Physics of Complex Systems


Gregory Falkovich, Head (until August 2010)


Nir Davidson, Head (from September 2010)
The Peter and Carola Kleeman Professorial Chair of Optical Sciences

Elisha Moses is an experimentalist studying Neuro-Physics:
We are interested in experimental investigation of physical aspects in the brain. At present we are pursing three main directions. Information flow. We construct living linear neural networks under our microscope that allow us to follow precisely the propagation of information along a biological Shannon-like information channel. Both one-dimensional and two-dimensional hippocampal cultures are studied using both optical and electric detection. Using a novel application of percolation theory, we obtain quantitative biological information about the connectivity of the living neural network. Interaction of neurons with electromagnetism. We stimulate neurons using a non-invasive method, both in human brains and in cultured dishes, by applying a strong and short magnetic pulse. Applications to synchrony in the brain and the study of aspects of Schizophrenia offer a fascinating perspective.

Joel Stavans' group is currently engaged in studies of the interaction of proteins and DNA using single-molecule techniques, and the behavior of genetic networks in bacterial cells. Research on protein-DNA interactions is currently focused on fidelity in RNA interference. These studies are conducted using a variety of fluorescence techniques including fluorescence resonance energy transfer (FRET), and fluorescence anisotropy, at the ensemble and single-pair level. The group is also characterizing and modelling the properties of the dynamical response of small genetic networks in bacterial cells, in both large populations and single cells. Experiments are currently being carried out on (a) development of bacterial multicellular organisms, and (b) small RNA-controlled networks.

Victor Steinberg's group is studying dynamics of various single flexible micro-objects and hydrodynamics of their solutions and suspensions. This year the following projects are under investigation: (i) Properties of elastic turbulence and mixing in polymer solutions with polymer concentrations from dilute till concentrated regimes; (ii) Single polymer dynamics and conformations in elastic turbulence and molecular stress sensor; (iii) Convective turbulence in SF6 near its gas-liquid critical point; (iv) Turbulent drag reduction in swirling flow due to addition of polymers; (v) Dynamics of a vesicle in shear, mixed and elongation flows (vi)Hydrodynamics and rheology of vesicle suspension; (vii) Development of technology of capsule production and dynamics of a single capsule in a general flow: (viii) Dynamics of a single Red Blood Cell in a general flow.

Eytan Domany's research turned in the last years towards problems in Biology and Bioinformatics, with emphasis on development and application of methods for the visualization and analysis of data from high thoughput experiments. Computers play a central role in nearly all aspects of the group's work. Clustering, sorting and a variety of other statistical methods are used to study biological data such as gene expression, DNA copy number, micro RNA etc, coming from various experimental platforms. We collaborate with several Weizmann research groups from the Life Sciences, as well as with laboratories at other Israeli institutions and hospitals, and also with groups from the US and Europe. Our main focus is on cancer, but we are open to other problem areas as well. Our activities range from rigorous mathematical work, through development of novel computational tools, their algorithmic implementation and application to analyze data obtained by our collaborating labs. A certain level of activity in Statistical Mechanics is maintained; for example, the structure of RNA and its binding to micro RNA are studied.

Gregory Falkovich studies systems far from equilibrium, in particular, turbulence. His main interest on a fundamental side is in symmetries. He studies anomalies i.e. breakdown of symmetries that do not disappear when symmetry-breaking factor goes to zero. With collaborators in France and Italy, he discovered new emerging symmetries like conformal invariance in inverse turbulent cascades and now tries to incorporate this in turbulence theory. He also studies interplay between nonlinearity and randomness in the systems of fluid-mechanical type. Another direction of work is on spectral condensates that appear in inverse cascades and condensate-turbulence interaction.

David Mukamel's group is active in the general area of statistical physics, with particular emphasis on (a) collective properties of systems driven out of thermal equilibrium, (b) thermodynamic and dynamical properties of systems with long-range interactions in equilibrium, and (c) statistical properties of biopolymers. Some similarities between non equilibrium systems and those with long-range interactions are being explored, and denaturation phenomena in DNA molecules are studied.

