Upcoming Seminar

  • Title of the talk: "Investigation of magnetized accretion flow properties around a black hole and prospects with Astrosat"
    Speaker: Dr. Biplob Sarkar, The ICFAI University, Tripura
    Date & Time: 22 April 2019, 04:00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk: Click here for the abstruct.

Past Seminar

  • Title of the talk: "Likely lurking lights?"
    Speaker: Prof. Biswarup Mukhopadhyaya, HRI, Allahabad
    Date & Time: 05 April 2019, 04:00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    The possibility of light scalars evading our notice for example, in two Higgs doublet scenarios will be discussed, along with some of their implications.

  • Title of the talk: "The quantum fate of black hole horizons"
    Speaker: Dr. Debajyoti Sarkar, Albert Einstein Center (AEC) for Fundamental Physics, Universität Bern
    Date & Time: 26 Feb 2019, 04:30 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    I will discuss the possibility that in the semi-classical gravitational theory the black hole horizon is non-perturbatively replaced by a wormhole, whose parameters make it a perfect mimicker of a classical black hole. Based on work with Clément Berthiere and Sergey Solodukhin (PLB 786 (2018), 21-27; arXiv 1712.09914 [hep-th]).

  • Title of the talk: "Ab initio design strategies for functional materials: Role of temperature-dependent excitations"
    Speaker: Dr. Biswanath Dutta, Post Doc at Delft University of Technology
    Date & Time: 19 Feb 2019, 05:15 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

  • Title of the talk: "Hydrogen-carbide interactions in steels: Ab-initio combined with experiment"
    Speaker: Dr. Poulumi Dey, Assistant Professor at Delft University of Technology
    Date & Time: 19 Feb 2019, 04:00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk: Click here for the abstruct.

  • Title of the talk: "Emergent Phenomena in Quantum Materials​"
    Speaker: Dr. Sreementa Mitra, Post Doc at IISc Bangalore
    Date & Time: 18 Feb 2019, 05:20 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk: Click here for the abstruct.

  • Title of the talk: "Status of neutrino mass-mixing parameters"
    Speaker: Dr. Francesco Capozzi, Max Planck for Physics, Munich, Germany
    Date & Time: 06 Feb, 2019, 04.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

  • Title of the talk: "What does the future bring? A look at high temperature superconducting technology for commercial applications in near future"
    Speaker: Dr. Devendra K Namburi, Cambridge University
    Date & Time: 07 Jan, 2019, 03.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk: Click here for the abstruct

  • Title of the talk: "Emergence of Complex Topology in Oxide Heterostructure"
    Speaker: Dr. Sujit Das, Department of Materials Science & Engineering, University of California, Berkeley, CA 94720, USA
    Date & Time: 17 Jan, 2019, 04.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    Complex topological configurations are a fertile arena to explore novel emergent phenomena and exotic phases in condensed-matter physics. For example, the recent discovery of polarization vortices and the associated complex-phase coexistence and response under applied fields in superlattices of (PbTiO3)n/(SrTiO3)n suggests the presence of a complex, multi-dimensional system capable of exotic physical responses1,2,3,4. Here, by varying epitaxial constraints we report the discovery of room-temperature polar skyrmions in a lead-titanate layer confined by strontium-titanate layers, imaged by atomic-resolution scanning transmission electron microscopy5. Phase-field modeling and second-principles calculations reveal that the polar skyrmions have a skyrmion number of +1, and resonant soft X-ray diffraction experiments show circular dichroism confirming chirality. Such nanometer-scale polar skyrmions are the electric analogs of magnetic skyrmions, and could advance ferroelectrics towards new levels of functionality. Also, it has been observed the negative capacitance region in this nanometer scale objects6,7 and phenomenon could be controlled by electric field and temperature. Such phenomena could advance ferroelectrics towards new levels of functionality.

  • Title of the talk: "Optical Tweezer Phonon Laser"
    Speaker: Prof. Mishkatul Bhattacharya, Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
    Date & Time: 04 Jan, 2019, 04.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    We theoretically propose and experimentally realize a phonon laser using an optically levitated nanoparticle. In our system, mechanical gain and nonlinearity are supplied optically. We present theoretical evidence for stimulated emission of phonons, and experimental observations of i) threshold behavior as a function of gain, ii) the transition in phonon statistics from Boltzmann to Poisson across the threshold, and iii) subthermal phonon number squeezing far above threshold. The experimental data agrees well with our microscopic quantum mechanical theory. Our work represents a substantial advance in the generation of coherent phonons in levitated systems and can be readily extended to other physical platforms.

