• Physics
  • INDIAN INSTITUTE OF TECHNOLOGY KANPUR

Colloquium 2015

 

 

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 Professor Amalendu Chandra
Department of Chemistry, Indian Institute of Technology Kanpur
Hybrid Quantum-Classical Studies of an Enzymatic Reaction in Aqueous Solution
1st January, 2016
2.30 pm
FB-382                                                                                                                                                                                                  Transaminase is an enzyme which reversibly catalyzes the transamination reaction. Aspartate Transaminase (AspTase) is a key enzyme of amino acid metabolism process. In the present talk, we will discuss our recent studies on the mechanism of the transamination reaction in the active site of AspTase using hybrid quantum-classical molecular dynamics simulation with the aid of metadynamics technique.
 
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 Professor Abhijit Mookerjee
S.N. Bose National Center for Basic Sciences, Kolkata
DEALING WITH DISORDER
6th November, 2015 (Friday).
4 pm
FB-382                                                                                                                                                                                                   In the world of real materials disorder is ubiquitous.Nevertheless, condensed matter theoreticians still find it difficult to
ditch the Bloch bandwagon : periodicity, plane waves, crystallinity - the lot. We shall declare with Heine "Let us throw k-space out of the window"(Lectures in Physics, vol 35, Academic Press)  and face the consequences.The lecture will focus on the last aspect.
 
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 Professor Sukanta Bose
The Inter-University Centre for Astronomy and Astrophysics, Pune, India
Gravitational waves and the neutron star equation of state
29th October, 2015 (Thursday)
4 pm
FB-382                                                                                                                                                                                                   The two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) began observation runs a few weeks ago. A few other detectors in the world, possibly including one in India, called LIGO-India, are expected to join them in the coming years to usher in the era of gravitational wave (GW) astronomy. Such a multi-baseline network will be able to localize GW transients, e.g., the merger of neutron star binaries, that it detects to within a few to tens of square-degrees. This presents both an opportunity and a challenge to other observatories that are in pursuit of their electromagnetic (EM) and particle counterparts, e.g., in the form of afterglows. The opportunity is to develop a more complete understanding of these sources. To wit, are short duration gamma-ray bursts and kilonovae indeed associated with the merger of binaries involving neutron stars? On the other hand, the challenge is to be able to scan the large error boxes in the sky of GW networks in an ingenious way so as not to miss observing an EM counterpart. After describing the general aspects of what is clearly a multi-messenger endeavor, I will discuss how Indian telescopes can contribute to this effort. I will also discuss how GW observations of neutron stars can improve our understanding of nuclear interactions in ways that complement the knowledge acquired from terrestrial labs.
 
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 Professor Amit Agarwal 
Indian Institute of Technology, Kanpur
Collective spin and density excitations (plasmons) in 2 dimensional electron gas, and Dirac systems (such a graphene)
16th October, 2015 (Friday)
4 pm
FB-382                                                                                                                                                                                                   In this talk we will discuss some of our recent works related to collective spin and density excitations, beginning with our prediction of a new long lived collective spin mode in a two dimensional electron gas. This new spin mode arises as a consequence of the interplay between spin polarization and electron electron interactions, and can be used as a interconnect between spin-torque oscillators. Further we study charge-plasmons in spin polarized graphene, and propose a new way to measure spin polarization. We derive explicit expressions for the plasmon dispersion in the undamped regime. From this, we are able to calculate the critical wave vector beyond which the plasmon enters the electron-hole continuum, its quality factor decreasing sharply. We find that the value of the critical wave vector is strongly spin polarization-dependent, in a way that has no analogue in ordinary two-dimensional electron gases. We show that the effect is robust with respect to the inclusion of disorder and we suggest that it can be exploited to experimentally determine the spin polarization of graphene. Additionally we will also discuss the collective density oscillations of a collection of charged massive Dirac particles, in one, two and three dimensions and their one dimensional superlattice. Our analytical results will be useful for exploring the use of massive Dirac materials as electrostatically tunable plasmonic metamaterials and can be experimentally verified by infrared spectroscopy as in the case of graphene.
 
