Poster List

Presenter: Pritam Roy

Affiliation: SNBNCBS

Abstract: Device-independent quantum Key Distribution (DI-QKD) secures cryptographic key exchange using nonlocal correlations, validated through Bell violations while requiring minimal trust in devices. We propose a novel sequential attack strategy, where an eavesdropper (Eve) performs unsharp measurements to preserve Bell violations and masks interference as noise. This approach allows Eve to extract significant key information without collective measurements. When combined with collective attacks, sequential attacks drastically reduce secure key rates, potentially rendering them zero under certain conditions. Our findings reveal that the interplay of sequential and collective attacks poses a critical threat to DI-QKD security, highlighting the limitations of relying solely on Bell nonlocality in real-world implementations.

Presenter: Rajdeep Paul

Affiliation: IITH

Abstract: The self-testing refers to novel device-independent certification protocols based on the optimal quantum violation of a Bell’s inequality where the devices are uncharacterized and the dimension of the system remains unspecified. We put forth a protocol that self-tests noisy quantum instruments, in particular, the unsharp parameter of smeared projective measurements. Our certification scheme relies on the optimal quantum violation of a suitably chosen Bell-type preparation noncontextuality inequality [2] featuring two space-like separated observers (Alice and Bob) who perform three measurement settings each. We employ a sequential quantum correlation scenario, where Alice shares an entangled state with multiple sequential Bobs. In order to demonstrate simultaneous quantum violations, we require unsharp measurements for all observers except the last.

Presenter: Ayan Patra

Affiliation: HRI

Abstract: We present a framework for quantum channels disrupting resources in communication and computation. Process resource-breaking channels impair protocols like teleportation and dense coding, while magic-breaking channels eliminate non-stabilizer properties critical for computation. We explore various properties of these channels, provide inclusion conditions, and conduct a detailed study of qubit channels.

Presenter: Komal Kumar

Affiliation: BITS Pilani Hyderabad Campus

Abstract: The fully entangled fraction (FEF) measures the proximity of a quantum state to maximally entangled states. FEF > 1/d, in two qudit systems is a significant benchmark for various quantum information processing protocols including teleportation. The negativity of quantum conditional entropies (QCE) plays a decisive role in tasks like state merging and dense coding. In the present work, we investigate the relation of these two important yardsticks. FEF is intricately linked with k- copy nonlocality and k- copy steerability. The relations between FEF and QCE facilitates to find conditions for k- copy nonlocality and k- copy steerability based on QCE. We obtain such conditions for certain classes of states in two qubits and two qudits. Applications of the relations obtained are provided in the context of work extraction, faithful entanglement and entropic uncertainty relations.

Presenter: Arun Kumar Das

Affiliation: SNBNCBS

Abstract: Measurement incompatibility has proved to be an important resource for information processing. In this work, we present an operational approach that leverages classical operations on the inputs and outputs of measurement devices to explore different layers of incompatibility among the measurements performed by the device. We study classifications of measurement incompatibility with respect to two types of classical operations, viz., coarse-graining of measurement outcomes and disjoint-convex-mixing of different measurements. We derive analytical criteria for determining when a set of projective measurements is fully incompatible with respect to coarse-graining or disjoint-convex-mixing. Robustness against white noise for different layers of incompatibility for mutually unbiased bases is investigated. Furthermore, we study operational witnesses for incompatibility subject to these classical operations, using the input-output statistics of Bell-type experiments as well as for experiments in the prepare-and-measure scenario.

Presenter: Nripendra Majumdar

Affiliation: IIT Tirupati

Abstract: The well-known entropy measure, von Neumann entropy, is studied in Quantum information theory but is incompatible with thermodynamic entropy. The very difficulty is its invariance under unitary transformation, which is in contradiction with the entropy increment in the isolated system. So, the observational entropy and its parameterized form &alpha- Observational entropy have been studied in recent advancements. We have explored the role of &alpha-OE in the thermodynamics contexts, including entropy production and the Clausius inequality. Also, the results show that &alpha-OE is not only a theoretical formulation but has practical implications for quantifying entropy production in open and closed quantum systems. Furthermore, we have shown the relation between &alpha-OE and Helmholtz free energy, highlighting its potential as a tool for thermodynamic analysis in a quantum system.

Presenter: TAMAL GUHA

Affiliation:HKU, Hong Kong

Abstract: A fundamental property of quantum theory is that a single qubit can carry at most 1 bit of classical information. But does the same intuition hold for noisy qubit channels? That is, can we replace a noisy qubit channel by a noisy c-bit channel of the same capacity for classical information processing? We answer this question in the negative!

Presenter:Satyaki Manna

Affiliation: IISER TVM

Abstract: We adopt a novel perspective, measuring the communication complexity of a task by the minimal distinguishability required to accomplish it, while leaving dimension of communicated tasks unconstrained. Distinguishability is defined as the maximum probability of correctly guessing sender’s input from message, quantifying message’s distinctiveness relative to sender’s input.

Presenter:Jatin Ghai

Affiliation: IMSc

Abstract: For establishing optimal teleportation fidelity between a sender and a reciever in a quantum repeater scenario with multiple segments, we propose a protocol for a certain class of noisy states in any intermediary segment, which achieves the same fidelity as that in entanglement swapping protocol while consuming less entanglement.

Presenter:Jai Lalita

Affiliation: IIT Jodhpur

Abstract: Our study focuses on preparing robust entangled states using quantum circuits that can be implemented on superconducting hardware. We present quantum circuits for state preparation and validate them through tomographic reconstruction on the IBM device. These states can replace the Bell state in scenarios with non-Markovian errors.

Presenter: Amit Kundu

Affiliation: SNBNCBS

Abstract: Network Nonlocality is an advanced study of quantum nonlocality that comprises network structure beyond Bell’s theorem. The development of
quantum networks have the potential to bring a lot of technological
applications in several quantum information processing tasks. Here, the
focus is on how the role of the independence of the measurement choices by
the end parties in a network work and can be used to affect the security of a
quantum network. In both three-parties two-sources bilocal network and
four-parties three-sources star network scenarios, this study can show, a
practical way to understand the relaxation of the assumptions and how it affects a network
communication. Theoretically, it has been proved that by relaxing the
independence of the measurement choices of only one end party, a Standard
Network Nonlocality (SNN) and stronger Full Network Nonlocality
(FNN) can be created and the maximum quantum violation by the classical
no-signalling local model can be obtained.

Presenter: Sneha Munshi

Affiliation: IIT Hyderabad

Abstract: The nonlocality arising in a multi-party network involving multiple independent sources radically differs from the standard multipartite Bell nonlocality involving a single source. The notion of the full network nonlocality (FNN) characterizes the quantum correlations that cannot be reproduced by a local-nonlocal model featuring one local source and the rest of nonlocal no-signaling sources. However, the demonstration of FNN was limited to bilocal and trilocal star-shaped network scenarios involving three or two dichotomic measurements for edge parties. In this paper, we first demonstrate that a large class of prevailing network inequalities does not exhibit FNN. We then introduce an elegant set of arbitrary-party and unbounded-input network inequalities in star-shaped and linear-chain networks whose optimal quantum violation exhibits FNN, certifying that the nonlocality is genuinely distributed to the entire network. Contrasting to existing demonstrations of FNN that inevitably require fixed-input and four-output elegant joint measurements for the central party, our generalized inequalities are more experimentally friendly, requiring only two-output measurements. Moreover, our derivation of optimal quantum violation is fully analytic and devoid of assuming the dimension of the quantum system, thereby showcasing its potential for device-independent self-testing.