  • Title of the talk: "First-principle study of thermal conductivity of DX centers in GaAs"
    Speaker: Dr. Ashish Kundu, Projectass, TU Wien, Vienna, Austria
    Date & Time: 03 Jan, 2019, 10.00 am
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    The lattice thermal conductivity is a dominant mechanism over a wide range of carrier concentrations in several III-V semiconductors. The manipulation and control of the lattice thermal conductivity have impacted an enormous variety of technical applications. We study the influence of DX centers (deep-level defect) formed by SAs, SeAs and TeAs impurities in GaAs, on the lattice thermal conductivity from first principles. We find that DX centers lead to a substantial reduction of the lattice thermal conductivity for all considered impurities. This reduction is due to enhanced phonon scattering rates caused by the lattice distortion. Further decrease of thermal conductivity is found for few DX centers due to resonance phonon scattering.

  • Title of the talk: "E(6) inspired U(1)' extension of MSSM: from Dark Matter to LHC"
    Speaker: Prof. Mariana Frank, Concordia University, Montreal, Canada
    Date & Time: 11 December, 2018, 04.30 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    I review briefly the motivation for supersymmetry, and for extending the gauge symmetry by an extra U(1), consistent with symmetry breaking from E6 SUSY GUT. Imposing universality conditions from the GUT scale, and using experimental constraints, I perform a scan of the parameters of the model. Both the right-handed sneutrino and the lightest neutralino can serve as DM candidates. Constraints from cosmic abundance and direct detection restrict the parameter space in each case. Finally, I discuss the possibility of observing signals of such models at the LHC. In particular, chargino pair production leading to 2 leptons and missing energy can yield significant signal to background enhancements.

  • Title of the talk: "Effective Field Theory -- Why and How ?"
    Speaker: Dr. Joydeep Chakrabortty, Associate Professor, Department of Physics, IIT Kanpur
    Date & Time: 22 December, 2018, 11.00 am
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    The present era of particle physics is a "Curious case of Beyond the Standard Model (BSM) physics". Effective Field Theory (EFT) could be pragmatic approach to understand BSM, if any. But EFT is more than that. It can be used as a field theoretic tool to understand physics of different scales. In this talk I will try to explain how one can use the the EFT as a tool to bridge the physics of different scales in the language of functional methods. In this context I will talk about the working principle of our EFT code "CoDEx". I will also discuss the future directions of the formal aspects of EFT that we are interested in.

  • Title of the talk: "Lattice matrix elements for new physics searches"
    Speaker: Prof. Amarjit Soni, Brookhaven National Lab, USA
    Date & Time: 03 December, 2018, 10.00 am
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    It is an integral fact that QCD is an integral part of the Standard Model as well as any of its extensions. But in the low energy sector it is highly non-perturbative. The only rigorous method to treat such a theory is the lattice. In this talk, after a very brief introduction of this method, several applications specifically designed to search for new physics will be discussed.

  • Title of the talk: "Light for Information Security"
    Speaker: Dr. Naveen K Nishchal, IIT Patna
    Date & Time: 26 November, 2018, 03.00 pm
    Venue: Seminar Room, Department of Physics, Organised by SPIE IITG Studnet Chapter
    Abstract of the talk:

  • Title of the talk: "Using Cosmic Microwave Background Radiation to probe the Universe"
    Speaker: Prof. T R Seshadri, University of Delhi
    Date & Time: 19 November, 2018, 05.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

  • Title of the talk: "Resonating Group Method - Overview and Applications"
    Speaker: Dr. Vanamali C. Shastry
    Date & Time: 14 November, 2018, 05.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    Resonating Group Method (RGM) is a technique used to study many-body systems. Since its formulation in 1937, such a methodology has been state-of-the-art in studies relating to clustering phenomena in the light nuclei. It has also been extensively used in studying condensed matter systems. In this talk, I plan to discuss the formal aspects of RGM and its applications to nuclear physics.

