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Programme

8th November, 2019 (Friday) | VENUE : CLT (Central Lecture Theatre)

16:30 - 17:00          High Tea

17:00          Inauguration

  Time

Speaker

Title of the Talk

LINK
SESSION CHAIR : Prof. L. SRIRAMKUMAR

17:15

Prof. G Baskaran Room Temperature Superconductivity - RVB Theory Perspective
ABSTRACT There have been claims, since 1946, of experimental observation of ambient temperature superconductivity at ambient pressures (ATSAP). They are unfortunately ephemeral, elusive and unstable.Reproducibility is a major issue. I find that stable ATSAP is in principle possible, within real world solid state and quantum chemical constraints. Resonating valence bond theory, based on an electronic mechanism, allows this. However, most often other competing orders win. Superconducting order gets suppressed. Can theory offer some guidance to make Superconductivity a winner ?

17:45

Dr. Vidya Praveen Bhallamudi Sensitive magnetic and optical tools for quantum and nano applications​  

18:15

Dr. Ayan Mukhopadhyay A story of fields and strings: Planckian regimes, GUTs, Nano-machines and Earthquakes  

18:45

Dr. Lakshmi S Mohan Probing leptonic CP violating phase using low energy atmospheric neutrinos
ABSTRACT The leptonic CP phase $\delta_{CP}$ is one of the current unknowns in neutrino oscillation physics. Its measurement is ambiguous with the hierarchy of neutrino masses. Low energy (sub GeV) atmospheric neutrinos can be used to measure this phase irrespective of the neutrino mass hierarchy. Another advantage is the huge flux at low energies which give us a large number of events. When binned in the observed energy and direction of the final state lepton in charged current interaction of neutrinos and anti-neutrinos, a clear distinction between different values of $\delta_{CP}$ is obtained.

9th November, 2019 (Saturday) | VENUE : CLT (Central Lecture Theatre)

SESSION CHAIR : Prof. PREM B. BISHT

09:30

Prof. C. Vijayan You cannot have your laser and eat it too!
ABSTRACT Exploration of less-trodden paths of light-matter interaction have often helped to obtain a deep understanding of the underlying physical mechanisms. One such area of recent interest is that of optical transport in random media, where light undergoes multiple scattering by scatterers of microscopic dimensions, positioned randomly either naturally, or by design. We report on some recent strategies for the control of the scattering pathways leading to random lasing with wavelength tunability and plasmonic enhancement. Biocompatible fluorescent materials with built-in structural features capable of forming feedback loops are shown to hold promise as media for random lasing. The main motivation, however, is not the design of edible laser media, but the development of simple and novel platforms for understanding light scattering scenarios in random media and exploring their scope for applications.

10:00

Dr. Sunethra Ramanan Superfluidity in neutron star
ABSTRACT The superfluid phase in neutron star matter was theoretically predicted with a gap of about 1 MeV as early as 1960. However, even today pairing in neutron stars remains an open question. The attractive force required for the formation of Cooper pairs is provided by the interaction between the neutrons. A correct description of the superfluid state is crucial to understand the cooling of neutron stars. The neutrons pair to form a superfluid in the inner layers of the crust and in the outer layers of the core of the star. Using pure neutron matter as an approximation to neutron star matter (which is asymmetric matter with more neutrons than protons), I will discuss the recent approaches to neutron superfluidity both in the crust and core of the star including medium corrections. ?

10:30

Anu B Photoluminescence enhancement in carbon dot TiO2 nanotube heterostructure
ABSTRACT Carbon quantum dots(CQD) have significant PL emission in the visible range. Since higher PL efficiency is required for diverse applications, we studied the emission of CQD films by depositing them on TiO2 nanotube (TNT) substrates. We observed nearly three times increase in the total emission. The efficient transfer of the carriers from TNT to CQD is found to be the dominant phenomenon leading to the increase in PL emission intensity.

10:45

Shubhayan Bhattacharya Dissipative quality factor of whispering gallery modes for sensors
ABSTRACT Whispering gallery modes (WGMs) of dielectric microstructures have high quality (Q) factor and low mode volume. The net Q-factor of a coated microresonator depends on the thickness and refractive index of the coated material and can be used as a sensor for these parameters. To understand the mechanism, experiments have been performed on metal-ligand charge transfer complex of Ru salt coated microcavities. Electric field calculations show that the evanescent wave is extended into the coated layer- useful to couple the modes of the microcavity to the photoluminescence of the coated material.

11:00-11:30                        Coffee Break

SESSION CHAIR : Prof. SURESH GOVINDARAJAN

11:30

Prof. V Balakrishnan Mortal random walks and the renormalization  of hitting time distributions on hierarchical graphs
ABSTRACT Random walks are ubiquitous in the modelling of stochastic aspects of physical phenomena. First-passage-time or hitting-time distributions play an important role in this regard. Non-standard diffusive behaviour is common in random walks on fractal and/or hierarchical structures. It is shown that the introduction of mortality for random walkers provides a very powerful statistic in the analysis of such walks. In particular, the central role of a scaling function of the survival probability is demonstrated.

