Tight upper bound of genuine four party Svetlichny type nonlocality with and without local filtering

Identifying the nonlocality of a multiparty quantum state is an important task in quantum mechanics. Seevinck and Svetlichny [Phys. Rev. Lett. 89, 060401 (2002)], and independently, Collins and co-workers [Phys. Rev. Lett. 88, 170405 (2002)] have generalized the tripartite notion of Svetlichny nonlocality to n-parties. Here we have developed a tight upper bound for genuine four party Svetlichny type nonlocality. The constraints on the quantum states for the tightness of the bound are also presented. The method enables us to provide necessary and sufficient conditions for violating the four qubit Svetlichny type inequality for several quantum states. The relations between the genuine multipartite entanglement and the maximal quantum value of the Seevinck and Svetlichny operators for pure four qubit states are also discussed. Consequently, we have exhibited genuine four qubit hidden nonlocality under local filtering. Our result provides an effective and operational method for further study of multipartite quantum nonlocality.Comment: 10 pages, 2 figures, revtex, comments welcome. arXiv admin note: text overlap with arXiv:quant-ph/0602143, arXiv:1710.01601 by other author

Attitude towards plain packaging of tobacco products among the adult population in Bangladesh: a mixed method approach

Background The aim of this study was to investigate the attitude and reactions towards plain tobacco pack among the adult population in Bangladesh. Methods This was a cross-sectional study with mixed method approach. Data was collected from 458 respondents through face-to-face interview for quantitative part and another 40 through in-depth interview with 10 key informants' interview for qualitative part. In every cases of this study, dummy cigarette plain packet, which was developed in comparison with the existing graphic health warning pack,were used. To measure respondents' attitude on different aspect of plain tobacco pack, a five-point scale was used in this study. Response options for all items were: completely agree (5), slightly agree (4), neither agree nor disagree, that is neutral (3), slightly disagree (2) and completely disagree (1). Furthermore, reaction of the respondents observed by the researcher and it was noted under four subheadings like- Alertness, Unpleased, Concerned and Discomfort. Using a four point scale, response was taken and the options were: more (4), moderate (3), little (2) and negative answer to the statement (1). Thematic content analysis was performed and SPSS version 22.0 software was used for data analysis. Results Of the total respondents 96.5% were positive about the introduction of plain packaging of tobacco products in Bangladesh. About 94% respondents' perceived that it would reduce the attractiveness and appeal of tobacco products. Plain pack was believed to be able to prevent the tobacco advertisement and branding promotion, reduce youth experimentation, misleading consumers, youth tobacco initiation, and motivate tobacco users to quit by the majority of the participants. Conclusions The findings of this study provide baseline information to initiate debate with country policy makers to formulate plain packaging of tobacco products legislation in Bangladesh