  • Title of the talk: "Dark Matter: The Particle Perspective"
    Speaker: Dr. Subhaditya Bhattacharya
    Date & Time: 31st October, 2018, 05.15 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

  • Title of the talk: "Understanding the nature of the interstellar dust and organics: A combined approach"
    Speaker: Dr. Isaki SAKON, The University of Tokyo
    Date & Time: 30th October, 2018, 11.30 am
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

  • Title of the talk: "An overview of C-MET's R&D activities and Rare Earth based ceramics and composites for microwave circuit applications"
    Speaker: Dr. Dr. N.R. Munirathnam, Director General, Centre for Materials for Electronics Technology, (C-MET: R&D laboratory under Ministry of Electronics and Information Technology (MeitY), Govt. of India)
    Date & Time: 22nd October, 2018, 04.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    C-MET a scientific R&D laboratory under Ministry of Electronics & IT is working on requirement driven R&D in the fields of Microwave substrates, sensors and actuators, Supercapacitors, purification of metals, wide bandgap compound semiconductors, recycling of electronic waste in environmental friendly manner, extraction of refractory metal like hafnium at pilot plant scale, antennas for NavIC, Li-ion batteries and LTCC packaging. Broadly the areas of R&D status are covered.

    Microwave dielectric materials gained immense importance in wireless applications and many of the high dielectric ceramics are composed of rare earth elements as one of the constituents which in turn help in fine tuning the end properties by judiciously substituting rare earth ions having varying ionic radii. The personal communication devices and other wireless technology industries, such as direct broadcasting, global positioning systems, mobile communication systems etc. have witnessed an explosive and unprecedented growth in applications. The application areas are fast ranging from simple dielectric resonator to complex 3D modules realized through Low Temperature Co-fired Technology. More recently, rare earths based Ultra Low Temperature Co-fired Ceramics (ULTCC) are also finding applications in realizing miniaturised and cost effective devices including Substrate Integrated Waveguide (SIW) circuits. In order to meet these stringent requirements, novel materials with high dielectric constant and low loss tangent are required. High dielectric constant reduces the circuit size since the wavelength travelling through the medium is inversely proportional to the square root of the dielectric constant. On the other hand, extremely low loss tangent improves the signal integrity and avoids cross talks. Cu-cladded rare earth ceramic filled PTFE planar laminates are the ideal choice for high end microwave circuit fabrication which are currently available only from imported sources. Understanding the need for indigenous technology, C-MET has developed a proprietary and patented process methodology comprising of Sigma Mixing, Extrusion, Calendering followed by Hot pressing (SMECH Process) to fabricate dimensionally stable planar and isotropic PTFE/ceramic composite laminates. Pore free and dimensionally stable planar laminates have been prepared by incorporating variety of rare earth titanate ceramics in the PTFE matrix through SMECH process. C-MET has successfully developed wide variety of filled PTFE substrates with dielectric constant ranging from 2.2 to 14.8 together with ultra-low loss tangent ( 0.0018 at 10 GHz) and the technology for the same is already transferred to Industry for commercial production. High power solid state amplifiers have been fabricated by Raja Ramanna Centre for Advanced Technology (RRCAT), Department of Atomic Energy, Indore operating at a centre frequency of 505.8 MHz, which can withstand output power up to 750 kW. Excellent RF performance was obtained in terms of output power, gain and efficiency during system level evaluation and accordingly the high power solid state amplifiers have been successfully deployed in INDUS-2 particle accelerator.

  • Title of the talk: "Nano-fabrication and measurement on Superconducting Quantum Circuit Elements"
    Speaker: Dr. Dibyendu Hazra, Aalto University, Finland
    Date & Time: 11th October, 2018, 11.00 am
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    Superconducting Quantum Circuit elements, the Josephson junctions, in particular, play a pivotal role in the diverse field, like, nano-scale magnetometry and quantum computation using superconducting circuits. In this talk, I shall describe the nano-fabrication and measurements of different types of superconducting quantum circuit elements, particularly, the different avatar of Josephson junctions and superconducting resonators. The detailed nano-fabrication processes, which involved electron beam and photolithography, reactive ion etching, thin film evaporation, to mention only a few, will be spelled out. In this regard, I shall describe a thermal model to explain the origin of hysteresis in nano-bridge quasi-Josephson element and explain how the model, followed by experimental findings, would help us unearthing new phenomena and optimizing device design. I shall, then, present our experimental results on high-impedance kinetic-inductance resonators, quantum-noise-limited microwave amplifier, and microwave single-photon-detector. Finally, I shall touch upon our recent unpublished result on nano-bolometer with record-breaking low noise equivalent power.

