Multipartite quantum correlation and entanglement in four-qubit pure states

Based on the quantitative complementarity relations, we analyze thoroughly the properties of multipartite quantum correlations and entanglement in four-qubit pure states. We find that, unlike the three-qubit case, the single residual correlation, the genuine three- and four-qubit correlations are not suited to quantify entanglement. More interestingly, from our qualitative and numerical analysis, it is conjectured that the sum of all the residual correlations may constitute a good measure for the total multipartite entanglement in the system.Comment: 7 pages, 3 figue

Leaf Volatiles from Two Corydalis Species Lure A Keystone Seed-dispersing Ant and Enhance Seed Retrieval

It has been reported that a suit of plant traits can regulate the ant-seed interaction and subsequently affect the seed dispersal. However, the role of plant volatiles in attracting the ants for seed dispersal remains little examined. We used a Y-tube olfactometer to test behavior response of a keystone seed-dispersing ant (Pristomyrmex pungens Mayr) to leaves and seeds of five co-occurring myrmecochorous Corydalis species (C. wilfordii Regel, C. racemosa (Thunberg) Persoon, C. sheareri S. Moore, C. balansae Prain and C. incisa (Thunberg) Persoon). Of the five species, only C. wilfordii and C. racemosa leaves emits heavily volatiles. We also performed seed cafeteria experiments to assess the effect of leaf volatiles from C. racemosa on seed retrieval by presenting simultaneously the seeds near the fresh leaf and the leaf immersed by diethyl ether both in the field and lab. The experiment using Y-tube showed that the ants were only significantly attracted by the fresh leaves of two species, C. wilfordii and C. racemosa. The cafeteria experiments showed that ants spent less time to detect the C. racemosa seeds which were near the fresh leaf, and transported these seeds more quickly. This indicated that the leaf volatiles can function as an attractant for the dispersing ants, and ant preference in turn enhance the seed retrieval. The findings reveal that leaf volatiles can play na important but underestimated role in shaping the ant-seed dispersing interactions