In Uzy Smilansky's group, research on Quantum Chaos evolves around the following topics: Quantum graphs - spectral statistics, scattering and trace formulae. The morphology of nodal lines of billiards wave functions and the number of nodal domains are investigated, with two aims: To establish a criterion of quantum chaos, and to determine the extent by which knowledge of the nodal set determines the billiard shape. We have still some interest in the following subjects: Conditions for hyperbolicity for billiards on surfaces with constant curvatures. Quantization of billiards in homogeneous magnetic fields, and the density of exterior and interior edge states. The classical and quantum spectral duality.

Nir Davidson's group develops new techniques for laser cooling and trapping of neutral atoms. They are studying ultra cold and dense atomic ensembles that have very long atomic coherenece times for quantum memories and single photon nonlinear optics. They are also conducting experiments in a Bose-Einstein condensate including measurements of its zero-temperature excitation spectra its ground state properties and its coherence. The group is also studying phase locking of large laser arrays both for practical high power application and for simulation of spin systems in condensed matter spin and dynamical networks.

Asher A. Friesem is participating in basic investigations on the resonance behavior of grating-waveguide structures and on phase locking, combining and synchronization of many lasers for a variety of applications.

Yaron Silberberg and his group are studying ultrafast, nonlinear and quantum optics. Using femtosecond optical pulses, they study how the shape of these pulses affects the interaction between the light and atoms or molecules. In particular, the group investigates how shaped pulses can be used in nonlinear laser spectroscopy and microscopy. Novel microscopy is also a drive in another area of research of the group, where the quantum properties of light are investigated with the goal of improving the limits of optical imaging. Finally, the group also studies the propagation of light in periodic media, using it as a model system that can explain phenomena in condense matter and atomic physics.

Adam Schwimmer continued to study various aspects of Quantum Field Theory and String theory and their interrelation. In particular the group studied the relation between Conformal Field Theories appearing on the boundary of AdS type space-times and the String Theory description in the bulk. The role played by the stringy Solitons ("D-branes") in holographic theories was elucidated.

Tsvi Tlusty and his group deal with modeling living information systems, their molecular components and the way they evolve. A central question in this field is the impact of the inherent molecular recognition noise on the design of information channels. We examine this question in the contexts of the genetic code and the transcription regulatory network (with Uri Alon). Currently we use this approach to look into the problem of chromosome organization and its relation to gene expression. On a microscopic scale, we examine the actual physical forces that act during molecular recognition and suggest that the structure of certain bio-recognizers has evolved to optimize the quality of detection. Another aspect of molecular recognition that we study concerns the function of strongly selected proteins, such as Rubsico, the enzyme that facilitates photosynthesis. Other research activities include modeling 2D neural networks in terms of percolating random graphs (with Elisha Moses) and the theory of particle-laden microfluidic flow (with Roy Bar-Ziv).

Dan Oron and his group are studying nonlinear dynamics in nanocrystals using ultrafast time-resolved techniques as well as quasi-continuous-wave energy- and frequency- resolved methods. Much of the research effort is aimed towards utilizing the unique resonant properties of semiconducting and metallic nanoparticles towards applications as nonbleaching contrast agents in bioimaging. The group also studies the fundamental aspects of exciton-exciton interactions in multicomponent semiconductor quantum dots and in doped quantum dots. In this context, possible applications in optical gain devices and in photovoltaics are explored.

Roee Ozeri's group uses laser cooled and trapped ions for quantum information, quantum optics and quantum metrology experimental studies. In one project we focus on the quantum information aspects of ion-photon interactions. The coupling of an ion-qubit to the elecro-magnetic vacuum through spontaneous photon scattering is studied as a generic model for quantum noise. The decoherence induced as well as active methods to correct for it through quantum feedback are explored. In a second project we are using trapped-ions as highly sensitive local probes of a quantum-degenerate gas of neutral atoms. In particular we are interested in measuring forces that are mediated between trapped ions via a quantum degenerate gas.

