High-Energy Physics
Quantum gravity & quantum black holes
Ram Brustein
Quantum black hole swallows matter and evaporates quantum mechanically
Are Einstein's equations and general relativity compatible with quantum mechanics? In spite of intense efforts over the last 40 years by some of the best physicists we still do not know the answer . I study the properties of black holes and other space-times with horizons to probe the laws of quantum gravity. Based on our recent research, our proposed answer is: Yes. The apparent incompatibilities between general relativity and quantum mechanics originate from the extreme approximation of treating spacetime as a strictly classical geometric object.
Astrophysics and Cosmology
Virial shocks
Uri Keshet
In the hierarchical paradigm of large-scale structure formation, galaxy clusters are the largest objects ever to virialize. These island universes are thought to grow by accreting mass through surrounding large scale, strong yet elusive, virial shocks. A combination of analytical, numerical, and observational techniques has recently led us to the first detections of these shocks, thus providing new routes for studying large-scale structure, tracing the cosmic-web, constraining shock physics, and probing dark matter and dark energy.
Condensed Matter Theory
Non-equilibrium steady state of low-dimensional systems
Doron Cohen
It is possible to induce non-equilibrium steady state current, which required e.g. a radiation source. We have studied the non-monotonic dependence of the current on the intensity of the driving, and its statistical properties. We also have addressed questions that concern the relaxation of such current, and how it depends on percolation and localization properties of the model.
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).
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.
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).