Browsing by Author "Balaž, Antun"

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    AEDGE: Atomic Experiment for Dark Matter and Gravity Exploration in Space
    El-Neaj, Yousef Abou; Alpigiani, Cristiano; Amairi-Pyka, Sana; Araújo, Henrique; Balaž, Antun; Bassi, Angelo; Bathe-Peters, Lars; Battelier, Baptiste; Belić, Aleksandar; Bentine, Elliot; Bernabeu, José; Bertoldi, Andrea; Bingham, Robert; Blas, Diego; Bolpasi, Vasiliki; Bongs, Kai; Bose, Sougato; Bouyer, Philippe; Bowcock, Themis; Bowden, William; Buchmueller, Oliver; Burrage, Clare; Calmet, Xavier; Canuel, Benjamin; Caramete, Laurentiu-Ioan; Carroll, Andrew; Cella, Giancarlo; Charmandaris, Vassilis; Chattopadhyay, Swapan; Chen, Xuzong; Chiofalo, Maria Luisa; Coleman, Jonathon; Cotter, Joseph; Cui, Yanou; Derevianko, Andrei; De Roeck, Albert; Đorđević, Goran S.; Dornan, Peter; Doser, Michael; Drougkakis, Ioannis; Dunningham, Jacob; Dutan, Ioana; Easo, Sajan; Elertas, Gedminas; Ellis, John; El Sawy, Mai; Fassi, Farida; Felea, Daniel; Feng, Chen-Hao; Flack, Robert; Foot, Chris; Fuentes, Ivette; Gaaloul, Naceur; Gauguet, Alexandre; Geiger, Remi; Gibson, Valerie; Giudice, Gian; Goldwin, Jon; Grachov, Oleg; Graham, Peter W.; Grasso, Dario; van der Grinten, Maurits; Gündogan, Mustafa; Haehnelt, Martin G.; Harte, Tiffany; Hees, Aurélien; Hobson, Richard; Hogan, Jason; Holst, Bodil; Holynski, Michael; Kasevich, Mark; Kavanagh, Bradley J.; von Klitzing, Wolf; Kovachy, Tim; Krikler, Benjamin; Krutzik, Markus; Lewicki, Marek; Lien, Yu-Hung; Liu, Miaoyuan; Luciano, Giuseppe Gaetano; Magnon, Alain; Mahmoud, Mohammed Attia; Malik, Sarah; McCabe, Christopher; Mitchell, Jeremiah; Pahl, Julia; Pal, Debapriya; Pandey, Saurabh; Papazoglou, Dimitris; Paternostro, Mauro; Penning, Bjoern; Peters, Achim; Prevedelli, Marco; Puthiya-Veettil, Vishnupriya; Quenby, John; Rasel, Ernst; Ravenhall, Sean; Ringwood, Jack; Roura, Albert; Sabulsky, Dylan; Sameed, Muhammed; Sauer, Ben; Schäffer, Stefan Alaric; Schiller, Stephan; Schkolnik, Vladimir; Schlippert, Dennis; Schubert, Christian; Sfar, Haifa Rejeb; Shayeghi, Armin; Shipsey, Ian; Signorini, Carla; Singh, Yeshpal; Soares-Santos, Marcelle; Sorrentino, Fiodor; Sumner, Timothy; Tassis, Konstantinos; Tentindo, Silvia; Tino, Guglielmo Maria; Tinsley, Jonathan N.; Unwin, James; Valenzuela, Tristan; Vasilakis, Georgios; Vaskonen, Ville; Vogt, Christian; Webber-Date, Alex; Wenzlawski, André; Windpassinger, Patrick; Woltmann, Marian; Yazgan, Efe; Zhan, Ming-Sheng; Zou, Xinhao; Zupan, Jure
    We propose in this White Paper a concept for a space experiment using cold atoms to search for ultra-light dark matter, and to detect gravitational waves in the frequency range between the most sensitive ranges of LISA and the terrestrial LIGO/Virgo/KAGRA/INDIGO experiments. This interdisciplinary experiment, called Atomic Experiment for Dark Matter and Gravity Exploration (AEDGE), will also complement other planned searches for dark matter, and exploit synergies with other gravitational wave detectors. We give examples of the extended range of sensitivity to ultra-light dark matter offered by AEDGE, and how its gravitational-wave measurements could explore the assembly of super-massive black holes, first-order phase transitions in the early universe and cosmic strings. AEDGE will be based upon technologies now being developed for terrestrial experiments using cold atoms, and will benefit from the space experience obtained with, e.g., LISA and cold atom experiments in microgravity. KCL-PH-TH/2019-65, CERN-TH-2019-126.
