ICTS

Understanding the fate of interacting quantum systems away from equilibrium remains a central challenge in statistical physics. While the contrast between ergodic (thermal) and many-body localized (MBL) phases is now well established, the possibility of (rare) intermediate nonergodic extended regimes and their dynamical signatures continues to attract significant interest. In this talk, I will present evidence for a many-body critical (MBC) phase in interacting quasiperiodic systems, showing an intermediate behaviour between ergodic and MBL phases. Such systems, being both periodically driven and undriven ones, possess a critical phase in the noninteracting limit from which the interaction-induced MBC can emerge. Remarkably, we find evidence of unusual Widom lines on the phase diagram in the form of lines of pronounced peaks or dips in the Fock-space localization properties inside the MBC and MBL phases. These Widom lines either emerge as a continuation of the precursor phase transition line terminating at the triple point, or originate from a phase boundary.

Projected ensembles—defined as ensembles of pure states on a subsystem conditioned on measurement outcomes on its complement—provide probes of quantum information beyond the reduced density matrix. This perspective has enabled a refined notion of quantum equilibration in the form of deep thermalisation, wherein projected ensembles dynamically approach universal maximum-entropy ensembles in closed quantum systems. In this talk, I will introduce a distinct paradigm of deep thermalisation for mixed states, which differs qualitatively from the pure-state case. In this formulation, the deep thermal ensemble arises by tracing out auxiliary degrees of freedom from a maximum-entropy ensemble defined on an augmented system, with the resulting ensemble structure depending explicitly on the entropy of the initial state. I will demonstrate that such ensembles emerge dynamically in generic, locally interacting chaotic spin chains. I will then show how the statistical mechanics of mixed-state projected ensembles constrains their role as probes of information scrambling, leading to measurement-invisible quantum correlations (MIQC)—an emergent phenomenon in which extensive multipartite entanglement coexists with vanishing measurement influence between subsystems. Finally, I will discuss future directions that leverage mixed-state deep thermalisation to develop finer probes of quantum information, including access to correlations in replicated Hilbert spaces that are inaccessible to conventional correlation functions.

Quantum many-body scars (QMBS) represent a mechanism for weak ergodicity breaking, characterized by the coexistence of atypical non-thermal eigenstates within an otherwise thermalizing many-body spectrum. In this work, we revisit the spin-1 XY model on a periodic chain and construct several new families of exact scar eigenstates embedded within its extensively degenerate manifolds that owe their origins to an interplay of U(1) magnetization conservation and chiral symmetries. We go beyond previously studied towers of states and first identify a novel set of interference-protected eigenstates resembling Fock space cage states, where destructive interference confines the wave function to sparse subgraphs of the Fock space. These states exhibit subextensive entanglement entropy, and when subjected to a transverse magnetic field, form equally spaced ladders whose coherent superpositions display long-lived fidelity oscillations. We further reveal a simpler organizing principle behind these nonthermal states by using the commutant algebra framework, in particular by showing that they are simultaneous eigenstates of non-commuting local operators. Moreover, in doing so, we uncover two more novel families of exact scars: a tower of volume-entangled states, and a set of mirror-dimer states with some free local degrees of freedom. Our results illustrate the power and interplay of interference-based and algebraic mechanisms of non-ergodicity, offering systematic routes to identifying and classifying QMBS in generic many-body quantum systems.

I will discuss some aspects of junctions of graphene quantum Hall states

Fracture or cracking is usually studied as two-dimensional mosaics. The fracture surface which opens up in the third dimension, is along the thickness of the sample. The thickness is usually very small compared to the lateral dimensions of the pattern. A spectacular and distinctive departure from these everyday examples of cracks are columnar joints. Here, molten volcanic lava, by the sea, cools and cracks under appropriate thermal and elastic conditions, causing the crack system to grow downward, creating long, vertical columns with polygonal cross-section. The focus of the study is on the elongated interfaces of these columns: how the cross-section of their outlines gradually undergoes a metamorphosis from a disordered-looking Gilbert tessellation to a well-ordered hexagonal Voronoi pattern. As the columns grow downwards to lengths of several metres (in natural systems), their outline continuously changes, the centre may shift, causing the column to twist. For the first time the evolution of these crack mosaics has been simulated and mapped as a trajectory of a 4-vector tuple in a geometry-topology domain. The trajectory of the columnar joint systems is found to depend on the crack seed distribution and crack orientation. An empirical relationship between system energy and the crack mosaic shape parameter has been proposed based on principles of fracture mechanics. The total system energy shows a power-law dependence on shape parameter with the exponent 0.3 and the shape parameter value is 0.75, at crack maturation. The parameter values are validated by matching the proposed relation with energy estimates existing in literature. The relation not only matches the visible changes in geometry but provides a feasible measure of energy of the system. The geometric energy for the polygonal mosaics in the transverse section has also been estimated as function of time. The geometric energy moves towards a minimum as the mosaic becomes more Voronoi-like at maturation.

