Spectral Properties From Lyman-alpha to H-alpha For An Essentially Complete Sample of Quasars I: Data

We have obtained quasi-simultaneous ultraviolet-optical spectra for 22 out of 23 quasars in the complete PG-X-ray sample with redshift, z<0.4, and M_B<-23. The spectra cover rest-frame wavelengths from at least Lyman-alpha to H-alpha. Here we provide a detailed description of the data, including careful spectrophotometry and redshift determination. We also present direct measurements of the continua, strong emission lines and features, including Lyman-alpha, SiIV+OIV], CIV, CIII], SiIII], MgII, H-beta, [OIII], He5876+NaI5890,5896, H-alpha, and blended iron emission in the UV and optical. The widths, asymmetries and velocity shifts of profiles of strong emission lines show that CIV and Lyman-alpha are very different from H-beta and H-alpha. This suggests that the motion of the broad line region is related to the ionization structure, but the data appears not agree with the radially stratified ionization structure supported by reverberation mapping studies, and therefore suggest that outflows contribute additional velocity components to the broad emission line profiles.Comment: 42 pages, 10 figures, 13 tables. Accepted by AJ. Supplemental figures not included. Full version available at http://physics.uwyo.edu/~shang/pgxpaper/ShangPaper.pd

Exact zero-point energy shift in the e⊗(n E)e\otimes (n~E), t⊗(n H)t\otimes (n~H) many modes dynamic Jahn-Teller systems at strong coupling

We find the exact semiclassical (strong coupling) zero-point energy shifts applicable to the $e\otimes (n E)$ and $t\otimes (n H)$ dynamic Jahn-Teller problems, for an arbitrary number $n$ of discrete vibrational modes simultaneously coupled to one single electronic level. We also obtain an analytical formula for the frequency of the resulting normal modes, which has an attractive and apparently general Slater-Koster form. The limits of validity of this approach are assessed by comparison with O'Brien's previous effective-mode approach, and with accurate numerical diagonalizations. Numerical values obtained for $t\otimes (n H)$ with $n =8$ and coupling constants appropriate to C$_{60}^-$ are used for this purpose, and are discussed in the context of fullerene.Comment: 20 pages, 4 ps figure

Dynamics of the Lyman alpha and C IV emitting gas in 3C 273

In this paper we study the variability properties of the Lyman alpha and C IV emission lines in 3C273 using archival IUE observations. Our data show for the first time the existence of variability on time scales of several years. We study the spatial distribution and the velocity field of the emitting gas by performing detailed analyses on the line variability using correlations, 1D and 2D response functions, and principal component analysis. In both lines we find evidence for two components, one which has the dynamic properties of gas in Keplerian motion around a black hole with a mass of the order of 10^9 Mo, and one which is characterized by high, blue-shifted velocities at large lag. There is no indication of the presence of optically thick emission medium neither in the Lya, nor in the Civ response functions. The component characterized by blue-shifted velocities, which is comparatively much stronger in Civ than in Lya, is more or less compatible with being the result of gas falling towards the central black hole with free-fall acceleration. We propose however that the line emission at high, blue-shifted velocities is better explained in terms of entrainment of gas clouds by the jet. This gas is therefore probably collisionally excited as a result of heating due to the intense infrared radiation from the jet, which would explain the strength of this component in Civ relative to Lya. This phenomenon might be a signature of disk-jet interaction.Comment: 16 pages, 10 figures. Accepted for publication in ApJ. Uses aaste

Quantum Non-demolition Measurements on Qubits

We discuss the characterization and properties of quantum non-demolition (QND) measurements on qubit systems. We introduce figures of merit which can be applied to systems of any Hilbert space dimension thus providing universal criteria for characterizing QND measurements. We discuss the controlled-NOT gate and an optical implementation as examples of QND devices for qubits. We also discuss the QND measurement of weak values

Swift observations of the 2006 outburst of the recurrent nova RS Ophiuchi: I. Early X-ray emission from the shocked ejecta and red giant wind