Nirit Dudovich's group studies basic phenomena in strong field light-matter interactions. In particular, the group focuses on the generation and measurement of attoseconds pulses (1 attosecond is 10-18 seconds). The advent of time resolved measurements with attosecond resolution opens new fields in which the observation of fast electronic dynamics can be attained. The group develops new approaches to observe highly nonlinear interactions and to manipulate their evolution in time and space.

Ofer Feinerman's group studies the collective behavior of ants. Experimental tools are developed to allow the observation and manipulation of ants on all relevant scales from the individual to the whole colony. These novel tools are then used to address questions regarding information flow through the ant colony as it performs specific behaviors. On the larger scale, we measure colony reactions, as well as their functional consequences, in the face of shifting environmental conditions. We then relate these measurements to, smaller scale processes that involve the integration of fragmented information collected by individual ants via an interaction network.

http://www.weizmann.ac.il/complex/

Research Staff, Visitors and Students

Professors

Nir Davidson, Ph.D., Weizmann Institute of Science, Rehovot, Israel
       The Peter and Carola Kleeman Professorial Chair of Optical Sciences
Eytan Domany, Ph.D., Cornell University, Ithaca, United States
       The Henry J. Leir Professorial Professorial Chair
Gregory Falkovich, Ph.D., Novosibirsk State University
Elisha Moses, Ph.D., Weizmann Institute of Science, Rehovot, Israel
David Mukamel, Ph.D., Weizmann Institute of Science, Rehovot, Israel
       The Harold J. and Marion F. Green Professorial Chair
Yaron Silberberg, Ph.D., Weizmann Institute of Science, Rehovot, Israel
       The Harry Weinrebe Professorial Chair of Laser Physics
Joel Stavans, Ph.D., University of Chicago, United States

Professors Emeriti

Asher Friesem, Ph.D., University of Michigan, Ann Arbor, United States
Adam Schwimmer, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Uzy Smilansky, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Victor Steinberg, Ph.D., Laboratory of Critical Phenomena, Moscow, Russian Federation

Senior Scientists

Nirit Dudovich, Ph.D., Weizmann Institute of Science, Rehovot, Israel
       Yigal Allon Fellow
Ofer Feinerman, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Dan Oron, Ph.D., Weizmann Institute of Science, Rehovot, Israel
       Yigal Allon Fellow
Roee Ozeri, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Tsvi Tlusty, Ph.D., Weizmann Institute of Science, Rehovot, Israel
       Center for Complexity Science Fellowship

Assistant Staff Scientists

Barry Bruner, Ph.D., University of Toronto, Ontario, Canada
Rinat Goren, Ph.D., Weizmann Institute of Science, Rehovot, Israel

Engineer

Rostyslav Baron, Ph.D., Institute of Low Temperatures, Kharkov's, Russian Federation

Consultants

Eldad Bettelheim, The Hebrew University of Jerusalem, Jerusalem, Israel
Itzhak Fouxon, Tel Aviv University, Tel-Aviv, Israel
Asher Friesem
Libi Hertzberg
Yariv Kafri, Technion - Israel Institute of Technology, Haifa, Israel
Ido Kanter, Bar-Ilan University, Ramat-Gan, Israel
Eliezer Rabinovici, The Hebrew University of Jerusalem, Jerusalem, Israel
Noam Shental, The Open University, Raanana, Israel
Shira Silberberg
Shmuel Starobinets
Shimon Yankielowicz, Tel Aviv University, Tel-Aviv, Israel
Liu Yonggang (left May 2010)
Norman Zabusky
Or Zuk, MIT, Harvard, USA

