Globular clusters (GCs) are the oldest stellar system in the Galaxy, in which the millisecond pulsars are widely believed to be the only steady {gamma}-ray emitters. So far 9 {gamma}-ray GCs have been identified and a few candidates such as 2MS-GC01
and IC 1257 have been suggested. In this work, after analyzing the publicly-available Fermi-LAT data we confirm the significant {gamma}-ray emission from 2MS-GC01 and IC 1257 and report the discovery for {gamma}-ray emission from NGC 5904 and NGC 6656 within their tidal radii. Also a strong evidence of significant {gamma}-ray emission is found from FSR 1735. From the observed {gamma}-ray luminosities, the numbers of MSPs that are expected to be present in these GCs are estimated.
We propose a method for nano-scale characterization of long range magnetic order in diluted magnetic systems to clarify the origins of the room temperature ferromagnetism. The GaN:Mn thin films are grown by metal-organic chemical vapor deposition wit
h the concentration of Ga-substitutional Mn up to 3.8%. Atomic force microscope (AFM) and magnetic force microscope (MFM) characterizations are performed on etched artificial microstructures and natural dislocation pits. Numerical simulations and theoretical analysis on the AFM and MFM data have confirmed the formation of long range magnetic order and ruled out the possibility that nano-clusters contributed to the ferromagnetism. We suggest that delocalized electrons might play a role in the establishment of this long range magnetic order.
Geometric phases, arising from cyclic evolutions in a curved parameter space, appear in a wealth of physical settings. Recently, and largely motivated by the need of an experimentally realistic definition for quantum computing applications, the quant
um geometric phase was generalized to open systems. The definition takes a kinematical approach, with an initial state that is evolved cyclically but coupled to an environment --- leading to a correction of the geometric phase with respect to the uncoupled case. We obtain this correction by measuring the nonunitary evolution of the reduced density matrix of a spin one-half coupled to an environment. In particular, we consider a bath that can be tuned near a quantum phase transition, and demonstrate how the criticality information imprinted in the decoherence factor translates into the geometric phase. The experiments are done with a NMR quantum simulator, in which the critical environment is modeled using a one-qubit system.