We study a site percolation model on a two-dimensional square lattice in which bonds between occupied nearest neighbors incur an energy cost. This leads to a competition between entropy-driven cluster growth and energetic suppression (or enhancement) of the connectivity. Using Monte Carlo simulations and real-space renormalization group methods, we show that the percolation threshold shifts continuously with bond energy. We also discuss the variation of the critical exponents with varying energy cost.

We consider an analytically tractable model that exhibits the main features of the Page curve characterizing the evolution of entanglement entropy during evaporation of a black hole. Our model is a gas of non-interacting fermions on a lattice that is released from a box into the vacuum. More precisely, our Hamiltonian is a tight-binding model with a defect at the junction between the filled box and the vacuum. In addition to the entanglement entropy we consider several other observables, such as the spatial density profile and current, and show that the semiclassical approach of generalized hydrodynamics provides a remarkably accurate description of the quantum dynamics including that of the entanglement entropy at all times. Our hydrodynamic results agree closely with those obtained via exact microscopic numerics. We find that the growth of entanglement is linear and universal, i.e, independent of the details of the defect. The decay shows 1/t scaling for conformal defect while for non-conformal defects, it is slower. Our study shows the power of the semiclassical approach and could be relevant for discussions on the resolution of the black hole information paradox.

We investigate steady-state current fluctuations in a one-dimensional hardcore lattice gas on a ring, where particles undergo symmetric, extended-range hopping under mass-conserving dynamics. The hop length is drawn from a distribution characterized by a length scale—referred to as the hopping range—and a move is executed only if the inter-particle gap is greater than or equal to the selected hop length. We focus on two analytically tractable cases: (i) finite-range hopping, and (ii) infinite-range hopping. In the infinite-range case, the system is known to exhibit a clustering (condensation) transition below a critical density. We show that, at the critical point, the mobility diverges, while the bulk-diffusion coefficient remains finite. This behavior contrasts with that of equilibrium systems with short-range hopping, where the bulk-diffusion coefficient typically vanishes at criticality, whereas the mobility remains finite.

Have you ever wondered what creates the noise you hear when you peel a Velcro from your bag or shoe? Are there patterns in this noise? We probe this question using a combination of high-speed imaging, acoustic emission and high-frequency displacement controlled force measurements. We find that the acoustic signal originates from the repeated detachment of hook–loop connections at the interface, which results in sporadic fluctuations in the measured force. Such burst-like activity resembles the crackling noise observed in a wide class of driven disordered systems, where energy is released through avalanches spanning a broad range of scales. By changing the peeling rate of the Velcro from 1mm/min to 500 mm/min, we find the scaling exponents in the event sized distributions and inter-event waiting times. Such a simple system as a Velcro offers insight into driven disordered interfaces by revealing patterns in seemingly mundane sounds.

We investigate the two-dimensional behavior of colloidal patchy ellipsoids specifically designed to follow a two-step assembly process from the monomer state to mesoscopic liquid-crystal phases via the formation of the so-called bent-core units at the intermediate stage. Our model comprises a binary mixture of ellipses interacting via the Gay-Berne potential and decorated by surface patches, with the binary components being mirror-image variants of each other - referred to as left-handed and right-handed ellipses according to the position of their patches. The surface patches are designed so as in the first stage of the assembly the monomers form bent-cores units, i.e. V-shaped dimers with a specific bent angle. The Gay-Berne interactions, which act between the ellipses, drive the dimers to subsequently form the characteristic phase observed in bent-core liquid crystals. We numerically investigate -- by means of both Molecular Dynamics and Monte Carlo simulations -- the described two-step process: we first optimize a target bent-core unit and then fully characterize its state diagram in temperature and density, defining the regions where the different liquid crystalline phases dominate.