Visiting Scientists

Michael Aizenman, Princeton University, NJ, U.S.A.
Rebecca Aron
Myron Bander, University of California at Berkeley, U.S.A.
Andre Barato
Jeremie Bec
Gregory Berkolaiko, Texas A&M University, U.S.A.
Francesca Biagioni
David Biron, University of Chicago, Il, U.S.A.
Samuel Bottani
Margit Burmeister, University of Michigan, U.S.A.
Alssandro Campa
Hui Cao
Christoph Dellago
Julien Deschamps
Jean-Pierre Eckmann, University of Geneva, Switzerland
Martin Einhorn
Venkatesan Guruswani
Tomer Hertz
Jonathan Home
Daniel Kahneman
Eugene Kanzieper
Jorge Kurchan
David Kutasov, University of Chicago, Il, U.S.A.
Vladimir Lebedev, Landau Inst.., Moscow, Russia
Jonathan Levitt
Sergei Lukaschuk, University of Hyderabad, India
Alexandeu Mezincescu, University of Maimi, U.S.A.
Sushil Mujumdar, Tata Inst. of Fund. Rese. Mumbai, India
Nir Navon
David Nelson
Herbert Neuberger
Vladimir Al Osipov
Harald Posch, University of Vienna, Austria
Sidney Redner
Vladimir Rittenberg, University of Bonn, Germany
Assaf Rotem, Harvard University , MA, U.S.A.
Stefano Ruffo, University of Florence, Italy
Tobias Schaetz
Gunter Schuetz, HLRZ, Julich, Germany
Akira Shudo
Neil Smith, University of California at San Diego, CA, U.S.A.
Sander Tans
Jean-Paul Thiery
Vinod Vaikuntanathan
Sergey Vergeles, Landau Inst.., Moscow, Russia
Pedro Vidal
Petr Vorobev, Landau Inst.., Moscow, Russia
Geoffrey West
Jianying Zhou

Postdoctoral Fellows

Itai Afek, Weizmann Institute of Science, Israel
Nir Bar-Gill, Weizmann Institute of Science, Israel
Dipankar Bhattacharyya, University of Calcutta
Michael Gilbert G. Bon, Ecole Polytechnique
Yaron Bromberg, Weizmann Institute of Science, Israel
Barry Dov Bruner, Ph.D., University of Toronto
Raphael Benjamin Chetrite, Ecole Normale Superieur De Lyon
Adi Diner, Ph.D., Weizmann Institute of Science, Israel
Tamar Friedlander, Technion - Israel Institute of Technology, Israel
Nicolas Alexandre Be Galle, University of Lille 1
Shamik Gupta, Tata Institute of Fundamental Research
Yair Horesh, Ph.D., Bar-Ilan University, Israel
Adi Natan, Weizmann Institute of Science, Israel
Fabien Piotet, Ph.D., Bristol University
Vaibhav Shridhar Prabhudesai, Ph.D., Tata Institute of Fundamental Research
Tridib Sadhu, Tata Institute of Fundamental Research, Mumbai
Yonatan Savir, Weizmann Institute of Science, Israel
Gabriel Seiden, Technion - Israel Institute of Technology, Israel
Dov Steiner, Hebrew University of Jerusalem, Israel
Sanjiv Kumar Tiwari, Ph.D., Indian Institute of Technology Kanpur India

Research Students

Itai Afek Eldad Afik
Nitzan Akerman Ido Almog
Amnon AmirAmit Aronovitch
Assaf Avidan Ram Band
Amir Bar Noa Bossel
Yaron Bromberg Or Cohen
Jonathan Coslovsky Yehonatan Dallal
Zvicka Deutsch Yotam Drier
Yehonatan Elon Ittai Fattal
Moti Fridman Yinnon Glickman
Amit Godel Ori Hirschberg
Stella Itzhakov Ori Katz
Shlomi Kotler Yoav Lahini
Adam Lampert Michael Levant
Adam Mani Shiri Nitzan- Meshner
Micha Nixon Idan Oren
Rami Pugatch Oren Raz
Shamir Rosen Yoav Sagi
Yonatan Savir Osip Schwartz
Dror Shafir Michal Sheffer
Asif Sinay Eran Small
Hadas Soifer (Yeger) Shani Stern
Haim Suchowski Asaf Tal
Marija Vucelja Amit Zeisel

Administrator

Israel Gonen