A recurring desire within nanophotonics is to control light-matter interactions by engineering material systems and nanostructures that can confine light within subwavelength volumes. In this talk, the speaker will present some of their recent works where they inverse design both material systems and photonic structures to realize complex photonic devices with different functionalities for advanced sensing applications. In the first half of this talk, he will present their works on light-matter coupled polaritonic metasurfaces where they integrate photonic structures with quantum engineered resonant nonlinearities in III-V semiconductor heterostructures to achieve all-dielectric metasurfaces with record high nonlinear response for nonlinear and quantum light generation [1-3]. In the second half, he will present some of their ongoing efforts in silicon photonics where they have designed disorder-based complex photonic devices and optical computing architectures for low power and ultrafast image and data processing for remote sensing applications [4].

In this talk the speaker will be narrating his works on black hole shadow in different backgrounds with various matter fields. Shadow is the apparent image of the black hole event horizon and can be useful in understanding aspects of fundamental physics and gravity in strong field regime. In one of his works, he studied the shadow on higher curvature background and found that curvature parameter impacts the shadow size depending on the background spacetime under consideration. Then he considered a model of dark matter surrounding a rotating charged black hole and looked into the null geodesics in such a scenario. The unstable null geodesics form the shadow and are impacted by dark matter. Using the data of M87* he obtained bounds on the dark matter as well as the plasma parameter. Besides in another scenario he considered a black hole surrounded by plasma in a de Sitter background and obtained the shadow as seen by a comoving observer. Here, also using the EHT data, he put bounds on the plasma parameter. Finally, he studied the quasi-normal modes of a perturbed charged black hole immersed in dark matter and found that the QNM gets affected by dark matter. Recently he has been working on weak lensing in the presence of quintessence. He wish to study the dark matter halo models and their observational effect on the shadow structure and quasinormal modes.

The speaker and his team propose an ion-atom hybrid system for quantum computing. They consider, as a model system, a single ion qubit in a Paul trap and two atomic qubits in two separate optical tweezers that are placed several microns away from the ion. They propose a protocol for ion-atom two-qubit control phase gate operation based on Rydberg excitation of the atom and the manipulation of the ionic phonon due to the long-range atom-ion interaction. They also demonstrate two-qubit control phase-gate operation between two distant (more than 20 micron separation) neutral atom qubits by leveraging the ion-mediated interaction between the atomic qubits. They discuss possible routes to scaling up the system and the possibility of multi-qubit gate operations.

The strength of spin-orbit coupling (SOC) in 5d iridates is often considered intrinsic; however, our recent work demonstrates that it can be significantly tuned by manipulating the Ir charge state through chemical substitution. In this talk, I will discuss our study on a series of iridium- ruthenium triple perovskites, Ba₃MRuIrO₉ (M = Li, Mg, In), where Ir and Ru form structural dimers along the c-axis and a geometrically frustrated lattice in the ab-plane. Using DFT+U+SOC calculations and atomistic spin dynamics simulations, we show that the nominal Ir charge state evolves from +6 (5d³) in Ba₃InRuIrO₉ to +4 5d³) in Ba₃InRuIrO₉. This variation leads to a dramatic enhancement of SOC strength across the series, giving rise to distinct ground states: a correlation-driven insulator (Li), a SOC-assisted Mott insulator with unconventional magnetism (Mg), and a Jeff = 1/2 Mott-Hubbard insulator (In). In particular, I will highlight how strong SOC in Ba₃InRuIrO₉ induces significant Dzyaloshinskii-Moriya and bond-dependent anisotropic interactions, promoting magnetic frustration and a multivalley energy landscape. These features point to the potential realization of a quantum spin liquid phase in Ba₃InRuIrO₉.

Physicists are beginning to discover “tetraquarks,” exotic particles built from four quarks instead of the usual two (mesons) or three (protons and neutrons). The latest excitement is a particle that contains two heavy quarks (one charm, c, and one bottom, b) plus two light antiquarks (ū and đ). If it exists, this bcud tetraquark would be the first of its kind and would deepen our understanding of how quarks bind together.

To search for the bcud tetraquark, we run super‑computer simulations of quantum chromodynamics (QCD) on a space‑time grid, a technique known as Lattice QCD. Using four separate data sets with slightly different grid spacings and sizes, we watched how a D meson (containing one charm one light quark) and B meson (containing one bottom and one light quark) interact.

The key question is: do these two mesons interact together to form a stable tetraquark state? The answer appears to be yes. After carefully removing lattice artefacts, we see a bound state in both the scalar and axial‑vector channels. Thus our calculations predict a bcud tetraquark should form in nature.

Confirming this particle experimentally would test QCD in a brand‑new regime, guide future searches at the LHC and Belle II, and help map the rich “periodic table” of multiquark bound states.

The Giant Metrewave Radio Telescope (GMRT), located near Pune, India, has one of the world's most sensitive radio interferometers operating at metre wavelengths (150-1500 MHz). Consisting of 30 fully steerable parabolic dishes, each 45 meters in diameter, (now the upgraded) GMRT offers a unique combination of wide frequency coverage, high angular resolution, and sensitivity, enabling groundbreaking discoveries in radio astronomy.

A key scientific focus of GMRT is the observation of radio galaxies. The colossal energy output of radio galaxies across vast volumes influences galaxy formation, the growth of supermassive black holes, and the evolution of clusters and the cosmic web. For instance, radio galaxies in groups and clusters eject significant energy into their environments, regulating gas cooling and galaxy evolution through processes such as energy ejection, mixing, and entrainment. Multi-frequency radio observations with GMRT enable spectral-ageing studies to constrain the formation models, while complementary X-ray data (from Chandra and XMM-Newton) provide constraints on the surrounding hot gas environments.

This presentation will consist of two parts: (i) an introduction to the upgraded GMRT, highlighting its technical advancements, and (ii) recent insights from radio and X-ray studies aimed at understanding the nature of these enigmatic radio galaxies.