Environment-mediated interactions provide a minimal route to many natural and synthetic sytems leading to various emergent pattern formations. In this talk, I will be discussing autochemotaxis using an active random walker model, where the dynamics of agents are coupled to their self-generated chemical field, focusing on how local feedback mechanisms shape emergent phenomena.

We first study a self-interacting walker that deposits a chemical trail while moving. The chemical field attracts the walker and also evaporates in time, while the chemotactic response saturates at high concentrations. The interplay between deposition, evaporation, and nonlinear feedback generates a rich dynamical phase behavior, including transitions between extended and compact trajectories and a re-entrant regime where stronger feedback leads to effective delocalisation. This framework demonstrates how environmental memory can control transport and trajectory morphology even at the single-particle level.
 
We then extend the model to the collective behaviour of many interacting agents, where the chemical deposition is controlled by the motility of individuals. The resulting stochastic dynamics lead to spontaneous self-organization into network-like structures—fractal webs, bands, and aggregates—depending on the rates of chemical production and decay. These results illustrate how simple microscopic rules can produce complex collective structures reminiscent of biological pattern formation.

Active Brownian motors, a class of inherently non-equilibrium systems, exhibit autonomous directed motion due to internal self-propulsion mechanisms. Leveraging the random motion of active Brownian particles within spatially asymmetric environments has demonstrated potential applications in micro-scale sorting, nano-scale cargo transport, and precise drug delivery systems. In this work, we examine the performance of chiral active Brownian particles within an asymmetric sawtooth potential. We analyze the Power output, energy input, thermodynamic efficiency, entropy, and fluctuations under these conditions through extensive simulations. We offer insights into the system’s dynamical behaviors, where we obtained at the non-adiabatic limit, the efficiency can be enhanced with increasing translational diffusion coefficient, hence attaining stochastic resonance. We have also shown how efficiency increases with chirality and validated the fluctuation theorem for entropy. The correlation between efficiency and entropy is shown at moderate values of chirality, and when the distributions of efficiency are plotted, it is observed that with chirality, the fluctuations no longer dominate the mean values, showing it is a good physical quantity for measuring the overall performance of the system.

While many organisms stop growing after they reach a target size, in many others, growth occurs throughout their life. What physical mechanisms distinguish determinate and indeterminate growth? What sets the final size and growth rates? Here, we develop a minimal continuum model where (i) growth, defined as an increase in the macroscopic size of the system, is implicit (not prescribed) (ii) the domain is deformable (iii) complexities associated with signaling morphogens and growth anisotropy are neglected. In our minimal model, bounded and unbounded growth result from the competition between material properties of the tissue and active stresses driven by cell proliferation. There are two phases: One where growth halts after reaching a final size (determinate growth), and the other where the domain keeps growing linearly in time (indeterminate growth). Analysis of the steady state fields in the controlled growth phase reveals that the final size is a scaled version of the initial size, with the scaling dependent on parameters like the elasticity, magnitude of active stress and homeostatic density of the tissue. For low birth-death rates, the model also shows tissue-scale oscillations. In 2D, the two phases persist. However, growth is isotropic and the expression for final size only acquires a dimension-dependent modification.Â

Both noise and loss are thought to be detrimental to quantum properties and generally lead to a featureless steady state. I will talk about how fluctuating the loss rate of a simple two-site system can stabilize a limit cycle with large average entanglement, which are absent without the noise.

In most of works related to Boussinesq approximation, constant brunt-Vaisala frequency (N) is assumed. However, in oceans, N does not take constant value, through out the depth of the ocean and it varies with the depth of the ocean. In most of the cases, it is surface intensified, which means N has highest value near the surface of the ocean up to 200 meters from the top and then from 200 m to the bottom of the ocean, it remains constant. 
 
 In my recent work, it is found that for stably stratified case, a columnar vortex breaks down into quadrupolar structure and for unstratified case it breaks down into tripolar structure in a plane Couette flow. This work has been performed using first-principles classical 3D molecular dynamics simulations in a Yukawa liquids, which is also called a Complex plasma. These liquids often remains in strongly correlated regimes and it is non-newtonian in nature. We can ask several of questions, such as , what happens to the aforementioned system when subjected to non-linear stratification, what is the effect of strong correlations, how a conventional liquid behave under such circumstances? These questions will be addressed during the poster presentation.

