Astrophysics and Cosmology
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.
Condensed Matter Experimental
To many physicist the subject of fluctuations appears esoteric and even pointless; spontaneous fluctuations seem nothing but an unwanted evil which only an unwise experimenter would encounter. In reality, noise enables a deep insight into physics of the system. Recently, we have employed noise to discriminate various resistivity states in the ferromagnetic insulating manganite La0.86Ca0.14MnO3. Different states arise due to transitions between local minima of the electronic glass potential landscape. Remarkably, freezing into the glass state is marked by the onset of non-Gaussian noise.
Condensed Matter Theory
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.
Biological and Soft Matter Physics
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.
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.
Atomic, Molecular and Optical Physics
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).