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- Physics
- UIN Suska Riau
- Xi'an University of the Science and Technology
- University of Riau
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Vortex solitons in Bose–Einstein condensates with spin–orbit coupling and Gaussian optical lattices
摘要： We investigate the generation and stability of three-dimensional (3D) solitons in binary atomic Bose–Einstein condensates with spin–orbit coupling (SOC) and Super-Gaussian optical lattices. We examine the stability of 3D solitons using their norm and energy. The evolution of solitons is made more stable and their resistance to collapse more robust by the introduction of Gaussian lattices. Depending on the relative strength of SOC, the nonlinearity modulation parameter, and the lattice parameters, we observe stable solitons of the semi-vortex and mixed-mode type. In addition, we demonstrate the robustness of solitons in propagation and collisions.
关键词： Spin–orbit coupling,Gaussian lattices,Bose–Einstein condensates,Vortex solitons
更新于2025-09-19 17:15:36
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Novel Hexadeca-Substituted Metal Free and Zinc(II) Phthalocyanines; Design, Synthesis and Photophysicochemical Properties
摘要： The syntheses of a novel 1,4,8,11,15,18,22,25-octahexyloxy-2,3,9,10,16,17,23,24-octa-(4-trifluoromethoxyphenyl) phthalocyanine (3a) and its zinc(II) phthalocyanine derivative (3b) have been described and characterized by elemental analysis, 1H NMR, 13C NMR, 19F NMR, mass, UV-Vis and FT-IR. The newly prepared metal-free phthalocyanine and its zinc(II) counterpart are soluble in most organic solvents. The photophysical and photochemical properties such as aggregation, fluorescence, singlet oxygen generation and photodegradation under light irradiation of these phthalocyanines have been investigated in DMF. The hexadeca-substituted phthalocyanines (3a and 3b) showed longer absorption and emission wavelength values when compared to that of reported phthalocyanine derivatives due to substitution of the all possible positions in the phthalocyanine framework. The zinc(II) phthalocyanine derivative does not only have a good singlet oxygen generation but also has other photophysicochemical properties that enables this phthalocyanine to be useful as a photosensitizer for cancer treatment using photodynamic therapy.
关键词： phthalocyanine,Suzuki-coupling,photodynamic therapy,photochemical,photophysical
更新于2025-09-19 17:15:36
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Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED
摘要： Ultrastrong-coupling between two-level systems and radiation is important for both fundamental and applied quantum electrodynamics (QED). Such regimes are identified by the breakdown of the rotating-wave approximation, which applied to the quantum Rabi model (QRM) yields the apparently less fundamental Jaynes-Cummings model (JCM). We show that when truncating the material system to two levels, each gauge gives a different description whose predictions vary significantly for ultrastrong-coupling. QRMs are obtained through specific gauge choices, but so too is a JCM without needing the rotating-wave approximation. Analysing a circuit QED setup, we find that this JCM provides more accurate predictions than the QRM for the ground state, and often for the first excited state as well. Thus, Jaynes-Cummings physics is not restricted to light-matter coupling below the ultrastrong limit. Among the many implications is that the system's ground state is not necessarily highly entangled, which is usually considered a hallmark of ultrastrong-coupling.
关键词： quantum Rabi model,circuit QED,gauge invariance,Jaynes-Cummings model,ultrastrong coupling,quantum electrodynamics
更新于2025-09-19 17:15:36
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Effects of near-field electromagnetic coupling in dimers of nanoparticles with a silver core and a J-aggregate dye shell
摘要： We report a theoretical study of the plasmon – exciton coupling effect on the absorption spectra of pairs of closely spaced double-layer hybrid nanoparticles consisting of a metallic core and a J-aggregate dye shell. The effect of frequency conversion of plasmonic lines due to the near-field interaction between plasmons and Frenkel excitons of the organic shell is demonstrated. The effect leads to the appearance of additional spectral lines in the long-wavelength part of the spectrum of the system of hybrid particles. The shapes and the relative intensities of the additional lines exactly reproduce the specific features of the original spectrum of plasmonic absorption bands in uncoated metallic nanoparticles. The discovered phenomenon can be used to design new types of high-sensitivity nanosensors, based on plasmon – exciton effects and principles of near-field optics.