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    C and Fortran OpenMP programs for rotating Bose–Einstein condensates
    Kishor Kumar, Ramavarmaraja; Lončar, Vladimir; Muruganandam, Paulsamy; Adhikari, Sadhan K.; Balaž, Antun
    We present OpenMP versions of C and Fortran programs for solving the Gross–Pitaevskii equation for a rotating trapped Bose–Einstein condensate (BEC) in two (2D) and three (3D) spatial dimensions. The programs can be used to generate vortex lattices and study dynamics of rotating BECs. We use the split-step Crank–Nicolson algorithm for imaginary- and real-time propagation to calculate stationary states and BEC dynamics, respectively. The simulation input parameters for the C programs are provided via input files, while for the Fortran programs they are given at the beginning of each program and therefore their change requires recompilation of the corresponding program. The programs propagate the condensate wave function and calculate several relevant physical quantities, such as the energy, the chemical potential, and the root-mean-square sizes. The imaginary-time propagation starts with an analytic wave function with one vortex at the trap center, modulated by a random phase at different space points. Nevertheless, the converged wave function for a rapidly rotating BEC with a large number of vortices is most efficiently calculated using the pre-calculated converged wave function of a rotating BEC containing a smaller number of vortices as the initial state rather than using an analytic wave function with one vortex as the initial state. These pre-calculated initial states exhibit rapid convergence for fast-rotating condensates to states containing multiple vortices with an appropriate phase structure. This is illustrated here by calculating vortex lattices with up to 61 vortices in 2D and 3D. Outputs of the programs include calculated physical quantities, as well as the wave function and different density profiles (full density, integrated densities in lower dimensions, and density cross-sections). The provided real-time propagation programs can be used to study the dynamics of a rotating BEC using the imaginary-time stationary wave function as the initial state. We also study the efficiency of parallelization of the present OpenMP C and Fortran programs with different compilers. Program summary Program title: BEC-GP-ROT-OMP, consisting of: (1) BEC-GP-ROT-OMP-C package, containing programs (i) bec-gp-rot-2d-th and (ii) bec-gp-rot-3d-th; (2) BEC-GP-ROT-OMP-F package, containing programs (i) bec-gp-rot-2d-th and (ii) bec-gp-rot-3d-th. Program files doi: http://dx.doi.org/10.17632/cw7tkn22v2.2 Licensing provisions: Apache License 2.0 Programming language: OpenMP C; OpenMP Fortran. The C programs are tested with the GNU, Intel, PGI, Oracle, and Clang compiler, and the Fortran programs are tested with the GNU, Intel, PGI, and Oracle compiler. Nature of problem: The present Open Multi-Processing (OpenMP) C and Fortran programs solve the time-dependent nonlinear partial differential Gross–Pitaevskii (GP) equation for a trapped rotating Bose–Einstein condensate in two (2D) and three (3D) spatial dimensions in a fully anisotropic traps. Solution method: We employ the split-step Crank–Nicolson algorithm to discretize the time-dependent GP equation in space and time. The discretized equation is then solved by imaginary- or real-time propagation, employing adequately small space and time steps, to yield the solution of stationary and non-stationary problems, respectively.
