Quantum-confined ion superfluid in nerve signal transmission

We propose a process of quantum-confined ion superfluid (QISF),which is enthalpy-driven confined ordered fluid,to explain the transmission of nerve signals.The ultrafast Na^+ and K^+ ions transportation through all sodium-potassium pump nanochannels simultaneously in the membrane is without energy loss,and leads to QISF wave along the neuronal axon,which acts as an information medium in the ultrafast nerve signal transmission.The QISF process will not only provide a new view point for a reasonable explanation of ultrafast signal transmission in the nerves and brain,but also challenge the theory of matter wave for ions,molecules and particles.

Quantum-confined superfluid: From nature to artificial

Biological ion channels show that ultrafast ions and molecules transmission are in a quantum way of single molecular or ionic chain with a certain number of molecules or ions, and we define it as ＂quantum-confined superfluid＂ （QSF）. This ordered ultrafast flow in the confined channel can be considered as ＂quantum tunneling fluid effect＂ with a ＂tunneling distance＂, which is corresponding to the period of QSF. Recent research demonstrated that artificial biomimetic nanochannels also showed the phenomenon of QSF, such as ion and water channels. The introduction of QSF concept in the fields of chemistry and biology may create significant impact. As for chemistry, the QSF effect provides new ideas for accurate synthesis in organic, inorganic, polymer, etc. We believe the implementation of the idea of QSF will promote the development of QSF biochemistry, biophysics, bioinformatics and biomedical science.

Laser-annealing-made amplified spontaneous emission of "giant" CdSe/CdS core/shell nanocrystals transferred from bulk-like shell to quantum-confined core

'Giant' Cd Se/Cd S core/shell nanocrystals(NCs) were synthesized with thick Cd S shell(15 monolayers), and the x-ray diffraction(XRD) measurement indicates there is a zinc blende phase in the thick Cd S shell, whereas it transformed into wurtzite phase under 5 min radiation with a 400 nm, 594 μJ∕cm2femtosecond(fs) laser beam.The evolution of the NCs’ spontaneous emission under the fs laser radiation was recorded with a Hamamatsu streak camera. The as-synthesized NCs exhibit an amplified spontaneous emission(ASE) at 530 nm, which comes from a bulk-like Cd S shell due to the interfacial potential barrier, which could slow down the relaxation of holes from the shell to the core. After being annealed by an fs laser, the ASE of the g-NCs is transferred from a bulk-like Cd S shell to a quantum-confined Cd Se core because the phase transformation determined with the XRD measurement could remove the interfacial barrier. Besides the ASE at 643 nm, two shorter-wavelength ASE peaks at 589 and 541 nm, corresponding to optical transitions of the second(1P) and third(1D) electron quantization shells of the Cd Se core, also appear, thus indicating that Auger recombination is effectively suppressed.

The role of surface charges in the blinking mechanisms and quantum-confined Stark effect of single colloidal quantum dots

The two frequently observed phenomena,photoluminescence(PL)blinking and quantum-confined Stark effect(QCSE)-induced spectral diffusion,are not conducive to the applications of colloidal quantum dots(QDs).It remains elusive how these two phenomena are linked to each other.Unraveling the potential link between blinking and QCSE could facilitate the adoption of appropriate strategies that can simultaneously suppress both PL blinking and spectral diffusion.In this work,we investigated the blinking mechanism and QCSE of single CdSe/CdS/ZnS QDs in the presence of positive and negative surface charges using single-dot PL spectroscopy.We found that the negative surface charges can simultaneously suppress PL blinking and spectral diffusion of single QDs.On the other hand,the positive surface charges could change the blinking mechanisms of QDs from Auger-blinking to band-edge carrier(BC)-blinking.Two types of QCSE were observed,and a significant QCSE-induced spectral broadening of 5.25 nm was measured,which could be attributed to the hopping of surface charges between different surface-trap sites.Based on these findings,several theoretical models are proposed to explain various phenomena observed.

Effects of a prestrained InGaN interlayer on the emission properties of InGaN/GaN multiple quantum wells in a laser diode structure

The electroluminescence （EL） and photoluminescence （PL） spectra of InGaN/GaN multiple quantum wells （MQWs） with a prestrained InGaN interlayer in a laser diode structure are investigated. When the injection current increases from 5 mA to 50 mA, the blueshift of the EL emission peak is 1 meV for the prestrained sample and 23 meV for a control sample with the conventional structure. Also, the internal quantum efficiency and the EL intensity at the injection current of 20 mA are increased by 71% and 65% respectively by inserting the prestrained InGaN interlayer. The reduced blueshift and the enhanced emission are attributed mainly to the reduced quantum-confined Stark effect （QCSE） in the prestrained sample. Such attributions are supported by the theoretical simulation results, which reveal the smaller piezoelectric field and the enhanced overlap of electron and hole wave functions in the prestrained sample. Therefore, the prestrained InGaN interlayer contributes to strain relaxation in the MQW layer and enhancement of light emission due to the reduction of QCSE.

Piezoelectric constant temperature dependence in strained [111]-oriented zinc-blende MQW-SOAs

Here,we present a study of the effective piezoelectric constant(e_(14_(e)))temperature dependence in strained[111]-oriented zinc-blende quantum wells(QWs)embedded within a semiconductor optical amplifier(SOA).We determined e_(14_(e)) using a method that was insensitive to the segregation phenomenon and to the temperature dependence of the bandgap energy,which required neither fitting parameters nor temperature-dependent expressions for energy and out-of-plane effective masses of electrons and heavy holes.An e_(14_(e))=−0.0534±0.0040 C·m^(−2) at 23°C was obtained for an SOA with 1.2 nm[111]-oriented strained In0.687Ga0.313As/In0.807Ga0.193As0.304P0.696 QWs.Unlike previously published research,where e_(14_(e)) magnitude increased as temperature rised,we extracted an e_(14_(e)) magnitude that decreased as temperature increased.

High speed optical modulation in Ge quantum wells using quantum confined stark effect

We focus on the optimization of SiGe material deposition, the minimization of the parasitic capacitance of the probe pads for high speed, low voltage and high contrast ratio operation. The device fabrication is based on processes for standard Si electronics and is suitable for mass-production. We present observations of quantum confinement and quantum-confined Stark effect （QCSE） electroabsorption in Ge quantum wells （QWs） with SiGe barriers grown on Si substrates. Though Ge is an indirect gap semiconductor, the resulting effects are at least as clear and strong as seen in typical III-V QW structures at similar wavelengths. We also demonstrated a modulator, with eye diagrams of up to 3.5 GHz, a small driving voltage of 2.5 V and a modulation bandwidth at about 10 GHz. Finally, carrier dynamics under ultra-fast laser excitation and high- speed photocurrent response are investigated.