Presenter: TAPASWINI PATRO

Affiliation: IIT Hyderabad

Abstract: Entanglement is necessary for demonstrating Bell nonlocality, but it is not sufficient. One needs suitable measurements to reveal the nonlocality. However, there are states which can not show nonlocality for any measurements – known as the Bell-local states. Any statistics produced from that state admits a local model. Importantly, there are two ways to activate the nonlocality even for the Bell-local states, i) Using local filtering operation ii) Using multiple copies of Bell local states. Both the approaches are quite nontrivial and conceptually rich. Recently, a new approach is introduced (Quantum, 5, 499(2021)), which is based on broadcasting. It is shown that the Bell-local state can also exhibit a form of nonlocality – the Broadcasting nonlocality. However, there is limitation in the parameter range beyond which broadcasting nonlocality cannot be demonstrated. In this work, we proposed a novel scheme to demonstrate that the Bell-local state can exhibit Broadcasting nonlocality if that state demonstrate EPR steering. This opens up a new avenue of research regarding quantum correlation through broadcasting nonlocality. The implications of our scheme in device-independent random number generation and self-testing are rigorously discussed.

Presenter: Amit Mukherjee

Affiliation: IIT Jodhpur

Abstract: Vehicle routing problems, rooted in the celebrated “Chinese postman problem”, involve strategic decision-making for efficient vehicle scheduling and routing. We explore a class of such problems where Bell-nonlocal correlations provide advantages in optimizing the costs for non-communicating postmen, establishing a novel utilization of quantum entanglement in traffic routing.

Presenter: Ashmi.A

Affiliation: IISER Pune

Abstract: We propose a novel method to classify noises present in quantum key distribution protocol using supervised machine learning models. Our contributions include identification of relevant features for noise classification, as well generation of benchmark dataset using BB84 and BBM 92 protocol. We show our method provides 99.8% to 100% accuracy of classifying depolarizing and bit-flip noises on the test dataset.

Presenter: Saikat Patra

Affiliation: IISER Berhampur

Abstract: In this work, we have introduced a distance measure to derive the optimal violation of Bell-CHSH inequality in a device-independent scenario. Next, implementing the distance measure as a tool for a class of mixed entangled states, we reveal hidden nonlocality using a particular local filtration operation. Further, we establish that any such filtration operation is non-Markovian in nature.

Presenter: Dinesh Kumar Panda

Affiliation: NISER Bhubaneswar

Abstract: Maximally entangled single-particle states (MESPS), i.e., single-particle Bell states, have the potential to encode and process more quantum information and are more robust to decoherence compared to their nonlocal two-particle counterparts. We developed a general formalism to generate MESPS at recurring time steps of a cyclic quantum walk with any single qubit-coin (e.g., Hadamard gate) from separable initial states. Notably, such a single-coin experimental realization for MESPS using photons exploiting its polarization states and different time bins is the most straightforward. In addition, we show the single coins with effective-single and two coins generate periodic MESPS at time steps up to 10 and beyond. Beyond revealing this novel protocol for generating maximal entanglement, we propose an application of the produced MESPS in quantum cryptography and show that the protocol is secure against eavesdropping. We also put forth a photonic circuit for it’s experimental realisation. We show these MESPS as cryptographic keys can strengthen quantum-secure communication. For details, refer to: Dinesh Kumar Panda and Colin Benjamin, Physical Review A 108, L020401 (2023) (Letters) (DOI: https://doi.org/10.1103/PhysRevA.108.L020401 ).

Presenter: Barnik Bhaumik

Affiliation: IISER TVM

Abstract: We investigate a communication task involving multiple senders (n-parties) transmitting messages to a single receiver, with the focus on a success metric that evaluates their performance. Each sender receives two bits of input, resulting in 2n outputs from the receiver. By self-testing approach, we rigorously demonstrate how quantum resources enable enhanced success compared to classical protocols. Further we introduce the concept of robust self-testing, which can be used to certify the 2-qubit maximally entangled Bell basis measurement which broadens our understanding of semi device-independent protocols in the context of blind tomography.

Presenter: Rahul V

Affiliation: IIT T

Abstract: Multipartite entanglement is a fundamental aspect of quantum mechanics, crucial to advancements in quantum information processing and quantum computation. Within this field, Genuinely Multipartite Entanglement (GME), being entangled in all bipartitions, and Absolutely Maximally Entanglement (AME), maximally entangled in all bipartitions, represent two significant types of entanglement with diverse applications. In this work, we introduce a new measure called the GME-AME multipartite entanglement measure, with a non-zero value representing the GME states and the maximum value is reached only by the AME states. The measure is applied to study the multipartite entanglement of four partite systems using the operator to state mapping, and the four partite qutrit states are classified according to the measure. With various examples, we show that our measure is robust in classifying the four partite entangled states.

Presenter: RANENDU ADHIKARY

Affiliation: ISI KOLKATA

Abstract: Self-testing is crucial for certifying quantum systems with minimal assumptions. A key challenge—self-testing non-maximally entangled states with genuine multipartite nonlocality—remains unsolved. Addressing this, we propose a Cabello-like paradox for any-party scenarios, enabling detection and self-testing of such states within the standard framework, advancing understanding of multipartite entanglement.

Presenter: Ram Krishna Patra

Affiliation: SNBNCBS

Abstract: The extension of point-to-point communication to multi-node configurations has significant applications in internet and telecommunication networks. Quantum resources promise notable advantages in such settings. Here, we demonstrate a novel quantum advantage in simulating Multiple Access Channels (MAC)—a common network configuration where multiple distant senders transmit messages to a single receiver (e.g., the uplink from several mobile phones to a server). Specifically, we show that qubit transmission outperforms its classical counterpart, even when the latter is supplemented with classical shared randomness. Remarkably, unlike the seminal quantum superdense coding protocol, this advantage is achieved without any pre-shared entanglement between the senders and the receiver—a feat prohibited by Holevo and Frenkel-Weiner no-go theorems in the one-sender-one-receiver scenario. The receiver’s ability to simultaneously decode quantum systems from multiple senders underpins this distinct advantage in the MAC setup. Some of our MAC designs are inspired by constructs in quantum foundations, such as the Pusey-Barrett-Rudolph theorem and `quantum nonlocality without entanglement’. Beyond network applications, this quantum advantage reveals a deeper connection to `quantum nonlocality without inputs’ phenomenon and suggests potential for semi-device-independent certification of entangled measurements.

