Biological and Soft Matter Physics
Mechanisms of Species Diversity Change in Stressed Environments
Ehud Meron
A transition from a banded vegetation pattern to a spotted pattern induced by a local clear-cut dis
The impacts of environmental changes on species diversity, and thus on ecosystem function and stability, is a central topic of current ecological research. At the landscape scale, where symmetry breaking vegetation patterns appear, a transition from one pattern state to another may take place (Animation). Using a mathematical modeling approach, we developed a theory of plant communities in water limited system, and are currently using it to highlight mechanisms of species diversity change in response to climate changes and disturbances.
Condensed Matter Theory
Nonequillibrium dynamics
Yevgeny Bar Lev
Spreading of density excitation in a two-dimensional Fermi-Hubbard model
While conventionally condendsed matter theory was moslty concerned with equilibrium or stationary states situations, recent theoretical and experimental progress spurred interest in nonequillibrium. In our group we study various situations of nonequillibrium dynamics, such as transport, quenches and external driving.
Condensed Matter Experimental
Mechanical properties on the nm scale
Yishay Manassen
Strain map from Gd islands and Local young modulus of nanoparticles.
The scanning tunneling microscope is a device capable of observing an image with atomic resolution and is capable of observing physical phenomena on the atomic scale. In this study we are interested in the nm scale mechanical properties, normally studied macroscopically, which can vary in different locations on the surface. These properties are the stress and strain tensors, the elastic constants, the surface energy and stress. These values can be measured either using a external perturbation (the STM tip) or internal perturbation (a heteroepitaxial island, chemical reaction).
Astrophysics and Cosmology
Black Holes
Uri Keshet
Stellar trajectories around SgA*, the central black hole of the Milky Way
Black holes play a dual role in physics, both as astronomical objects routinely discovered nowadays in binaries and in galactic centers, and as basic elements in quantum gravity. The presence of a supermassive black hole in the center of our own galaxy is evident from the trajectories of stars around a small region known as SgA* (see movie). We study black holes such as the one hiding in SgA*, and their dense stellar environment.
High-Energy Physics
Cosmology
Ram Brustein
A new class of cosmic inflation models
The early universe is used as a theoretical laboratory for studying fundamental physics, the laws of gravity and quantum mechanical aspects of matter under extreme conditions. We study models of cosmic inflation in the early universe and dark energy in the late universe and their possible realizations in quantum field theory and string theory models. Our recent research focuses on models of high-scale inflation which produce an observable signal of gravitational waves in the cosmic microwave background.
Atomic, Molecular and Optical Physics
Quantum Interferences and Lasing without inversion
Reuben Shuker
Sub-natural-width peak
Quantum-interference-related phenomena have many implications in physics. Quantum interference between two independent quantum channels in three-level systems gives rise to various coherent phenomena, such as electromagnetically induced transparency (EIT), coherent population trapping (CPT), lasing/gain without inversion (LWI/GWI), enhancement of refraction index, sub- and super-luminal light propagation etc. These phenomena open a wide-range perspective for new type of phase-sensitive spectroscopy. An example is the possibility to get sub-natural line widths (see movie).