Recent studies have revealed that certain nuclear parameters are more dominant than others in governing global neutron star properties, such as its structure or oscillation mode characteristics. Although neutron stars can in general be assumed to be cold, in astrophysical scenarios such as newly born neutron stars or remnants of binary neutron star mergers, finite temperature effects play a non-negligible role. In this work, we perform a consistent and systematic investigation of the role of nuclear parameters and thermal effects on neutron star properties and fluid oscillation modes within a full general relativistic scheme. We impose constraints on the parameter space of the relativistic mean field model using state-of-the-art information from terrestrial experiments and multimessenger astrophysical data. We find effective nucleon mass to be the most important nuclear parameter controlling astrophysical observables of hot neutron stars, similar to the cold beta equilibrated matter. However, we conclude that the interplay among saturation properties and astrophysical observables depends not only on the thermal configurations considered but also on the constraints imposed. We also investigated the role of nuclear saturation parameters on some universal relations for hot neutron stars which are important in gravitational wave asteroseismology. Our investigation confirmed that these relations are mostly insensitive to nuclear saturation properties and mainly affected by variation of charge fraction in the star.

Quantum Computer has become quite a craze, and a matter of huge curiosity at the moment. Getting the appropriate physical qubits is at the core of realizing a quantum computer. In this talk, various physical qubits, and the current status of quantum computer based on such qubits will be discussed. The architecture behind IBM and Google Quantum Computer will be discussed briefly. The talk will be kept at an elementary level so that it's comprehensible to the general audience.

Particle diffusion in heterogeneous systems poses the following question: Can a single available model describe the entire dynamics of a particle in complex biological, soft matter systems? Indeed, often several different physical mechanisms are at work, and it is more insightful to rank them based on the likelihood of them explaining the dynamics. The first part of this talk will discuss — within the Bayesian framework—(i) how model selection can be done by assigning probabilities to each feasible model and (ii) how to estimate the parameters of each model.  The second part of this talk will discuss how the results of Bayesian analysis can lead to meaningful model building. Fractional Brownian motion (FBM), a Gaussian, non-Markovian, self-similar process with stationary long-correlated increments, has been identified to give rise to the anomalous diffusion behavior in a great variety of physical systems. The correlation and diffusion properties of this random motion are fully characterized by its index of self-similarity or the Hurst exponent. Inspired by the results discussed in the first part,  generalizations of FBM will be introduced to include (a) Hurst index that randomly changes from trajectory to trajectory but remains constant along a given trajectory, and (b) Hurst index that varies stochastically in time along a trajectory. Finally real-world examples will be presented for all the three processes.

Accretion physics has become more important recently due to the detection of the first horizon-scale images of the supermassive black holes of M 87∗ and Sgr A∗ by the Event Horizon Telescope (EHT). General relativistic magnetohydrodynamic (GRMHD) simulations of magnetized accretion flows onto a Kerr black hole have been used to interpret them. However, further testing the theory of gravity by using horizon-scale images requires performing consistent GRMHD simulations in non-Kerr spacetime. This talk will be mainly focused on the validity of gravity theories around compact objects from current and future observations with the help of GRMHD and GRRT simulations.

The ability to cool and manipulate atoms at ultracold temperatures has opened new avenues for exploring fundamental quantum phenomena and developing next-generation quantum technologies. In this talk, it will be discussed how ultracold atoms serve as a versatile platform for studying quantum many-body physics, synthetic gauge fields, and quantum simulation of condensed matter systems. In particular, recent advancements in generating synthetic magnetic fields with ultracold erbium atoms to investigate quantum Hall physics and topological phases will be discussed. Additionally, quantum synchronization in spin-1 systems will be also discussed, which offers new insights into non-equilibrium quantum dynamics. Beyond fundamental studies, these techniques have potential applications in quantum metrology and quantum information processing. An overview of experimental challenges and future directions, emphasizing how precise control over atomic systems can drive advancements in quantum science and technology will be discussed.

Fast radio bursts (FRBs) are a remarkable class of transient astronomical phenomena detectable over cosmological distances. Their defining characteristics, including high dispersion measures and short pulse width, position them as invaluable tools for advancing our understanding of cosmology. This presentation will begin with a brief overview of FRBs, highlighting their discovery, properties, and observational signatures. Subsequently, the focus will shift to key cosmological insights enabled by their study. By examining a sample of localized FRBs, the speaker will demonstrate how these phenomena provide a novel approach to addressing the Hubble tension, a persistent discrepancy in the determination of the Hubble constant. Furthermore, the implications of alternative cosmological models on the precision of fundamental constants, such as the fine-structure constant, the proton-to-electron mass ratio, and constraints on the fraction of primordial black holes constituting dark matter, will be explored. The presentation will conclude with a discussion of the capabilities of existing and upcoming observational facilities, emphasizing their potential to detect a statistically significant population of FRBs and thereby enhance our understanding of the Universe.

Research pursuits across many physics disciplines require complex experimental facilities operated by multinational collaborations to advance the state-of-the-art in knowledge. These scientific communities have been learning how to build collaborations that build upon regional capabilities and interests over decades, iteratively with each new generation of large scientific facilities required to advance their scientific knowledge. Much of this effort has naturally focused on collaborations for the construction of hardware and instrumentation. Software has however also become a critical element to design and maximize the physics discovery potential of large data intensive science projects. To fully realize their discovery potential a new generation of software algorithms and approaches is required. Building these research software collaborations is challenging and inherently international, matching the international nature of the experimental undertakings themselves.

Experimental high-energy physics is one of these research fields. These experiments are very data intensive and “team-science” driven. This talk will discuss some of the experimental challenges, scientific achievements, collaborative successes and how this field is moving forward to enable successful research software collaborations and research software careers.

Speaker will also introduce a new initiative, HSF-India, aiming to implement new and impactful research software collaborations between India, Europe and the U.S. The experimental scope of this project is relatively broad, aiming to bring together researchers across facilities with common problems in research. Speaker will describe the scope of this initiative, its mechanisms for fostering new collaborations, and ways for interested research groups to get involved.