We study the nonequilibrium ordering dynamics of antiferromagnetically coupled Kuramoto oscillators on lattices. In one dimension, the system develops zigzag order but exhibits anomalously slow coarsening, with defect density decaying as ( D(t) \sim t^{-1/4} ) despite diffusive scaling of the characteristic time ( t_c \sim N^2 ). This coexistence of a decay exponent ( \delta = 1/4 ) and dynamical exponent ( z = 2 ) indicates a breakdown of standard coarsening behavior. We show that defect motion is strongly constrained by the underlying zigzag structure, leading to slow annihilation dynamics. A continuum description involving competing second- and fourth-order terms explains the observed scaling. In two dimensions, geometric frustration prevents long-range order, although the initial decay remains similar. These results demonstrate how frustration and continuous phase variables can produce anomalous relaxation in deterministic systems.

We study coarsening in achiral banana shaped bent-core liquid crystals by quenching them from high concentration polar smectic (SmX) phase to lower concentrations that favour the enigmatic twist-bend (TB) phase [1,2]. Our novel result is an intermediate splay-bend state prior to the asymptotic TB phase. The latter grows via the annihilation of beta lines that are analogous to string defects in the usual nematic liquid crystals [3]. Moving ahead, our observations and methodologies are relevant for a large class of chiral soft matter systems that are unraveling novel topological knots and their self-assembly [5,6].
 
 [1] A. Jakli, O. D. Laverntovich, and J. V. Selinger, Rev. Mod. Phys. 90, 045004 (2018). [2] I. Dozov, Europhys. Lett. 56, 247 (2001).
 
 [3] N. Birdi, N. B. Wilding, S. Puri, and V. Banerjee, Soft Matter 21, 4606 (2025).
 
 [4] J.-S. B. Tai and I. I. Smalyukh, Science, 365, 1449 (2019).
 
 [5] R. Subert, G. Campos-Villalobos and M. Dijkstra, Nat Commun 15, 6780 (2024).

We consider a ladder system where one leg, referred to as the “bath,” is governed by an Aubry-André (AA)-type Hamiltonian, while the other leg, termed the “subsystem,” follows a standard tight-binding Hamiltonian. We investigate the localization properties in the subsystem induced by its coupling to the bath. For the coupling strength larger than a critical value (𝑡′>𝑡′
 
 ð‘), the analysis of the static properties shows that there are three distinct phases as the AA potential strength 𝑉 is varied: a fully delocalized phase at low 𝑉, a localized phase at intermediate 𝑉, and a weakly delocalized (fractal) phase at large 𝑉. The fractal phase also appears in a narrow region along the boundary between the delocalized and localized phases. An analysis of the projected wave-packet dynamics in the subsystem shows that the delocalized phase exhibits a ballistic behavior, whereas the weakly delocalized phase is subdiffusive. Interestingly, the narrow fractal phase shows a super- to subdiffusive behavior as we go from the delocalized to localized phase. When 𝑡′

I will be discussing how Quantum Mechanical Hilbert space H is paradoxical under SO(2,1) group action. This makes the Hilbert space susceptible to arbitrary duplications very much like the famous Banach-Tarski paradox for spheres. This has an interesting physical consequence that lower-dimensional quantum gravity emerges naturally from quantum mechanics which mediates a decoherence of the quantum system. This presents a means of decoherence that is intrinsic to the mathematical foundations of Quantum Mechanics. For this meeting, I will specially be discussing how paradoxical set theoretic concepts like equidecomposability can lead to dualities between statistical many-body and single particle systems a la Banach-Tarski and overcoming potential challenges in accomplishing such a duality. Such a duality if accomplished can grant us enormous computational advantage in computing the observables in many statistical systems.

We compute mass density correlations of a one-dimensional gas of hard rods at both microscopic and macroscopic scales. We provide exact analytical calculations of the microscopic correlation. For the correlation at macroscopic scale, we utilize Ballistic Macroscopic Fluctuation Theory (BMFT) to derive an explicit expression for the correlations of a coarse-grained mass density, which reveals the emergence of long-range correlations on the Euler space-time scale. By performing a systematic coarse-graining of our exact microscopic results, we establish a micro-macro correspondence and demonstrate that the resulting macroscopic correlations agree precisely with the predictions of BMFT. This analytical verification provides a concrete validation of the underlying assumptions of hydrodynamic theory in the context of hard rod gas.