关键词： near-field electromagnetic coupling,nanophotonics,Frenkel excitons,dimers of metalorganic nanoparticles,plasmon – exciton interaction,molecular J-aggregates,localised plasmons,absorption spectra
更新于2025-09-19 17:15:36
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Transient Dynamics of Super Bloch Oscillations of a 1D Holstein Polaron under the Influence of an External AC Electric Field
摘要： Theoretical formalism for DC-field polaron dynamics is extended to the dynamics of a 1D Holstein polaron in an external AC electric field using multiple Davydov trial states. Effects of carrier–phonon coupling on detuned and resonant scenarios are investigated for both zero and nonzero phase. For slightly off-resonant or detuned cases, a beat between the usual Bloch oscillations and an AC driving force results in super Bloch oscillations, that is, rescaled Bloch oscillations in both the spatial and the temporal dimension. Super Bloch oscillations are damped by carrier–phonon coupling. For resonant cases, if the carrier is created on two nearest-neighboring sites, the carrier wave packet spreads with small-amplitude oscillations. Adding carrier–phonon coupling localizes the carrier wave packet. If an initial broad Gaussian wave packet is adopted, the centroid of the carrier wave packet moves with a certain velocity and with its shape unchanged. Adding carrier–phonon coupling broadens the carrier wave packet and slows down the carrier movement. Our findings may help provide guiding principles on how to manipulate the dynamics of the super Bloch oscillations of carriers in semiconductor superlattice and optical lattices by modifying DC and AC field strengths, AC phases, and detuning parameters.
关键词： Davydov Ansatz,polaron dynamics,carrier–phonon coupling,super Bloch oscillations
更新于2025-09-19 17:15:36
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Coupling of the First and Second Excited States of R6G Dye with the Fabry-Perot Cavity
摘要： Coupling of macroscopic ensembles of highly concentrated R6G molecules with aluminum and silver Fabry–Perot cavities of different sizes, in which one or two standing wave modes are in resonance with the absorption transition(s) of the dye molecules, have been studied. (i) It has been found that strong coupling of the cavity with one molecular eigenstate (S0!S1 transition) does not perturb the energies of the other molecular states. (ii) The S0!S2 absorption transition is too weak to strongly couple to the resonant cavity (“λ” standing wave mode). However, the resonant cavity causes a blue shift of the S0!S2 excitation band. (iii) The splitting of the dispersion curve is theoretically predicted and experimentally observed at strong coupling of the cavity resonance (“λ” standing wave mode) with the material resonances of Ag, including bound electron and “epsilon equal zero” transitions.
关键词： spectroscopy,Fabry–Perot cavity,energy splitting,excited states,spectral shifts,rhodamine 6G dye,strong coupling
更新于2025-09-19 17:15:36
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Growth of single crystalline GePb film on Ge substrate by magnetron sputtering epitaxy
摘要： A novel direct synthesis of 1,3-dioxo-substituted allenes was developed by copper(I)-catalyzed coupling of a-oxo-alkynes and a-oxo-diazos. It was a sequence of adding substrates-controlled method and the desired products were synthesized chemoselectively by adding a-oxo-alkyne terminally.
