Balagarh Bijoy Krishna Mahavidyalaya

The zero-error capacity of a noisy classical channel quantifies its ability to transmit information with absolute certainty, i.e., without any probability of error. In contrast to Shannon's standard channel capacity, which remains unaffected by preshared no-signaling correlations, zero-error capacity can be enhanced through nonlocal correlations. In this work, we investigate zero-error communication utility of nonlocal correlations arising in the 2-2-m Bell scenario, where two parties have two inputs and m possible outcomes per input. For all m 2, we construct examples of noisy classical channels with zero unassisted zero-error capacity that, when assisted by extremal 2-2-m nonlocal correlations, can transmit one bit of information. Extending this analysis to the 2-m-2 Bell scenario, we identify channels with zero unassisted zero-error capacity that can nonetheless perfectly transmit log m bits of information. While nonlocal correlations arising from quantum entangled states cannot achieve a positive zero-error capacity for these channels, we show that they can, however, enhance the success probability of one-shot transmission of classical messages. We also derive a nontrivial upper bound on the extent to which a given no-signaling correlation can activate the zero-error capacity of noisy classical channels. Finally, we show that the maximal zero-error communication advantage achievable with a no-signaling correlation lower bounds its classical simulation cost, thus linking its usefulness for communication to the classical cost of simulating it.

An in-situ electrochemical deposition technique was utilized to develop Co3O4/crystalline graphene (Co3O4/cGr) nanocomposite 2D layered structure on indium oxide (ITO) coated polyethylene terephthalate (PET) flexible structure. Thorough characterizations of the deposited material have been carried out, interestingly that indicated the formation of crystalline graphene in the nanocomposite with an approximate layer count in the graphene stack within 18 and 20 and interlayer spacing of around 0.35 and 0.34 nm. The core-level ionization followed by non-radiative relaxation in Auger spectrum revealed the presence of mixed states of cobalt (i.e., Co (II) and Co(III)) in a spinel oxide structure, whereas, elemental mapping underscored well-distribution of cobalt, oxygen and carbon in the deposited film; that in turn refers to a highly active surface. On the other hand, electrochemical technique for the detection of neurotransmitters like dopamine can be a single-key solution to sensitive, selective and rapid determination of the analyte; where, such unique structural, compositional and surface features of the developed electrode material (Co3O4/cGr) could be well-contributing. Dopamine is a neurotransmitter that plays very important role in regulating human nervous actions and any imbalance in its abundance can cause severe issues like depression, hypertension, Parkinson's diseases and Schizophrenia, to name a few. This makes it very essential to detect the level of dopamine in human serum/plasma with best possible accuracy. So, in this work, the developed Co3O4/cGr nanocomposite was also explored for its possible application as an electrochemical dopamine sensor, and the results in terms of sensitivity, selectivity and reproducibility were quite encouraging.

It is a well-known fact that measurement incompatibility is a necessary resource to generate nonlocal correlations in usual Bell scenario that typically involves single quantum source. We can provide with some contrasting findings if we consider connected structure of multiple quantum sources. Precisely, we demonstrate that non n-locality can be detected in standard quantum network even when only a single party performs incompatible measurements. More interestingly, for any finite n ≥ 3, non n-local correlations can be generated in any standard linear n-local network when all the parties perform compatible measurements. Such an observation is topology specific as one of the parties must perform incompatible measurement to exhibit non n-locality in any non-linear network endowed with star topology. However, we observe that in any non-standard network (all sources independent and nonlocal), to generate fully network nonlocal correlations, all the parties must perform incompatible measurements. Such a finding is intuitive as more resource is required to generate stronger form of quantum non-classicality. We also demonstrate that merely providing resource of measurement incompatibility to all the parties is not sufficient for non n-locality detection in any quantum network.

Entanglement and nonlocality are two important nonclassical features of quantum correlations. Recently the study of quantum correlations in networks has undergone remarkable progress owing to technological development towards scalable quantum networks. However, compared to standard Bell scenario, manifestation of the interplay between these two aspects has received less attention in network scenarios featuring independent sources. In this work we have analyzed the relation between entanglement content of the sources and detectable non n-locality in two distinct network topologies(linear and star). We have studied the extremal violations of n-local inequalities(compatible with linear and star network) for any fixed amount of entanglement(in terms of concurrence) of the independent sources. It is observed that each of the sources must be entangled for detecting non n-locality in linear network. However, the same is not true for star n-local network. Present analysis is revealing that entanglement of all the independent sources is not a necessity for generation of non n-local correlations in star topology. Characterization of sources in terms of minimum entanglement requirement for any fixed violation amount of the n-local inequalities is also provided. Interestingly, detection of non n-locality is ensured in the network if product of concurrence of all the sources involved exceeds 1/2. .

We investigate the joint measurability of incompatible quantum observables on ensembles of parallel and antiparallel spin pairs. In parallel configuration, two systems are identically prepared, whereas in antiparallel configuration each system is paired with its spin-flipped counterpart. We demonstrate that the antiparallel configuration enables exact simultaneous prediction of three mutually orthogonal spin components -- an advantage unattainable in the parallel case. As we show, this enhanced measurement compatibility in antiparallel configuration is better explained within the framework of generalized probabilistic theories, which allow a broader class of composite structures while preserving quantum descriptions at the subsystem level. Furthermore, this approach extends the study of measurement incompatibility to more general configurations beyond just the parallel and antiparallel cases, providing deeper insights into the boundary between physical and unphysical quantum state evolutions. To this end, we discuss how the enhanced measurement compatibility in antiparallel configuration can be observed on a finite ensemble of qubit states, paving the way for an experimental demonstration of this advantage.