Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure

Synthetic magnetism in cold atomic gases opened the doors to many exciting novel physical systems and phenomena. Ubiquitous are the methods used for the creation of synthetic magnetic fields. They include rapidly rotating Bose-Einstein condensates employing the analogy between the Coriolis and the Lorentz force, and laser-atom interactions employing the analogy between the Berry phase and the Aharonov-Bohm phase. Interestingly, radiation pressure - being one of the most common forces induced by light - has not yet been used for synthetic magnetism. We experimentally demonstrate a synthetic Lorentz force, based on the radiation pressure and the Doppler effect, by observing the centre-of-mass motion of a cold atomic cloud. The force is perpendicular to the velocity of the cold atomic cloud, and zero for the cloud at rest. Our novel concept is straightforward to implement in a large volume, for a broad range of velocities, and can be extended to different geometries.Comment: are welcom

Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure

We theoretically predict a novel type of synthetic Lorentz force for classical (cold) atomic gases, which is based on the Doppler effect and radiation pressure. A fairly uniform and strong force can be constructed for gases in macroscopic volumes of several cubic millimeters and more. This opens the possibility to mimic classical charged gases in magnetic fields, such as those in a tokamak, in cold atom experiments.Comment: are welcom

State-Dependent Optical Lattices for the Strontium Optical Qubit

We demonstrate state-dependent optical lattices for the Sr optical qubit at the tune-out wavelength for its ground state. We tightly trap excited state atoms while suppressing the effect of the lattice on ground state atoms by more than four orders of magnitude. This highly independent control over the qubit states removes inelastic excited state collisions as the main obstacle for quantum simulation and computation schemes based on the Sr optical qubit. Our results also reveal large discrepancies in the atomic data used to calibrate the largest systematic effect of Sr optical lattice clocks.Comment: 6 pages, 4 figures + 6 pages supplemental materia

Distribution of marine viruses in the Central and South Adriatic Sea

The seasonal distribution of marine viruses and their relationship with heterotrophic bacteria in the coastal and offshore area of the central and southern Adriatic were studied. Additionally, the percentage of high (HNA) and low (LNA) nucleic acid bacteria between the total number of bacteria and the distribution of heterotrophic nanoflagellates (HNF) as a major predator of bacteria were studied as well. The viral abundance ranged from 3.55 to 27.32 × 106 virus-like particles mL-1, and was on average 25-fold higher than bacterial abundances at all investigated stations. The highest viral abundances were found at coastal stations, especially in the area influenced by the rivers Krka and Jadro, whereas the lowest values were found in the open sea and in the coastal area of the southern Adriatic. No significant difference in relationship of viruses with HNA and LNA bacterial groups were established. The ratio between viruses and bacteria (VBR) was higher during the colder part of the year, which coincided with lower HNF abundance and vice versa during the warmer part of the year. This suggests that HNF grazing could be more important in controlling bacterial abundance during the warmer part of the year, and viral lysis during the colder part of the year

Comparative study of light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells

We perform a comparative study of light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells using electromagnetically induced transparency (EIT) in warm rubidium vapor. The use of a buffer-gas-filled cell resulted in $\approx$10-fold improvement in storage time and efficiency compared to antirelaxation-coated cells. We achieve up to sixfold enhancement in buffer-gas-filled memory efficiency, while maintaining a similar memory lifetime, by employing a near-resonant EIT $\Lambda$-scheme instead of a resonant one. Our findings contribute to the development of field-deployable quantum memories. quantum memories.Comment: 8 pages, 6 figure

Dynamics of picoplankton community from coastal waters to the open sea in the Central Adriatic

Flow cytometry was used to describe seasonal cycles of Prochlorococcus (Prochl), Synechococcus (Syn), picoeukaryotes and heterotrophic bacteria in the central Adriatic Sea along the trophic gradient from January to December 2010. All picoplankton parameters decreased from eutrophic to oligotrophic areas, while the biomass ratio of bacterial to autotrophic picoplankton showed an increase along the trophic gradient. Bacterial biomass ranged from 5.28 to 21.20 μg C l-1. Increased values were present during warmer seasons with the domination of low nucleic acid (LNA) group of bacteria. The high nucleic acid (HNA) bacterial group dominated during the winter and the spring. Bacterial production ranged from 0.09 -0.45 × 104 cells ml-1 h-1 .At coastal stations increased production was present during the winter and the spring and was more or less uniform at open sea stations. Biomasses of Syn and Prochl ranged from 0.16 to 11.47 µg C-1 l-1 and from 0.01 to 3.08 µg C l-1, respectively. They were elevated during the summer and the autumn at coastal stations and during the late winter at the open sea. Syn biomass always dominated over Prochl participating with 61.6-97.2% in biomass of cyanobacteria. Biomass of picoeukaryotes ranged from 1.21 to 21.85 µg C l-1 and was the highest during the winter. Their biomass notably prevailed in autotrophic picoplankton (APP) biomass over that of picocyanobacteria during the whole year. Autotrophic components (Prochl, Syn and picoeukaryotes) made greater contribution to the picoplankton biomass in mesotrophic and eutrophic areas, while heterotrophic bacteria became more important under oligotrophic conditions

