A scheme for two-dimensional (2D) atom localization via probe absorption in a three-level $$\Lambda${}$-type atomic system is suggested. The required atom-field configuration is obtained when the atom interacts with a weak probe field and two orthogonal standing-wave fields where each standing-wave field is obtained from the superposition of the two standing-wave fields along the corresponding directions. We study the effect of the probe field detuning and phase shifts associated with the standing-wave fields. Two equally probable position information of the single atom are observed in the conditional position probability distribution. However, a unique position of the single atom in the 2D $xy$ plane is observed for some arbitrary choices of the phases associated with standing-wave fields and by selecting slightly different wavelengths of standing-wave fields.

We propose a scheme to generate structured light using a medium consisting of semiconductor quantum dots via four-wave mixing (FWM). We consider a four-level quantum-dot structure where two strong electromagnetic fields couple upper-level biexciton transitions, whereas a weak field is applied to one of the ground-level exciton transitions. A weak signal field is generated, corresponding to a second ground-level exciton transition; thus the overall configuration transforms into a closed-loop diamond-type shape. To realize a spatially dependent modulating quantum-dot medium, we consider strong coupling fields as structured lights and investigate different regions of spatially structured electromagnetically induced transparency via absorption of the generated signal field. The azimuthal phase-dependent modulation of the absorption profile of the generated signal field is the key factor behind the creation of structured light. In addition, we also demonstrate transfer of orbital angular momentum (OAM) of the control beam to the generated beam through the FWM process and study the effect of phase mismatch on efficiency of the OAM transfer.

In this study, dichlorodifluoromethane (R12) gas and mixtures with nitrogen (N ₂ ) andair at different pressures and mixing ratios have been investigated and showedgood alternative to gas in terms of high‐voltage application.Mixed gases contain R12 gas, they offer good dielectric properties andpossibility to be used in low‐temperature environment. Synergistic effects andself‐recoverability test have been performed. Dielectric strength underquasi‐uniform field showed in the order of air in alternating current (AC), directcurrent (DC) and impulse was examined. Mixture R12/N ₂ (80/20%) couldreach over 0.90–0.95 times to that of gas at 50 lb/in ² at AC andR12/air (70/30%) gives 0.80–0.90 to gas. R12 gas presents brilliantself‐recoverability. The optimal ratio to switch gas is R12/N ₂ (80/20%) andR12/air (70/30%) is based on the authors’ experimental condition and setup.