Retrieval of phase memory in two independent atomic ensembles by Raman process

In spontaneous Raman process in atomic cell at high gain, both the Stokes field and the accompanying collective atomic excitation (atomic spin wave) are coherent. We find that, due to the spontaneous nature of the process, the phases of the Stokes field and the atomic spin wave change randomly from one realization to another but are anti-correlated. The phases of the atomic ensembles are read out via another Raman process at a later time, thus realizing phase memory in atoms. The observation of phase correlation between the Stokes field and the collective atomic excitations is an important step towards macroscopic EPR-type entanglement of continuous variables between light and atoms

Coherent population trapping and dynamical instability in the nonlinearly coupled atom-molecule system

We study the possibility of creating a coherent population trapping (CPT) state, involving free atomic and ground molecular condensates, during the process of associating atomic condensate into molecular condensate. We generalize the Bogoliubov approach to this multi-component system and study the collective excitations of the CPT state in the homogeneous limit. We develop a set of analytical criteria based on the relationship among collisions involving atoms and ground molecules, which are found to strongly affect the stability properties of the CPT state, and use it to find the stability diagram and to systematically classify various instabilities in the long-wavelength limit.Comment: 11 pages, 8 figure

Effect of synthesized temperature on the assembly and properties of four lanthanide supramolecular frameworks

Four new lanthanide coordination polymers, [H3O][Ln3(HPA)10(H2O)3·2H2O] (Ln = Pr for 1, Ln = Nd for 2), [Ln2(HPA)6(H2O)4·2H2O] (Ln = Sm for 3, Ln = Tb for 4) (HHPA =3-(4-hydroxyphenyl)propanoic acid), were successfully synthesized and characterized. 1 and 2 are isostructural and have 1D metal chain structure, while 3 and 4 show 0D network with binuclear subunits. The results indicated that the effect of reaction temperature can modulate the final structures. The HPA ligands adopt bidentate chelating and tridentate chelating bridging modes to coordinate with Ln(III) ions in 1-4. It has been shown that 4 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+.               KEY WORDS: Sensor, Lanthanide, Structure, Temperature Bull. Chem. Soc. Ethiop. 2019, 33(1), 113-125DOI: https://dx.doi.org/10.4314/bcse.v33i1.1

Optimal design of nonuniform FIR transmultiplexer using semi-infinite programming

This paper considers an optimum nonuniform FIR transmultiplexer design problem subject to specifications in the frequency domain. Our objective is to minimize the sum of the ripple energy for all the individual filters, subject to the specifications on amplitude and aliasing distortions, and to the passband and stopband specifications for the individual filters. This optimum nonuniform transmultiplexer design problem can be formulated as a quadratic semi-infinite programming problem. The dual parametrization algorithm is extended to this nonuniform transmultiplexer design problem. If the lengths of the filters are sufficiently long and the set of decimation integers is compatible, then a solution exists. Since the problem is formulated as a convex problem, if a solution exists, then the solution obtained is unique and the local solution is a global minimum

A note on entropic force and brane cosmology

Recently Verlinde proposed that gravity is an entropic force caused by information changes when a material body moves away from the holographic screen. In this note we apply this argument to brane cosmology, and show that the cosmological equation can be derived from this holographic scenario.Comment: 5 pages, no figures;references adde