I am an external collaborator of the eROSITA science team. It is an X-ray instrument built by the MPE in Germany. It was successfully launched in July 2019. eROSITA will map the entire sky in X-ray band and it will be 25 times more sensitive than the previous ROSAT All Sky Survey. 

Visit https://zoom.us/my/jac1604 to watch live. 

Physicists should take an active role in explaining science to the general public. As an example, I will explain why I think nuclear power is (still) a good idea.

 

Refreshments will be served in CP 179 at 3:15 PM

Abstract: Quantum Field Theory is a universal language to describe a multitude of physical phenomena from elementary particle and condensed matter physics. Often apparent complexity of the described phenomena is attributed to strong coupling in the underlying QFT. Accordingly, understanding strongly-coupled dynamics became a universal theoretical challenge relevant for many areas of contemporary physics. Remarkably, the past decade was characterized by an accelerated development of several original approaches to this problem, leading to a plethora of new results. In my talk I will focus on several non-pertubative methods, most notably holographic correspondence, and describe recent progress and hot research topics. Refreshments will be served in CP 179 at 3:15 PM

A single sheet of sp^2-hybridized carbon atoms, called Graphene, is presently one of the most widely studied materials in the scientific community. Following a bried introduction of Graphene and its unique properties, I will present evidence for the amplification of surface plasmon coupled emission (SPCE) from Graphene-Ag hybrid films. SPCE is a novel analytical technique in which the isotropic emission of a fluorophore is combined with the surface plasma resonance of a Ag (or Au) think film to yield highly directional emission from the so-called plasmaphore, and thus greatly increased sensitivity. In another project, we harnessed the nonlinear optical properties of Graphene in conjunction with those of C_60 to fabricate an all-optical analog of a diode. Our all-carbon optical diode, built from a Graphene and C_60 sandwiched structure, is passive, polarization independent and most importantly has no phase-matching constraints. Evidence for tunable nonreciprocity factor and potentially large bandwidth capability with be presented. This work was done in collaboration with team members from Clemson University, USA (M. Karakaya, R. Podila, K. Lingam), Sri Sathya Sai Institute of Higher Learning, India (P. Mulpur, B. Anand, R. S. Satish) and Raman Research Institute, India (R. Philip).

 

Refreshments will be served in CP 179 at 3:15 PM

The space we live in -- the space measured in miles, kilometers and parsecs -- has an internal structure of its own. Surprisingly, this structure is intimately related to quantum information theory, a field at the intersection of physics and computer science. To understand this connection, I exploit the holographic duality: an alternative description of the world as a gigantic hologram, which can be deduced from careful reasoning about the physics of black holes. The final conclusion is that the fabric of space encodes streaming compression protocols analogous to the one used by Netflix. Consequences of this assertion range from condensed matter physics to the most fundamental ways in which we conceptualize space and time.

 

Refreshments will be served in CP 179 at 3:15 PM

A revision of our system of units, the SI, is currently discussed and may be implemented as early as 2018. The new SI is a logical extension of an argument made in 1983 when the meter was redefined to be based on the exact value of the speed of light. In the new SI all units will be derived from seven fundamental reference constants, thus replacing the seven base units of the current system.

For example, the unit of mass, the kilogram, is currently defined by an artifact called the International Prototype of the Kilogram (IPK). In the future we will be able to realize the unit of mass, not just at the kilogram level, from a fixed value of the Planck constant, which has units of kg m^2/s.

One condition for redefinition is agreement between different measurements of the Planck constant.  Currently two measurement strategies lead to values with relative uncertainties less than 100 parts per billion (ppb): (1) Avogadro’s number can be determined by estimating the number of atoms in a well characterized crystal. From Avogadro’s number h can be calculated using the Rydberg constant, which is known with much smaller uncertainty (2) A watt balance can be used to measure mechanical power in units of electrical power. Electrical power can be measured as the product of the Planck constant and two frequencies by utilizing the Josephson effect and the Quantum Hall effect. NIST has carried out measurements of h with watt balances for over 20 years. In 2012/13 a new team has performed a largely independent determination of h. I will describe this measurement and measurements from other laboratories.

Refreshments will be served in CP 179 at 3:15 PM