Rapid-adiabatic-passage-based super-resolution microscopy in semiconductor quantum dot system

We theoretically investigate rapid adiabatic passage(RAP)-based super-resolution imaging in a two-level quantum dot system interacting with two structured beams. To understand the physical mechanism behind the formation of super-resolution for the experiment of Kaldewey {\it et. al.,}[Nature Photonics 10.1038/s41566-017-0079-y (2018)], we first use Liouville's density matrix where photon-mediated radiative and non-radiative decays are incorporated. A suitably chosen spatiotemporal envelope of the structured beams enables the formation of a super-resolution image. We also find that the feature size of the image depends on the intensity of the Laguerre Gaussian beam(LG). However, the created image resolution undergoes distortion due to the existence of a low-intensity circular ring. The unwanted circular ring arises from the dominance of the LG beam tail over the super-Gaussian(SG) beam tail, initiating the residual population transfer from the ground state to the excited state. This limitation can be overcome by using the Bessel-modulated truncated structured LG and SG beams. We next study the dynamics of the semiconductor quantum dot system at finite temperatures wherein the phonon interaction becomes imperative. We employ the polaron-transformed master equation to explore the system at higher temperatures. Our numerical results confirm that the sharpness of the image remains intact at low temperatures with weak phonon coupling. Hence, the proposed scheme may open up applications in nano-scale imaging with quantum dots.Comment: 14 pages, 12 figure

Self-induced Transparency in a Semiconductor Quantum Dot medium at ultra-cold temperatures

We investigate the feasibility of minimum absorption and minimum broadening of pulse propagation in an inhomogeneously broadened semiconductor quantum dot medium. The phonon interaction is inevitable in studying any semiconductor quantum dot system. We have used the polaron transformation technique to deal with quantum dot phonon interaction in solving system dynamics. We demonstrate that a short pulse can propagate inside the medium with minimal absorption and broadening in pulse shape. The stable pulse area becomes slightly higher than the prediction of the pulse area theorem and is also dependent on the environment temperature. The change in the final pulse shape is explained very well by numerically solving the propagation equation supported by the susceptibility of the medium. Our system also exhibits the pulse breakup phenomena for higher input pulse areas. Therefore, the considered scheme can have important applications in quantum communication, quantum information, and mode-locking with the advantage of scalability and controllability.Comment: 11 pages, 11 figure

Nondegenerate two-photon lasing in a single quantum dot

We propose two-mode two-photon microlaser using a single semiconductor quantum dot grown inside a two-mode microcavity. We explore both incoherent and coherent pumping at low temperatures to achieve suitable conditions for two-mode two-photon lasing. The two-mode two-photon stimulated emission is strongly suppressed but the single-photon stimulated emission is enhanced by exciton-phonon interactions. In coherently pumped quantum dot one can achieve large two-mode two-photon lasing where single-photon lasing is almost absent. We also discuss generation of steady state two-mode entangled state using two-photon resonant pumping.Comment: 12 pages, 13 figure

Influence of SiO(2) and Al(2)O(3) Fillers on Thermal and Dielectric Properties of Barium Zinc Borate Glass Microcomposites for Barrier Rib of Plasma Display Panels (PDPs)

In a lead-free low temperature sinterable multicomponent barium zinc borate glass system, BaO-ZnO-B(2)O(3)- SiO(2)-Li(2)O-Na(2)O (BZBSLN), the influence of SiO(2) (amorphous) and Al(2)O(3) (crystalline, a-alumina) ceramic fillers on the softening point (T(s)), glass transition temperature (T(g)), coefficient of thermal expansion (CTE), and dielectric constant (epsilon(r)) has been investigated with a view to its use as the barrier ribs of plasma display panels (PDPs). The interaction of fillers with glass which occurred during sintering at 570 degrees C has also been studied by XRD and FTIR spectroscopic analyses. It is observed that the filler has partially dissolved in the glass at the sintering temperature leaving some residual filler which results in ceramic-glass microcomposites. The distribution of fillers in the glass matrix and microstructures of the composites have been analyzed by SEM images. It has been seen that the T(s), T(g), CTE and epsilon(r) slightly increased with the increase of Al(2)O(3) content. In the case of SiO(2) filler, the T(s) and T(g) gradually, increased whereas CTE and epsilon(r) gradually decreased along with the addition or SiO(2). These experimentally measured properties have also been compared with the theoretically predicted values. Both the experimental and theoretical predictions of these properties with added filler contents have been found to be correlated very well. In consideration of the desired properties of barrier rib of PDPs with respect to use on PD200 glass substrates, the addition of Al(2)O(3) filler to BZBSLN glass has been found to be more preferable than SiO(2) filler

Tandem Cooperative Friedel-Crafts Reaction of Aldehydes with Electron Deficient Arenes Through Catalyst-Activation via Hydrogen Bonding Network

Since its discovery in 1877, the Friedel-Crafts alkylation reaction has been the method of choice to prepare various aryl hydrocarbons. Recent developments for this reaction have resulted in the synthesis of these compounds in one pot process with various metal as well as metal free protocols. However, the alkylation of common feedstock aldehydes using electron-deficient arenes and also with two different arene nucleophiles are quite challenging and scantily explored. Herein, we provide a solution to these problems by a new concept, “catalyst activation” accomplished by increasing the Brønsted acidity of p-toluenesulfonic acid (pTSA) through strong hydrogen bonding with hexafluoroisopropanol (HFIP). The real-time NMR titration, as well as computational studies, reveal multiple roles of HFIP in increasing the Brønsted acidity of para-toluene sulphonic acid (pTSA) and stabilization of the transition states formed during the electrophilic aromatic substitution. The developed process has a great potential for industrial application reflected in the synthesis of various bio-active natural products like arundine, tartarinoid C, and several other bioactive molecules. Also, the used HFIP was recovered in a gram-scale synthesis making this protocol highly cost-effective and conducive to industrial production