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Welcome to the website of the Slovenian cold atom lab. We use an ultracold quantum gas of cesium to explore matter waves and to develop quantum devices.

BEC is a state of coupled bosonic atoms at a temperature near absolute zero. Under these conditions, a large fraction of the atoms occupy the lowest quantum state, while the quantum nature of atoms is manifested in the form of superfluidity. The superfluidity is a macroscopic phenomenon where the material behaves as a quantum fluid that flows without viscosity and is analogous to the phenomenon of superconductivity in solids. Because of this analogy the BEC can be used as a quantum simulator of solid state physics, e.g., to study superconductivity and, in more general, to explore the physics of strongly correlated electrons.

Recent highlights

  • Preparation of ultra-cold atomic-ensemble arrays using time-multiplexed optical tweezers
    We use optical tweezers based on time-multiplexed acousto-optic deflectors to trap ultra-cold cesium atoms in one-dimensional arrays of atomic ensembles. For temperatures between 2.5 μK and 50 nK we study the maximal time between optical tweezer pulses that retains the number of atoms in a single trap. This time provides an estimate on the maximal number of sites in an array of time-multiplexed optical tweezers
  • Single-shot measurement of magnetic gradients with cold cesium atoms
    A novel method for detecting the gradient of a magnetic field uses an elongated cloud of cesium atoms cooled near the absolute zero. Since the rotation of atomic spins depends on the magnetic field, an image of the spin states can be used to measure how the magnetic field changes along the cloud. The gradient is determined from a single image, which is an advantage over standard methods where multiple images are needed.

Using lasers and magnetooptical trap the cesium atoms in the ultrahigh vacuum are first slowed down and caught, and thus cooled to the temperature range of several hundred μK. In the next step, by means of Raman transitions, the cesium atoms end up in one of the well-defined low-lying energy states and the temperature falls below 1 μK. At the same time the atoms are caught in the so-called optical trap by a set of extremely powerful laser beams. The atoms are further cooled by evaporation, which lowers the temperature to the range of nK, which is low enough for the atoms to condense.

Photo credits: Arne Hodalič and Katja Bidovec

Selected Publications

Preparation of ultra-cold atomic-ensemble arrays using time-multiplexed optical tweezers
Katja Gosar, Vesna Pirc Jevšenak, Tadej Mežnaršič, Dušan Babič, Igor Poberaj, Erik Zupanič, and Peter Jeglič
Single-shot Stern-Gerlach magnetic gradiometer with an expanding cloud of cold cesium atoms
Katja Gosar, Tina Arh, Tadej Mežnaršič, Ivan Kvasič, Dušan Ponikvar, Tomaž Apih, Rainer Kaltenbaek, Rok Žitko, Erik Zupanič, Samo Beguš, and Peter Jeglič
Phys. Rev. A 103, 022611 (2021), arXiv:2011.09779
Emission of correlated jets from a driven matter-wave soliton in a quasi-one-dimensional geometry
Tadej Mežnaršič, Rok Žitko, Tina Arh, Katja Gosar, Erik Zupanič, and Peter Jeglič
Phys. Rev. A 101, 031601(R) (2020), arXiv:1905.10286
Cesium bright matter-wave solitons and soliton trains
Tadej Mežnaršič, Tina Arh, Jure Brence, Jaka Pišljar, Katja Gosar, Žiga Gosar, Rok Žitko, Erik Zupanič, and Peter Jeglič
Phys. Rev. A 99, 033625 (2019), arXiv:1902.03144


Ongoing Projects

Physics of quantum and functional materials

Physics of quantum technologies

Development of building blocks for new European quantum communication network

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Latest news

  • Prize of dr. Uroš Seljak
    Katja Gosar is among the recipients of the Prize of dr. Uroš Seljak for the best scientific publications by students in the Bachelor and Masters level. The prizes were awarded by the honorary patron, the President of the Republic of Slovenia, Borut Pahor, donor dr. Uroš Seljak, University of Ljubljana and the American-Slovenian Educational Foundation…
  • Congratulations to dr. Tadej Mežnaršič for successfully defending his doctoral dissertation
    Congratulations to dr. Tadej Mežnaršič for successfully defending his doctoral dissertation! The thesis, titled Cesium Bose-Einstein condensates in confined geometries, can be accessed online.