 pm/°C
The stability analysis of the dike slope in Bdg reservoir under the seepage of flood
AbstractThe research on the mechanics of flood infiltration induced dike collapse and its evaluating method is a complicated problem which is difficult to be solved and interested by academic field and engineering field. To solve the problem of dike slope stability under flood infiltration, the unstable seepage field of dike slope is simulated under the condition of flood discharge combining with the shear strength reduction finite element method. The paper studies the changes of unstable seepage field when flood .Combined with engineering slope example, numerical simulation is carried out and some significance conclusions are drawn through the calculation result of the example
Investigation on dynamic characteristics of mechanical assembly
Mechanical assembly is important process affecting product dynamic quality. To completely inspect assembly quality, dynamic characteristic analysis is necessary. Based on substructuring dynamic analysis, this paper theoretically analyzes the changes of dynamic characteristics due to assembling process. Assembly coupling dynamic stiffness computed by inverse substructuring analysis is considered as a critical measure on the changes. The results obtained have been well validated by a lumped-parameter model for two-level of substructures
Sudden death of entanglement with Hamiltonian ensemble assisted by auxiliary qubits
In this paper, we theoretically propose a method to simulate the longitudinal
relaxation of a single qubit by coupling it to an auxiliary qubit. In order to
mimic the finite-temperature relaxation, we utilize the Hamiltonian-ensemble
approach [Kropf, Gneiting, and Buchleitner, Phys. Rev. X 6, 031023 (2016)] and
in each realization the auxiliary qubit possesses a random level spacing. The
longitudinal relaxation arises as a consequence of the ensemble average and the
interaction between the working qubit and the auxiliary qubit. Furthermore, we
apply this approach to investigate the influence of the longitudinal relaxation
and the transverse relaxation on the entanglement dynamics of two qubits. It is
discovered that the sudden death of the entanglement will occur as long as the
longitudinal relaxation is present. The transverse relaxation assists the
longitudinal relaxation and thus accelerates the finite-time disentanglement.Comment: 8 pages,7 figure
Observation of forbidden phonons and dark excitons by resonance Raman scattering in few-layer WS
The optical properties of the two-dimensional (2D) crystals are dominated by
tightly bound electron-hole pairs (excitons) and lattice vibration modes
(phonons). The exciton-phonon interaction is fundamentally important to
understand the optical properties of 2D materials and thus help develop
emerging 2D crystal based optoelectronic devices. Here, we presented the
excitonic resonant Raman scattering (RRS) spectra of few-layer WS excited
by 11 lasers lines covered all of A, B and C exciton transition energies at
different sample temperatures from 4 to 300 K. As a result, we are not only
able to probe the forbidden phonon modes unobserved in ordinary Raman
scattering, but also can determine the bright and dark state fine structures of
1s A exciton. In particular, we also observed the quantum interference between
low-energy discrete phonon and exciton continuum under resonant excitation. Our
works pave a way to understand the exciton-phonon coupling and many-body
effects in 2D materials.Comment: 14 pages, 11 figure
Multifunctional imaging enabled by optical bound states in the continuum with broken symmetry
For photonic crystal slab (PCS) structures, bound states in the continuum
(BICs) and circularly polarized states (dubbed C-points) are important
topological polarization singularities in momentum-space and have attracted
burgeoning attention due to their novel topological and optical properties. In
our work, the evolution of polarization singularities from BICs to C-points is
achieved by breaking the in-plane C2 symmetry of a PCS structure of a square
lattice with C4v symmetry. Correspondingly, a BIC is split into two C-points
with opposite chirality, incurring distinct optical transmission responses with
the incidence of right or left circular polarization (RCP or LCP). Harnessing
such chirality selectivity of the C-points, we propose a multifunctional
imaging system by integrating the designed PCS into a conventional 4-f imaging
system, to realize both the edge imaging and conventional bright-field imaging,
determined by the circular polarization state of the light source. In addition
to multifunctional imaging, our system also provides a vivid picture about the
evolution of the PCS platforms' singularities.Comment: 11 pages, 4 figure
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