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    Cold atoms in space: community workshop summary and proposed road-map
    Alonso, Iván; Alpigiani, Cristiano; Altschul, Brett; Araújo, Henrique; Arduini, Gianluigi; Arlt, Jan; Badurina, Leonardo; Balaž, Antun; Bandarupally, Satvika; Barish, Barry C.; Barone, Michele; Barsanti, Michele; Bass, Steven; Bassi, Angelo; Battelier, Baptiste; Baynham, Charles F. A.; Beaufils, Quentin; Belić, Aleksandar; Bergé, Joel; Bernabeu, Jose; Bertoldi, Andrea; Bingham, Robert; Bize, Sébastien; Blas, Diego; Bongs, Kai; Bouyer, Philippe; Braitenberg, Carla; Brand, Christian; Braxmaier, Claus; Bresson, Alexandre; Buchmueller, Oliver; Budker, Dmitry; Bugalho, Luís; Burdin, Sergey; Cacciapuoti, Luigi; Callegari, Simone; Calmet, Xavier; Calonico, Davide; Canuel, Benjamin; Caramete, Laurentiu-Ioan; Carraz, Olivier; Cassettari, Donatella; Chakraborty, Pratik; Chattopadhyay, Swapan; Chauhan, Upasna; Chen, Xuzong; Chen, Yu-Ao; Chiofalo, Maria Luisa; Coleman, Jonathon; Corgier, Robin; Cotter, J. P.; Cruise, A. Michael; Cui, Yanou; Davies, Gavin; Roeck, Albert De; Demarteau, Marcel; Derevianko, Andrei; Clemente, Marco Di; Đorđević, Goran S.; Donadi, Sandro; Doré, Olivier; Dornan, Peter; Doser, Michael; Drougakis, Giannis; Dunningham, Jacob; Easo, Sajan; Eby, Joshua; Elertas, Gedminas; Ellis, John; Evans, David; Examilioti, Pandora; Fadeev, Pavel; Fanì, Mattia; Fassi, Farida; Fattori, Marco; Fedderke, Michael A.; Felea, Daniel; Feng, Chen-Hao; Ferreras, Jorge; Flack, Robert; Flambaum, Victor V.; Forsberg, René; Fromhold, Mark; Gaaloul, Naceur; Garraway, Barry M.; Georgousi, Maria; Geraci, Andrew; Gibble, Kurt; Gibson, Valerie; Gill, Patrick; Giudice, Gian F.; Goldwin, Jon; Gould, Oliver; Grachov, Oleg; Graham, Peter W.; Grasso, Dario; Griffin, Paul F.; Guerlin, Christine; Gündoğan, Mustafa; Gupta, Ratnesh K.; Haehnelt, Martin; Hanımeli, Ekim T.; Hawkins, Leonie; Hees, Aurélien; Henderson, Victoria A.; Herr, Waldemar; Herrmann, Sven; Hird, Thomas; Hobson, Richard; Hock, Vincent; Hogan, Jason; Holst, Bodil; Holynski, Michael; Israelsson, Ulf; Jeglič, Peter; Jetzer, Philippe; Juzeliūnas, Gediminas; Kaltenbaek, Rainer; Kamenik, Jernej F.; Kehagias, Alex; Kirova, Teodora; Kiss-Toth, Marton; Koke, Sebastian; Kolkowitz, Shimon; Kornakov, Georgy; Kovachy, Tim; Krutzik, Markus; Kumar, Mukesh; Kumar, Pradeep; Lämmerzahl, Claus; Landsberg, Greg; Poncin-Lafitte, Christophe Le; Leibrandt, David R.; Lévèque, Thomas; Lewicki, Marek; Li, Rui; Lipniacka, Anna; Lisdat, Christian; Liu, Mia; Lopez-Gonzalez, J. L.; Loriani, Sina; Louko, Jorma; Luciano, Giuseppe, Gaetano; Lundblad, Nathan; Maddox, Steve; Mahmoud, M. A.; Maleknejad, Azadeh; March-Russell, John; Massonnet, Didier; McCabe, Christopher; Meister, Matthias; Mežnaršič, Tadej; Micalizio, Salvatore; Migliaccio, Federica; Millington, Peter; Milosevic, Milan; Mitchell, Jeremiah; Morley, Gavin W.; Müller, Jürgen; Murphy, Eamonn; Müstecaplıoğlu, Özgür E.; O’Shea, Val; Oi, Daniel K. L.; Olson, Judith; Pal, Debapriya; Papazoglou, Dimitris G.; Pasatembou, Elizabeth; Paternostro, Mauro; Pawlowski, Krzysztof; Pelucchi, Emanuele; Pereira dos Santos, Franck; Peters, Achim; Pikovski, Igor; Pilaftsis, Apostolos; Pinto, Alexandra; Prevedelli, Marco; Puthiya-Veettil, Vishnupriya; Quenby, John; Rafelski, Johann; Rasel, Ernst M.; Ravensbergen, Cornelis; Reguzzoni, Mirko; Richaud, Andrea; Riou, Isabelle; Rothacher, Markus; Roura, Albert; Ruschhaupt, Andreas; Sabulsky, Dylan O.; Safronova, Marianna; Saltas, Ippocratis D.; Salvi, Leonardo; Sameed, Muhammed; Saurabh, Pandey; Schäffer, Stefan; Schiller, Stephan; Schilling, Manuel; Schkolnik, Vladimir; Schlippert, Dennis; Schmidt, Piet