Atomic, Molecular and Optical Physics
*Tracing and control of electronic motion in atoms, molecules, and nanostructures in space and time (4D). Progress in lightwave electronics. *Table-top XUV and soft X-ray laser-like sources. Nano-scale spatial resolution to optical science of attosecond pulses. *New dynamic imaging modalities – significantly improved spatial/temporal resolution, new contrast imaging for lifescience and nanotechnology. *And much more…
Biological systems show a plethora of fascinating self-organized behaviors that range from organ to cellular levels, such as spiral waves, pulses, synchronization, and steady states that are periodic in space. These non-equilibrium phenomena emerge through either spontaneous or forced symmetry breaking mechanisms. Employing nonlinear dynamics methods, we attempt to understand specific cases (localized waves in the inner ear) as well as gain general insights into the emergence of traveling waves with motivation taken from molecular motors, actin polymerization and cardiac system.
Astrophysics and Cosmology
My astrophysical interests include gamma-ray bursts, cosmic ray origin, high energy astrophysical neutrino sources, and gravitational waves. If gamma-ray bursts and gravitational wave signals happen together, what caused them? Should we expect neutrinos and ultrahigh energy cosmic rays as well? I also think about the foundations of quantum mechanics. Why quantum mechanics? Is there a way to understand what the wave function really means? Is gravity a necessary consequence of quantum mechanics? Why is gravity so much weaker than electromagnetism?
Condensed Matter Theory
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.
Biological and Soft Matter Physics
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.
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.
Condensed Matter Experimental
In the STM image shown, observed in our lab, we see some disordered white spots. The STM does not have chemical identification capability. Such chemical identification is observed macroscopically using macroscopic magnetic resonance – both of electrons and nuclei. We develop a magnetic resonance technique on the single atom level, observed via a Larmor frequency component in the tunneling current. We identify the type of atoms under the tip using their spectrum – for example the SiC hyperfine spectrum. Preliminary results showed the observation of the nuclear transitions (NMR) with the STM.