Optical vector network analysis of ultra-narrow transitions in 166^{166}Er3+^{3+}:7^7LiYF4_4

We present optical vector network analysis (OVNA) of an isotopically purified $^{166}$Er$^{3+}$:$^7$LiYF$_4$ crystal. The OVNA method is based on generation and detection of modulated optical sideband by using a radio-frequency vector network analyzer. This technique is widely used in the field of microwave photonics for the characterization of optical responses of optical devices such as filters and high-Q resonators. However, dense solid-state atomic ensembles induce a large phase shift on one of the optical sidebands which results in the appearance of extra features on the measured transmission response. We present a simple theoretical model which accurately describes the observed spectra and helps to reconstruct the absorption profile of a solid-state atomic ensemble as well as corresponding change of the refractive index in the vicinity of atomic resonances.Comment: 4 pages, 5 figure

Morphological Features of Mountain Maple (Acer Spicatum Lam.) in the R.I. Schroeder Arboretum

В статье приводится описание ползучих побегов клёна колосистого (Acer spicatum Lam.), обнаруженных в дендрарии имени Р.И. Шредера. Помимо раскопки побегов и их осмотра, были сделаны фотографии, на одной из которых для иллюстрации статьи побеги были дополнительно выделены в графическом редакторе. По итогам исследования были сделаны выводы о том, что изучаемый вид склонен в некоторых условиях образовывать длинные ползучие укореняющиеся побеги, располагающиеся как над, так и под землёй, с ответвляющимися вертикальными стволами. Выявленные морфологические особенности представляют интерес для дальнейшего изучения.The article describes the creeping shoots of a spiky maple (Acer spicatum Lam.) found in the R.I. Schroeder Arboretum. In addition to excavating the shoots and examining them, photographs were taken, one of which was further highlighted in a graphic editor to illustrate the article. As a result of the study, it was concluded that the species studied tends to form in some conditions long creeping rooting shoots located both above and below the ground, with branching vertical stems. The morphological features identified are of interest for further study

Synchronous Quantum Memories with Time-symmetric Pulses

We propose a dynamical approach to quantum memories using a synchronous oscillator-cavity model, in which the coupling is shaped in time to provide the optimum interface to a symmetric input pulse. This overcomes the known difficulties of achieving high quantum input-output fidelity with storage times long compared to the input signal duration. Our generic model is applicable to any linear storage medium ranging from a superconducting device to an atomic medium. We show that with temporal modulation of coupling and/or detuning, it is possible to mode-match to time-symmetric pulses that have identical pulse shapes on input and output.Comment: 4 pages, 4 figure

Effect of transition layers on the electromagnetic properties of composites containing conducting fibres

The approach to calculating the effective dielectric and magnetic response in bounded composite materials is developed. The method is essentially based on the renormalisation of the dielectric matrix parameters to account for the surface polarisation and the displacement currents at the interfaces. This makes it possible the use of the effective medium theory developed for unbounded materials, where the spatially-dependent local dielectric constant and magnetic permeability are introduced. A detailed mathematical analysis is given for a dielectric layer having conducting fibres with in-plane positions. The surface effects are most essential at microwave frequencies in correspondence to the resonance excitation of fibres. In thin layers (having a thickness of the transition layer), the effective dielectric constant has a dispersion region at much higher frequencies compared to those for unbounded materials, exhibiting a strong dependence on the layer thickness. For the geometry considered, the effective magnetic permeability differs slightly from unity and corresponds to the renormalised matrix parameter. The magnetic effect is due entirely to the existence of the surface displacement currents.Comment: PDF, 33 pages, 10 figure

Generation of a wave packet tailored to efficient free space excitation of a single atom

We demonstrate the generation of an optical dipole wave suitable for the process of efficiently coupling single quanta of light and matter in free space. We employ a parabolic mirror for the conversion of a transverse beam mode to a focused dipole wave and show the required spatial and temporal shaping of the mode incident onto the mirror. The results include a proof of principle correction of the parabolic mirror's aberrations. For the application of exciting an atom with a single photon pulse we demonstrate the creation of a suitable temporal pulse envelope. We infer coupling strengths of 89% and success probabilities of up to 87% for the application of exciting a single atom for the current experimental parameters.Comment: to be published in Europ. Phys. J.