Coherent population transfer beyond the adiabatic limit: generalized matched pulses and higher-order trapping states

We show that the physical mechanism of population transfer in a 3-level system with a closed loop of coherent couplings (loop-STIRAP) is not equivalent to an adiabatic rotation of the dark-state of the Hamiltonian but coresponds to a rotation of a higher-order trapping state in a generalized adiabatic basis. The concept of generalized adiabatic basis sets is used as a constructive tool to design pulse sequences for stimulated Raman adiabatic passage (STIRAP) which give maximum population transfer also under conditions when the usual condition of adiabaticty is only poorly fulfilled. Under certain conditions for the pulses (generalized matched pulses) there exists a higher-order trapping state, which is an exact constant of motion and analytic solutions for the atomic dynamics can be derived.Comment: 15 pages, 9 figure

Measuring a coherent superposition

We propose a simple method for measuring the populations and the relative phase in a coherent superposition of two atomic states. The method is based on coupling the two states to a third common (excited) state by means of two laser pulses, and measuring the total fluorescence from the third state for several choices of the excitation pulses.Comment: 7 pages, 1 figure, twocolumn REVTe

Disentangling the near infrared continuum spectral components of the inner 500 pc of Mrk 573: two-dimensional maps

We present a near infrared study of the spectral components of the continuum in the inner 500$\times$500 pc$^2$ of the nearby Seyfert galaxy Mrk573 using adaptive optics near-infrared integral field spectroscopy with the instrument NIFS of the Gemini North Telescope at a spatial resolution of $\sim$50 pc. We performed spectral synthesis using the {\sc starlight} code and constructed maps for the contributions of different age components of the stellar population: young ($age\leq100$ Myr), young-intermediate ($100<age\leq700$ Myr), intermediate-old ($700$ Myr $2$ Gyr) to the near-IR K-band continuum, as well as their contribution to the total stellar mass. We found that the old stellar population is dominant within the inner 250 pc, while the intermediate age components dominate the continuum at larger distances. A young stellar component contributes up to $\sim$20% within the inner $\sim$70 pc, while hot dust emission and featureless continuum components are also necessary to fit the nuclear spectrum, contributing up to 20% of the K-band flux there. The radial distribution of the different age components in the inner kiloparsec of Mrk573 is similar to those obtained by our group for the Seyfert galaxies Mrk1066, Mrk1157 and NGC1068 in previous works using a similar methodology. Young stellar populations ($\leq$100 Myr) are seen in the inner 200-300 pc for all galaxies contributing with $\ge$20% of the K-band flux, while the near-IR continuum is dominated by the contribution of intermediate-age stars ($t=$100 Myr-2 Gyr) at larger distances. Older stellar populations dominate in the inner 250 pc

A New Superwind Wolf-Rayet Galaxy Mrk 1259

We report the discovery of a starburst-driven wind (superwind) from the starburst nucleus galaxy Mrk 1259. The estimated number ratio of Wolf-Rayet (WR) to O stars amounts to ~0.09. While the nuclear emission-line region is due to usual photoionization by massive stars, the circumnuclear emission-line regions show anomalous line ratios that can be due to cooling shocks. Since the host galaxy seems to be a face-on disk galaxy and the excitation conditions of the circumnuclear emission-line regions show the spatial symmetry, we consider that we are seeing the superwind nearly from a pole-on view. Cooling shock models may explain the observed emission line ratios of the circumnuclear regions although a factor of 2 overabundance of nitrogen is necessary. All these suggest that the high-mass enhanced starburst occurred ~5X10^6 years ago in the nuclear region of Mrk 1259.Comment: To be published in the Astrophysical Journal Letters, 15 pages, 4 figure

The issue of time in generally covariant theories and the Komar-Bergmann approach to observables in general relativity

Diffeomorphism-induced symmetry transformations and time evolution are distinct operations in generally covariant theories formulated in phase space. Time is not frozen. Diffeomorphism invariants are consequently not necessarily constants of the motion. Time-dependent invariants arise through the choice of an intrinsic time, or equivalently through the imposition of time-dependent gauge fixation conditions. One example of such a time-dependent gauge fixing is the Komar-Bergmann use of Weyl curvature scalars in general relativity. An analogous gauge fixing is also imposed for the relativistic free particle and the resulting complete set time-dependent invariants for this exactly solvable model are displayed. In contrast with the free particle case, we show that gauge invariants that are simultaneously constants of motion cannot exist in general relativity. They vary with intrinsic time

Outflows in the Narrow Line Region of Bright Seyfert Galaxies - I: GMOS-IFU Data

We present two-dimensional maps of emission-line fluxes and kinematics, as well as of the stellar kinematics of the central few kpc of five bright nearby Seyfert galaxies -- Mrk\,6, Mrk\,79, Mrk\,348, Mrk\,607 and Mrk\,1058 -- obtained from observations with the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) on the Gemini North Telescope. The data cover the inner 3\farcs5$\times$5\farcs0 -- corresponding to physical scales in the range 0.6$\times$0.9 to 1.5$\times$2.2\,kpc$^2$ -- at a spatial resolution ranging from 110 to 280 pc with a spectral coverage of 4300 -- 7100\,\AA\ and velocity resolution of $\approx$ 90\,km\,s$^{-1}$. The gas excitation is Seyfert like everywhere but show excitation, but show excitation gradients that are correlated with the gas kinematics, reddening and/or the gas density. The gas kinematics show in all cases two components: a rotation one similar to that observed in the stellar velocity field, and an outflow component. In the case of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas velocity dispersion is observed in association to the outflows according to two patterns: at the locations of the highest outflow velocities along the ionization axis or perpendicularly to it in a strip centered at the nucleus that we attribute to an equatorial outflow. Bipolar outflows are observed in Mrk\,348 and Mrk\,79, while in Mrk\,1058 only the blueshifted part is clearly observed, while in the cases of Mrk\,6 and Mrk\,607 the geometry of the outflow needs further constraints from modeling to be presented in a forthcoming study, where the mass flow rate and powers will also be obtained.Comment: 20 pages, accepted by MNRA

Coherent properties of a tripod system coupled via a continuum

We present results from a study of the coherence properties of a system involving three discrete states coupled to each other by two-photon processes via a common continuum. This tripod linkage is an extension of the standard laser-induced continuum structure (LICS) which involves two discrete states and two lasers. We show that in the tripod scheme, there exist two population trapping conditions; in some cases these conditions are easier to satisfy than the single trapping condition in two-state LICS. Depending on the pulse timing, various effects can be observed. We derive some basic properties of the tripod scheme, such as the solution for coincident pulses, the behaviour of the system in the adiabatic limit for delayed pulses, the conditions for no ionization and for maximal ionization, and the optimal conditions for population transfer between the discrete states via the continuum. In the case when one of the discrete states is strongly coupled to the continuum, the population dynamics reduces to a standard two-state LICS problem (involving the other two states) with modified parameters; this provides the opportunity to customize the parameters of a given two-state LICS system