Presenter: Sayan Sengupta

Affiliation: NIT Sikkim

Abstract: We explore the effects of noisy quantum channels on the Average \( L_1 \)-norm of Coherence and the Average Concurrence for Haar random single-qubit and two-qubit states. Specifically, we examine how classical correlations and non-Markovianity in dephasing, depolarizing, bit flip, and phase flip channels influence these measures. Our results show that in the case of the correlated depolarizing channel, the Average \( L_1 \)-norm of coherence does not exhibit any revival, indicating that classical correlations do not preserve coherence. However, we observe that classical correlations can slow the decay of coherence and help sustain some degree of entanglement under the depolarizing channel. Furthermore, we find that classical correlations have no significant effect on the Average \( L_1 \)-norm of coherence in correlated Markov bit flip and phase flip channels. These findings provide valuable insights into the behavior of quantum systems under correlated noisy conditions.

Presenter: Mu-En Liu

Affiliation: NCKU, Taiwan

Abstract: Sufficiently small reduced states of a closed system are close to the maximally mixed state in general and, hence, separable. In contrast, we show that sufficiently large reduced states are typically entangled for all bipartitions. When combined with appropriate uniqueness results, we conclude that entanglement transitivity is generic in closed systems.

Presenter: Ananya Chakraborty

Affiliation: S.N.Bose National Centre for Basic Sciences

Abstract: Distributed computing faces challenges in optimizing inter-server communication. Leveraging multipartite quantum entanglement, a multi-qubit GHZ state allows computing functions with one bit of communication per sender, reducing classical requirements by
n-1 bits for n senders. This scalable quantum advantage is robust against noise, highlighting its experimental potential.

Presenter: Shaileyee Bhowmick

Affiliation: IISER Mohali

Abstract: Non local quantum correlations can go beyond entanglement. Quantum discord is such a witness, possessed even by the separable states. The quantum discord for tripartite qubit states, along with its decompositions has been experimentally determined for three qubit states. The definition is a generalization of the bipartite quantum discord and follows the same postulates. The experimental results obtained are in excellent agreement with the theoretical predictions, for the tripartite quantum discord as well as the bipartite decompositions, present in the tripartite states.

Presenter: Devibala E

Affiliation: Madurai Kamaraj University (MKU), Madurai, Tamil Nadu

Abstract: We analyzed the output of conditional measurements as displaced qudits (DQ), with coherent states and photon number states as inputs. The study focuses on generating optimal squeezing through DQ. We observed that the non-Gaussianity and quadrature squeezing features of DQ are complementary to each other.

Presenter: Pratik Ghosal

Affiliation: SNBNCBS

Abstract: We explore the advantages of causal indefiniteness in retrieving classical information encoded in ensembles of multipartite quantum states by spatially separated parties. We demonstrate that, in general, parties in an indefinite causal structure outperform those operating in a definite causal background. In the bipartite case, we establish a strict duality between the optimal success probabilities of the data-retrieval task and the Guess-Your-Neighbour’s-Input game, and derive a necessary condition for useful quantum processes, one that is stricter than causal-inseparability. Additionally, we report an interesting super-activation phenomenon.

Presenter: Swati Kumari

Affiliation: IIT Dharwad

Abstract: To understand Bell-nonlocal correlations as an information-theoretic resource, it is natural to ask how much classical communication is required to reproduce them in addition to shared randomness. In particular, one may be interested in the minimal average (classical) communication cost (MACC) required to simulate any given Bell-nonlocal correlation. In the simplest Bell scenario, we show that the MACC of any given correlation is even linearly related to its nonlocal content, as well as its nonlocality robustness, another well-known nonlocality measure. More generally, our numerical studies suggest that the MACC of any given correlation can again be lower and upper bounded by appropriate linear functionals of the nonlocality robustness. Improvements over the best-known value of MACC in some simple Bell scenarios will also be presented.

Presenter: Suman Mandal

Affiliation: UCF, USA

Abstract: Variational quantum algorithms (VQAs) offer promise for NISQ devices but face challenges from barren plateaux, where parameter optimization stagnates due to vanishing gradients. This research explores the inevitability of barren plateaux in deep circuits through numerical simulations and analytical models, highlighting their impact on scalability and potential mitigation strategies.

Presenter: KOUSTAV DAS CHAKLADAR

Affiliation: AU

Abstract: This study examines the impact of impenetrable spherical cavity confinement on electron momentum distribution in hydrogen and lithium atoms. Using the Ritz variational method, Fourier-Dirac transformation, and model potentials, it explores oscillatory wavefunctions, Compton profiles, Shannon entropy, and BBM inequality, providing novel insights, including an analytic oscillation frequency expression

Presenter: Arkaprava Sil

Affiliation: IIT (ISM) Dhanbad

Abstract: The interplay between multipartite entanglement and other quantum properties during dynamical evolution of a many-body system can provide insights into various quantum phenomena. Here, we study the Quantum game of life – a class of cellular automata model where evolution occurs depending on a local update rule. We investigate how entanglement, specially multipartite entanglement spreads in the system and examine the possible presence of dynamical phase transition. Additionally, we use the recently introduced “link representation formalism” to better understand the extensive/non-extensive growth of bipartite entanglement in the model.

Presenter: Samrat Sen

Affiliation: SNBNCBS, Kolkata

Abstract: Nonlocality, central to Bell’s theorem, enables device-independent protocols like secure key distribution. We explore nonlocality distillation using wirings to amplify weak quantum correlations.
Our logical OR-AND wiring protocol
a) distills correlations
b) demonstrates that distillable no-signaling and quantum correlations have a nonzero measure in eight-dimensional space
b) and effectively detects post-quantum correlations.

Presenter: ARUN KUMAR DAS

Affiliation: SNBNCBS

Abstract: Measurement incompatibility has proved to be an important resource for information processing. In this work, we present an operational approach that leverages classical operations on the inputs and outputs of measurement devices to explore different layers of incompatibility among the measurements performed by the device. We study classifications of measurement incompatibility with respect to two types of classical operations, viz., coarse-graining of measurement outcomes and disjoint-convex-mixing of different measurements. We derive analytical criteria for determining when a set of projective measurements is fully incompatible with respect to coarse-graining or disjoint-convex-mixing. Robustness against white noise for different layers of incompatibility for mutually unbiased bases is investigated. Furthermore, we study operational witnesses for incompatibility subject to these classical operations, using the input-output statistics of Bell-type experiments as well as for experiments in the prepare-and-measure scenario.

Presenter: V VIJAYAKRISHNAN

Affiliation: JNCASR

Abstract: A classical game consists of an initial state, strategies, and payoffs. Adding entanglement creates a quantum game, distinguishing it from its classical counterpart. This work validates the modified quantization scheme, under amplitude damping noise, demonstrating that quantum games transition to classical as noise nullifies entanglement effects, thereby capturing complete game dynamics.

Presenter: Rakshaditya Dutta

Affiliation: IISER Pune

Abstract: Hypergraphs based on Kochen-Specker proofs have been previously used to show that a quantum advantage exists for one shot classical communication, on qudits (d=4). We show that the hypergraphs can be used to construct communication tasks on qubits and qutrits, and further show that qutrits give an advantage. No such advantage is found for qubits.

Presenter: Shivam Sinha

Affiliation: IIT Tirupati

Abstract: We extend the scope of observational entropy by generalizing it to a parameterized version called &alpha-observational entropy (&alpha-OE). &alpha-OE is expressed in terms of the Petz-Renyi relative entropy between the states on which a quantum-to-classical channel is applied. We prove various properties of the &alpha-OE.

