Hrvoje Buljan
Department of Physicy
Faculty of Science
University of Zagreb
Address: Bijenička c. 32, 10000 Zagreb, Croatia
Mail: hbuljan_at_phy.hr
Phone: ++385 1 460 5591

Position: Professor

Duty: Chairman (2014-2016)

Short BIO

 

Hrvoje Buljan received a MSc degree in physics from the University of Zagreb in 1997 and defended his PhD thesis at the same university in 2002 (supervisor Vladimir Paar). In the period from 2002-2004 he was a postdoctoral fellow at the Technion, Israel Institute of Technology in the group of Moti Segev. His research at the time was focused on nonlinear optical phenomena. In particular, the focus was on propagation of partially coherent optical waves in nonlinear photonic structures, and nonlinear phenomena such as incoherent solitons and modulation instability in these systems. After the postdoc period he moved back to the University of Zagreb as an Assistant Professor and formed his group with activities also in ultracold atomic gases. The research in his group focused on one-dimensional time-dependent quantum many-body systems, which were in the last decade experimentally realized in ultracold atomic gases. In recent years his research topics include also plasmons in graphene. HB authored and co-authored more than 50 publications in peer reviewed journals with ~1300 citations.

 

HB was promoted to the rank of Associate Professor of Physics at the University of Zagreb in 2009, and to the rank of Full Professor in 2013. He received the Annual Croatian State Award for Science in 2010. He mentored three PhD theses and more than 25 diploma theses. HB was the PI on several research projects: (2007-2013) Nonlinear phenomena and wave dynamics in photonic systems funded by the Ministry of Science in Croatia (MZOŠ); (2007-2009) PI of a Croatian-German bilateral project (in collaboration with Dr. Thomas Gasenzer, Institut for Theoretical Physics, Heidelberg) funded by MZOŠ and DAAD; (2008-2010) PI of a Croatian-Israeli bilateral project  (in collaboration with Prof Dr. Mordechai Segev, Technion, Israel Institute of Technology) funded by MZOŠ and Ministry of Science of the State of Israel; (2013-2015) PI of the Unity Through Knowledge Grant titled Pseudomagnetic forces and fields for atoms and photons (Co-PI Prof. Marin Soljačić, MIT). He teaches Classical Electrodynamics (3rd year undergraduates), Nonlinear Optics, and Nonlinear Continua (post-graduate courses).

Curriculum Vitae with List of Publications

Currently running projects (as Principal Investigator)

1. Pseudomagnetic forces and fields for atoms and photons, funded by the Unity through Knowledge Fund (UKF), www.ukf.hr 


2. Optics and Photonics in novel materials and plasma, short-term support from the University of Zagreb

 

Previous Projects (as PI)

 

3.  2007- Principal investigator of a project Nonlinear phenomena and wave dynamics in photonic systems (119-0000000-1015) funded by the Ministry of Science in Croatia (MZOŠ)

 

4. 2007-2009 Principal investigator of a Croatian-German bilateral project (in collaboration with Dr. Thomas Gasenzer, Institut for Theoretical Physics, Heidelberg) funded by MZOŠ and DAAD

 

5. 2008-2010 Principal investigator of a Croatian-Israeli bilateral project  (in collaboration with Prof Dr. Mordechai Segev, Technion, Israel Institute of Technology) funded by MZOŠ and Ministry of Science of the State of Israel

 

Participation in projects (not all are listed)

 

6. 2009-2012 Collaborator on the project Application of advanced computing in strongly correlated systems funded by NZZ, PI Prof.dr.sc. Tamara Nikšić

 

7. 2009-2012 Collaborator on the FP7 project SOLeNeMaR (Strenghtening the SOLid-state research capacities in Zagreb by the introduction of Nuclear Magnetic Resonance method) PI: Prof.dr.sc. Miroslav Požek

 

Topics of interest

1. Nonlinear optics: nonlinear wave phenomena, solitons, modulation instability (MI), ...

In the field of nonlinear optics, perhaps the main results are as follows. In Ref. [1] we outlined the theory for propagation of incoherent white light in noninstantaneous nonlinear media, and predicted modulation instability of white light [1]. This theory opened the way to subsequent theoretical studies of incoherent white-light solitons in versatile types of media [2,3]. The predictions of the properties of MI were later successfully experimentally demonstrated in [4]. Other predictions were also successfully verified in the experiments of other authors in versatile types of media.

[1] H. Buljan, A. Šiber, M. Soljačić, M. Segev, Phys. Rev. E 66, 035601(R) (2002).

[2] H. Buljan, M. Segev, M. Soljačić, N.K. Efremidis, D.N. Christodoulides, Opt. Lett. 28, 1239 (2003).

