Scattering phase shifts in quasi-one-dimension

Scattering of an electron in quasi-one dimensional quantum wires have many unusual features, not found in one, two or three dimensions. In this work we analyze the scattering phase shifts due to an impurity in a multi-channel quantum wire with special emphasis on negative slopes in the scattering phase shift versus incident energy curves and the Wigner delay time. Although at first sight, the large number of scattering matrix elements show phase shifts of different character and nature, it is possible to see some pattern and understand these features. The behavior of scattering phase shifts in one-dimension can be seen as a special case of these features observed in quasi-one-dimensions. The negative slopes can occur at any arbitrary energy and Friedel sum rule is completely violated in quasi-one-dimension at any arbitrary energy and any arbitrary regime. This is in contrast to one, two or three dimensions where such negative slopes and violation of Friedel sum rule happen only at low energy where the incident electron feels the potential very strongly (i.e., there is a very well defined regime, the WKB regime, where FSR works very well). There are some novel behavior of scattering phase shifts at the critical energies where $S$-matrix changes dimension.Comment: Minor corrections mad

Study of Electromagnetically Induced Transparency using long-lived Singlet States

The long-lived singlet states are useful to study a variety of interesting quantum phenomena. In this work we study electromagnetically induced transparency using a two-qubit system. The singlet state acts as a `dark state' which does not absorb a probe radiation in the presence of a control radiation. Further we demonstrate that the simultaneous irradiation of probe and control radiations acts as a dynamical decoupling preserving the singlet state at higher correlation for longer durations.Comment: 4 pages, 4 figure

Dose-dependent Pupicidal, Adulticidal and Ovicidal Activities of Leaf Extracts of Tiliacora Acuminata on Japanese Encephalitis Vector Culex Vishnui Group

Vector of Japanese encephalitis is Culex vishnui group of mosquito and control of that mosquito is facing threat due to emergence of resistance to synthetic insecticides. Insecticides of plant origin now act as suitable alternate for control of JE vector. To investigate dose-dependent pupicidal, adulticidal and ovicidal activities, crude and acetone extracts of leaf of Tiliacora acuminata were used against Cx. vishnui group of mosquito. In case of dose-dependent pupicidal activity, highest mortality observed at 1.5% concentration of crude extract and 75 ppm of acetone extract with 45.67% and 67.67% mortality respectively after 36 h of exposure followed by 24h and 12h. In case of adulticidal activity, highest mortality in crude extract was observed at 2.5% concentration with 73% of adult mosquitoes were dead, but in acetone extract at 120 ppm concentration shows nearly about 67% mortality of adult mosquitoes after 24 h of exposure. While in ovicidal activity at 0.5% crude extract have 11.67% egg hatching so nearly about 88.33% ovicidal activity takes place at this concentration. In acetone extract, there was nearly about 93.33% ovicidal activities at 55 ppm concentration. So leaf extracts of T. acuminata may be used as better pupicidal, adulticidal and ovicidal plant origin insecticide for control of Cx. vishnui group of mosquito. Further research is required to isolate and characterize the active principle of T. acuminata plant leaf extract