Continuous measurement of quantum systems provides a standard route to quantum trajectories through the successive acquisition of information which further results in measurement back-action. In this work, we harness this back-action as a resource for global U(1) symmetry restoration where continuous measurement is combined with a U(1)-preserving unitary evolution. Starting from a U(1) symmetry-broken initial state, we simulate quantum trajectories generated by continuous measurements of both global and local observables. We show that under global monitoring, states containing superpositions of distant charge sectors restore symmetry faster than those involving nearby sectors. We establish the universality of this behavior across different measurement protocols. Finally, we demonstrate that local monitoring can further accelerate symmetry restoration for certain states that relax slowly under global monitoring.

How are the spatial and temporal patterns of information scrambling in locally interacting quantum many-body systems imprinted on the eigenstates of the system's time-evolution operator? We address this question by identifying statistical correlations among sets of minimally four eigenstates that provide a unified framework for various measures of information scrambling. These include operator mutual information and operator entanglement entropy of the time-evolution operator, as well as more conventional diagnostics such as two-point dynamical correlations and out-of-time-ordered correlators. We demonstrate this framework by deriving exact results for eigenstate correlations in a minimal model of quantum chaos -- Floquet dual-unitary circuits. These results reveal not only the butterfly effect and the information lightcone, but also finer structures of scrambling within the lightcone. Our work thus shows how the eigenstates of a chaotic system can encode the full spatiotemporal anatomy of quantum chaos, going beyond the descriptions offered by random matrix theory and the eigenstate thermalisation hypothesis.

Thermalization and information scrambling in out-of-equilibrium quantum many-body systems are deeply intertwined: Local subsystems dynamically approach thermal density matrices while their entropies track nonlocal information spreading. Projected ensembles, i.e., ensembles of pure states conditioned on measurement outcomes of complementary subsystems, provide higher-order probes of thermalization, converging at late times to universal maximum-entropy ensembles constrained by conservation laws. In this work we introduce the partial projected ensemble (PPE) as a framework to study how the spatiotemporal structure of information scrambling is imprinted on projected ensembles. The PPE consists of an ensemble of mixed states induced on a subsystem by measurements on a spatially separated part of its complement, while tracing out the remainder, naturally capturing scenarios involving discarded outcomes or noise-induced losses. We show that the statistical fluctuations of the PPE faithfully track the causal lightcone of information spreading, thereby revealing how scrambling dynamics is encoded in the ensemble structure. In addition, we demonstrate that the probabilities of bit-string probabilities (PoPs) associated with the PPE exhibit distinct dynamical regimes and provide an experimentally accessible probe of scrambling. Both the PPE fluctuations and PoPs display exponential sensitivity to the size of the discarded region, reflecting an exponential degradation of quantum correlations under erasure or loss. We substantiate these findings using the nonintegrable kicked Ising chain, combining numerics in the ergodic regime with exact results at its self-dual point, and extend our analysis to the many-body localized (MBL) regime using simulations supported by analytical results for the â„“-bit model. The linear and logarithmic light cones characteristic of ergodic and MBL regimes, respectively, emerge naturally from the PPE dynamics, establishing it as a powerful tool for probing scrambling and deep thermalization.

Chaotic transitions in inertial fluids typically proceed through a direct energy cascade from large to small scales. In contrast, active systems, composed of self propelled units, inject energy at microscopic scales and therefore exhibit an inverse cascade, giving rise to distinctly unconventional flow patterns. Here, we investigate an active mixture consisting of both apolar and polar self driven components, a setting expected to display richer behaviours than those found in living liquid crystal (LLC) systems, where the apolar constituent is passive. Using numerical solutions of the corresponding hydrodynamic equations, we uncover a variety of complex dynamical states. Our results reveal a non-monotonic response of the apolar species to changes in the density and activity of the polar component. In an intermediate regime, reminiscent of LLC-induced disorder, the system develops a dynamically disordered phase characterised by high-density, chaotically evolving band-like structures and by the continual creation and annihilation of half integer topological defects. We show that this regime exhibits spatiotemporal chaos, which we quantify through two complementary measures: the spectral properties of density fluctuations and the maximal Lyapunov exponent. Together, these findings broaden the understanding of complex transitions in active matter and suggest potential experimental realisations in bacterial suspensions or synthetic microswimmer assemblies.

Brownian heat engines or stochastic heat engines have attracted a lot of attention in past decades. In this talk we will discuss a general variational technique for microscopic engines that is motivated from the optimal control theory used in optimization of macroscopic heat engines. We will show how this method is robust and superior over existing methods used for Brownian heat engine optimization and how it takes into account the realistic and experimentally relevant constraints. We will apply this technique to a generally damped Brownian particle confined in a harmonic potential, and discuss how simultaneous tunning of several target functions to achieve maximum power or efficiency. We will also discuss how optimizing temperature protocols, generally overlooked in existing literature, can influence the performance of the stochastic engines.

