Recurrence network analysis in a model tripartite quantum system

In a novel approach to quantum dynamics, we apply the tools of recurrence network analysis to the dynamics of the quantum mechanical expectation values of observables. We construct and analyse $\epsilon$-recurrence networks from the time-series data of the mean photon number in a model tripartite quantum system governed by a nonlinear Hamiltonian. The role played by the intensity-dependent field-atom coupling in the dynamics is investigated. Interesting features emerge as a function of a parameter characterising this intensity-dependent coupling in both the short-time and the long-time dynamics. In particular, we examine the manner in which standard measures of network theory such as the average path length, the link density and the clustering coefficient depend on this parameter.Comment: Comments are welcome (7 pages, 6 figures

Dynamics of a multipartite hybrid quantum system with beamsplitter, dipole-dipole and Ising interactions

The possibility of exploiting heterogeneous quantum systems to high precision, for storing, processing, and transmitting information makes them ideal candidates for multi-tasking purposes in quantum communication. Appropriate quantum systems involving a judicious choice of interactions which augment each other, are potentially useful for probing deep into quantum regimes. Here, we make use of one such hybrid bipartite quantum model, with one subsystem made of a pair of qubits and another comprising a pair of oscillators, to study the entanglement dynamics, and the entanglement transfer between discrete and continuous variables. Our basic model is the standard double Jaynes-Cummings system, which is known to support both entanglement transfer and entanglement sudden death, under suitable conditions. In this work, we generalise this model to include further experimentally relevant interactions, such as the beamsplitter-type exchange interaction between the oscillators, and dipole-dipole and Ising-type interactions between the qubits. The manner in which various interactions and initial oscillator states affect the entanglement dynamics, is examined theoretically, for generic experimental conditions. Using exact analytical solutions, we show that compared to the beamsplitter or dipole-dipole interaction, the Ising interaction can have a significant positive impact on entanglement sudden death and birth, and postponement of the onset of these phenomena, apart from producing substantial reduction in the time duration of the death.Comment: 16 pages, 7 figure

Replacing conventional surface irrigation with micro-irrigation in vegetables can alleviate arsenic toxicity and improve water productivity

Arsenic (As), a heavy metal(loid), is exceedingly hazardous and carcinogenic and harms people, soil, plants, and water. Vegetable consumption can be a source for the absorption of As in humans. To find a feasible mitigation technique, a field experiment was conducted with broccoli (cv. Green Magic) and cauliflower (cv. Pusa Snowball) in geogenically arsenic-contaminated areas (West Bengal, India) for two consecutive years in a randomized block design replicated seven times with surface irrigation of 20 mm depth, gravity drip and sprinkler irrigation at 1.0 and 0.7 of pan evaporation replenishment. Results revealed that the lowest As accumulation in the edible heads was accomplished by micro-irrigation (0.34 and 0.31 mg kg−1) over the farmer's practice of surface irrigation (0.42 and 0.38 mg kg−1) for broccoli and cauliflower. Micro-irrigation improved the average head yield by 5.26 and 6.53%, weight by 6.37 and 3.06%, and diameter by 1.14 and 1.23% for broccoli and cauliflower respectively and also resulted in substantial water saving to an extent of 37.3%. Further reduction in As stress reduced the activity of antioxidant enzymes like catalase, superoxide dismutase and peroxidase; and reduced the dietary carcinogenic risk like Severity Adjusted Margin of Exposure (SAMOE) from moderate-high to low. Accordingly, drip irrigation without water stress can benefit vegetable growing in the As-contaminated regions based on the competitive advantage