Search

The separability in multiqubit pure and mixed GHZ and W states with an accelerating qubit has been characterized using Abe Rajagopal (AR) $ q $-conditional entropy. We observe that the pure multiqubit GHZ and W states in the inertial : non-inertial bipartition with one of their qubits being accelerated will remain non-separable irrespective of the qubit's acceleration. In these systems, we effectively captured the variation of their non-separability with respect to the acceleration of the qubit and the AR $ q $-conditional entropy parameter $ q $. However, in the corresponding multiqubit mixed states obtained by introducing a noise to the above pure states, one could get stronger conditions on their separability in the inertial : non-inertial bipartition, in terms of the mixing parameter, acceleration of the qubit and the number of qubits in the system, in the asymptotic limit of parameter $ q $. These conditions obtained from AR $ q $-conditional entropy serves as a necessary conditions for separability in such multiqubit states with a relativistic qubit., Comment: 15 pages, 6 figures

Quantum information with many-body quantum spin systems has, from time to time, given intriguing and intuitive outcomes to our understanding of multiport quantum communications. We identify that in an anisotropic many-body quantum spin system with two- and three-body interactions, when its two-spin subsystems are all negative under partial transpose, one can restrict this system for realizing only the multiport quantum dense coding protocol which has $(N-1)$ senders and a single receiver. All other single and multi channel dense coding protocols will have quantum dense coding capacities less than that of their respective classical capacities. We characterize the multiport quantum dense coding capacity with $(N-1)$ senders and a single receiver for this system with respect to its system parameters. We also define a magnetic field averaged dense coding capacity for this system, which allows us to comprehensively capture the influence of the entire range of external applied magnetic field and characterize its variation with respect to other system parameters., Comment: 9 pages, 5 figures, RevTeX4-2

The shareability of quantum correlations among the constituent parties of a multiparty quantum system is restricted by the quantum information theoretic concept called monogamy. Depending on the multiparty quantum systems, different measures of quantum correlations show disparate signatures for monogamy. We characterize the shareability of quantum correlations, from both entanglement-separability and information-theoretic kinds, in a multiparty quantum spin system containing two- and three-body interactions with respect to its system parameters and external applied magnetic field. Monogamy score in this system exhibits both monogamous and non-monogamous traits depending on the quantum correlation measure, strengths of system parameters and external magnetic field. The percentage of non-monogamous states when the information-theoretic quantum correlations are considered is higher than that of the entanglement-separability kind in allowed ranges of these variables. The integral powers of the quantum correlation measures for which the non-monogamous states become monogamous are identified., Comment: 12 pages, 7 figures, RevTeX4-2, journal accepted version

Space biology research aims to understand fundamental effects of spaceflight on organisms, develop foundational knowledge to support deep space exploration, and ultimately bioengineer spacecraft and habitats to stabilize the ecosystem of plants, crops, microbes, animals, and humans for sustained multi-planetary life. To advance these aims, the field leverages experiments, platforms, data, and model organisms from both spaceborne and ground-analog studies. As research is extended beyond low Earth orbit, experiments and platforms must be maximally autonomous, light, agile, and intelligent to expedite knowledge discovery. Here we present a summary of recommendations from a workshop organized by the National Aeronautics and Space Administration on artificial intelligence, machine learning, and modeling applications which offer key solutions toward these space biology challenges. In the next decade, the synthesis of artificial intelligence into the field of space biology will deepen the biological understanding of spaceflight effects, facilitate predictive modeling and analytics, support maximally autonomous and reproducible experiments, and efficiently manage spaceborne data and metadata, all with the goal to enable life to thrive in deep space., Comment: 28 pages, 4 figures

Human space exploration beyond low Earth orbit will involve missions of significant distance and duration. To effectively mitigate myriad space health hazards, paradigm shifts in data and space health systems are necessary to enable Earth-independence, rather than Earth-reliance. Promising developments in the fields of artificial intelligence and machine learning for biology and health can address these needs. We propose an appropriately autonomous and intelligent Precision Space Health system that will monitor, aggregate, and assess biomedical statuses; analyze and predict personalized adverse health outcomes; adapt and respond to newly accumulated data; and provide preventive, actionable, and timely insights to individual deep space crew members and iterative decision support to their crew medical officer. Here we present a summary of recommendations from a workshop organized by the National Aeronautics and Space Administration, on future applications of artificial intelligence in space biology and health. In the next decade, biomonitoring technology, biomarker science, spacecraft hardware, intelligent software, and streamlined data management must mature and be woven together into a Precision Space Health system to enable humanity to thrive in deep space., Comment: 31 pages, 4 figures

Screw conveyors are widely employed in industry for the bulk transport of particulate materials. Several studies have attempted to correlate the discharge rate with the rotation speed of the screw via experiments and particle dynamics simulations. However, a detailed mechanical model that would assist in the optimal design of screw conveyors has not been attempted. In this study, we first construct a simple model that assumes the entire granular medium to move as a rigid body sliding along the surfaces of the screw and barrel. By enforcing the balances of linear and angular momentum to a suitably chosen continuum element, we show that under certain limiting conditions, the discharge rate for a given angular velocity and screw geometry can be obtained. Further, we show that the discharge can be maximized by setting the ratio of the pitch to barrel diameter to a particular value. We then study the detailed flow within the conveyor using the Discrete Element Method, which reveals that a significant fraction of the material exhibits solid body motion, in agreement with the simple model. We assess the effect of relaxing the limiting conditions employed in the model, thereby determining the connection between the friction at the walls and the kinematics of flow. Finally, the trend in variation of average axial velocity with the pitch to barrel diameter ratio in the presence of gravity is compared with that from our model and simulations in the absence of gravity. We observe that both the trends are qualitatively the same indicating that the dependence of average axial velocity on the geometry of the conveyor is not altered by the introduction of gravity.