O.; Schnatz, Harald; Schneider, Jean; Schneider, Ulrich; Schreck, Florian; Schubert, Christian; Shayeghi, Armin; Sherrill, Nathaniel; Shipsey, Ian; Signorini, Carla; Singh, Rajeev; Singh, Yeshpal; Skordis, Constantinos; Smerzi, Augusto; Sopuerta, Carlos F.; Sorrentino, Fiodor; Sphicas, Paraskevas; Stadnik, Yevgeny V.; Stefanescu, Petruta; Tarallo, Marco G.; Tentindo, Silvia; Tino, Guglielmo M.; Tinsley, Jonathan N.; Tornatore, Vincenza; Treutlein, Philipp; Trombettoni, Andrea; Tsai, Yu-Dai; Tuckey, Philip; Uchida, Melissa A.; Valenzuela, Tristan; Van Den Bossche, Mathias; Vaskonen, Ville; Verma, Gunjan; Vetrano, Flavio; Vogt, Christian; Klitzing, Wolf, Von; Waller, Pierre; Walser, Reinhold; Wille, Eric; Williams, Jason; Windpassinger, Patrick; Wittrock, Ulrich; Wolf, Peter; Woltmann, Marian; Wörner, Lisa; Xuereb, André; Yahia, Mohamed; Yazgan, Efe; Yu, Nan; Zahzam, Nassim; Cruzeiro, Emmanuel, Zambrini; Zhan, Mingsheng; Zou, Xinhao; Zupan, Jure; Zupanič, Erik
    We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies.
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    Dynamics of Weakly Interacting Bosons in Optical Lattices with Flux
    Hudomal, Ana; Vasić, Ivana; Buljan, Hrvoje; Hofstetter, Walter; Balaž, Antun
    Realization of strong synthetic magnetic fields in driven optical lattices has enabled implementation of topological bands in cold-atom setups. A milestone has been reached by a recent measurement of a finite Chern number based on the dynamics of incoherent bosonic atoms. The measurements of the quantum Hall effect in semiconductors are related to the Chern-number measurement in a cold-atom setup; however, the design and complexity of the two types of measurements are quite different. Motivated by these recent developments, we investigate the dynamics of weakly interacting incoherent bosons in a two-dimensional driven optical lattice exposed to an external force, which provides a direct probe of the Chern number. We consider a realistic driving protocol in the regime of high driving frequency and focus on the role of weak repulsive interactions. We find that interactions lead to the redistribution of atoms over topological bands both through the conversion of interaction energy into kinetic energy during the expansion of the atomic cloud and due to an additional heating. Remarkably, we observe that the moderate atomic repulsion facilitates the measurement by flattening the distribution of atoms in the quasimomentum space. Our results also show that weak interactions can suppress the contribution of some higher-order nontopological terms in favor of the topological part of the effective model.
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    Faraday and Resonant Waves in Dipolar Cigar-Shaped Bose-Einstein Condensates
    Vudragović, Dušan; Balaž, Antun
    Faraday and resonant density waves emerge in Bose-Einstein condensates as a result of harmonic driving of the system. They represent nonlinear excitations and are generated due to the interaction-induced coupling of collective oscillation modes and the existence of parametric resonances. Using a mean-field variational and a full numerical approach, we studied density waves in dipolar condensates at zero temperature, where breaking of the symmetry due to anisotropy of the dipole-dipole interaction (DDI) plays an important role. We derived variational equations of motion for the dynamics of a driven dipolar system and identify the most unstable modes that correspond to the Faraday and resonant waves. Based on this, we derived the analytical expressions for spatial periods of both types of density waves as functions of the contact and the DDI strength. We compared the obtained variational results with the results of extensive numerical simulations that solve the dipolar Gross-Pitaevskii equation in 3D, and found a very good agreement.
