News

Guilhem Poy from Faculty of Mathematics and Physics at University of Ljubljana and Slobodan Žumer from Jozef Stefan Institute in collaboration with the group of Ivan Smalyukh from University of Colorado in Boulder in Physical Review X published the paper that Control of Light by Topological Solitons in Soft Chiral Birefringent Media, was highlighted in APS Physics Focus by the editorial article “Liquid-Crystal Vortices Focus Light”. Topological solitons appearing in different areas of physics are fascinating localized perturbations of ordering fields enjoying topological protection. The authors demonstrate refraction, reflection, and lensing of weak laser beams by various topological solitons in frustrated chiral nematics and show how interactions of light with such topological solitons are well described using a generalized Snell’s law and ray-tracing models. These may lead to new means for controlling flow of light for use in optics and photonics.

Slobodan Žumer from Jozef Stefan Institute and Guilhem Poy from Faculty of mathematics and Physics at University of Ljubljana in collaboration with Andrew Hess and Ivan Smalyukh from University of Colorado in Boulder published the paper Chirality-enhanced periodic self-focusing of light in birefringent soft media in Physical Review Letters. It presents numerical, experimental and theoretical evidence of chirality enhanced nonlinear optical response of frustrated chiral nematics. In achiral nematics, the reorientation of molecules around laser beams with appropriate power is responsible for the generation of spatial optical solitons called “nematicons”. In unwounded chiral nematics, the frustration caused by a confinement incompatible with their lowest-energy states allows a relatively weak light to locally destabilize the initially uniform orientational fields and thus boost their nonlinear optical responses. Our research findings are expected to allow new self-focusing based applications.

Dr Matjaž Gomilšek: Jožef Stefan Golden Emblem Prize for his doctoral thesis “Quantum spin liquids on

geometrically frustrated kagome lattices”, Ljubljana, Jožef Stefan Institute

Prof. Samo Kralj, PhD: the Zois Certificate of Recognition for important research achievements in the

field of soft-matter physics, Ljubljana

As a member of an international consortium, “Jožef Stefan” Institute received the European Athena project, whose aim is the implementation of gender equality plans to release the potential of research institutions in Europe. The F5 department will have an active role in this project, joined by 9 other “Jožef Stefan” Institute departments (U1, F4, K1, K3, K5, K7, E3, E5 and E7). Despite the large number of highly qualified women with degrees, women make up only a third of research workforce in the EU. The aims of this project are to remove the barriers that make it difficult for women to become employed in a research facility and to be promoted to researchers, to strengthen the presence of the gender dimension within research programs and to address the gender inequality in decision making. The two main project goals are development and implementation of a plan for gender equality on a systemic, institutional level. The members of the international consortium are research institutions from Central and Eastern Europe and from remote regions with a low gender equality index, as the project aims to reduce the gap between research organizations across Europe.

During a football match at the Stožice Stadium in Ljubljana in 2019, the F5 department researchers measured nanoparticle air pollution. During the match, the fans of both teams used pyrotechnic devices to support their teams despite the prohibition. Researchers of the Department of Condensed Matter Physics, Luka Pirker, Anton Gradišek, Bojana Višić and Maja Remškar discovered the number of nanoparticles in the range between 30 nm to 300 nm increased by 1200 percent when flares were light and the players inhaled 300 % more particles than usual. In addition to carbon, the chemical analysis also showed the presence of potentially poisonous elements which are used for colouring and as fuel such as strontium (red colour), barium (green colour), potassium, magnesium and chloride. The findings were published in the Atmospheric Environment journal.