The Sun is the first astronomical object in which magnetic fields were discovered in 1908 by using the Zeeman effect. Even before this discovery of magnetic fields in sunspots, it was known that there is a 11-year cycle of sunspots, which could be identified as the magnetic cycle of the Sun after this discovery. The magnetic field of the Sun is also behind many other phenomena, such as the violent explosions known as solar flares, the corona much hotter than the solar surface and the solar wind. Only within the last few decades, major developments in plasma physics and magnetohydrodynamics (MHD) have at last provided a broad framework for the theoretical understanding of these phenomena connected with the solar magnetic fields. The speaker will give a general introduction to this field – with some emphasis on the research interests of their group. A more detailed account of this field can be found in his recently published popular science book: http://www.amazon.in/Natures-Third-Cycle-Story-Sunspots/dp/0199674752/

Despite being successful in the weak field regime, the validity of general relativity remains elusive in the strong field regime. Many problems occur when trying to unify general relativity with quantum theory in a self-consistent manner. Moreover, it is speculated that quantum theory should modify black hole singularity. Recent GW astronomy has opened the door to test general relativity in the strong field regime of black holes, mainly the merger of binary black holes. The observed ringdown waveform of the merger remnant is consistent with GR prediction. However, several research papers have shown that any horizonless compact object with a photon sphere can also mimic such a waveform. Interestingly enough, it is known that such black hole alternatives can cure some of GR's drawbacks. However, they are known to violate some energy conditions or are formed beyond standard model fields.  At this point, whether they are stable under linear perturbations naturally comes to mind. In this talk, I will focus on wormholes as an ECO. Under some special situations, it is found by Kar-Lahiri-Sengupta that wormholes on the brane do not require any exotic matter to sustain them. Here I will discuss the perturbation of this wormhole under known bosonic perturbations. In the next part of the talk, I will model the Damour-Solodukhin wormhole residing inside the galactic halo and discuss the effect of dark matter on it's stability. Finally, we will model a star like ECO by putting a partially reflecting surface near the location of the would-be horizon. Considering plasma accretion around this ECO spacetime, we have studied the propagation of electromagnetic waves through plasma. I will discuss interesting phenomenology regarding this perturbation scheme.  

I will describe predictions of the simplest interaction theory, which approximates key features of nuclei and certain atoms, for rearrangement collisions of composite particles. The results present a starting point for subsequent refinements of the theory by a systematic consideration of more than the unnaturally large 2- and 3-body scales in order to attain high-accuracy predictions for nuclear fusion. The discussion is limited to the non-relativistic 4-body system. 

It is believed that at the early stage of the Universe, roughly 10 seconds after the Big Bang, the temperature dropped sufficiently to allow the first atomic nuclei to form. Subsequent nuclear reactions produced stable helium and lithium isotopes and negligible traces of heavier elements. This process is known as the primordial nucleosynthesis of light elements or Big Bang Nucleosynthesis (BBN). At the end of BBN, the specific primordial abundances left an observable imprint in the current Universe. This echo nowadays serves to test the Hot Big Bang theory and the Standard Model of particle physics. An accurate description of BBN nuclear reactions is crucial in studying primordial nucleosynthesis. Nowadays, reaction dynamics can be calculated by applying highly sophisticated ab initio theoretical methods. In my contribution, I will discuss how a systematic approach to describing nuclear interactions and ab initio methods might contribute to revealing mysteries about this early stage of the Universe. 

There is still a lot we don’t understand about how matter behaves around Sagittarius A*, the supermassive black hole at the center of our galaxy. Both theories and observations struggle to fully explain its behavior. In this talk, I will discuss some of the most recent results on this topic and potential future directions. 

The basic group theory will be discussed with the focus on space groups.

Recent years have witnessed a spate of interest in understanding the general "Target problem". This encompasses an overarching range of scenarios in which some "agents" perform a deterministic or stochastic motion to search for a or many certain immobile or mobile "targets". Such problems arise in physics, chemistry, biology and in other cross-disciplines namely the evolution of stock markets, evolutionary games, ecology, computer science etc. In particular, designing navigation strategies for this search-time optimization remains the key interest in the field. I will provide a brief introduction of the subject and then discuss one such strategy based on the intermittency of the searchers followed by a memory erasure. I will then try to convince how this mechanism leads to a universal efficiency gain in arbitrary complex systems.

Laser cooling and trapping of atoms is an important tool in modern quantum technologies. In this talk, I will discuss various aspects of the laser cooling and trapping of atoms. Further I will also discuss how these  atoms are used in quantum technologies such as optical clock, gravimeter and quantum computation and simulation.

Experimental advancements have led the path of diode formation from a semiconductor diode to the very recent fabrication of a superconducting diode (SD) [1-2] where unidirectional non dissipative supercurrent flows. The tunability of the unidirectional supercurrent via the phase difference between superconductor leads has drawn the attention of the community and brought Josephson diode (JD) [3-4] to the forefront of research. In studying the superconductor based heterojunctions, quantum dot (QD) acts a promising weak-link to study the supercurrent in a Josephson junction (JJ). The gate tunability of the QD energy level acts as an effcient tool to control the flow of Josephson current (JC) in thesee heterojunction [5]. In order to achieve the diode effect in the JJ, the main motivation lies in the mechanism of breaking the time-reversal symmetry and the inversion symmetry in the system [1, 4]. With this notion we investigate a chiral QD-based Josephson junction and show two different ways to establish Josephson diode effect (JDE) with high rectification coefficient (RC). The presence of electron-electron interaction spontaneously creates an imbalance between up- and down-spin electrons during the non-equilibrium transport making the QD effectively magnetic. The simultaneous presence of the chirality and the interaction eventually results in the field-free JDE in the chiral QD junction [6]. Whereas, the presence of structural asymmetry in the heterojunctions induces Rashba spin-orbit interaction (RSOI) that breaks the inversion symmetry of the system. To understand the effect of this underlying possibility of the RSOI on the diode effect, we consider a QD in the presence of an external magnetic field and RSOI [7]. We employ the Keldysh non-equilibrium Green's function technique to study the behavior of the Josephson current (JC) and the RC of our JD. We show a sign-changing behaviour of the RC with the Coulomb correlation and the lead-to- dot coupling strength and find the maximum magnitude of the RC 72% for moderate∼ interaction strength [6]. Our QD with RSOI induces JDE in the heterojunction with a large RC that can be tuned to be as high as 70% by an external gate potential, indicating a giant JDE in our QD junction [7]. Our result also shows that the rectification property could be enhanced with the inclusion of chirality in the QD. Interestingly we find that the sign and magnitude of the RC are highly controllable by the magnetic field, RSOI and the Coulomb correlation in the QD. Our proposed QD based JD may be a potential switching component in superconductor based devices.