  • Title of the talk: "Enhancing quantum correlations in optomechanical systems"
    Speaker: Dr. Subhadeep Chakraborty
    Date & Time: 9th October, 2018, 5.00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    In this talk, we will talk about our theoretical study on the quantum correlations present in an optomechanical system. Under experimentally achievable conditions, we will demonstrate that a significant enhancement of the steady-state entanglement could be achieved at a considerably lower driving power, which is also extremely robust with respect to the system parameters and environmental temperature. We then employ Gaussian quantum discord (QD) as a more genuine measure of the quantumness of the correlation.
    [This work is published in JOSA B, Vol. 34,1503 (2017) and recognised as one of the top downloaded papers of 2018 in the journal.]

  • Title of the talk: "Optical Tweezers"
    Speaker: Prof. Bosanta R. Boruah
    Date & Time: 9th October, 2018, 5:30 pm-5:45 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    The technique/concept that led to first half of the Nobel Prize.

  • Title of the talk: "Chirped Pulse Amplification"
    Speaker: Prof. Amarendra K. Sarma
    Date & Time: 9th October, 2018, 5:45 pm-6:00 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    The technique/concept that led to second half of the Nobel Prize.

  • Title of the talk: "Impact of top quark in Diphoton production from gluon fusion at NLO"
    Speaker: Dr. Manoj Mandal, Post doctoral fellow, IIT Guwahati
    Date & Time: 27th September, Thursday, 5.15 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    We present a framework that allows to evaluate the next-to-leading order (NLO) corrections in QCD of the Di-photon production through gluon fusion, retaining full top quark mass effects, numerically. Our method starts from the generation of the necessary amplitudes followed by the reduction of the integrals using the Integration-By-Parts reduction and the numerical evaluation of the master integrals via combination of differential equation and sector decomposition. Specifically, we will show the results for the inclusive cross-section and the invariant mass distribution for the first time, thereby exhibiting the importance of the inclusion of the top mass effects.

  • Title of the talk: "Universal Particle Localization Underlying Glass Formation."
    Speaker: Dr. Tarak Patra, Post Doctoral Fellow,(ANL, USA)
    Date & Time: September 13, Thursday, 5-6 pm
    Venue: Seminar Room, Department of Physics
    Abstract of the talk:

    Despite more than half a century of research, the fundamental nature of the glass transition remains one of the major open questions in materials science and condensed matter physics. Computer simulations have provided key insights into this problem, but their ability to firmly establish the underlying nature of glass formation have been limited by the extreme computational difficulty of directly probing the deeply supercooled regime most relevant to this process. Here we describe a new protocol for simulation of the glass transition enabling facile access to in-equilibrium segmental relaxation times approaching and exceeding one microsecond - well into the deeply supercooled regime of most glass-forming liquids. Coupled with a well-validated strategy for extrapolation to experimental timescales, this approach provides vastly improved prediction of experimental glass transition temperatures. Here, we combine data acquired through this protocol for the deeply supercooled regime of polymeric, inorganic, organic, and metallic glass formers to identify microscopic phenomenological features shared across all classes of glass-forming liquid in the deeply supercooled regime. Further, correlations between glass formation and conductivity of polymeric materials are addressed.

  • 27 Aug 2018, 5 pm: Weekly Seminar : Speaker Prof. Parongama Sen, Department of Physics, Calcutta University, Title of the talk: Nonequilibrium behaviour of classical spin models: some applications in social phenomena.
  • 16 Aug 2018, 5 pm: Weekly Seminar : Speaker Dr. Saikat Chakraborty, IIT Kanpur, Title of the talk: Anisotropy evolution in $f(R)$ gravity.
  • 14 Aug 2018, 5 pm: Weekly Seminar : Speaker Professor Achanta Venu Gopal, TIFR, Title of the talk: Broadband plasmonics in the optical and THz range.