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    Ground state of an ultracold Fermi gas of tilted dipoles in elongated traps
    Veljić, Vladimir; Lima, Aristeu R. P.; Chomaz, Lauriane; Baier, Simon; Mark, Manfred J; Ferlaino, Francesca; Pelster, Axel; Balaž, Antun
    Many-body dipolar effects in Fermi gases are quite subtle as they energetically compete with the large kinetic energy at and below the Fermi surface (FS). Recently it was experimentally observed in a sample of erbium atoms that its FS is deformed from a sphere to an ellipsoid due to the presence of the anisotropic and long-range dipole-dipole interaction Aikawa et al (2014 Science 345 1484). Moreover, it was suggested that, when the dipoles are rotated by means of an external field, the FS follows their rotation, thereby keeping the major axis of the momentum-space ellipsoid parallel to the dipoles. Here we generalise a previous Hartree-Fock mean-field theory to systems confined in an elongated triaxial trap with an arbitrary orientation of the dipoles relative to the trap. With this we study for the first time the effects of the dipoles' arbitrary orientation on the ground-state properties of the system. Furthermore, taking into account the geometry of the system, we show how the ellipsoidal FS deformation can be reconstructed, assuming ballistic expansion, from the experimentally measurable real-space aspect ratio after a free expansion. We compare our theoretical results with new experimental data measured with erbium Fermi gas for various trap parameters and dipole orientations. The observed remarkable agreement demonstrates the ability of our model to capture the full angular dependence of the FS deformation. Moreover, for systems with even higher dipole moment, our theory predicts an additional unexpected effect: the FS does not simply follow rigidly the orientation of the dipoles, but softens showing a change in the aspect ratio depending on the dipoles' orientation relative to the trap geometry, as well as on the trap anisotropy itself. Our theory provides the basis for understanding and interpreting phenomena in which the investigated physics depends on the underlying structure of the FS, such as fermionic pairing and superfluidity
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    Interplay of coherent and dissipative dynamics in condensates of light
    Radonjić, Milan; Kopylov, Wassilij; Balaž, Antun; Pelster, Axel
    Based on the Lindblad master equation approach we obtain a detailed microscopic model of photons in a dye-filled cavity, which features condensation of light. To this end we generalise a recent non-equilibrium approach of Kirton and Keeling such that the dye-mediated contribution to the photon-photon interaction in the light condensate is accessible due to an interplay of coherent and dissipative dynamics. We describe the steady-state properties of the system by analysing the resulting equations of motion of both photonic and matter degrees of freedom. In particular, we discuss the existence of two limiting cases for steady states: photon Bose-Einstein condensate and laser-like. In the former case, we determine the corresponding dimensionless photon-photon interaction strength by relying on realistic experimental data and find a good agreement with previous theoretical estimates. Furthermore, we investigate how the dimensionless interaction strength depends on the respective system parameters.
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    OpenMP Fortran programs for solving the time-dependent dipolar Gross-Pitaevskii equation
    Young-S., Luis E.; Muruganandam, Paulsamy; Balaž, Antun; Adhikari, Sadhan K.
    In this paper we present Open Multi-Processing (OpenMP) Fortran 90/95 versions of previously published numerical programs for solving the dipolar Gross-Pitaevskii (GP) equation including the contact interaction in one, two and three spatial dimensions. The atoms are considered to be polarized along the z axis and we consider different cases, e.g., stationary and non-stationary solutions of the GP equation for a dipolar Bose-Einstein condensate (BEC) in one dimension (along x and z axes), two dimensions (in x-y and x-z planes), and three dimensions. The algorithm used is the split-step semi-implicit Crank-Nicolson scheme for imaginary- and real-time propagation to obtain stationary states and BEC dynamics, respectively, as in the previous version (Kishor Kumar et al., 2015 [3]). These OpenMP versions have significantly reduced execution time in multicore processors.
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    OpenMP solver for rotating spin-1 spin–orbit- and Rabi-coupled Bose–Einstein condensates
    Muruganandam, Paulsamy; Balaž, Antun; Adhikari, Sadhan K.
    We present OpenMP version of a Fortran program for solving the Gross–Pitaevskii equation for a harmonically trapped three-component rotating spin-1 spinor Bose–Einstein condensate (BEC) in two spatial dimensions with or without spin–orbit (SO) and Rabi couplings. The program uses either Rashba or Dresselhaus SO coupling. We use the split-step Crank–Nicolson discretization scheme for imaginary- and real-time propagation to calculate stationary states and BEC dynamics, respectively.
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    Perspective on quantum bubbles in microgravity
    Lundblad, Nathan; Aveline, David C.; Balaž, Antun; Bentine, Elliot; Bigelow, Nicholas P.; Boegel, Patrick; Efremov, Maxim A.; Gaaloul, Naceur; Meister, Matthias; Olshanii, Maxim; Sá de Melo, Carlos A. R.; Tononi, Andrea; Vishveshwara, Smitha; White, Angela C.; Wolf, Alexander; Garraway, Barry M.
