The certificate of success for a number of important quantum information processing protocols, such as entanglement distillation, is based on the difference in the entanglement content of the quantum states before and after the protocol. In such case
s, effective bounds need to be placed on the entanglement of non-local states consistent with statistics obtained from local measurements. In this work, we study numerically the ability of a novel type of homodyne detector which combines phase sensitivity and photon-number resolution to set accurate bounds on the entanglement content of two-mode quadrature squeezed states without the need for full state tomography. We show that it is possible to set tight lower bounds on the entanglement of a family of two-mode degaussified states using only a few measurements. This presents a significant improvement over the resource requirements for the experimental demonstration of continuous-variable entanglement distillation, which traditionally relies on full quantum state tomography.
Observations of the HI 21cm transition line promises to be an important probe into the cosmic dark ages and epoch of reionization. One of the challenges for the detection of this signal is the accuracy of the foreground source removal. This paper inv
estigates the extragalactic point source contamination and how accurately the bright sources ($gtrsim 1$ ~Jy) should be removed in order to reach the desired RMS noise and be able to detect the 21cm transition line. Here, we consider position and flux errors in the global sky-model for these bright sources as well as the frequency independent residual calibration errors. The synthesized beam is the only frequency dependent term included here. This work determines the level of accuracy for the calibration and source removal schemes and puts forward constraints for the design of the cosmic reionization data reduction scheme for the upcoming low frequency arrays like MWA,PAPER, etc. We show that in order to detect the reionization signal the bright sources need to be removed from the data-sets with a positional accuracy of $sim 0.1$ arc-second. Our results also demonstrate that the efficient foreground source removal strategies can only tolerate a frequency independent antenna based mean residual calibration error of $lesssim 0.2 %$ in amplitude or $lesssim 0.2$ degree in phase, if they are constant over each days of observations (6 hours). In future papers we will extend this analysis to the power spectral domain and also include the frequency dependent calibration errors and direction dependent errors (ionosphere, primary beam, etc).
Vacuum ultraviolet (VUV) transmission spectra show a clear polarization effect in pi electronic transition in spin coated atactic polystyrene (aPS) films of thickness below 4Rg, where Rg (~20.4nm) is the radius of gyration of the polymer. This transi
tion associated with pendant benzene rings in polystyrene. The polarization effect clearly indicates pendant benzene ring alignment on a macroscopic scale. Study of core electron (1s) transition through near edge x-ray absorption fine structure (NEXAFS) spectroscopy confirms the ordering and shows that the rings are oriented towards out-of-plane direction with a tilt angle ~63 degree with the sample plane, which is consistent with the observed in-plane (sample surface) VUV polarization. These results indicate the transition of a common polymer, like polystyrene, inherently disordered in the bulk, to an orientationally ordered phase under a certain degree of confinement.