12:00

Krishnakumar Ravindran Measurement of strong-phase difference between D0/D0bar decaying to KsK
ABSTRACT We present a measurement of the strong-phase difference between D0/D0-> KsKK using a data sample corresponding to an integrated luminosity of 2.93 fb-1 collected in e+e- collisions at a centre-of-mass energy corresponding to the mass of the psi(3770). The D0 and D0bar meson pairs produced are in a quantum-correlated state, their subsequent decays are recorded by the BESIII 4pi magnetic spectrometer. The measured value of the strong-phase difference is an essential input to the determination of the value of CKM angle gamma through the decay B->DK-. The measurement is the most precise to date.

12:15

Md Alibordi New Physics in the semileptonic hyperon decays including leptonic mass effect
ABSTRACT Beyond standard model new couplings are studied in the semileptonic decay of hyperon for the decay mode $\Xi^{0}\to \Sigma^{+}l\nu_{l}\,\, (l=e\,,\mu)$ followed by non-leptonic decay of $\Sigma^{+}\to p+\pi^{0}$. This model independent analysis is containing the parametric space for branching ratio compared to existing experimental results.

12:30

Sarath Srinivas S In-medium SRG using Gaussian Process Regression
ABSTRACT Neutron matter properties can be studied using In-medium Similarity Renormalization Group technique. Here, we attempt to numerically solve the IM-SRG flow equations for the 2- body vertex in continuum using Gaussian Process Regression.
12:45 Niharika Rout Measurement of CKM angle φ3 at Belle II & the rediscoveries from the first data of Belle II
ABSTRACT The Belle II experiment at the SuperKEKB asymmetric e+e− collider in KEK, Japan will accumulate a data sample corresponding to an integrated luminosity of 50 ab^−1. Here, we present the key methods for the measurement of phi3 at Belle II experiment, the only CKM angle which is accessible via tree-level decays, and the rediscoveries from the first official data-set of Belle II. With the ultimate Belle II data sample of 50 ab−1, a determination of phi3 with a precision of 1 degree or better is foreseen.

13:00  - 14:30                     Lunch and poster session

SESSION CHAIR : Prof. P N Santhosh

14:30

Dr. Abhishek Misra Van der Waals materials: Physics and Applications  

15:00

Shashi Bhusan Mishra Pseudoatomization as a Route to Create a Suspended 2D Spin Lattice in Fluorine Intercalated Multilayer Graphene
ABSTRACT A suspended layer made up of long-range ordered spins could be created between multilayer graphene through intercalation. Stability and electronic structure studies reveal that when fluorine molecules are intercalated, their bonds get stretched enough to decouple their molecular eigenstates, resulting in a pseudoatomized layer which maintains a van der Waals separation of ~ 2.6 Å from the adjacent carbon layers. Consequently it generates a spin-half state at each fluorine site, which have strong ferromagnetic coupling resulting in a suspended 2D spin lattice.

15:15

Muhammed Juvaid M Opto-electronic tunability of large area ultra-smooth rGO thin films grown via PLD
ABSTRACT We present the growth of large area ultra-smooth reduced graphene oxide (rGO) thin films on a four inch wafer via beam scanning mode of Pulsed laser deposition technique. With the versatility of the PLD technique, the easy tuning of optoelectronic properties is achieved on rGO thin films without employing any buffer layers. These thin films can potentially employ in various optoelectronic applications due to its high transparency and p-type conductivity, where our rGO films shows highest performance as compared to existing p -type transparent conducting films.

15:30

Midhunlal P V

Investigation on the structure and magnetic moment compensation in ferrimagnetic full heusler systems mn2v1-xcoxz (z=ga, al; x=0, 0.25, 0.5, 0.75, 1)

ABSTRACT Half-metallic fully compensated ferrimagnets which exhibit zero magnetic moment with 100% spin polarization at the Fermi level are desired material for spintronic applications. Earlier reports showed that magnetic moment compensation by 50% Co substitution at the Mn site of the half-metallic Heusler alloys Mn2VZ(Z=Ga, Al) results in a drastic reduction of TC and deviation from half-metallicity. Through detailed analysis of experimental and ab initio calculation results, we have shown that magnetic moment compensation with high TC can be achieved by 50% Co substitution at the V site of Mn2VZ.