Colloidal gels formed through arrested phase separation exhibit a space-spanning percolating network of interconnected strands, which serve as mechanical building blocks at the mesoscale level. Under externally imposed loads, these strands break, leading to gel flow. In this talk, I will discuss the creep failure of various colloidal gels under a constant shear stress protocol to identify the failure mechanisms of these load-bearing strands. By analyzing strand-breaking statistics, we reveal a homogeneous failure pattern akin to ductile failure. Spatio-temporal analysis of various matrices links the structural and mechanical properties of the strands before and after failure. I will show how the viscosity bifurcation emerges from the interplay between shear rejuvenation and aging dynamics of colloidal gels. 

Recent progress in research has produced the discovery of many hitherto unknown connections among the different properties in the infrared sector of gauge theories and gravity. In this talk, we shall focus particularly on the gravity theories. Since the sixties, the role of certain infinite dimensional symmetries, named BMS symmetries in classical gravity has been explored. In the early sixties work by Weinberg showed that Scattering amplitude containing gravitons shows interesting factorization theorems when the energy of a graviton is taken to zero in the limiting sense. Such factorization theorems are known in the literature as Soft Graviton Theorems. A seminal work by Strominger et al in the last decade showed that the Weinberg Soft Graviton Theorem can be shown to be equivalent to the conjectured BMS symmetry of the quantum gravity S-matrix. This initiated a flurry of explorations leading to various proposals for extension of the BMS symmetries at the classical level on the one hand, and on the other, works by Sen et al have proved the Soft graviton Theorems in the most robust setup for arbitrary theories of quantum gravity, in arbitrary dimensions, when the zero energy limit is taken on an arbitrary but finite number of gravitons. Understanding these general soft theorems from the symmetries is an interesting research direction. We present our contribution in this direction, based on a proposed extension of the BMS Symmetries, called the generalized BMS Symmetries. Nearly half of the talk will be on introducing this general research direction. In the other half, we will report on our contribution in this direction so far and on a few ongoing works.

n the era of 'big-data', the growing demand for faster computing and higher data storage is pushing conventional electronic technologies to their limits. Spintronics has emerged as a transformative field that leverages the spin of electrons besides its charge to develop faster, more energy-efficient, and non-volatile devices. Recently, transition-metal oxides are being explored as a promising platform for advancing spintronics, offering a wide range of functional properties due to the complex interplay of charge, spin, orbital, and lattice dynamics. This talk will explore the fundamentals of spintronics, highlight the key breakthroughs that have shaped its evolution, and discuss the remarkable potential of transition-metal oxides. Together, let us examine the challenges and explore the exciting future possibilities in the realm of oxide spintronics.

Stochastic Optical Reconstruction Microscopy (STORM) is a powerful imaging technique that allows researchers to visualize biological samples with nanometer-scale resolution, surpassing the diffraction limit of conventional microscopy. This talk will take the audience on a journey from the fundamental principles of light microscopy to how STORM has revolutionized our ability to study the structure and dynamics of biological systems at the nanoscale. The presentation will cover the basic principles behind STORM, the steps involved in preparing samples, the imaging setup, and the image reconstruction process. By the end, attendees will gain an understanding of the principles, challenges, and potential applications of STORM in advancing our knowledge of cellular structures and processes.

The Aditya-L1 mission, launched on September 2, 2023, is India’s first space-based solar observatory strategically positioned at the Lagrangian point L1 to enable uninterrupted solar observations. This mission is equipped with Sun-as-a-star X-ray spectrometers, Solar Low Energy X-ray Spectrometer (SoLEXS) and the High Energy L1 Orbiting Solar Spectrometer (HEL1OS). These instruments are designed to capture detailed spectral data across a wide energy spectrum, essential for studying the Sun’s dynamic behavior. SoLEXS, operating in the 1-22 keV range, continuously monitors the Sun’s soft X-ray emissions, providing critical insights into flare mechanisms and coronal heating. HEL1OS extends these observations into the higher energy X-rays in the 10-150 keV range, enabling detailed investigation of non-thermal processes associated with high-energy solar phenomena. Together, both instruments provide high-resolution, high time-cadence X-ray spectra, crucial for understanding impulsive and dynamic processes in the solar corona, including solar flares. The combined data from SoLEXS and HEL1OS will allow for a more comprehensive study of the solar corona’s thermal and non-thermal processes and their evolution. This talk will present the first results from SoLEXS and HEL1OS, highlighting their role in decoding the complexities of solar activity. We will discuss the instruments’ contributions to understanding the mechanisms driving solar flares, the correlation between soft and hard X-ray emissions, and the potential for understanding solar events. Our findings underscore the significance of continuous monitoring and advanced instrumentation in advancing solar physics research.

Hypergeometric function theory and Feynman Integral calculus go hand in hand. A series of recent investigations that culminated in the construction of several Mathematica packages that are based on Mellin-Barnes techniques, Method of Regions, hypergeometric function theory, etc., is reviewed in this talk to encourage the community to explore the use of these packages. The talk will be easily accessible to early Ph. D. students in elementary particle physics and field theory, and also to other researchers who use hypergeometric functions such as in quantum chemistry and other branches of physics and mathematical physics.

The Higgs boson was discovered by the LHC experiments in 2012. Several Beyond the Standard Model theories predict this particle to be a portal to new physics interactions. Recent measurements hint at the branching fraction to undetected particles could be as high as 16%. It is thus important to directly search for possible rare and exotic decay modes of the Higgs boson. In this talk, we will discuss exotic Higgs boson decays in the context of a two-Higgs doublet model extended with a complex scalar singlet (2HDM+S) using data from the CMS experiment at LHC's Run-2. The findings in the H→ aa → ττbb final state analysis will be presented. We will also discuss how the CMS experiment trigger system can be utilized to find rare Higgs boson signatures, including new strategies being implemented for LHC Run-3.

