The head of our laboratory, Dr Antun Balaž, suddenly passed away on July 4, 2025, while attending a scientific conference in Szeged, Hungary. Antun was our friend, colleague, and mentor—someone we could always rely on, who was always ready to help, to find a solution to every problem, or simply to point out that there is no problem.

Antun was born on December 27, 1973, in Zrenjanin, where he completed elementary school and Zrenjanin Gymnasium as the top student of his generation. After completing his military service, he continued his education at the Faculty of Physics, University of Belgrade, graduating in 1997 in Theoretical and Experimental Physics with an average grade of 9.93. He defended his master’s thesis entitled “New Recursive Formula for Path Integrals in Quantum Mechanics: Analytical and Numerical Properties” in May 2004 at the Faculty of Physics, University of Belgrade. He completed his PhD on the topic “Speeding up the Convergence of Path Integrals” under the supervision of Dr Aleksandar Bogojević in December 2008. He was the recipient of the “Prof. Dr. Lj. Ćirković” award for best undergraduate thesis, the Annual Award of the Institute of Physics in Belgrade for best master’s thesis (2005), and the Annual Research Award of the Institute of Physics (2014).

He was one of the founders of our laboratory in 2004 and was its highly active member from the very beginning. Even before completing his PhD, he provided full support to younger colleagues, guiding them through their first steps in scientific research. Since 2014, he was the head of our laboratory, and shortly thereafter also led the accredited Center for the Study of Complex Systems, of which our lab is the main part. He ensured that every lab member had appropriate working conditions and felt like a valued part of the team. He oversaw the maintenance of the Paradox computing cluster, making it accessible also to users from other research institutions in Serbia.

In the early part of his career, his main research interests were the application of effective actions in the path integral formalism in quantum field theory. He later started independent research in the field of ultracold quantum gases and Bose–Einstein condensation, establishing scientific collaborations with research groups from Germany, Austria, Romania, Brazil, and India. His main research topics included collective and nonlinear excitations of Bose–Einstein condensates, including the effects of dipole–dipole interactions and disorder. Since 2015, he opened a new research direction on ultracold dipolar fermions, working on the development of a quantum Boltzmann formalism to describe Fermi surface deformation due to strong dipole–dipole interactions. In his scientific work, he developed numerous parallel numerical algorithms and software, published in leading journals in computational physics. He authored about 60 papers in international journals and gave numerous invited lectures at international conferences and at universities in Germany, Italy, USA, Spain, Slovenia, Romania, and others.

He led many scientific projects. From 2015 to 2019, he was principal investigator of a basic research project funded by the Ministry of Science, involving nearly all members of our laboratory. He also led several bilateral projects with Germany and Austria. He was highly active in leading the Serbian team in several FP6, FP7, Horizon 2020, and Horizon Europe projects in the fields of high-performance computing, distributed, and grid computing. Through these efforts, he contributed to the establishment and development of high-performance computing infrastructure in Southeastern Europe.

Since his undergraduate days, Antun was deeply involved in the education of young researchers and introducing them to scientific work. He was an associate and a lecturer in the physics and astronomy programs at the Petnica Science Center and a mentor for many student projects. Many of our colleagues remember their first steps into science beyond the school curriculum through Antun's lectures or projects in Petnica. In recent years, he also formally supported Petnica as a member of its Management Board. He was a member of the national committee for high school physics competition several times and participated in preparation of students for international competitions. As the team leader, he led Serbian teams at the International Physics Olympiads in 2002 and 2003. He coauthored physics textbooks for the 6th and the 7th grade of elementary school.

From 2002 to 2005, he worked part-time as a teaching assistant at the courses Quantum Field Theory, Quantum Electrodynamics, and Theory of Elementary Particles at the Faculty of Physics in Belgrade. Several current members of our lab who took those courses fondly remember those days and Antun’s dedication to preparing high-quality exercise problems and interesting, challenging homework assignments. From 2009 to 2014, he was an assistant professor at the Faculty of Sciences in Novi Sad, and from 2015 he taught in the PhD program at the Faculty of Physics in Belgrade. Since 2017, he was a member of the Doctoral Studies Council at the Faculty of Physics.

He mentored five defended doctoral dissertations—three at the Faculty of Physics in Belgrade (in 2011 and two in 2019), one at the Faculty of Sciences in Novi Sad (2017), and one at the Faculty of Technical Sciences in Novi Sad (2017). He also mentored many master’s and undergraduate theses and contributed to two doctoral dissertations at the Free University of Berlin in Germany.

Since 2015, he had served as Deputy Director of the Institute, responsible for science. In that role, he made significant contributions to the development of the institute’s research capacity and the launch of numerous research projects. Even before taking on that role, he was widely regarded as the go-to person for advice on preparing and managing research projects and academic promotions.

Since 2017, he had been a member of the Scientific Board for Physics under the ministry in charge of science, and its Chair since 2022. In this capacity, he contributed to improving evaluation criteria for scientific work and tirelessly advocated for better conditions for scientific research. He also contributed to the work of other scientific institutions. Since 2010, he had been a member of the Management Board of the Astronomical Observatory and served as its Chair from 2014 to 2018, playing an important role in the realization of the Vidojevica Astronomical Station project. He pursued his commitment to better science and a better society both within institutional frameworks and, when needed, beyond them.
The highest recognition of his work came in 2024, when he was elected Corresponding Member of the Serbian Academy of Sciences and Arts.

We received the news of his passing with disbelief and profound sorrow. Grateful for everything he did for our laboratory, our center, our institute, and science in Serbia as a whole, we will continue on the path he laid for us, guided by his vision.