The male fruit fly produces ∼ 1.8 mm long sperm, thousands of which can be stored until mating in a ∼ 200 ⁢ μm sac, the seminal vesicle. While the evolutionary pressures driving such extreme sperm (flagellar) lengths have long been investigated, the physical consequences of their gigantism are unstudied. Through high-resolution three-dimensional reconstructions of in vivo sperm morphologies and rapid live imaging, we discovered that stored sperm are organized into a dense and highly aligned state. The packed flagella exhibit system-wide collective ‘material’ flows, with persistent and slow-moving topological defects; individual sperm, despite their extraordinary lengths, propagate rapidly through the flagellar material, moving in either direction along material director lines. To understand how these collective behaviors arise from the constituents’ nonequilibrium dynamics, we conceptualize the motion of individual sperm as topologically confined to a reptation-like tube formed by its neighbors. Therein, sperm propagate through observed amplitude-constrained and internally driven flagellar bending waves, pushing off counter-propagating neighbors. From this conception, we derive a continuum theory that produces an extensile material stress that can sustain an aligned flagellar material. Experimental perturbations and simulations of active elastic filaments verify our theoretical predictions. Our findings suggest that active stresses in the flagellar material maintain the sperm in an unentangled, hence functional state, in both sexes, and establish giant sperm in their native habitat as a novel and physiologically relevant active matter system.

The gene regulation—the process that dictates the timing and extent of the flow of information from genetic material into proteins—lies at the core of cellular function and adaptability. Consequently, abnormal gene regulation is associated with various diseases, highlighting the critical need to understand the mechanisms of gene regulation. However, the complex network of biological reactions involving protein-protein and protein-DNA interactions, stochastic binding and unbinding of transcription factors (TFs) to promoters, and the wide range of timescales associated with these events often makes the study of gene regulation insufficient through a single experimental or theoretical technique. For instance, experimental methods, while providing significant insights into long-timescale regulatory outcomes, fall short in capturing transient molecular details. These details, however, can be complemented by computational methods such as molecular dynamics (MD) simulations. Yet, the high computational demand of MD simulations hinders their ability to access long-timescale regulatory outcomes, leaving a critical gap in understanding how molecular events propagate over time to influence gene regulation—information that is crucial for effective therapeutic design. In the first part of my talk, I will discuss how we have addressed this problem. We have developed a unified and novel computational framework termed “Molecules-to-Mechanisms”, which integrates MD-derived molecular information into a stochastic gene regulatory network to predict long-timescale regulatory outcomes. This approach has been successfully applied to a network involving the heterodimeric nuclear receptor RXR–RAR—a specific type of transcription factor whose activity is dictated by ligand binding—and has provided insights that are otherwise inaccessible to MD or experiments alone. The final part of my talk will focus on our just started effort on another aspect of gene regulation, which involves developing a statistical mechanics-based theoretical model to predict gene accessibility through the unwrapping of nucleosomes—the basic building blocks of chromatin, where 145–147 DNA base pairs remain wrapped around an octameric histone protein complex, enabling the packaging of meter-long DNA within a tiny nucleus. In particular, our efforts are directed toward developing a model that can quantitatively predict DNA accessibility as a function of the degree of post-translational modifications (PTMs) of histones—an important factor governing DNA accessibility.

We have considered here that the DNA supercoil can be treated as a spin system when spins are located on the axis forming an antiferomagnatic chain. When spins are described in the Lie algebra of the linking number can be ascertained from the Chern-Simons topology associated with the spin system .The elastic energy associated with bending (curvature) and twisting (torsion) can be formulated in terms of gauge fields. It is shown that bend and twist are not two separate entities but one depends on the other. This formalism helps us to depict the thermodynamic entropy as entanglement entropy and the entanglement of spin can be used as a resource for genetic information .This implies that the transcription of genetic information can be considered in the framework of quantum information theory. The present analysis also suggests that DNA loops in a supercoil appear as topological solitons (skyrmions).