Whether neutrinos are Majorana or Dirac particles is an open question. Theoretically, it is also possible that neutrinos are pseudo-Dirac, which are fundamentally Majorana fermions, but essentially act like Dirac fermions in most experimental settings, due to small active-sterile mass splitting. Such small values of mass splitting can only be accessed via active-sterile oscillations over an astrophysical baseline, or via decays of neutrinos over a cosmological time scale. In this talk, we will use the multi-messenger observation of high-energy neutrino sources and the excess extragalactic radio background to probe two different regimes of the pseudo-Dirac neutrino parameter space. 

With two Nobel prizes, each for the integer and fractional quantum Hall effects, and the electronics states being dubbed as the first realization of a topological insulator, along with a spinor version of it discovered in 2005, the research on the topic has created never-ending interest in the community. While the integer version of it invokes non-interacting electrons and can be understood easily, the fractional variant is suggestive of a strongly interacting scenario, and hence required the best minds to solve the problem. Backed by a robust Laughlin (variational) wavefunction, J.K. Jain proposed a composite Fermion picture that reduces an interacting problem to a non-interacting one with several of the 'daughter fractions' given by a 'hierarchy picture' that supports emergence of certain fractional plateaus that are precluded by the Laughlin wavefunction.

Neutrinos are the second most abundant particles in the Universe after photons (i.e. in the visible Universe). We know probably everything about photons. We know about the other less abundant particles as well. Interpolating, we ought to know about neutrinos as well, right? Well, they are spin-1/2, neutral and massless elementary particles. But that has been proposed around a 100 years ago. Is that the whole story? We don't know. One improvement on this front is that they are not massless. But what's their mass? They come in three flavours, but which one is massive and which is lightest? In this talk, we will try to tackle some of these questions with the help of a phenomenon known as NEUTRINO OSCILLATIONS. We will also discuss in brief other neutrino related activities going on around the world which are linked in a way to the neutrino oscillation physics.

Single-photon sources play an important role in quantum optics and quantum information processing. The “Photon blockade” (PB) effect describes how the absorption of a photon in a non-linear (or anharmonic) cavity resonator blocks the transmission of the later incoming photons. As a result, one can observe an orderly output of photons one by one with strong photon antibunching. A two-level quantum emitter (2LQE) interacting with a cavity field is an important model for investigating the PB effect. This talk discusses the concept of photon blockade in a 2LQE-cavity system. Firstly, we discuss the classical theory of coherence with the example of Young’s double-slit interference and Hanbury Brown and Twiss experiment. We then introduce the quantum coherence functions and the required criteria for photon antibunching in terms of the second-order coherence function. Next, we discuss the conventional photon blockade (CPB) and unconventional photon blockade (UPB) in a 2LQE-cavity system. The CPB and UPB are based on the strong anharmonicity and quantum interference effects, respectively. We conclude our talk by highlighting the important results and the scope for future research.

The interplay between theoretical and experimental physics is the driving force behind many of the most significant advances in science. This general talk will explore how these two branches of physics work together to drive the discovery, design, and development of new materials with unprecedented properties. Through examples in areas such as nanomaterials, ferroelectric materials, and advanced alloys, we will illustrate how theoretical predictions guide experimental synthesis and characterization, while experimental results, in turn, refine and challenge existing theories. For instance, developing ferroelectric and magnetoelectric materials involves complex theoretical modelling to predict their behaviour under different conditions, followed by experimental validation to optimize their properties for applications in memory devices and sensors. This talk will also highlight the inner workings of experimental physics research labs, providing insights into the methodologies, tools, and challenges faced in the process of material discovery. Additionally, we will present some recent experimental data on the magnetoelectric effect, demonstrating the practical outcomes of the theory-experiment synergy. By highlighting similar collaborative research, the talk aims to emphasize how the continuous interaction between theory and experiment accelerates the development of materials that underpin technological innovation and address global challenges.

In this talk, I will introduce the concept of deep neural networks and backpropagation and then show how my group has implemented this idea to classify compounds into superconductors and non-superconductors. The group has also made an effort to predict the transition temperature of superconductors by training on a large database of superconductors called the SUPERCON database which is maintained in Japan. The largely unsolved challenge in all these deep learning methods is that they interpolate well but extrapolate poorly. We want to predict new materials that superconduct at room temperature for which we have no training data so we have to extrapolate. This is an unsolved problem in machine learning. In this talk, I will introduce the concept of deep neural networks and backpropagation and then show we have implemented this idea to classify compounds into superconductors and non-superconductors. We have also made an effort to predict the transition temperature of superconductors by training on a large database of superconductors called the SUPERCON database which is maintained in Japan. The largely unsolved challenge in all these deep learning methods is that they interpolate well but extrapolate poorly. We want to predict new materials that superconduct at room temperature for which we have no training data so we have to extrapolate. This is an unsolved problem in machine learning.

In this work, we achieved multiferroicity in a 2D heterostructure by combining a 2D ferromagnet with a 2D ferroelectric material. Electrical control of atom-thick van der Waals (vdW) ferromagnets is crucial for the development of future magnetoelectric nanodevices. We demonstrate that non-volatile and reversible electric control of 2D ferromagnets can be accomplished through this method. Additionally, we highlight the industrial applications of such heterostructures in memory and FET (Field-Effect Transistor) construction.

The choice of gravity model, i.e., Renormalization Group correction to General Relativity (RGGR), can potentially explain the kinematics of dark matter deficit galaxies such as NGC1052-DF2 and NGC1052-DF4. Similarly, we investigate the dynamics of a diverse collection of rotationally supported galaxies in the Spitzer Photometry for Accurate Rotation Curve (SPARC) catalog. SPARC compiles mass models for 175 galaxies with observed rotation curves measured in the near-infrared region. We phenomenologically constrain the RGGR model parameter and the mass-to-light ratio for a large sample of galaxies. Our statistical analysis finds RGGR to be a consistent fit for the observed galaxy kinematics. Additionally, our study validates the expected linear relation between the RGGR model parameter and the baryonic mass for the SPARC galaxies. Our findings motivate an alternative understanding in contrast to the dark matter explanation of the galactic dynamics.