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 Professor Srubabati Goswami
Physical Research Laboratory, Ahmedabad
Neutrinos: The Invisible Messengers
9th October, 2015
4 pm
FB-382                                                                                                                                                                                                   Neutrinos are all pervading yet elusive. Since its discovery the question which has puzzled physicists is whether they have mass or not. Finally, the observation of neutrino oscillations in terrestrial experiments established that the neutrinos indeed have small but non-zero mass. In this talk I will discuss the salient features of neutrino oscillations, the current status of the oscillation parameters and the present unknowns. I will mention some of the future experiments that can determine these unknown parameters giving special emphasis on the India-based Neutrino Observatory (INO) experiment. I will also discuss some of the implications of small neutrino masses in terms of probing physics beyond the Standard Model.
 
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 Professor Arvind Ayyer
Indian Institute of Science, Bangalore
Two Species Semipermeable Exclusion Processes
11th September, 2015
4 pm
FB-382                                                                                                                                                                                                   One of the primary motivations of nonequilibrium statistical physics is the study of systems connected to reservoirs at different temperatures. In that context, exact solutions of model systems lend insight into the behaviour of real systems. In joint works with E. R. Speer and J. L. Lebowitz, we study and solve exactly one particular model system. We consider two-species variants of the totally asymmetric simple exclusion process (TASEP) on an interval connected to reservoirs. Most of the time will be spent discussing an "integrable" variant in which second-class particles are not allowed to leave. In this case, we can both prove and understand the nonequilibrium steady state and phase diagram in great detail. Time permitting, we will consider other variants which permit exact analysis.
 
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 Professor Pankaj Jain
Department of Physics, Indian Institute of Technology Kanpur
Large Scale Anisotropy in the Universe
4th September, 2015
4 pm
FB-382                                                                                                                                                                                                   The cosmological principle states that the Universe is homogeneous and isotropic on large distance scales. However I will argue that the Big Bang paradigm is consistent with small deviations from this principle. At very early times the Universe need not be isotropic and homogeneous. It acquires this property during the inflationary phase of its expansion. The early anisotropic and inhomogeneous phase can affect observations today, leading to a violation of the cosmological principle. These may provide an explanation for a diverse set of observations that indicate a deviation from the standard expectations of the Big Bang model. These include anisotropy in radio polarization, radio flux, optical polarizations, CMBR large scale anisotropies as well as the hemispherical anisotropy in CMBR. Curiously many of these observation indicate a preferred direction pointing roughly in the direction of the Virgo cluster. I will review these observations and the theoretical models which aim to explain them.
 
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 Professor Dibyendu Das
Indian Institute of technology Bombay
Can spatial order and disorder coexist? Case studies of Porod law violation in non-equilibrium systems.
28th August, 2015
4 pm
FB-382                                                                                                                                                                                                     Although seemingly strange, in many non-equilibrium systems large scale spatial ordering may often coexist with large scale fluctuations. Thus they are neither cleanly ordered nor disordered in the conventional sense. This is in contrast to coarsening systems approaching equilibrium steady states, which usually exhibit growth of clean order, marked by a universal characteristic form of the scaled structure function called the Porod law.  In the talk, many systems exhibiting Porod law violation would be discussed. The connection of this violation to the underlying fractal-like spatial density structure would be sketched.
 
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 Professor Avinash Khare
Department of Physics and Astrophysics, University of Delhi, Delhi
A model for the dust cluster explosion
21st August, 2015
4 pm
FB-382                                                                                                                                                                                                      A model for the dust cluster explosion where micron/sub-micron sized particles are accelerated at the expense of plasma thermal energy, in the afterglow phase of a complex plasma discharge is proposed. The model is tested by MD simulations of dust particles in a confining potential. The nature of the explosion (caused by switching off the discharge) and the concomitant dust acceleration is found to depend critically on the pressure of the back ground neutral gas. At low gas pressure, the explosion is due to unshielded Coulomb repulsion between dust particles and yields maximum acceleration while in the high pressure regime it is due to shielded Yukawa repulsion and yields much feebler acceleration. These results are in agreement with recent experimental findings
 