Axons grow to extreme lengths and hence are subjected to large stretch deformations during limb or other bodily movements. Axons in the brain too undergo significant deformations even during normal activities, and can be damaged causing concussion or traumatic brain injury during head impacts. Have axons evolved special strategies to withstand large deformations? To this end, we investigate the mechanical responses of microtubules and the actin-spectrin periodic scaffold in axons. Our experiments suggest that microtubules are able to relax mechanical stress by unbinding of crosslinks, whereas the spectrin scaffold can buffer excess tension by unfolding of spectrin repeats--triply folded alpha helices connected by linker domains. This, in effect, makes the parallel array of microtubules behave elastically at short times (sudden deformations) and fluid-like at long times. The spectrin scaffold, on the other hand, behaves as a non-linear viscoelastic solid. We'll discuss the functional consequences of these differential contributions and how it might help us better understand axonal susceptibility to injuries like concussion, traumatic brain injury and stretch injuries to nerve fibers.

Collisional models give the state-of-the-art fundamental models to describe experimental measurements of quantum systems, for example, detection of photons. We study a cavity-qubit collisional model which, in the appropriate limit, reproduces the standard continuous-time description of photon detection from a cavity with incoherent gain. Despite this equivalence in the continuous limit, we demonstrate that the discrete-time dynamics is fundamentally different. By exactly mapping the cavity population dynamics onto a random walk in an effective energy landscape, we show that the collisional model generically lacks any steady state, even in parameter regimes where the corresponding Lindblad dynamics admits one. Instead, the system exhibits an infinite hierarchy of long-lived metastable states, corresponding to progressively deeper valleys of the effective potential. As a result, the dynamics becomes glassy, characterized by slow activated transitions between metastable states. We show that the mean first-passage times show Arrhenius-like behavior, with activation barriers set by the effective landscape. Our results reveal an unexpected connection between quantum models of photon detection and classical glassy dynamics. They provide a way for controlled analog simulation of glassy dynamics in cavity and circuit QED experiments. They also have potential consequences for dissipative quantum algorithms.

In this brief presentation, I will at first present the Yang-Lee theorems very briefly. After that I will present my work in this subject applicable to statistical field theory.

Roughness is typically regarded as an impediment to transport at both macroscopic and microscopic scales. However, on the microscopic scale, the thermal fluctuations make the particle motion more complex, and this might lead to some interesting particle behaviours in the presence of roughness. Most studies of Brownian motion, ratchet systems, and stochastic resonance have focused on smooth energy landscapes, even though realistic biological and physical systems often involve roughness or spatial perturbations. So it is important to understand how the roughness in potential will impact various noise-induced phenomena. It has been reported that the average velocity of a Brownian particle has been improved by roughness in the potential in the presence of a time-dependent force or non-Gaussian noise. We have also reported earlier that the roughness in a washboard potential can enhance the particle current and diffusion of a Brownian particle, both in the overdamped and underdamped regimes. However, the transport coherence and efficiency of an overdamped rocking ratchet in the presence of a rough potential have not been deeply explored. We first investigate an overdamped rocking ratchet with a superimposed rough potential. Our results show that the roughness in the potential significantly improves particle current, transport coherency and also the efficiency in the presence of a small load. In addition, we also investigated the stochastic resonance in the presence of a rough bistable potential. Using the input energy from the external drive as a quantifier of resonance, we show that the system exhibits a pronounced resonance-like response when roughness parameters are varied. Our findings establish that roughness can actually be beneficial in enhancing transport coherence and stochastic resonance phenomena in Brownian systems driven far from equilibrium.

We investigate the translocation dynamics of a flexible polymer through extended pores using Langevin dynamics simulations. Our study focuses on the interplay between pore geometry and surface topography, considering both cylindrical and conical architectures. The geometric profile of the conical pores is systematically tuned via the apex angle $\alpha$. While surface patterning and conical asymmetry are expected to influence local transport, our results reveal that the average translocation time $\langle \tau \rangle$ follows a consistent scaling law with respect to the chain length $N$ and pore length $L_p$ across all studied configurations. Specifically, we demonstrate that the scaling exponents remain invariant regardless of whether the pore interior is patterned or unpatterned.

I will present a model of many sokobans and boxes on a finite line. The sokobans are diffusing agents that can push a box to an empty site directly beyond the box, and interact with other sokobans via hardcore exclusion. The model has many transient states, and shows irreversibility and strong ergodicity breaking. I will show a decomposition of the configuration space arising from the dynamics, and the non-ergodic non-equilibrium Boltzmann entropy of the system that we have computed.