15:45

Akshay Influence of Defects and Crystallinity on the Rate Capability and Cycling Stability of Lithium Intercalation in MoS2 Nanosheets
ABSTRACT Continuous capacity loss or gain in electrodes during extended cycling is very intriguing. Influence of crystallinity and defects on capacity retention during high current cycling of MoS2 nanosheets in intercalation regime are investigated. Strong correlation with irreversible lithium intake during first cycle is found. Excess lithium trapped during first cycle is contemplated to shuttle around upon cycling, enhancing the diffusion of Li ions. This increases accessibility of defect rich MoS2 for lithium intercalation. Defect suppressed MoS2 without such lithium show capacity fading.
16:00 Vasumathy Ravishankar

Ion Permeation Through Thermally Tuned Microstructure in Graphene Oxide Membranes

ABSTRACT Graphene oxide (GO), an important material for sieving and filtration, has a hierarchical microstructure; nanosheets of uniformly stacked GO with separations termed nanochannels form lamellae. In thick GO films, collections of lamellae are separated by voids. Current literature proposes ion permeation assuming GO as consisting only of lamellae. However, the contribution of voids cannot be ignored. In this work, electro-impedance spectroscopy (EIS) was used to study GO films with tuneable nanochannel spacing and microstructural disorder, aiming to discern contributions of nanochannels and voids. Increase in permeation resistance despite increase in microstructural disorder suggests that nanochannels play a dominant role in ion permeation. These results were also supported by strong dynamics in the response of films prepared at higher annealing temperatures.

16:15

Anubhab Sahoo Intense field light matter interaction in and on solid medium using high power laser systems.
ABSTRACT The development of chirp pulse amplification (CPA) of laser systems has enabled to produce femtosecond laser pulses of peak power as high as several tera-watts (TW). The generation of these short pulses, highly dependent on the compressor gratings. The spatial and temporal distortion of pulses can be controlled using adaptive optics and acousto-optic programmable disperse filter (DAZZLER) while gratings are still hot. In the second part, nonlinear transmission measurement from quartz will be discussed to explain the nonlinear ionization process involved during the intense field interaction.

16:30 -17:00                               Coffee Break

SESSION CHAIR : Prof. SETHUPATHI K.
17:00 H.V. Ragavendra Non-Gaussian signatures of primordial features from excited initial state
ABSTRACT Specific deviations from a nearly scale-invariant power spectrum of primordial perturbations have been known to improve the fit to the cosmological data. These deviations, known as features, can be generated in slow roll inflation by evolving the perturbations from excited initial states. In this talk, we shall discuss as to how we can infer the initial state of the perturbations from these features. We shall also describe the calculation of the scalar bispectrum from such states, and illustrate the magnitude and shape of the resulting scalar non-⁠Gaussianity parameter.
17:15 Akshaya .J Finding good quantum codes using the Cartan form
ABSTRACT We present a simple and fast numerical procedure to search for good quantum codes for arbitrary noise processes. In a key departure from earlier works, we use the worst-case fidelity as the figure of merit for the goodness of a code. While this involves a triple optimization in general, we reduce the complexity of the problem by fixing the form of the recovery to be a near-optimal recovery map, adapted to the noise in question. For qubit codes, this results in a simple form for the objective function, which makes the optimization tractable via a simple gradient descent algorithm. Furthermore, we parametrize our search space of encoding unitaries using the Cartan decomposition. Since the noise under consideration is local, the Cartan form allows us to truly search over the nonlocal parts of the encoded space, leading to families of codes which can be implemented as simple quantum circuits. Finally, we present examples of good codes obtained via our numerical procedure.
17:30 Vandana Yadav

Unequal load sharing in force induced catatrophes for a microtubule bundle

ABSTRACT Microtubule(MT) filaments are important components of the cytoskeleton of a eukaryotic cell. Motivated from mathematical and experimental studies, we study the effect of a forced barrier on the statistics of catastrophe events in a single MT as well as bundle of two microtubules. We use a one-dimensional stochastic model of a MT with random growth and hydrolysis, interacting with a rigid barrier which is subjected to thermal noise and an external force. Our results predict that the catastrophe frequency of a single filament monotonically increases with the force and saturates at large forces.
17:45 Rahul Vaippully Study of cell membrane thermal slope fluctuations using pitch mode of optical tweezers
ABSTRACT We present our work involving study of the slope fluctuations in addition to the vertical membrane fluctuations using a trapped birefringent particle attached to the membrane. We rely on the high resolution mapping of the pitch angle, done for the first time using optical tweezers. We find using this technique that the slope power spectrum follows f^(-1) law which we also explain theoretically.
18:00 G Manikandan Biopolymer Based Soft Actuators
ABSTRACT We present the development of a biopolymer-based soft actuator and its actuation performance with water vapor as a stimulus. Actuation characteristics of a free-standing membrane were recorded in real-time by using the high-speed camera. The amplitude of the actuation, response time, and relaxation time are estimated and compared with the performance with existing polymer actuators. The role of the chemistry of the solvent vapor and the geometrical shape of the membrane on its actuation behavior and the physical principles responsible for the actuation will be presented in detail.

18:15 onwards                 Culture Performance followed by Dinner



 
Department of Physics - 2019