Crossed optical cavities with large mode diameters

We report on a compact, ultrahigh-vacuum compatible optical assembly to create large-scale, two-dimensional optical lattices for use in experiments with ultracold atoms. The assembly consists of an octagon-shaped spacer made from ultra-low-expansion glass, to which we optically contact four fused-silica cavity mirrors, making it highly mechanically and thermally stable. The mirror surfaces are nearly plane-parallel which allows us to create two perpendicular cavity modes with diameters $\sim$1 mm. Such large mode diameters are desirable to increase the optical lattice homogeneity, but lead to strong angular sensitivities of the coplanarity between the two cavity modes. We demonstrate a procedure to precisely position each mirror substrate that achieves a deviation from coplanarity of $d = 1(5)$ $\mu$m. Creating large optical lattices at arbitrary visible and near infrared wavelengths requires significant power enhancements to overcome limitations in the available laser power. The cavity mirrors have a customized low-loss mirror coating that enhances the power at a set of relevant wavelengths from the visible to the near infrared by up to three orders of magnitude.Comment: 4 pages, 4 figures, 1 page supplemental materia

Cavity-Enhanced Optical Lattices for Scaling Neutral Atom Quantum Technologies to Higher Qubit Numbers

We demonstrate a cavity-based solution to scale up experiments with ultracold atoms in optical lattices by an order of magnitude over state-of-the-art free space lattices. Our two-dimensional optical lattices are created by power enhancement cavities with large mode waists of 489(8) $\mu$m and allow us to trap ultracold strontium atoms at a lattice depth of 60 $\mu$K by using only 80 mW of input light per cavity axis. We characterize these lattices using high-resolution clock spectroscopy and resolve carrier transitions between different vibrational levels. With these spectral features, we locally measure the lattice potential envelope and the sample temperature with a spatial resolution limited only by the optical resolution of the imaging system. The measured ground-band and trap lifetimes are 18(3) s and 59(2) s, respectively, and the lattice frequency (depth) is long-term stable on the MHz (0.1\%) level. Our results show that large, deep, and stable two-dimensional cavity-enhanced lattices can be created at any wavelength and can be used to scale up neutral-atom-based quantum simulators, quantum computers, sensors, and optical lattice clocks.Comment: 18 pages, 10 figure

Analysis of phytoplankton community in the vicinity of domestic sewage outflow during stratified conditions

The response of phytoplankton community structure to anthropogenically-derived nutrient from the submarine sewage outflow was analysed in a shallow coastal area of the middle Adriatic Sea. The study was conducted during the eight-year period (2002-2010) at six stations in the Brač Channel, aiming to assess the potential change in the state of biological and environmental parameters before and after the sewage commissioning. The research was particularly focused on phytoplankton producers during the summer which is considered to be critical due to water stratification and low water dynamics. The results show an increase in phytoplankton biomass in the deep layer after the discharge activation that was significant (M-W test; U=584.5, p<0.01), but not related to any intense phytoplankton bloom or oxygen deficiency. Temporal variability of total phytoplankton abundances throughout the research period indicated a significant increase in 2005, the year following the sewage outflow activation. Pairwise Dunn's multiple comparison test emphasised the difference in the years before the sewage activation (2002, 2003) compared to 2005 (2002 vs. 2005, R=-60.92 p<0.001; 2003 vs. 2005, R=-63.92 p<0.001). This situation was soon followed by the rapid equalization in phytoplankton abundances. Considering the entire research period, there were no changes in contributions of major phytoplankton groups, but the increase in overall species diversity was recorded, supporting the view that moderate inputs may stimulate plankton taxonomic diversity in coastal ecosystems. Increased ciliate and copepod nauplii abundance was also observed but was considered to be caused by natural variability