关键词： Alkynes,Cross-coupling,Allenes,Copper catalyst,Diazo compounds
更新于2025-09-19 17:15:36
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In vivo neurovascular response to focused photoactivation of Channelrhodopsin-2
摘要： The rapid growth in the use of optogenetics for neuroscience applications is largely driven by two important advantages: highly specific cellular targeting through genetic manipulations; and precise temporal control of neuronal activation via temporal modulation of the optical stimulation. The difference between the most commonly used stimulation modalities, namely diffused (i.e. synchronous) and focused (i.e. asynchronous) stimulation has not been described. Furthermore, full realization of optogenetics’ potential is hindered by our incomplete understanding of the cellular and network level response to photoactivation. Here we address these gaps by examining the neuronal and cerebrovascular responses to focused and diffuse photostimulation of channelrhodopsin in the Thy1-ChR2 mouse. We presented the responses of photoactivation via 470-nm fiber optic illumination (diffuse) alongside 458-nm raster-scan (focused) stimulation of the barrel field. Local field potentials (LFP) assessment of intracerebral electrophysiology and two-photon fluorescence microscopy measurements of red blood cell (RBC) speed (vRBC) in cortical penetrating vessels revealed ~40% larger LFP responses (p=0.05) and twice as large cerebrovascular responses (p=0.002) under focused vs. diffuse photostimulation (focused: 1.64±0.84mV LFP amplitude and 75±48% increase in vRBC; diffuse: 1.14±0.75mV LFP amplitude and 35±23% increase in vRBC). Compared to diffuse photostimulation, focused photostimulation resulted in a ~65% increase in the yield of cerebrovascular responses (73±10% for focused and 42±29% for diffuse photostimulation) and a doubling of the signal-to-noise ratio of the cerebrovascular response (20.9±14.7 for focused and 10.4±1.4 for diffuse photostimulation). These data reveal important advantages of focused optogenetic photoactivation, which can be easily integrated into single- or two-photon fluorescence microscopy platforms, as a means of assessing neuronal excitability and cerebrovascular reactivity, thus paving the way for broader application of optogenetics in preclinical models of CNS diseases.
关键词： Thy1-ChR2,neurovascular coupling,optogenetics,two-photon fluorescence microscopy
更新于2025-09-19 17:15:36
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Hierarchical assembly of silver and gold nanoparticles in two-dimension: Toward fluorescence enhanced detection platforms
摘要： Two-dimensional (2D) metal nanoparticle platforms hold great potential in high-throughput point-of-care testing on basis of their excellent fluorescence enhancement effect. Self-assembly of metal nanoparticles (NPs) is versatile but simple for the preparation of 2D platforms; however, the surface charges on NPs would repel each other and induce large gaps on platforms, which hinder the generation of intense hotspots in electromagnetic fields and thus weaken the fluorescence enhancement effect. Here, we presented the hierarchical assembly of large-sized silver (Ag) NPs and small-sized gold (Au) NPs for constructing fluorescence enhanced platforms. The small Au NPs with weak fluorescence were chosen to complementarily fill into the larger gaps of the pre-assembled Ag platforms for increasing the electromagnetic hotspots. The resulting Ag/Au hybrid platforms (1-, 3- and 6-Ag/Au) exhibited growing fluorescence enhancement effects and the maximum enhanced factor reached 3.6-fold. The inserting of small Au NPs enhanced the fluorescence emission of fluorescent dye (cyanine-5) on the Ag platforms, especially on the monolayer 1-Ag platform, which increased by 161.6%. Moreover, the finite-difference time-domain (FDTD) calculations revealed the underlying cause of the improved electromagnetic fields in the Ag/Au hierarchical architecture in comparison to the Ag or Au NP. This work presents the hierarchical assembly is expected to be a powerful tool in the large-scale fabrication of fluorescence enhanced detection platforms.
关键词： Hotspot,Metal nanoparticles,Fluorescence enhancement,Self-assembly,Plasmon coupling
更新于2025-09-19 17:15:36
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Nonlinear Performance of Few-Mode Fiber Links with Intermediate Coupling
摘要： This paper reviews and extends the study of nonlinear performance of few-mode fiber links operating in all different linear coupling regimes for different mode delay maps. Nonlinear performance was estimated using the four-wave-mixing theory and the split-step Fourier method including semi-analytical solutions for linear mode coupling of arbitrary strength. The optimum link configurations minimizing the nonlinear penalty at practical levels of training sequence length are presented, including: the required coupling strength to give nonlinear distortion below that of the single-mode propagation without mode coupling, and the impact of mode delay maps. Finally, different approximate solution methods of the multimode nonlinear Schr?dinger equation are compared, highlighting the accuracy of a stochastic solution method including distributed linear mode coupling.
关键词： Mode-division multiplexing,few-mode fiber,linear mode coupling,fiber nonlinearity
更新于2025-09-19 17:15:36