Certain aspects of critical phenomena were not understandable without the renormalization group. In this talk, it will be emphasized those aspects of critical phenomena and shown how renormalization group theory can resolve those issues.

The increasing dependence on energy storage systems has experienced rapid growth, primarily driven by the need for decarbonization and the efficient harnessing of renewable energy sources like solar and wind power. Li-ion systems have historically played a pivotal role among various energy storage technologies, owing to their high energy density and lightweight properties, which are essential for providing adequate energy storage capabilities. However, specific applications, particularly in mini-grid and off-grid energy storage, emphasize factors like cost-effectiveness, environmental safety, and sustainability. In such contexts, Li-ion batteries may not be the most suitable choice due to concerns regarding safety, high costs, limited resource availability, and the use of potentially flammable electrolytes. In contrast, aqueous Zn-ion batteries have emerged as compelling alternative systems and have garnered substantial attention in the field of electrochemical energy storage for several reasons. Aqueous Zn-ion batteries can be manufactured in open environments, and they offer distinct advantages, such as high gravimetric capacity (820 mAh/g) and volumetric capacity (5855 mAh/cm3) for Zn anodes, along with a low redox potential (-0.762 V vs. SHE). These characteristics make them well-suited for use in aqueous electrolytes, and the two-electron transfer process during redox reactions enables high-energy density in Zn-ion batteries. Furthermore, Zn reserves are significantly more abundant (four times) than Li reserves, and the cost of Zn ($0.5 - $1.5/lb) is substantially lower than that of Li (~$8 - $11/lb). Zn-ion batteries typically employ cost-effective Zn salts, such as ZnSo4, as the aqueous electrolyte, which exhibits higher ionic conductivity (approximately 1 S/cm). My talk will primarily focus on the realization of high-performance Zn-ion batteries, with a particular emphasis on strategies for suppressing dendrite growth, developing high-capacity cathodes, and designing special electrodes tailored for planar Zn-ion micro-batteries.

The dark sector may be very rich with multiple possibilities regarding the number of stable particles, their nature and production mechanism. In this talk, I'll first discuss the motivation for multi-component and asymmetric dark matter, the stabilizing symmetries, and the role of conversions in determining the final relic abundance. In the second part, I'll present a model that involves two DM components which may be symmetric/asymmetric and produced via either freeze-in or freeze-out. We investigate the role played by asymmetries in determining the yield and nature of dark matter, and provide a mechanism to realize asymmetric freeze-in. In some scenarios, the energy density of the particle may be determined by an asymmetry even if it is asymptotically symmetric in nature. The model also predicts an interesting monochromatic neutrino line that may be searched for at neutrino telescopes.

The remarkable precision of LEP and other lepton colliders in the past has been instrumental for testing and understanding the Standard Model. In particular, it was possible to estimate, by their effects on loop quantum corrections, the top quark and Higgs boson masses before observation of these particles at hadron colliders. At a time when Nature asks broad questions to which the Standard Model offers no answers, particle physicists are eager to use all available means that could give hints towards physics that go beyond the present framework. Colliders of the next generation might well play this exploratory role. However, precise calculations of radiative corrections within the Standard Model remain essential for future physics studies. In the talk, physics opportunities for future colliders will be described. The most demanding calculations connected with determining electroweak observables near the Z-boson resonance will be discussed. The connection between high-energy and intensity low-energy frontier studies will also be discussed.

Recent evidence of the decay $B \to K+ inv $ by Belle II show around a 3 \sigma deviation from the standard model prediction. This measurement is explained with a dark scalar, S, that couples to the standard model particles and a massive sterile neutrino, N, which mixes with the active neutrinos. The flavor changing neutral current process $B \to K S \to K \nu \bar{\nu}$ then explains the Belle II measurement. The same set up can also explain the excess in electron like events observed in the MiniBooNE experiment and the muon g-2. I will discuss how the massive sterile neutrino can be probed in charged current B decays such as $B \to D^(*) \ell N $ at Belle II FASER and the DUNE near detector experiments.

Inflationary cosmology, although empirically successful in explaining the universe as we observe today, fundamentally it is not satisfactory to address all the issues. I will point out a couple of shortcomings in the existing explanation of generation of primordial density perturbations which are interpreted as the "seeds of structure formation". After stressing some problems associated with the usual choice of an all homogeneous and isotropic quantum vacuum state (Bunch-Davies vacuum), a complete guide will be provided to construct an alternative quantum state which is manifestly inhomogeneous and anisotropic (referred as the T-vacuum). Finally, I shall ponder on the physical implications of this novel vacuum state.

The Standard Model (SM) of particle physics has been highly successful in describing the fundamental particles and their interactions. The discovery of the Higgs boson at the Large Hadron Collider (LHC) was a significant achievement, which was the last missing piece in SM. However, the Higgs boson self-coupling is yet to be measured. I will discuss its present status and prospects at future LHC runs. Then, I will outline exotic decays of the Higgs boson, still allowed by the current experimental data. The SM Higgs sector is extended further with additional scalars to explain several experimental observations and theoretical issues. One such well-motivated beyond the SM (BSM) model is the minimal supersymmetric extension of the Standard Model (MSSM). While the current runs of the LHC have not yielded any new particles, it serves as a catalyst for refining our search strategies and exploring alternative channels within the allowed parameter space. In this context, I will present BSM Higgs searches and a possible signature in terms of long-lived particles.