[3] H. Buljan, T. Schwartz, M. Segev, M. Soljačić, D.N. Christodoulides, J. Opt. Soc. Am. B 21, 397 (2004).

[4] T. Schwartz, T. Carmon, H. Buljan, and M. Segev, Phys. Rev. Lett. 93, 223901 (2004).

The prediction the existence and properties of random-phase lattice solitons (solitons propagating in nonlinear periodic lattices) was made in Ref. [5], and HB co-authored the experimental work [6] which verified the predictions and proved that these solitons do exist. This paper opened the way for subsequent theoretical and experimental work on incoherent light dynamics in nonlinear periodic (but also random) lattices. Even though it is not related to the scientific content of the work, it is interesting to note that Ref. [6] is the first scientific paper published in Nature magazine with Croatian affiliation (after independence in 1991).

[5] H. Buljan, O. Cohen, J.W. Fleischer, T. Schwartz, M. Segev, Z.H. Musslimani, N.K. Efremidis, and D.N. Christodoulides, Phys. Rev. Lett. 92, 223901 (2004).

[6] O. Cohen, G. Bartal, H. Buljan, T. Carmon, J.W. Fleischer, M. Segev, and D.N. Christodoulides, Nature (London) 433, 500 (2005)

2. Ultracold atomic gases: nonequilibrium dynamics of one-dimensional Bose gases

The most distinguished result is probably the formula developed for calculating the reduced one-body density matrix (which furnishes all one-body observables) for the strongly interacting 1D Bose gas (referred to as the Tonks-Girardeau gas) in Ref. [7]. This result is important because the formula is very simple and numerically exact calculations can be made for a fairly large numbers of interacting quantum particles (say 100 and even more), and it allows insight into the strongly correlated regime, both in- and out-of-equilibrium (it is valid for time-dependent problems as well).

[7] Pezer and H. Buljan, Momentum distribution dynamics of a Tonks-Girardeau gas: Bragg reflections of a quantum many-body wave packet, Phys. Rev. Lett. 98, 240403 (2007).

Next result is an exact study of free expansion of the so-called Lieb-Liniger gas [8] (an interacting 1D Bose gas). Free expansion is related to time-of flight experiments. It is important to understand when interactions are present. Ref. [8] provides exact results from the weakly to the strongly interacting regime for a generic initial wave packet. Our papers on the time-dependent Lieb-Liniger gas are to the best of our knowledge first results on this topic. We have utilized and perhaps one could say brought to light an idea by M. Gaudin from the 1980s.

[8] D.  Jukic, R. Pezer, T. Gasenzer, and H. Buljan, "Free expansion of a Lieb-Liniger gas: Asymptotic form of the wave functions" Phys. Rev. A 78, 053602 (2008).

An interesting early paper on the range of validity of Gross-Pitaevskii theory for investigating dynamics of solitons in Bose-Einstein Condensates:

[9] H. Buljan, M. Segev, and A. Vardi, Phys. Rev. Lett. 95, 180401 (2005).

3. Plasmons in graphene

In Ref. [10] we presented the potential of plasmons in a new material – graphene – for their use in nanophotonics. This work has attracted lots of attention. We continued along this line of research (please see full list of publications). Recently we published a review paper [11] and N&V article in Nature Photonics [12].

 

[10] Jablan, H. Buljan, and M. Soljačić "Plasmonics in graphene at infra-red frequencies," Phys. Rev. B 80, 245435 (2009).

 

[11] M. Jablan. M. Soljačić, and H. Buljan, “Plasmons in graphene: Fundamental properties and potential applications” Proceedings of the IEEE 101, 1689 (2013), invited review article

 

[12] H. Buljan, M. Jablan, and M. Soljačić, “Damping of Plasmons in Graphene”, Nature Photonics 7, 346 (2013), N&V article.

 

Mentorship

1. Dario Jukić defended his PhD Thesis in February 2012 (Thesis title: Nonequilibrium dynamics of exactly solvable one-dimensional many-body Bose systems)

2. Marinko Jablan defended his PhD Thesis in March 2012 (Thesis title: Electrodynamic properties of graphene and their technological applications)

3. Karlo Lelas defended his PhD Thesis in July 2012 (Thesis title: Correlations in strongly-interacting one-dimensional many body systems.

4.  Mentor for more than 25 diploma theses

5. Mentor of the student work for which Marinko Jablan was awarded Science award (2008) awarded annually for one student publication in all natural sciences by the Croatian National Foundation for Science

6.  Mentor of the student work for which Dario Jukić was awarded Science award (2009)

7. Mentor of the student work for which Ozana Čelan was awarded Rectors award (2009)