Note On Certain Inequalities for Neuman Means

In this paper, we give the explicit formulas for the Neuman means $N_{AH}$, $N_{HA}$, $N_{AC}$ and $N_{CA}$, and present the best possible upper and lower bounds for theses means in terms of the combinations of harmonic mean $H$, arithmetic mean $A$ and contraharmonic mean $C$.Comment: 9 page

Observation of prolonged coherence time of the collective spin wave of atomic ensemble in a paraffin coated Rb vapor cell

We report a prolonged coherence time of the collective spin wave of a thermal 87Rb atomic ensemble in a paraffin coated cell. The spin wave is prepared through a stimulated Raman Process. The long coherence time time is achieved by prolonging the lifetime of the spins with paraffin coating and minimize dephasing with optimal experimental configuration. The observation of the long time delayed-stimulated Stokes signal in the writing process suggests the prolonged lifetime of the prepared spins; a direct measurement of the decay of anti-Stokes signal in the reading process shows the coherence time is up to 300 us after minimizing dephasing. This is one hundred times longer than the reported coherence time in the similar experiments in thermal atomic ensembles based on the Duan-Lukin-Cirac-Zoller (DLCZ) and its improved protocols. This prolonged coherence time sets the upper limit of the memory time in quantum repeaters based on such protocols, which is crucial for the realization of long-distance quantum communication. The previous reported fluorescence background in the writing process due to collision in a sample cell with buffer gas is also reduced in a cell without buffer gas.Comment: 4 pages, 4 figure

The practice exploration of case teaching mode in the environmental monitoring course teaching

In view of that short and strong practical nature of the core courses in the environmental monitor, and the shortcomings of the case teaching modes of the project completion environmental protection acceptance case in the present individual application project, the project completion acceptance actual case method is set up in the course of the course of the course of environmental monitoring, and the practical case of the project completion acceptance test for the project completion of the project completion of the project is set up in the practical case, which is proved by the practice of the project completion environmental protection acceptance monitoring report of the packaging material of jiangsu shentai packaging material co., LTD. The project has been done with the study of the environment and the teaching model of the project, and it has been applied to the students as the main subject, and it has been taught to do a better job in monitoring the environment after graduation. Keywords Environmental monitoring; The acceptance of the environmental protection project case; The teaching method DOI: 10.7176/JEP/10-6-1