    Progress in understanding quantum systems has been driven by the exploration of the geometry, topology, and dimensionality of ultracold atomic systems. The NASA Cold Atom Laboratory (CAL) aboard the International Space Station has enabled the study of ultracold atomic bubbles, a terrestrially-inaccessible topology. Proof-of-principle bubble experiments have been performed on CAL with an radiofrequency-dressing technique; an alternate technique (dual-species interaction-driven bubbles) has also been proposed. Both techniques can drive discovery in the next decade of fundamental physics research in microgravity.
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    Shell-shaped Bose-Einstein condensates based on dual-species mixtures
    Wolf, Alexander; Boegel, Patrick; Meister, Matthias; Balaž, Antun; Gaaloul, Naceur; Efremov, Maxim A.
    Ultracold quantum gases confined in three-dimensional bubble traps are promising tools for exploring many -body effects on curved manifolds. As an alternative to the conventional technique of radio-frequency dressing, we propose to create such shell-shaped Bose-Einstein condensates in microgravity based on dual-species atomic mixtures, and we analyze their properties as well as the feasibility of realizing symmetrically filled shells. Beyond similarities with the radio-frequency dressing method, as in the collective excitation spectrum, our approach has several natural advantages like the robustness of the created quantum bubbles and the possibility of magnifying shell effects through an interaction-driven expansion.
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    Spin-1 spin–orbit- and Rabi-coupled Bose–Einstein condensate solver
    Ravisankar, Rajamanickam; Vudragović, Dušan; Muruganandam, Paulsamy; Balaž, Antun; Adhikari, Sadhan K.
    We present OpenMP versions of FORTRAN programs for solving the Gross–Pitaevskii equation for a harmonically trapped three-component spin-1 spinor Bose–Einstein condensate (BEC) in one (1D) and two (2D) spatial dimensions with or without spin–orbit (SO) and Rabi couplings. Several different forms of SO coupling are included in the programs. We use the split-step Crank–Nicolson discretization for imaginary- and real-time propagation to calculate stationary states and BEC dynamics, respectively. The imaginary-time propagation programs calculate the lowest-energy stationary state. The real-time propagation programs can be used to study the dynamics. The simulation input parameters are provided at the beginning of each program. The programs propagate the condensate wave function and calculate several relevant physical quantities. Outputs of the programs include the wave function, energy, root-mean-square sizes, different density profiles (linear density for the 1D program, linear and surface densities for the 2D program). The imaginary- or real-time propagation can start with an analytic wave function or a pre-calculated numerical wave function. The imaginary-time propagation usually starts with an analytic wave function, while the real-time propagation is often initiated with the previously calculated converged imaginary-time wave function.
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    Stability of quantum degenerate Fermi gases of tilted polar molecules
    Veljić, Vladimir; Pelster, Axel; Balaž, Antun
    A recent experimental realization of a quantum degenerate gas of K-40 Rb-87 molecules opens up prospects of exploring strong dipolar Fermi gases and many-body phenomena arising in that regime. Here, we derive a mean-field variational approach based on the Wigner function for the description of the ground-state properties of such systems. We show that the stability of dipolar fermions in a general harmonic trap is universal as it only depends on the trap aspect ratios and the dipoles' orientation. We calculate the species-independent stability diagram and the deformation of the Fermi surface (FS) for polarized molecules, whose electric dipoles are oriented along a preferential direction. Compared to atomic magnetic species, the stability of a molecular electric system turns out to strongly depend on its geometry and the FS deformation significantly increases.
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    VI-SEEM DREAMCLIMATE Service
    Vudragović, Dušan; Ilić, Luka; Jovanović, Petar; Ničković, Slobodan; Bogojević, Aleksandar; Balaž, Antun
    Premature human mortality due to cardiopulmonary disease and lung cancer is found in epidemiological studies to be correlated to increased levels of atmospheric particulate matter. Such negative dust effects on the human mortality in the North Africa - Europe - Middle East region can be successfully studied by the DREAM dust model. However, to assess health effects of dust and its other impacts on the environment, a detailed modelling of the climate for a period of one year in a high-resolution mode is required. We describe here a parallel implementation of the DREAM dust model, the DREAMCLIMATE service, which is optimised for use on the high-performance regional infrastructure provided by the VI-SEEM project. In addition to development and integration of this service, we also present a use-case study of premature mortality due to desert dust in the North Africa - Europe - Middle East region for the year 2005, to demonstrate how the newly deployed service can be used.