September 10, 2017: We have matter-wave bright solitons propagating without dispersion over a macroscopic distance of several millimeters!


A post shared by @ultracoollab on


A post shared by @ultracoollab on

April 20, 2017: Our first observation of ultra cold cesium molecules!


A post shared by @ultracoollab on


A post shared by @ultracoollab on

April 4, 2017: BEC party!


A post shared by @ultracoollab on


A post shared by @ultracoollab on




November 18, 2016: BEC?


A post shared by @ultracoollab on


October 6, 2016: We opened the UHV oven to replace the exhausted cesium dispensers.


A video posted by @ultracoollab on


September 8, 2016: Tadej Mežnaršič defended his master thesis entitled "Laser cooling of cesium atoms" (pdf, presentation). Congratulations!

May 31, 2016: Ticijana Ban, Damir Aumiler and Neven Šantić from Zagreb cold atoms group visited our lab.


A photo posted by @ultracoollab on


May 2016: We joined Slovenian Quantum Technology community. >>more


November 2015: We reached temperatures well below 1 microkelvin after the Raman sideband cooling stage! The Stern-Gerlach experiment demonstrates that the majority of atoms are in the mF=3 state. Below, a difference between 25 and 1 microkelvin is illustrated as observed in the time-of-flght experiments. Also the laser beams during different cooling stages are visualised.

September 28, 2015: Prof. Francesca Ferlaino and her Erbium group from Innsbruck visited our lab. Later we all attended the Workshop on Topological effects and synthetic gauge/magnetic fields for atoms and photons organised by Zagreb cold atoms group.


A photo posted by @ultracoollab on

September 2015: We are now capable of reaching temperatures below 10 microkelvin.

April 2015: An article about our Laboratory for cold atoms appeared in the daily newspaper Dnevnik (pdf).

March 2015: We have cold atoms! The current number of cesium atoms in the MOT is around 50 million atoms. Their temperature is well below mK as estimated by the release-and-catch method. 

February 2015: We are slowing down and cooling the cesium atomic beam in the Zeeman slower. The signal represents the atomic velocity distribution as a function of Zeeman slower magnetic field profile. The sharp peak on the left belongs to cooled atoms.



November 2014: For the first time in our laboratory, Nejc Rosenstein recorded the fluorescence of the cesium atomic beam inside the UHV system. We directed the collimated laser beam into the atoms, perpendicularly to the direction of their flight. The signal was recorded with cameras IDS UI-1240ML-NIR and Andor Neo. Even though the IDS camera is not suitable for our experiment because of relatively low sensitivity and inadequate dark signal surpression, we managed to detect the fluorescence signal. However, much better results were obtained with the Andor Neo camera. The camera sensor is cooled down to -40°C, which results in the reduction of the dark signal. The area in which the fluorescence was detected matches with the intersection area of atomic beam and the laser beam. We measured beam profiles simultaneously with the fluorescence imaging. All camera parameters and the settings of laser beam profiler remained unchanged during the acquisition of all three images shown below. The images were recorded at different laser light intensities and at different laser beam widths. 


July 2014: Pavel Kos and Nejc Janša, the Faculty of Mathematics and Physics undergraduate students, joined our team. They will design, build and test a tabletop modulation transfer spectroscopy of cesium atoms. In parallel they will help to assemble and test the MOT and compensation coils. >> more


April 2014: We measured our first Doppler-free saturation spectra of Cs D2 line!


January 2014: Rok Žitko built and tested a prototype of a very tiny servo motor controller based on ATtiny 85 microcontroller.


November 2013: Bakeout!


September 2013: We started the UHV system assembly. Custom-designed nonmagnetic MOT chamber with 2 x DN 200 CF, 12 x DN 40 CF and 4 x DN 16 CF viewports, was made of 316LN stainless steel by VAb GmbH.


June 2013: Gregor Bensa, a Faculty of Mathematics and Physics undergraduate student, began designing a laser shutter system for our cold atoms experiment. Two approaches will be followed, the hard disc mechanical shutter first developed at the University of Melbourne and the liquid crystal shutter based on a technology developed by Balder, a Slovenian optoelectronic company. Our main goal is reaching a maximum switching speed performance.


January 2013: Nejc Rosenstein, a Faculty of Mathematics and Physics postgraduate student, joined our team. He will design, build and test the Zeeman slower. Later he will focus on the characterisation of cesium beam and imaging of cold atom cloud.


The first optical table arrived!  


We finished a major reconstruction work in the laboratory including a separate power line, high temperature stability, an even distribution of cooled air, protection from the electromagnetic radiation, mechanical and acoustic isolation.




New power line (15 kW + 10 kW).


We started to cooperate informally with the research group of Prof. Dr. Rudolf Grimm, University of Innsbruck, Austria, which is recognized as one of the leading institutions in the physics of cold atoms. From the beginning of October 2011, Dr. Erik Zupanič is on the training in the Er group led by Prof. Dr. Francesca Ferlaino.

Courtesy of the Er team, University of Innsbruck.


We attended the EuroQUAM 2010 conference entitled »Cold Quantum Matter: Achievements and Prospects« in Ischgl, Austria.