Dense granular materials and other particle aggregates transmit stress in a manner that belies their microstructural disorder. A subset of the particle contact network is strikingly coherent, wherein contacts are aligned nearly linearly and transmit large forces. Important material properties are associated with these force chains, but their origin has remained a puzzle. We classify subnetworks by their linear connectivity, and show the emergence of a percolation transition at a critical linearity at which the network is sparse, coherent, and contains the force chains. The subnetwork at critical linearity closely reflects the macroscopic stress and explains distinctive features of granular mechanics.

We study the dynamics of microscopic quantum correlations, viz., bipartite entanglement and quantum discord between nearest neighbor sites, in Ising spin chain with a periodically varying external magnetic field along the transverse direction. Quantum correlations exhibit periodic revivals with the driving cycles in the finite-size chain. The time of first revival is proportional to the system size and is inversely proportional to the maximum group velocity of Floquet quasi-particles. On the other hand, the local quantum correlations in the infinite chain may get saturated to non-zero values after a sufficiently large number of driving cycles. Moreover, we investigate the convergence of local density matrices, from which the quantum correlations under study originate, towards the final steady-state density matrices as a function of driving cycles. We find that the geometric distance, $d$, between the reduced density matrices of non-equilibrium state and steady-state obeys a power-law scaling of the form $d \sim n^{-B}$, where $n$ is the number of driving cycles and $B$ is the scaling exponent. The steady-state quantum correlations are studied as a function of time period of the driving field and are marked by the presence of prominent peaks in frequency domain. The steady-state features can be further understood by probing band structures of Floquet Hamiltonian and purity of the bipartite state between nearest neighbor sites. Finally, we compare the steady-state values of the local quantum correlations with that of the canonical Gibbs ensemble and infer about their canonical ergodic properties. Moreover, we identify generic features in the ergodic properties depending upon the quantum phases of the initial state and the pathway of repeated driving that may be within the same quantum phase or across two different equilibrium phases., Comment: To appear in Journal of Magnetism and Magnetic Materials

We investigate the action of local and global noise on monogamy of quantum correlations, when monogamy scores are considered as observables, and three-qubit systems are subjected to global noise and various local noisy channels, namely, amplitude-damping, phase-damping, and depolarizing channels. We show that the dynamics of monogamy scores corresponding to negativity and quantum discord, in the case of generalized W states, as inputs to the noisy channels, can exhibit non-monotonic dynamics with respect to increasing noise parameter, which is in contrast to the monotonic decay of monogamy scores when generalized Greenberger-Horne-Zeilinger states are exposed to noise. We quantify the persistence of monogamy against noise via a characteristic value of the noise parameter, and show that depolarizing noise destroys monogamy of quantum correlation faster compared to other noisy channels. We demonstrate that the negativity monogamy score is more robust than the quantum discord monogamy score, when the noise is of the phase-damping type. We also investigate the variation of monogamy with increasing noise for arbitrary three-qubit pure states as inputs. Finally, depending on these results, we propose a two-step protocol, which can conclusively identify the type of noise applied to the quantum system, by using generalized Greenberger-Horne-Zeilinger and generalized W states as resource states. We discuss a possible generalization of the results to higher number of parties., Comment: 18 Pages, 9 Figures, 3 Tables, Including supplementary material and extended references

The time-dynamics of quantum correlations in the quantum transverse anisotropic XY spin chain of infinite length is studied at zero as well as finite temperatures. The evolution occurs due to the instantaneous quenching of the coupling constant between the nearest-neighbor spins of the model, which is either performed within the same phase or across the quantum phase transition point connecting the order-disorder phases of the model. We characterize the time-evolved quantum correlations, entanglement and quantum discord, which exhibit varying behavior depending on the initial state and the quenching scheme. We show that the system is endowed with enhanced bipartite quantum correlations compared to that of the initial state, when quenched from ordered to the deep disordered phase. However, bipartite quantum correlations are almost washed out when the system is quenched from disordered to the ordered phase with the initial state being at the zero-temperature. Moreover, we identify the condition for the occurrence of enhanced bipartite correlations when the system is quenched within the same phase. Finally, we investigate the bipartite quantum correlations when the initial state is a thermal equilibrium state with finite temperature which reveals the effects of thermal fluctuation on the phenomena observed at zero-temperature., Comment: 10 pages, 6 figures

We derive complementarity relations for arbitrary quantum states of multiparty systems, of arbitrary number of parties and dimensions, between the purity of a part of the system and several correlation quantities, including entanglement and other quantum correlations as well as classical and total correlations, of that part with the remainder of the system. We subsequently use such a complementarity relation, between purity and quantum mutual information in the tripartite scenario, to provide a bound on the secret key rate for individual attacks on a quantum key distribution protocol., Comment: 7 pages, 3 figures, 1 table; v2: table updated, implications unchanged

We investigate the entanglement patterns of photon-added and -subtracted four-mode squeezed vacuum states. Entanglements in different scenarios are analyzed by varying the number of photons added or subtracted in certain modes, which are referred to as the "player" modes, the others being "spectators." We find that the photon-subtracted state can give us higher entanglement than the photon-added state which is in contrast of the two-mode situation. We also study the logarithmic negativity of the two-mode reduced density matrix obtained from the four-mode state which again shows that the state after photon subtraction can possess higher entanglement than that of the photon-added state, and we then compare it to that of the two-mode squeezed vacuum state. Moreover, we examine the non-Gaussianity of the photon-added and -subtracted states to find that the rich features provided by entanglement cannot be captured by the measure of non-classicality., Comment: 14 pages, 14 figures