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 Professor Pratap Raychaudhuri
Tata Institute of Fundamental Research, Mumbai
Real space investigations of the order-disorder transition of the vortex                                                                                                    lattice using scanning tunneling spectroscopy
14th August, 2015
4 pm
FB-382                                                                                                                                                                                                     In an ideal Type II superconductor the magnetic flux which enters in the form of quantized flux tubes get arranged in a period fashion through mutual interactions, thereby mimicking a soft periodic solid.  However, in real superconductors the perfect periodic order of the flux line lattice is interrupted by structural defects in the crystal, which provide an additional disordered background potential for the flux tubes. The flux line lattice in a Type II superconductor thus provides a versatile model system to study the interplay between interactions and random pinning. In this talk, I will describe our recent investigations on the order-disorder transition of the flux line lattice, using direct imaging through low temperature scanning tunneling spectroscopy. Through simultaneous imaging of the flux line lattice and the crystal lattice, I will show that the order-disorder transition is strongly influenced their mutual coupling which reinforces the orientational order of the flux line lattice. In addition, I will show the existence of several metastable states, which can be accessed through different magneto-thermal cycling.                                                                                                                                                                                                    
 
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 Professor Mahendra K. Verma                                                                                                                                                            Indian Institute of Technology Kanpur                                                                                                                                           Dynamics vs. Thermodynamics: Who is the winner?                                                                                                                                   7th August, 2015                                                                                                                                                                                     4 pm                                                                                                                                                                                  FB-382                                                                                                                                                                                          Dynamics and Thermodynamics are two pillars of physics; both are used to describe the nature.  In this talk, we will contrast the assumptions of these two fields, specially for phase transitions. We will show how bifurcation theory with a small number of variables can describe the hysteresis and phase coexistence suitably.  Dynamics provides insights into how initial condition could play a major role in the system’s final state.
 
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Venue: 		 Professor  Biswarup Mukhopadhyay
Harish Chandra Research Institute, Allahabad, India
The Messiah of Mass and Message about More
31 July 2015 (Friday)
4 pm
FB-382
 
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Venue:		 Brajesh Kumar Mani
University of South Florida (USF), Tampa, USA
Many-body methods and physics of atomic and many-atomic system
17 April 2015 (Friday)
4 pm
FB-382
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Venue:		 Gagan Kumar
IIT Guwahati
Terahertz Photonics
10 April 2015 (Friday)
4 pm
FB-382
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Venue:		 Dr. R. Prabhu
HRI, Allahabad
Quantum communication networks
7th April, 2015 (Tuesday)
12 noon
FB-382
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Venue:		 Manoj K. Harbola
Department of Physics, IIT Kanpur
Excited-state energy functionals and ionization potential theorem
27 March 2015 (Friday)
4 pm
FB-382
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Venue:		 Prof. J. S. Yadav
Large Area X-ray Proportional Counter (LAXPC) instrument onboard
ASTROSAT
26 March, 2015 (Thursday)
4 pm
FB-382
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Venue:		 P. Viswanath
Centre for Nano and Soft Matter Sciences, Bangalore
Dynamics of liquid crystalline drops at air-water interface
20 March 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Justin David
Indian Institute of Science, Bangalore
Entanglement entropy and Holography
13 March 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Sunil K. Gupta
Precision measurements in Astroparticle Physics using state- of-the-art technology in GRAPES-3 experiment
Entanglement entropy and Holography
09 March 2015 (Monday)
4.00 pm
FB-382
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Venue:		 Gautam Sengupta
Department of Physics, IIT Kanpur
Space time Holography, Black Holes and Superconductors
27 Feb. 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Shashikant Dugad
Tata Institute of Fundamental Research, Mumbai
Searches for Fundamental Particles: An experimental overview
13 Feb. 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Joydeep Chakrabortty
Department of Physics, Indian Institute of Technology Kanpur
Looking at Particles through a Giant's eye.
10 Feb. 2015 (Tuesday)
4.00 pm
FB-382
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Venue:		 Arvind
Indian Institute of Science Education and Research, Mohali
Quantum entanglement: A central theme in quantum information processing
06 Feb. 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Ujjwal Sen
Harishchandra Research Institute, Allahabad
Strong Subadditivity in Quantum Information
30 Jan. 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Srihari Keshavamurthy
Department of Chemistry, Indian Institute of Technology Kanpur
Eigenstate Thermalization Hypothesis and Intramolecular
Vibrational Energy Flow - connecting two different "worlds"
23 Jan. 2015 (Friday)
4.00 pm
FB-382
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Venue:		 Sankalpa Ghosh
Indian Institute of Technology Delhi
Ultracold atoms in Synthetic Gauge field in an optical cavity
16 Jan. 2015 (Monday)
4.00 pm
FB-382
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Venue:		 Avinash Deshpande
Raman Research Institute, Bangalore
Fascinating Life-stories of Pulsars
09 Jan. 2015 (Monday)
4.00 pm
FB-382