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
The largest objects: galaxy clusters
Uri Keshet
The Perseus cluster core (Chandra) with highlighted spiral cold fronts and X-ray cavities.
Galaxy clusters, as the largest virialized objects ever to form in the Universe, link cosmology and astrophysics. These 'island-universe' objects are mainly composed of dark matter and a hot, dilute plasma. Their stability is an open question, as the strong X-ray emission should have naively led to catastrophic cooling and collapse. Over the past decade, mysterious spiral structures were found in practically all clusters. They may be driven by the giant black hole lurking in the center of every cluster, for example through the relativistically hot bubbles it injects into the plasma (figure).
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).
Biological and Soft Matter Physics
Single Cell Dynamics
Mario Feingold
During the lifetime of a bacterium it elongates linearly in three distinct regimes.
We use single cell phase-contrast and fluorescence time-lapse microscopy to monitor morphological changes during the division of E. coli. To bypass the limitations of optical resolution, we process the images using pixel intensity values for edge detection. We study the dynamics of the constriction width, W, and find that its formation starts shortly after birth much earlier than can be detected by simply viewing phase-contrast images. A simple geometrical model is shown to reproduce the behavior of W(t). Moreover, the time-dependence of the cell length, L(t), consists of three linear regimes.
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.
Condensed Matter Theory
Disordered Systems
Yevgeny Bar Lev
Characterization of the anomalous ergodic phase, leaves many questions open.
Disorder allows avoiding thermalization and defy conventional statistical mechanics, through the mechanisms of Anderson or many-body localization. We study these ergodicity breaking mechanisms in detail. In particular the nature of transport and correlations spreading in systems on the verge of localization.