Presenter: Harsha Miriam Reji

Affiliation: IIT Dharwad

Abstract: We study the genuine multipartite entanglement in fermionic multiqubit GHZ and W states with one of their qubits in acceleration. A comparison with bipartite entanglement in the system is also done.

Presenter: Nilaj

Affiliation: IISER-Mohali

Abstract: We analyze quantum success probability enhancement in intraparticle entanglement-resourced Random Access Code (RAC) protocols and link it to quantum measurement contextuality via Bell-type inequalities. Quantum violations quantitatively match success probability enhancements. This relationship is testable using a single-particle setup, eliminating the need to maintain coherence for spatially separated entangled particles.

Presenter: Subhankar Bera

Affiliation: SNBNCBS

Abstract: The notion of general quantum contextuality encompasses preparation as well as measurement contextuality. We propose a scheme to efficiently extract quantum advantage through construction of a generalized non-contextual polytope circumscribing both the preparation and measurement non-contextual polytopes, while ensuring that its dimension stays constant irrespective of the number of measurements and outcomes. The facet inequalities of our constructed polytope can thus be obtained in a computationally efficient manner, serving as necessary conditions for generalized noncontextuality. We illustrate the efficacy of our methodology through several distinct contextuality scenarios. Our approach enables to uncover several hitherto unexplored noncontextuality inequalities, demonstrating applications of quantum contextual correlations for oblivious communication, certification of non-projective measurements and witnessing the dimension of quantum systems.

Presenter: Sagnik Ray

Affiliation: IISER TVM

Abstract: This work addresses the fundamental question about whether any epistemic model can explain the statistics of general quantum preparations. We provide explicit examples where no such epistemic explanation can be found for anti-distinguishability of a set of quantum preparations, even for qubit systems. Moreover, we demonstrate how this phenomenon implies preparation contextuality.

Presenter: Ingita Banerjee

Affiliation: GU

Abstract: Quantum trajectory theory enables us to estimate the state of a quantum system conditioned on the measurements one performs. In cases where the measurement devices are inefficient, the conditioned state is generally not pure. For instance while measuring a resonantly driven two level atom, the only time when the state will be pure is immediately after a photon detection. In case of diffusive measurement scheme such as homodyne detection, it is never pure. This raises questions as,”Given that one did use a photodetector and did see a particular time-sequence of detections, how would the atom have behaved if instead one had chosen to measure the fluorescence using homodyne detection scheme? Here we give the best possible answer to this counterfactual question using Lewis approach of counterfactuals and try to give the best possible estimate about the quantum state using the methods of filtering and smoothing.

Presenter: Sahil Gopalkrishna Naik

Affiliation: S.N.B.N.C.B.S.

Abstract: The principle of information causality refines the no-signaling principle, ruling out non-quantum correlations. We demonstrate its role in deriving structural features of multipartite quantum systems, showing that neither maximal or minimal tensor product compositions align with nature, thus we derive the self-duality of quantum theory from a underlying physical principle.

Presenter: Kolahal Bhattacharya

Affiliation: SXCCAL

Abstract: The nonlocality problem of the Aharonov-Bohm effect has baffled many physicists over the decades since the original paper in 1959. Initially there was some skepticism among the scientific community about the validity of their claim. However, in 1980s Tonomura et al. presented the experimental evidence of the magnetic Aharonov-Bohm effect which established the so-called nonlocality. Not only that, it appeared to suggest that indeed potentials were more fundamental than fields in quantum theory. The electrostatic Aharonov-Bohm effect has not still been experimentally verified and it is somewhat controversial till date. In this poster, I discuss that there can be a semi-classical description of the classical conservative vector fields e.g. electrostatic and magnetostatic fields, that is manifested only at under specific conditions. In this limit, one needs to talk about the wavefunctions of the field. The wavefunctions have finite de Broglie wavelengths in the usual case, but they take the form of a non-square integrable plane wave (or a unitary phase) when the field strength is vanishing. In other words, the unitary phase, which is found to be picked up by the electron wavefunction, is nothing but the wavefunction of the vanishing field. This model can be used to interpret the Aharonov-Casher effect as well. We show that this model can throw light to the problems of the quantization of electric charge and magnetic flux. For example, it is possible to explain the flux quantum in the type-I superconductors based on this model. In fact, it can be argued that the observed flux quantum of h/2e in superconductors is a direct consequence of the non-vanishing wavefunctions of vanishing magnetic field in a superconductor.

Presenter: Dr. Shibdas Roy

Affiliation: TCG CREST

Abstract: We propose that gravity in curved spacetime yields quantum mechanics in flat spacetime. Quantum mechanics would not exist, if there was no gravity. The universe is classical and local (general relativistic) in curved spacetime, but the same universe is quantum and nonlocal (Newtonian), when treated in flat spacetime, for masses below Planck mass.

Presenter: Arijit Chatterjee

Affiliation: IISER Pune

Abstract: We construct a superposition between time evolution unitaries, and found them to produce an enhanced violation of Leggett-Garg Inequalities beyond its quantum bound (TTB). Along with its experimental demonstration using NMR architecture, we found dynamics under these superposed unitaries to be remarkably more robust against decoherence.

Presenter: Soumyabrata Hazra

Affiliation: IIIT Hydrabad

Abstract: The conventional approach of deriving facet inequalities of noncontextual polytope is computationally demanding. We propose an alternative methodology of constructing a polytope that encompasses the actual noncontextual polytope while ensuring that the dimension of the polytope associated with the preparations remains constant regardless of the number of measurements and their outcome size. We present an in depth analysis of 9 different contextuality scenarios. We use the derived inequalities and their quantum violation in different tasks like, certification of nonprojective measurement, certifying the dimension of quantum system, randomness certification.

Presenter: Sourav Kesharee Sahoo

Affiliation: IIT Kanpur

Abstract: This work explores gravitational self-interaction’s role in the emergence of classicality from quantum physics. For massive spin-1/2 particles, self-gravity prevents wave packet splitting, resulting in a single classical trajectory. Unlike decoherence models, this offers new insights and testable predictions for the foundational aspects of quantum mechanics.

Presenter: Anantha Krishnan, Anil Shaji, Debashis Saha

Affiliation: IISER TVM

Abstract: To address genuine network nonlocality and its noise robustness we introduce a causal domain-informed learning algorithm called the LHV k-rank Neural Network, which assesses the rank parameter of the non-ideal combined state produced by sources. Applied to the triangle network scenario, the neural network reveals that nonlocality persists only if the states remain pure. Remarkably, we find that even slight deviations from ideal Bell states due to noise cause GNN to vanish, exhibiting a discrete behavior that hasn’t been witnessed in standard bell scenarios. Apart from these results the work succeeds in showing that machine learning approaches with domain-informed constraints can greatly benefit the field of quantum foundations.

