Color centers NV- in diamonds - application of the Qudi environment

W ramach pracy wdrożono do laboratorium centrów barwnych w Zakładzie Fotoniki program komputerowy Qudi służący do automatyzacji pomiarów w doświadczeniach. Przystosowano go do posiadanej aparatury i przeprowadzono proste pomiary z jego użyciem.During this work the computer program Qudi was introduced into the color-centers laboratory at the Institute of Photonics. Qudi's function is to automatize measurments in experiments. The program was adapted to the equipment present in the laboratory and simple measurments were conducted

Studies of electromagnetically induced transparency in ladder-type system of Rubidium atoms

W pracy przedstawiono opis zbudowanego przez autora układu laserowego pozwalającego prowadzić spektroskopię EIT w komórce z ciepłymi parami rubidu. Układ umożliwia użycie jako wiązki sprzęgającej zarówno światła 776 nm (z górnym stanem 5D), jak 481 nm (z górnym stanem rydbergowskim o głównej liczbie kwantowej około 50). Przeprowadzono pomiary i symulacje pozwalające rozdzielić udział w widmie EIT wkładów od koherencji jedno- i dwufotonowej dla przypadku wiązki sprzęgającej 776 nm.The work presents the description of the laser system constructed by the author in order to conduct the EIT spectroscopy in hot Rubidium vapor. With the system it is possible to generate a coupling beam of 776 nm (for the upper state 5D) as well as 481 nm (for Rydberg states with the principal quantum number of the order of 50 used as the upper state). Measurements and simulations have been conducted to discriminate one-photon and two-photon coherence parts in the EIT spectrum obtained for 776 nm coupling beam

Steel Wire Mesh as a Thermally Resistant SERS Substrate

In this paper, we present novel type of Surface-enhanced Raman spectroscopy (SERS) platform, based on stainless steel wire mesh (SSWM) covered with thin silver layer. The stainless steel wire mesh, typically used in chemical engineering industry, is a cheap and versatile substrate for SERS platforms. SSWM consists of multiple steel wires with diameter of tens of micrometers, which gives periodical structure and high stiffness. Moreover, stainless steel provides great resistance towards organic and inorganic solvents and provides excellent heat dissipation. It is worth mentioning that continuous irradiation of the laser beam over the SERS substrate can be a source of significant increase in the local temperature of metallic nanostructures, which can lead to thermal degradation or fragmentation of the adsorbed analyte. Decomposition or fragmentation of the analysed sample usually causea a significant decrease in the intensity of recorded SERS bands, which either leads to false SERS responses or enables the analysis of spectral data. To our knowledge, we have developed for the first time the thermally resistant SERS platform. This type of SERS substrate, termed Ag/SSWM, exhibit high sensitivity (Enhancement Factor (EF) = 106) and reproducibility (Relative Standard Deviation (RSD) of 6.4%) towards detection of p-mercaptobenzoic acid (p-MBA). Besides, Ag/SSWM allows the specific detection and differentiation between Gram-positive and Gram-negative bacterial species: Escherichia coli and Bacillus subtilis in label-free and reproducible manner. The unique properties of designed substrate overcome the limitations associated with photo- and thermal degradation of sensitive bacterial samples. Thus, a distinctive SERS analysis of all kinds of chemical and biological samples at high sensitivity and selectivity can be performed on the developed SERS-active substrate

Suppression of dark-state polariton collapses in cold-atom quantum memory

We observe dark-state polariton collapses and revivals in a quantum memory based on electromagnetically induced transparency on a cloud of cold cesium atoms in a magnetic field. Using $\sigma^+$ polarized signal and control beams in the direction of the magnetic field, we suppress the dark-state polariton collapses by polarizing the atoms towards one of the stretched Zeeman states and optimizing the frequency detuning of the control beam. In this way, we demonstrate a quantum memory with only partial dark-state polariton collapses, making the memory usable at any storage time, not only at discretized times of revivals. We obtain storage time of more than 400 $\rm{\mu}$s, which is ten times longer than what we can achieve by trying to annul the magnetic field.Comment: 6 pages, 4 figure