Combining optical fibers with frequency combs provides a versatile platform for high-speed, remote, and distributed sensing of our
environment. In this talk, I will present a fiber-based electro-optic dual-frequency comb source operating at a 10 GHz repetition rate and
generating mutually coherent ultrashort (60 fs) pulses capable of multimodal sensing. Its capabilities are demonstrated through rapid
linear and nonlinear spectroscopy applications, such as opto-mechanical ultrasound sensing and coherent anti-Stokes Raman spectroscopy. I will
also discuss potential application avenues across multiple scales, including distributed monitoring of agriculture through ultrasound,
fiber-integrated particulate matter sensing and potentially quantum enhanced sensing. Integrating these techniques with India’s extensive
public fiber infrastructure could enable multipurpose networks that combine communication with large-scale environmental monitoring.

In general relativity, electromagnetic waves in the geometric-optics approximation follow null geodesics independently of polarization, while the polarization itself is transported along the ray. I will review this standard picture, including ambiguities in defining gravitational polarization rotation, and then discuss how birefringence can arise through modified classical couplings or quantum corrections.
I will then turn to finite-frequency corrections within ordinary general relativity and Maxwell theory, where photon helicity affects ray propagation beyond leading geometric optics. Recent results on the resulting gravitational birefringence, formal aspects of null-particle dynamics, and some observational implications will be presented.

Helical-coil (HC) targets provide a unique all-optical approach for manipulating laser-driven proton beams using electromagnetic pulses generated during the laser-target interaction itself. By tailoring the interaction between the propagating pulse and the proton beam, HC targets can simultaneously guide, energy-select and post-accelerate laser-accelerated protons within a compact target-integrated structure. Over the past decade, this concept has evolved from proof-of-principle demonstrations to a versatile beam-conditioning platform capable of controlling both the transverse and longitudinal phase space of laser-driven ion beams. This talk will provide an overview of the HC concept and its development, covering experimental demonstrations of beam collimation, spectral shaping, post-acceleration, scaling to higher-power laser systems, multi-stage acceleration schemes, and recent advances in longitudinal phase-space rotation and temporal compression. The prospects of HC-based manipulation for next-generation laser-ion accelerators and emerging applications will also be discussed.

Intermittency is ubiquitous in nature, where systems switch between distinct modes of dynamics in response to their surroundings or to events occurring during their evolution [1,2]. In the context of target search, such switching provides a natural way to combine qualitatively different modes of exploration. In this talk, I will develop a general perspective on intermittent search, beginning with facilitated diffusion as a paradigmatic example [3], and then discuss ego-eco-centric intermittency, where switching is mediated by external factors, primarily the environment [4]. I will next introduce a new class of event-driven strategies, in which the crossing of a threshold itself triggers intermittency, leading to an efficient collective search dynamics [5]. Across these examples, I will explore how intermittency reshapes the statistics of search and reveal a remarkably general consequence: suitably designed switching can generate a universal gain that persists irrespective of the underlying complexity of the system.

Hyperbolic lattices constitute a unique platform to study various novel quantum phenomena on a negatively curved space and identify the imprints of spatial curvatures therein. In this talk, first I will show a simple classification scheme on the family of two-dimensional bipartite hyperbolic lattices, resulting from simple but canonical spin-independent tight-binding model for free electrons, yielding three classes of ballistic quantum fluids on negatively curved space, namely Dirac liquids, Fermi liquids, and flat bands, that are, respectively, characterized by a vanishing, a finite, and a diverging density of states near the band center or zero-energy. Next, I will show that such systems can be susceptible to different types of spontaneously ordered phases (such as the charge and spin density waves) once Hubbard-like electronic interactions are considered, giving rise to dynamic magnetization in half-filled systems. In the second half of the talk, I will exclusively focus on hyperbolic Dirac systems in which orderings can only take place beyond critical strengths of interactions via a quantum phase transition. I will propose two realistic approaches to trigger such dynamic mass generations on curved space Dirac liquids at sufficiently weak interactions. I show that (a) the application of external magnetic fields and rotationally symmetric strain give rise to a finite density of states near zero energy in noninteracting systems, inducing various mass orderings at weak coupling. Finally, I will discuss the role of disorder or impurities in hyperbolic Dirac liquids. I show that, contrary to our traditional wisdom, planar dirty hyperbolic Dirac liquids show two distinct quantum phase transitions as the disorder strength is gradually increased in the system. First, the ballistic system undergoes a semimetal-to-metal transition at moderate disorder strength, which is subsequently followed by the Anderson metal-to-insulator transition, both being absent in two-dimensional Euclidean Dirac liquids, realizable on honeycomb lattices, for example. I will close the talk with some possible future directions to further unfold unique quantum aspects of hyperbolic crystals.

Two dimensional (2D) magnetic crystals Fe-Ge-Ga-Te exhibits promising features, such as large anomalous Hall effect (AHE), current-induced magnetization switching, and the stabilization of magnetic skyrmions, which are highly beneficial in spintronic-based memory devices[1-3]. However, experimental studies utilizing 2D magnetic materials have been largely limited to micrometer-sized flakes exfoliated from bulk single crystals. One of the major drawbacks of exfoliation methods is the non-uniform surface of films, which makes integration into conventional device fabrication schemes challenging. In this work, we present the epitaxial growth of large-scale Fe3XTe2 (X: Ge,Ga) 2D ferromagnet on graphene/SiC template using molecular beam epitaxy (MBE) [4,5]. The presence of same set of (00L) Bragg reflections for both Fe3GeTe2 (FGeT) and Fe3GaTe2 (FGaT) indicates the formation of isostructural phase with a space group P63/mmc, as shown in Figure 1(a,b). X-ray Magnetic Circular Dichroism (XMCD) measurements were performed on FGeT and FGaT films. Using sum-rule analysis, the total magnetic moment (μtotal) were determined for FGT (see Figure 1c) and FGaT (see Figure 1d) films. A nonzero μtotal for FGaT (~400 K) and FGeT (~210 K) reveals stable ferromagnetic ordering of Fe atoms in both 2D-FMs with a strong perpendicular magnetic anisotropy. The corresponding temperature-dependent magnetization (M-T) curves were further measured Superconducting Quantum Interference Device (SQUID) magnetometry. These findings are crucial for the development of energy efficient device for scalable spintronic applications.

For strongly correlated quantum systems, fundamental questions about the formation and stability of Floquet-Bloch sidebands (FBs) upon periodic driving remain unresolved. Here, we investigate the impact of electron-electron interactions and perturbations in the coherence of the driving on the lifetime of FBs by directly computing time-dependent single-particle spectral functions using exact diagonalization (ED) and matrix product states (MPS). We study interacting metallic and correlated insulating phases in a chain of correlated spinless fermions. At high-frequency driving, we obtain clearly separated, long-lived FBs of the full many-body excitation continuum. However, if there is significant overlap of the features, which is more probable in the low-frequency regime, the interactions lead to strong heating, which results in a significant loss of quantum coherence and of the FBs. Similar suppression of FBs is obtained in the presence of noise. The emerging picture is further elucidated by the behavior of real-space single-particle propagators, of the energy gain, and of the momentum distribution function, which is related to a quantum Fisher information that is directly accessible by spectroscopic measurements.