Presenter: Matthias Salzger

Affiliation: ICTQT

Abstract: We extend process theories, a framework for quantum and post-quantum theories, to incorporate spacetime’s causal structure. We embed processes into spacetime by considering their decompositions, localising individual “boxes” such that wires follow timelike paths. We then identify and analyse a hierarchy of decompositions in terms of their utility for embeddability.

Presenter: Debashis Saha

Affiliation: IISER TVM

Abstract: We present no-go theorems for &psi-epistemic models, even for qubits, by considering the epistemic overlap of probability distributions over the ontic states for multiple quantum states. Additionally, we explain how refuting maximally epistemic models connects to achieving quantum communication advantages.

Presenter: Amrapali Sen

Affiliation: ICTQT

Abstract: The theory of relativity is generally assumed to provide us with a speed limit for all interactions. In this work, we extend and prepare operational tools to include superluminal observers in quantum theory, and check if the principles of quantum theory can be derived from relativistic theories.

Presenter: Kunika Agarwal

Affiliation: SNBNCBS

Abstract: The Greenberger–Horne–Zeilinger (GHZ) paradox tests quantum nonlocality in systems with three or more subsystems, showing a 100% conflict between local hidden variable theories and quantum mechanics. This paper introduces a randomized GHZ game, demonstrating potentially stronger nonlocality and greater communication advantage than traditional GHZ correlations in multi-party tasks.

Presenter: Sneha Suresh

Affiliation: IISER, Thiruvananthapuram

Abstract: We consider four distinct scenarios for distinguishing (and anti-distinguishing) quantum measurements – (i) probing single systems and without access to the post-measurement states, (ii) probing entangled systems and without access to the post-measurement states, (iii) probing single systems with access to the post-measurement states, and (iv) probing entangled systems with access to the post-measurement states. For any set of measurements, distinguishability (and anti-distinguishability) in scenario (i) is always less than or equal to in any other scenario, while it reaches its highest possible value in scenario (iv). We establish that the relations form a strict hierarchy, and there is no hierarchical relation between scenarios (ii) and (iii).

Presenter: Parkhi Bhardwaj

Affiliation: Indian Institute of Technology Ropar

Abstract: We propose to generate beams with non-zero orbital angular momentum in the microwave domain using atomic vapor medium and coherent control techniques. Our approach utilizes a difference frequency generation process in a centrosymmetric medium in the presence of a dc electric field for frequency conversion and parametric amplification. By generating Laguerre-Gaussian fields in the microwave domain, we open up novel possibilities for advanced information processing in wireless communication and potential applications in quantum technologies.

Presenter: Anandamay Das Bhowmik

Affiliation: IISER Thiruvananthapuram

Abstract: Despite being the most fundamental object in quantum theory, physicists are yet to reach a consensus on the interpretation of a quantum wavefunction. In the broad class of realist approaches, quantum states are viewed as Liouville-like probability distributions over some space of physical variables where indistinguishabity of non-orthogonal states is attributed to overlaps between these distributions. Here we argue that such an interpretation of quantum indistinguishability is wrong. In particular, we show that quantum mechanical prediction of maximal violation of Mermin inequality in certain thought experiment is incompatible with all ontological interpretations for quantum theory where indistinguishability of non-orthonal quantum states is explained, even partially, in terms of overlap of their Liouville distributions.

Presenter: Yìlè Yīng

Affiliation: Perimeter Institute

Abstract: Nonclassical causal modeling was developed in order to explain violations of Bell inequalities while adhering to relativistic causal structure and faithfulness — that is, avoiding fine-tuned causal explanations. Recently, a no-go theorem that can be viewed as being stronger than Bell’s theorem has been derived, based on extensions of the Wigner’s friend thought experiment: the Local Friendliness (LF) no-go theorem. Here we show that the LF no-go theorem poses formidable challenges for the field of causal modeling, even when nonclassical and/or cyclic causal explanations are considered. We first recast the LF inequalities, one of the key elements of the LF no-go theorem, as special cases of monogamy relations stemming from a statistical marginal problem. We then further recast LF inequalities as causal compatibility inequalities stemming from a nonclassical causal marginal problem, for a causal structure implied by well-motivated causal-metaphysical assumptions. We find that the LF inequalities emerge from this causal structure even when one allows the latent causes of observed events to admit post-quantum descriptions, such as in a generalized probabilistic theory or in an even more exotic theory. We further prove that no nonclassical causal model can explain violations of LF inequalities without violating the No Fine-Tuning principle. Finally, we note that these obstacles cannot be overcome even if one appeals to cyclic causal models, and we discuss potential directions for further extensions of the causal modeling framework.

Presenter: Leo Adav

Affiliation: VIT, Vellore.

Abstract: This work revisits the Extended Wigner’s Friend
GendankenExperiment presented by Shan Gao in his 2019 paper and reexamines Shan Gao’s
claim that unitary quantum theory conflicts with special relativity. By exploring time as an emergent property and observer dependent measurements, we argumentatively challenge the necessity of a preferred Lorentz frame, offering a reconciliatory framework between quantum mechanics and relativity.

Presenter: Partha Patra

Affiliation: IITH

Abstract: One of the striking features of quantum theory is that all quantum statistics cannot be reproduced by a hidden variable model that deterministically assigns values to all the measurements independently of what other measurements are carried out simultaneously, is famously termed the Kochen-Speaker (KS) contextuality. The notion of KS contextuality has subsequently been generalized to preparations and transformations as well. The generalized contextuality (hereafter contextuality) has recently been studied extensively and shown to have the capability of enhancing several information processing tasks. It was believed that the measurement incompatibility is necessary to reveal the contextuality. However, recent work has shown that this is not true. The scheme that exemplifies the revelation of contextuality without incompatibility has used a five-outcome qubit measurement. The question remains: can a suitable example of contextuality be constructed without incompatibility in terms of a simpler measurement? In this work, through a two-party communication game, we prove that contextuality can be revealed without incompatible measurements in the simplest scenario that requires only a three-outcome measurement instead of five. Furthermore, we show that one way to realize the former five-outcome measurement is by a convex mixture of a set of five tree-outcome measurements that are incompatible. The upshot of our result is that, unlike the case of the five-outcome measurement, there is no way to simulate the constructed three-outcome measurement by a convex mixture of other incompatible measurements. Moreover, the proposed two-party communication game has a significant implication for single qubit communication, as it modifies the usual Holevo scenario by introducing an operational restriction on the preparation by one of the parties. In the wake of the revealed contextuality without incompatibility in such modified Holevo scenario we prove that a single qubit has the power to outperform a bit in such tasks. Hence, our result also opens up new pathway to view the information processing power of a single qubit.

Presenter: Snehasish Roy Chowdhury

Affiliation: ISI Kolkata

Abstract: We present a general framework for exploring quantumness of correlation in multipartite quantum states. By exploiting the different signatures reflected on observable quantities depending on whether subsystems of a composite systems are probed jointly or independently, we introduce an operational quantifier of nonclassicality, termed Ergo-Discord. As we show, this newly proposed quantifier faithfully captures nonclassicality in any bipartite quantum state, while being distinct from original quantum discord, thereby implying a qualitatively different resource theory of nonclassical correlation. Moreover, Ergo-discord uncovers an intriguing phenomenon called ‘nonlocal energy locking’, where useful form of energy (i.e. work) gets locked in correlation of nonclassical states. We also show that a mixed nonclassical state can lock more work than the maximally entangled state of the corresponding system establishing an astounding super-additivity phenomenon of nonlocal energy locking.

