Fast Radio Burst/Gamma-Ray Burst Cosmography

Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measure (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DM_{IGM} as a function of z, and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with potentially several 10s of FRB/GRB systems detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with SN Ia data, unprecedented constraints on dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value and luminosity distance (D_{L} (z)) is insensitive to dark energy models. This gives the prospects of applying SN Ia data to calibrate using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied, if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.Comment: Accepted for publication in Ap

Concentration for unknown atomic entangled states via cavity decay

We present a physical scheme for entanglement concentration of unknown atomic entangled states via cavity decay. In the scheme, the atomic state is used as stationary qubit and photonic state as flying qubit, and a close maximally entangled state can be obtained from pairs of partially entangled states probabilistically.Comment: Three pages, Two figure