The low-energy physics of fractional quantum Hall (FQH) states—a paradigm of strongly correlated topological phases of matter—to a large extent is captured by weakly interacting quasiparticles known as composite fermions. In this talk, I will demonstrate that some high-energy states in the FQH spectra necessitate a different description based on parton quasiparticles. The Jain states at filling factor ν = n / ( 2 p n ± 1 ) with integers n, p ≥ 2 support two kinds of collective modes: In addition to the well-known Girvin-MacDonald-Platzman (GMP) mode, they host a high-energy collective mode, which we interpret as the GMP mode of partons. I will elucidate observable signatures of the parton mode in the dynamics following a geometric quench. I will also present a microscopic wave function for the parton mode and demonstrate agreement between its variational energy and exact diagonalization. These results point to partons being “real” quasiparticles which, in a way reminiscent of quarks, become observable only at sufficiently high energies.

Modern scientific endeavors are increasingly becoming data-centric across a spectrum of scientific disciplines, including cosmology and astrophysics, biomedical sciences, material and drug discovery, and finance, to name a few. The increased focus on data has simultaneously led to a massive surge in data collection across disciplines, such that the term Big Data has entered common parlance. The advent of Big Data has simultaneously brought to front two of the central statistical challenges of our times: the detection and classification of structure in extremely large, high- dimensional, data sets, demanding increasingly more sophisticated methods to detect pattern and glean meaningful information. Among the most intriguing new approaches to this challenge is “TDA,” or “Topological Data Analysis,” one of the primary aims of which is providing non-metric, but topologically informative, pre-analyses of data which make later, more quantitative, analyses feasible. Algebraic and computational topology at the level of homology and persistent homology are the foundational pillars of TDA. These developments on the topological side are recent and add value to the already existing computational geometric tools and methodologies employed in investigating the data in various fields, such as the Minkowski functionals. Apart from presenting tools for data analysis, topo-geometrical formalisms also provide for methods resulting in state-of-the-art visualization techniques that are based on strong mathematical foundations.

This talk will have two distinct parts devoted to the theoretical background and experimental applications respectively. In the first part of my talk, I will present a summary of the theoretical and computational aspects of geometry and topology from the viewpoint of data analysis. Subsequently, in the second part of the talk, I will highlight applications by presenting examples from cosmological and biological datasets. I will begin with presenting an analysis of the topological properties of the temperature and polarization maps of the (CMB) radiation obtained by the Planck satellite. The CMB radiation represents the earliest visible light in the Universe and contains a treasure trove of information about the initial conditions of the Universe. The CMB also represents the largest canvas on which to test the fundamental assumptions of the cosmological principle. Within this context, I will discuss some of the anomalies that the CMB temperature and polarization maps exhibit with respect to the simulations based on the standard cosmological model, which assumes the initial fluctuation field to be an instance of an isotropic and homogeneous Gaussian random field. As a second example, I will present an analysis of the properties of growing bacterial colonies through topological methods.

One of the major challenges in condensed matter physics is to understand how many interacting electrons form different phases of matter. One such exotic phase of matter formed solely due to the presence of interactions is superconductivity. Ever since their discovery, superconductors have found applications across diverse fields of science starting from medical science to high energy and astrophysics, apart from the long sought after applications, like lossless power transmission and magnetic levitation trains. The practical applicability of superconductors depends heavily on the temperature regimes where they exhibit superconductivity. It is largely believed that electron-electron interactions hold a key in achieving high superconducting transition temperatures. Recently, superconductors have been combined with topology to obtain topological superconductors with potential applications for topological quantum computation. Real-world materials bring in disorder as an additional important component. Taking an example of a high temperature superconductor, I will show how three way interplay of strong electronic correlations, topology, and disorder generates a new quantum phase of matter: a fully gapped "phase crystal" state that breaks both translational and time reversal invariance, characterized by a modulation of the d-wave superconducting phase co-existing with a modulating extended s-wave superconducting order. In contrast to conventional wisdom, this phase crystal state is remarkably robust to omnipresent disorder, but only in the presence of strong correlations, thus giving a clear route to its experimental realization [1]. I will further discuss how understanding the roles of interactions, topology, and disorder can not only answer various existing unsolved puzzles, but also provide pathways to discovering new materials with novel functionalities.

The population of stellar mass Black Hole X-ray Binaries (BH-XRBs) residing outside our Galaxy includes Ultra-luminous X-ray binaries (ULXs) with luminosity >10³⁹ erg s^-1, as well as the High Mass X-ray Binaries (HMXBs) with luminosity of 10³⁷ - 10³⁹ erg s^-1. Some of these HMXBs, such as M33 X-7, IC10 X-1 and NGC 300 X-1 are home to the most massive stellar mass BH-XRBs ever found which makes them an excellent laboratory to study the binary evolution of massive stars. While the mass accretion in most of these HMXBs are governed by stellar wind from the massive companion, some of the sources (Ex: LMC X-3) are found to be powered by Roche lobe overflow. Thus, studying the distinct spectral and temporal X-ray properties in these sources would provide a link between extragalactic sources and their Galactic counterparts. These young extragalactic HMXBs also act as an ideal system to explore the hypercritical mass accretion theory since most of them are found to have evolved to have rapid spin. Thus, extensive observation and study of the extragalactic BH-XRBs is necessary in order to yield constraints important mechanisms such as mass accretion mechanism and geometry of accretion disk in these systems.

First, I will discuss a U(1)X⊗Z2⊗Z2′ extension of the Standard Model. The model contains three right-handed neutrinos (RHNs) NR and two scalars Φ, χ, additionally, which charged under U(1)X gauge only. NR3 fermion is odd  under Z2 and scalar χ is odd under Z2′ symmetry. Hence, both χ and NR3  contribute to the observed dark matter relic density, leading to two-component dark  matter candidates. We then study relic density and direct detection limit on our  model while taking into account the constraints coming from collider studies. Next, I will discuss a pseudo scalar DM in the above discussed model but no Z2 symmetries. The massive pseudo scalar results from breaking of  U1(x) gauge. We study for the allowed parameter space for the pseudo scalar as DM via dark matter lifetime constraints, relic density constraint and direct  detection bounds.