Presenter: Subhendu Bikash Ghosh

Affiliation: ISI Kolkata

Abstract: Comparison among quantum nonlocal correlations holds significant practical relevance. We, however, present instances of quantum nonlocal correlations that are incomparable in the strongest sense. Specifically, when starting with an arbitrary many copies of one nonlocal correlation, it becomes impossible to obtain even a single copy of the other correlation, and this incomparability holds in both directions. Our result challenges the notion of a `unique gold coin’, often referred to as the `maximally resourceful state’, in the resource theory of quantum nonlocality. Our result also put non-trivial restriction on nonlocality distillation.

Presenter: Sudip Chakrabarty

Affiliation: SNBNCBS

Abstract: We provide a criterion for detecting non-classicality of quantum states with negative Wigner function, evaluating Wigner moments which can be realised in a real experiment utilizing the mode SWAP operator without the need for full state tomography. We provide explicit examples to support our detection scheme.

Presenter: Ritesh Kumar Singh

Affiliation: IIT Hyderabad

Abstract: Randomness is an important resource with its applications in device-independent quantum key distribution and random number generation. Device-independent certification of randomness requires the violation of a Bell inequality implying that nonlocality and randomness are concomitant features of Bell inequality violation. Despite an apparent direct relation between the two, the situation is more complicated and it has been shown that maximally nonlocal theory does not allow maximal randomness [Phy. Rev. Lett. 114, 160502 (2015)]. This limitation arises from the fact that while the maximal nonlocal behaviour (Popescu-Rohlrich) with CHSH value 4 encompasses only 1 bit of certified global as well as local randomness in 222 (2 parties, 2 measurements with each party and each measurement having two outcomes). We define maximal random distribution as the one with equiprobable outputs for at least one specific combination of measurement settings. In this work we reanalyse the relation between randomness and nonlocality via maximally random theory which is defined as set of all maximally random distributions.

Presenter: Akarshit Baranwal

Affiliation: IIT Hyderabad

Abstract: Composition of two quantum systems remains a debatable question since the inception of quantum theory. No-signalling and local tomography principles warrants two extreme compositions, viz, the, minimal and maximal tensor products. The quantum tensor product composition falls within these two extremes. There remains a consensus that in a bipartite scenario the Bell experiment cannot distinguish between the quantum and beyond quantum composition. However, it is recently shown that the information causality principle is useful to rule out maximum and minimum tensor product compositions in time-like scenarios. In this work, we introduce a communication game – the 3 to 2 random access code and demonstrate the success probability in minimum and maximum tensor product compositions violates the quantum success probability. Importantly, the information causality remains satisfied. This opens up an avenue to explore what other principles can be used to rule out the beyond quantum correlations in the aforementioned communication game.

Presenter: Vishnu Purushothaman

Affiliation: IIT Hyderabad

Abstract: It is believed that Bell test cannot distinguish beyond quantum correlation, i.e., the maximum and the minimum tensor product compositions. Based on a communication game – the 3 to 2 random access code – we demonstrate how a Bell test can distinguish the quantum and beyond quantum compositions. The implications of such correlations are discussed.

Presenter: Surajit saha

Affiliation: CU

Abstract: This work explores the relationship between operational and ontological descriptions of quantum theory from a different perspective. We propose a set of urn models whose operational descriptions, in a certain limit defined by a characteristic function, are identical to various operations on qubits in operational quantum theory. We refer to this type of ontological model of operational quantum theory as urn ontology. We have also demonstrated that an urn ontology can be constructed for both quantum and beyond-quantum bipartite nonlocal correlations. Furthermore, urn ontology can provide insights into emergent quantum mechanics models, where the wavefunction does not play a dynamical role.

Presenter: Aditya L J

Affiliation: IISER TVM

Abstract: We study the stability of continuous time quantum walks(CTQWs) on complex network topologies like scale-free, Erdos-renyi and small world networks. Quantum walks are quantum analog for classical random walks. Our work focuses on analyzing fidelity of initial and evolved states, von neumann entropy and quantum classical distance. We also study the probability of quantum walker in each node. We present a comprehensive study of how different network topologies influence the behavior of CTQWs through simulation results. Our findings reveal the variations in quantum walk dynamics across different network topologies and provide insights into the impact of network topologies on stability of quantum walks. Through detailed simulations and comparisons, we aim to get a better understanding of the stability of quantum networks, which can impact both theoretical research and practical applications in quantum computing and network analysis.

Presenter: Rathnakaran S R

Affiliation: IIT Ropar

Abstract: Quantum thermodynamics explores fundamental limits of heat engines at atomic scales. Using a Heisenberg XY spin chain, we demonstrate an Otto-like cycle with a single heat bath, replacing the cold bath with projective measurements. An ancillary spin chain enhances efficiency and power through entanglement and local drives, surpassing the Otto limit.

Presenter: Rajeev Gangwar

Affiliation: IISER Mohali

Abstract: This paper distinguishes information revivals from backflows in non-Markovian quantum processes, showing revivals can occur without backflows. It examines non-causal revivals, connects them to short Markov chains and squashed non-Markovianity, and provides an operational condition to witness genuine backflows, enabling a convex resource theory of quantum non-Markovianity in dynamics.

Presenter: Aleek Maity

Affiliation: CMI

Abstract: The Lindblad equation governs the evolution of open quantum systems, while constrained classical systems evolve via Dirac brackets. We derive an intriguing, but precise classical-quantum correspondence between the aforementioned situations which connects the Lindblad operators to the constraints. The correspondence is illustrated in the ubiquitous example of coupled harmonic oscillators.

Presenter: Prem Kumar

Affiliation: IMSc

Abstract: The steady state of an open quantum system deviates from the Gibbs state. For a general spin-boson model, we use a fourth order master equation (in system environment coupling) to analytically calculate all the second-order corrections to the steady state and show its equivalence to the generalized equilibrium state.

Presenter: Gourab Das

Affiliation: IISER Kolkata

Abstract: Time crystals, a non-equilibrium phase of matter, emerged as a new concept to break spontaneous time translation symmetry. Most studies focus on the unitary dynamics in closed systems, but Time crystals become fragile after contact with the environment. However, dissipation due to a tailored environment can be a blessing in disguise for the stability of a periodic environment, where the system releases excess energy pumped by a periodic drive, with disturbance, to its environment via dissipation channels. We show the existence of such a time crystalline phase.

Presenter: Baibhab Bose

Affiliation: IITJ

Abstract: The field of information scrambling has seen significant growth over the last decade, where the out-of-time-ordered correlator (OTOC) has emerged as a prominent tool to probe it. In this work, we use bipartite OTOC, a particular form of OTOC, to study information scrambling in the atom–field interaction models and the model of the Ising spin chain interacting with a tilted magnetic field. This is done considering the effects of open quantum
systems. A relationship between information scrambling, using bipartite OTOC, and irreversibility, using entropy production, is probed under unitary
dynamics. The equivalence of bipartite OTOC with operator entanglement is explicitly shown for the Ising model.