RS Ophiuchi began its latest outburst on 2006 February 12. Previous outbursts have indicated that high velocity ejecta interact with a pre-existing red giant wind, setting up shock systems analogous to those seen in Supernova Remnants. However, in the previous outburst in 1985, X-ray observations did not commence until 55 days after the initial explosion. Here we report on Swift observations covering the first month of the 2006 outburst with the Burst Alert (BAT) and X-ray Telescope (XRT) instruments. RS Oph was clearly detected in the BAT 14-25 keV band from t=0 to $t\sim6$ days. XRT observationsfrom 0.3-10 keV, started at 3.17 days after outburst. The rapidly evolving XRT spectra clearly show the presence of both line and continuum emission which can be fitted by thermal emission from hot gas whose characteristic temperature, overlying absorbing column, $[N_H]_W$, and resulting unabsorbed total flux decline monotonically after the first few days. Derived shock velocities are in good agreement with those found from observations at other wavelengths. Similarly, $[N_H]_W$ is in accord with that expected from the red giant wind ahead of the forward shock. We confirm the basic models of the 1985 outburst and conclude that standard Phase I remnant evolution terminated by $t\sim10$ days and the remnant then rapidly evolved to display behaviour characteristic of Phase III. Around t=26 days however, a new, luminous and highly variable soft X-ray source began to appear whose origin will be explored in a subsequent paper.Comment: 20 pages, 4 figures (2 updated), accepted by Ap

Slow spin relaxation in a highly polarized cooperative paramagnet

We report measurements of the ac susceptibility of the cooperative paramagnet Tb2Ti2O7 in a strong magnetic field. Our data show the expected saturation maximum in chi(T) and also an unexpected low frequency dependence (< 1 Hz) of this peak, suggesting very slow spin relaxations are occurring. Measurements on samples diluted with nonmagnetic Y3+ or Lu3+ and complementary measurements on pure and diluted Dy2Ti2O7 strongly suggest that the relaxation is associated with dipolar spin correlations, representing unusual cooperative behavior in a paramagnetic system.Comment: Accepted for publication in Physical Review Letter

Optimal search strategies for hidden targets

What is the fastest way of finding a randomly hidden target? This question of general relevance is of vital importance for foraging animals. Experimental observations reveal that the search behaviour of foragers is generally intermittent: active search phases randomly alternate with phases of fast ballistic motion. In this letter, we study the efficiency of this type of two states search strategies, by calculating analytically the mean first passage time at the target. We model the perception mecanism involved in the active search phase by a diffusive process. In this framework, we show that the search strategy is optimal when the average duration of "motion phases" varies like the power either 3/5 or 2/3 of the average duration of "search phases", depending on the regime. This scaling accounts for experimental data over a wide range of species, which suggests that the kinetics of search trajectories is a determining factor optimized by foragers and that the perception activity is adequately described by a diffusion process.Comment: 4 pages, 5 figures. to appear in Phys. Rev. Let

Strongly enhanced photon collection from diamond defect centres under micro-fabricated integrated solid immersion lenses

The efficiency of collecting photons from optically active defect centres in bulk diamond is greatly reduced by refraction and reflection at the diamond-air interface. We report on the fabrication and measurement of a geometrical solution to the problem; integrated solid immersion lenses (SILs) etched directly into the surface of diamond. An increase of a factor of 10 was observed in the saturated count-rate from a single negatively charged nitrogen-vacancy (NV-) within a 5um diameter SIL compared with NV-s under a planar surface in the same crystal. A factor of 3 reduction in background emission was also observed due to the reduced excitation volume with a SIL present. Such a system is potentially scalable and easily adaptable to other defect centres in bulk diamond.Comment: 5 Pages, 5 figures (4 subfigures) - corrected typ

The Case for Optically-Thick High Velocity Broad Line Region Gas in Active Galactic Nuclei

A combined analysis of the profiles of the main broad quasar emission lines in both Hubble Space Telescope and optical spectra shows that while the profiles of the strong UV lines are quite similar, there is frequently a strong increase in the Ly-alpha/H-alpha ratio in the high-velocity gas. We show that the suggestion that the high velocity gas is optically-thin presents many problems. We show that the relative strengths of the high velocity wings arise naturally in an optically-thick BLR component. An optically-thick model successfully explains the equivalent widths of the lines, the Ly-alpha/H-alpha ratios and flatter Balmer decrements in the line wings, the strengths of CIII] and the lambda 1400 blend, and the strong variability of high-velocity, high-ionization lines (especially HeII and HeI).Comment: 34 pages in AASTeX, including 10 pages of figures. Submitted to Astrophysical Journa

Measuring a photonic qubit without destroying it

Measuring the polarisation of a single photon typically results in its destruction. We propose, demonstrate, and completely characterise a \emph{quantum non-demolition} (QND) scheme for realising such a measurement non-destructively. This scheme uses only linear optics and photo-detection of ancillary modes to induce a strong non-linearity at the single photon level, non-deterministically. We vary this QND measurement continuously into the weak regime, and use it to perform a non-destructive test of complementarity in quantum mechanics. Our scheme realises the most advanced general measurement of a qubit: it is non-destructive, can be made in any basis, and with arbitrary strength.Comment: 4 pages, 3 figure