Single photon emitters that can work on demand, that is, emit when triggered are of utmost importance for practical implementation of quantum information processing. For efficient single photon emitters, one would need to optimize the overall efficiency that includes both the quantum efficiency as well as the collection efficiency. Solid-state equivalent of 2-level systems like quantum dots or nanoparticles and colour centres in materials like nanodiamonds, SiC, among others are studied as dipole emitters that are embedded in different hosts. For higher quantum efficiency, manipulation of the photonic local density of states in the host medium is necessary to achieve maximum Purcell factor. Further design would require efficient out-coupling of photons to the far-field which is, typically, air or an optical fiber. In this talk, I will present dipole emitters in photonic crystal microcavity as well as metamaterials to enhance their overall emission efficiency in particular directions..

Quantum Hall effect is the quantization of conductivity in two-dimensional conductors in the presence of an external magnetic field. It occurs in two flavours: the integer quantum Hall effect; and the fractional quantum Hall effect. The former can be understood in terms of non-interacting electron cloud, but the latter requires interactions. The effect arises from the Landau quantization of the electron states in the presence of the external magnetic field. And, quantization of the conductivity is closely related to the Berry phase of the electrons. We shall explore this relation in the presentation.

While advanced nodes and newer materials are key to the growth of semiconductor industry, there is only so much that can be achieved by following the Moore’s law. Focus also needs to be shifted towards the expanding applications that the era of IoT & AI have brought along. Wafer fabrication equipment companies need to solve increasingly complex materials driven problems and help to accelerate time-to-market. In order to do that we need to capture massive data and critical info, make it structured, accessible and searchable. We need to develop tools and solutions with innovative usage of sensors and leveraging recent progress in machine learning to generate next generation predictive analytics. In a nut shell, making process equipment smarter and faster with synergistic hardware and computational enhancements. We need to be able to do faster development, qualification & ramp with predictable product performance. We need to be able to predict problems in processes/tools and find solutions even before they become a nuisance for fabs. This is where some of our new initiatives at Applied Materials come into picture. We use existing sensors and apply them to newer innovative usage to capture whatever is happening inside the process tools plasma, chamber walls & wafers. We will present some use cases in which optics and spectroscopy can be used in several innovative ways to improve their applicability and provide immense value to chip making companies.

The death of a star due to gravitational collapse results in the formation of astrophysical compact objects like white dwarfs, neutron stars and black holes. We focus our studies on stellar mass black holes that appear in accretion powered X-ray binary (XRB) systems. XRBs are known to produce X-ray outbursts, during which the flux from the source increases above its quiescent state and remain so for a duration of a few weeks to years. Using space based X-ray observatories (RXTE, Swift, NuSTAR, AstroSat and MAXI), we observe black hole XRBs (XTE J1859+226, GX 339-4, IGR J17091-3624, GRS 1915+105 & MAXI J1535-571) and model the temporal and spectral data to understand the physical processes that lead to the emission from the sources. We modelled the Quasi-periodic Oscillation (QPO) features in the power spectra of BHBs and their time evolution was explained with the propagation of shocks in the accretion flow. Further, we modelled the broadband energy spectra (0.5 – 150 keV) to understand source characteristics (eg: state transitions, flux contribution from disc and corona) using phenomenological models and estimated accretion parameters like accretion rates and size of compton corona (shock radius) using the two-component accretion flow model. Following this, we used three indirect methods to estimate the mass range of black holes (GX 339-4, IGR J17091-3624) whose mass cannot be estimated dynamically. Following this, I will present the properties of one of the most recently discovered BHB (MAXI J1535-571) and the characteristics of high frequency QPOs in the source GRS 1915+105 using observations from India’s first multi-wavelength astronomy satellite (AstroSat). Finally, I will discuss machine learning techniques for spectral state classification.

In the quest for realization of scalable on-chip quantum technology, semiconductor quantum dots (QDs) have emerged as a potential candidate. With the advanced lithography techniques it is possible now to grow a quantum dot at desired location inside a photonic crystal microcavity. As a result, new solid state on-chip cavity quantum electrodynamics (cavity-QED) systems have been developed. In this seminar I will discuss proposals for generating entangled photon sources, two-photon sources, microlasers and phonon assisted two-photon resonant interactions.

The Hyperspectral imaging used for the first time by NASA for remote sensing application originates by combing two most powerful subjects; Imaging Science and Spectroscopy. Whereas the human eye visualize objects over a narrow band of the electromagnetic spectrum (400 – 700nm); Hyperspectral imaging device could record images with high spatial and spectral resolution over a broad range of the electromagnetic spectrum. This fusion of spatial and spectral information opens a new avenue for analysis, and a unique opportunity for processing and understanding characteristics of an image scene. The goal of hyperspectral imaging is to obtain the spectrum for each pixel in the image of a scene, with the purpose of finding objects, identifying materials, or detecting processes.

Today, hyperspectral imaging systems are available for applications in astronomy, agriculture, biomedical imaging, geosciences, physics, and surveillance. In this presentation I will describe few application areas (mainly application of Hyperspectral Imaging in digital pathology) we are working in past few years and pathways to make cost-effective hyperspectral imaging solution to different fields.

Furthermore, I will discuss the journey of an Entrepreneurship to bring this technology to a viable product in Healthcare Industry.

The intriguing question, why the present scale of the universe is free from any perceptible footprints of rank-2 antisymmetric tensor fields (generally known as Kalb-Ramond fields), is addressed. A quite natural explanation of this issue is given from the angle of higher-curvature gravity, both in four- and in five-dimensional spacetime. The results here obtained reveal that the amplitude of the Kalb-Ramond field may be actually large and play a significant role during the early universe, while the presence of higher-order gravity suppresses this field during the cosmological evolution, so that it eventually becomes negligible in the current universe. Besides the suppression of the Kalb-Ramond field, the extra degree of freedom in F(R) gravity, usually known as scalaron, also turns out to be responsible for inflation. Such F(R) gravity with Kalb-Ramond fields may govern the early universe to undergo an inflationary stage at early times (with the subsequent graceful exit) for a wider range of F(R) gravity than without antisymmetric fields. Furthermore, the models—in four- and five-dimensional spacetimes—are linked to observational constraints, with the conclusion that the corresponding values of the spectral index and tensor-to-scalar ratio closely match the values provided by the Planck survey 2018 data.