Presenter: Sakil Khan

Affiliation: IISER Pune

Abstract: Recently, the “Bootstrap” technique was applied in Quantum Mechanics to solve the eigenspectra of Hermitian Hamiltonians and extended to non-Hermitian PT-symmetric systems. However, its application has been limited to real spectra. In this work, we establish bootstrap conditions for the non-Hermitian system and generate eigenspectra for a generic complex polynomial potential, which includes PT-symmetric Hamiltonians as a special case. Additionally, we demonstrate the method’s ability to obtain eigenspectra under various boundary conditions imposed on the eigenfunction, including the notable application of capturing the PT-symmetric phase transition.

Presenter: ATHULYA K P

Affiliation: IMSc Chennai

Abstract: We derive a completely positive post-Markovian master equation (PMME)
from a microscopic Markovian collisional model framework, incorporating bath memory effects via a probabilistic single-shot measurement approach. This phenomenological master equation is both analytically solvable and numerically tractable. Depending on the choice of the memory kernel function, the PMME can be reduced to the exact Nakajima-Zwanzig equation or the Markovian master equation, enabling a broad spectrum of dynamical behaviors. We also investigate thermalization using the derived equation, revealing that the post-Markovian dynamics accelerates the thermalization process, exceeding rates observed within the Markovian framework. Our approach solidifies the assertion that “collisional models can simulate any open quantum dynamics”, underscoring the versatility of the models in realizing open quantum systems.

Presenter: Sarfraj Md Juned Fency

Affiliation: IISER Kolkata

Abstract: DNP is a technique used to transfer polarization from an electron to a dipolar coupled nuclei. DNP has been known to the scientific community since the 1950s, yet, certain aspects of it are poorly understood. We explore the behavior of the system under varying microwave drive strength and the dipolar coupling strength using the fluctuation regulated quantum master equation. Our results reveal the existence of an optimal parameter regime in the parameter space of microwave drive strength and the strength of dipolar coupling strength, corroborating with the experimental observation. We also provide a physical explanation for this optimality, contributing to the deeper physical understanding of DNP.

Presenter: Bivas Mallick

Affiliation: S.N. Bose National Centre for Basic Sciences

Abstract: Non-Markovian effects in open quantum system dynamics usually manifest the backflow of information from the environment to the system, indicating complete-positive divisibility breaking of the dynamics. We provide a criterion for witnessing such non-Markovian dynamics exhibiting information backflow, based on partial moments of Choi matrices. The moment condition determined by the positive semi-definiteness of a matrix does not hold for a Choi state describing non-Markovian dynamics. We then present some explicit examples in support of our proposed non-Markovianity detection scheme. Finally, a moment-based measure of non-Markovianity for unital dynamics is formulated.

Presenter: Saheli Mukherjee

Affiliation: SNBNCBS

Abstract: We explore the impact of increasing the control dimension on the performance of the quantum switch. We focus on a quantifier of the quantum switch through the emergence of non-Markovianity and study its behavior when we increase the control dimension. Increasing the control dimension increases the non-Markovian memory.

Presenter: Anumita Mukhpadhyay

Affiliation: TCG CREST, AcSIR

Abstract: It is known that non-unital noise sometimes can increase quantum correlations. Here, we find that if noises acting on the system is unital (non-unital), then the noise acting on the environment should also be unital (non-unital) when the joint system-environment undergoes unitary evolution. This may help to control noise in enhancing quantum correlations for various applications.

Presenter: JISHA C

Affiliation: Motilal Nehru National Institute of Technology, Allahabad

Abstract: The study of quantum chaos encompasses the application of chaotic dynamical systems theory in the quantum regime. Statistical properties of chaotic quantum systems and their universality have been studied using Random Matrix Theory(RMT) for a long time.In RMT, Hamiltonians are treated statistically and ensembles of the same with general symmetric properties are considered.In RMT, open quantum systems are studied using the Ginibre ensembles whose eigenvalues are distributed in the two dimensional complex plane. In this work, we show that the fluctuation statistics of Ginibre ensembles of different symmetry classes are universal and quantum chaotic systems in the presence of a dissipative environment show similar spectral fluctuations. We study the short range correlations using spacing distributions and long range correlations using number variance.We develop the mechanism to unfold a spectra with non-uniform density at a non-local scale and also evaluate the number variance. We find that both short-range and long-range correlations are universal. We verify all our findings on a prototype model of chaos known as quantum kicked top in a dissipative environment.

Presenter: Titir Mukherjee

Affiliation: IISER K

Abstract: Our study explores the quantum dynamics of a soft impact oscillator system, where a mass-spring setup interacts with a wall connected to a stiffer spring. Using quantum Langevin equations, we investigate how dissipation affects quantum dynamics, revealing bifurcation patterns similar to classical systems when varying the wall position parameter.

Presenter: Shubhamay Panja

Affiliation: IISER K

Abstract: A pre-thermal state is a non-equilibrium state that occurs before the system becomes fully thermalized. In this state dynamics of the system are constrained by several quasi-conserved quantities. We study this dynamical path toward the complete thermalization of many interacting dipolar particles which also interact with themselves and their local environment.

Presenter: REJJAK LASKAR

Affiliation: ALIAH UNIVERSITY

Abstract: A quantum heat engine model is proposed, combining a three-level atomic system and a vibrating nanomirror connected via a laser field, maximizes output with increased photon distribution. Thermodynamic analysis shows energy absorption equals energy released, but efficiency decreases with increasing photon distribution.

Presenter: PRATYUSH BHATTACHARJYA

Affiliation: IISER KOLKATA

Abstract: The Unitary Group Adapted State-Specific Multi-Reference Coupled Cluster and its perturbative variant (UGA-SSMRCC and UGA-SSMRPT) developed by Mukherjee et al.has successfully realized the goal of studying bond dissociation in a numerically stable, spin-preserving and size-consistent manner. We explore the applicability of these theories for the construction of ab initio potential energy surface (PES) of atom-diatom reactive scattering problem.

Presenter: Pallabi Chatterjee

Affiliation: IISER Tirupati

Abstract: It is well known that unitary evolution tends to grow the entanglement, but continuous monitoring opposes this growth and results in the pinning of the wavefunction trajectories to the eigenstate of the measurement operators. In this poster, I present the fate of this measurement-induced phase transition in a periodically driven free-fermionic quantum system, where the hopping amplitude is varied periodically in time. I show, in the high-frequency limit, that a renormalization group analysis of the non-Hermitian quantum sine-Gordon model [as proposed in Phys. Rev. X 11, 041004 (2021)] reveals a gapless critical phase with logarithmic entanglement entropy growth and a gapped area-law phase, separated by a Berezinskii-Kosterlitz-Thouless (BKT) transition, which is in excellent agreement with our numerical results. Further, the numerical evidence suggests that such BKT transition also prevails in the low-frequency regime, and decreasing frequency tends to favor the critical phase.I will also show that if the hopping amplitude is varied completely symmetrically around zero in the form of square-pulse and sinusoidal drive, the BKT transition is absent in the thermodynamic limit, and the system always favors the area-law phase, independent of the frequency regime.

Presenter: SHAMIK CHANDA

Affiliation: IISER Kolkata

Abstract: The violation of Hund’s rule in some N-heterocyclic chromophores (cyclazine and its derivatives) is often attributed to an inversion of the the low-lying excited singlet (S1) or triplet (T1) states [1,2]. The negative energy difference between the excited states S1 and T1, denoted as ∆EST = E(S1)-E(T1) makes them templates for the fifth generation of OLED materials which aim to use reverse intersystem crossing (RISC) to increase quantum yield leading to thermally activated delayed fluorescence (TADF). These systems, popularly known as INVEST systems, exhibit both static and dynamic correlation. Common excited state methods such as CIS, RPA or LR-TDDFT, are unable to predict the inversion of ST gap. This has been attributed to lack of doubles correction in S1 [1]. However, S0, S1 and T1 states all exhibit a large contribution from doubles and higher excited configurations that need a delicate balance of static and dynamic correlation for accurate estimation. In this work we study a systematic hierarchy of single and multi-reference wavefunction based methods as well as DFT methods with the threefold goal of (a) understanding the important configurations in the states involved, (b) generating high quality benchmark numbers and finally, (c) determining a suitable cheap method with reasonable accuracy to be used for screening more applicable molecules with reasonable spin-orbit or spin-vibronic coupling as well as ISC and RISC rate constants are for synthesizable larger derivatives and n-mers of these templates for OLED applications. The role of spin-contamination and spin-polarization along with the suitable connections to minimal two and three state exciton models are drawn to identify the minimal physics governing the interactions in these molecules.

Presenter: SANTANU SARKAR

Affiliation: NIT SIKKIM

Abstract: The violation of Hund’s rule in some N-heterocyclic chromophores (cyclazine and its derivatives) is ofOur study investigates the average quantum coherences of qudits and redits, based on the symmetry of Haar-uniformly distributed random pure states. We explore how the coherence distribution changes under different types of disorder, especially glassy disorder, affecting the state parameters. The introduction of the disorder reduces the spread of the coherence distributions and makes them more symmetric.

Presenter: Raveena Arya

Affiliation: IISER KOLKATA

Abstract: This study explores the effects of impenetrable spherical confinement on two-electron atoms/ions, focusing on ground and low-lying singlet/triplet states. Using the radial Kohn-Sham equation, work-function-based exchange potential, and two correlation functionals, the research examines level crossings influenced by cavity radius and nuclear charge, revealing confinement-induced property changes.

Presenter: Sudipto Singha Roy

Affiliation: Indian Institute of Technology (Indian School of Mines) Dhanbad

Abstract: The Eigenstate Thermalization Hypothesis (ETH) has been highly influential in explaining thermodynamic behavior of closed quantum systems. As of yet, it is unclear whether and how the ETH applies to non-Hermitian systems. Here, we introduce a framework that extends the ETH to non-Hermitian systems, within which expectation values of local operators reproduce statistical and scaling predictions known from Hermitian ETH. We illustrate the validity of the framework on non-Hermitian random-matrix and Sachdev–Ye–Kitaev models. Further, we show numerically how the static ETH predictions become imprinted onto the dynamics of local observables. Our results generalize the celebrated ETH to the non-Hermitian setting, they show how it affects the system dynamics, and how the salient signatures can be observed in present-day cold-atom experiments.

Presenter: Jatin Ghildiyal

Affiliation: Indian Institute of Technology Ropar

Abstract: We show how two finite chains of spin-1/2 particles can get quantum synchronized via a common interaction with a central spin chain. These chains exhibit nonlinear coupling when represented in terms of pseudo-bosonic operators. This coupling leads to quantum synchronization, robust for a large variation in chain size and coupling strength. This work puts forward a generic formalism for quantum synchronization in both bosons and fermions.

Presenter: Prasant Mallik

Affiliation: IIT(ISM),Dhanbad, Jharkhand

Abstract: In this work, we introduce a framework to describe quantum systems with volume-law entanglement, combining Clifford circuits with the area-law. We aim to understand when this combination works and when it doesn’t, focusing on how area laws and non-stabilizerness affect quantum many-body systems. Our approach looks at classifying states based on two types of complexity: how easily they can be simulated classically and how much entanglement they have. We believe this work will be useful for simulating complex quantum states on current quantum simulation platforms.

Presenter: Saswato Sen

Affiliation: OIST

Abstract: We introduce a walk representation of the geometric Dirac equation, which is suitable for studying lattice QFT on random graphs. As an example, we use the walk representation to compute correlations on the Bethe lattice, a prototype for curved and random lattice.

Presenter: Nitesh K. Dubey

Affiliation: IIAP Bengaluru

Abstract: The entanglement observed by an observer using a quantum probe depends on several factors, such as the trajectory, the detector used, the coupling, and so on. I will present our study on the effects of Hawking radiation, local Unruh radiation, the anti-Hawking effect, and gravitational redshift on the entanglement of a fermionic field around a Schwarzschild black hole. The transition rate of a detector is a competing factor in entanglement measures. Therefore, I will first present the transition rate of a static Unruh-DeWitt detector linearly coupled to the scalar density of a massless Dirac field in the widely used vacua: the Hartle-Hawking, Unruh, and Boulware vacua. Then, I will discuss the anti-Hawking effect for detectors along various trajectories. Finally, I will address entanglement harvesting using detectors along static and geodesic trajectories and compare it with entanglement measures obtained via the resolvent technique in quantum field theory.

Presenter: Maaz Khan

Affiliation: IIIT Hyderabad

Abstract: Testing quantum entanglement at high-energy colliders has gained traction in recent years. We study information theoretic measures of two-body entanglement for different scattering processes at lepton colliders to see how interactions affect entanglement. We study general vertex terms and their effects on measures like concurrence, negativity, etc., for different final states.

Presenter: amir subba

Affiliation: IISER K

Abstract: We study H -> ZZ production process in final four lepton states at 13 TeV LHC in SMEFT framework. The anomalous HZZ couplings are parametrized with dimension-6 gauge invariant operators. We compute the eight polarizations of each Z boson and 64 spin-correlations as asymmetries in angular functions of final decayed leptons in the rest frame of the $Z$ boson. These asymmetries are further used to construct the joint density matrix (DM) for ZZ system. However, such DM suffers from negative probability and eigenvalues. To alleviate the negativity issues, we reconstruct the DM using asymmetries of symmetrized angular functions owing to the indistinguishability of two Z bosons. The symmetrized DM is further employed to compute lower bound for concurrence as a witness of entanglement measurable at the collider experiments. The ZZ system is found to be in an entangled state for all values of the anomalous couplings. Notably, while the lower bound exhibits poorer sensitivity to anomalous couplings compared to asymmetries, it demonstrates distinct behavior for CP-even and odd couplings.

Presenter: Beetehotra Roy

Affiliation: IISER K

Abstract: Emergence of bound states in QFT has been studied for half a century using various methods. Nonetheless, the methods have several limitations. In our work, we investigate the emergence of positronium as a bound state in QED using a recently developed nonperturbative unitary renormalization method.