Two-dimensional miscible-immiscible supersolid and droplet crystal state in a homonuclear dipolar bosonic mixture

The recent realization of binary dipolar BEC [Phys. Rev. Lett. 121, 213601 (2018)] opens new exciting aspects for studying quantum droplets and supersolids in a binary mixture. Motivated by this experiment, we study groundstate phases and dynamics of a Dy-Dy mixture. Dipolar bosonic mixture exhibits qualitatively novel and rich physics. Relying on the three-dimensional numerical simulations in the extended Gross-Pitaevskii framework, we unravel the groundstate phase diagrams and characterize different groundstate phases. The emergent phases include both miscible and immiscible single droplet (SD), multiple droplets (MD), supersolid (SS), and superfluid (SF) states. More intriguing mixed groundstates may occur for an imbalanced binary mixture, including a combination of SS-SF, SS-MD, and SS-SS phases. We observed the dynamical transition from a miscible MD state to an immiscible MD state with multiple domains formed along the axial direction by tuning the inter-species scattering length. Also by linear quenches of intra-species scattering lengths across the aforementioned phases, we monitor the dynamical formation of supersolid clusters and droplet lattices. Although we have demonstrated the results for a Dy-Dy mixture and for a specific parameter range of intra-species and inter-species scattering lengths, our results are generally valid for other dipolar mixtures and may become an important benchmark for future experimental scenarios.Comment: 15 pages, 14 figure

Performances in COVID 19 Management Across Countries: Do Subnational Finances Matter?

The spread of the COVID-19 pandemic has emphasized the role of governments in a public health emergency not only in developing countries, but in the developed world as well. This paper has a two-fold objective. First, we investigate the efficiency of COVID management using state-level data from three of the worst affected countries, USA, India, and Mexico, in three time periods in the pre-vaccine phase. Next, we explore the extent to which state government financial, sociodemographic, and governance indicators can explain the difference in efficiency. We use a two-stage non-parametric method. The first stage comprises of meta frontier analysis to derive efficiency scores for each state. We analyze state governments in these countries together (grand frontier) and separately (group frontier). Overall, grand efficiency continuously increased from August to November 2020. The grand efficiency scores of Mexico and the USA gradually increased on 3rd October and 29th November 2020. The results reflect that the USA was holding the leading position in terms of COVID-19 pandemic management at that time. In terms of group efficiency, American states performed consistently well with respect to their own country as well as other countries. However, if we compare the grand and group efficiency scores of all three countries, we find that states in India and Mexico performed well in their own countries but worse than USAstates in terms of the global scenario. The states of India always performed better within their own country than the states of the other two countries. The second analytical stage uses an exploratory median analysis to investigate the impact of different indicators on efficiency. State finance variables are positively associated with the grand efficiency score for all three time periods, while the association is negative for the expenditures to own revenue ratio and expenditures to total revenue ratios, debt ratios with respect to different fiscal indicators, and percentage of health expenditure over total expenditures and GSDP. These patterns are less consistent among countries when we look at group efficiency over time. We find a positive association of per capita total revenue with group efficiency scores for all countries over all time periods

Game-theoretic analysis to examine how government subsidy policies affect a closed-loop supply chain decision

The pros and cons of government subsidy policies in a closed-loop supply chain (CLSC) setting on optimal pricing, investment decisions in improving product quality, and used product collection under social welfare (SW) optimization goal have not been examined comprehensively. This study compares the outcomes of three government policies under manufacturer-Stackelberg (MS) and retailer-Stackelberg (RS), namely (i) direct subsidy to the consumer, (ii) subsidy to the manufacturer to stimulate used product collection, and (iii) subsidy to the manufacturer to improve product quality. Results demonstrate that the greening level, used product collection, and SW are always higher under the RS game, but the rate of a subsidy granted by the government is always higher under the MS game. Profits for the CLSC members and SW are always higher if the government provides a subsidy directly to the consumer, but productivity of investment in the perspective of the manufacturer or government are less. In a second policy, the government organizations grant a subsidy to the manufacturer to stimulate used product collection, but it does not necessarily yield the desired outcome compared to others. In a third policy, the manufacturer receives a subsidy on a research and development (R&D) investment, but it yields a sub-optimal greening level. This study reveals that the outcomes of subsidy policies can bring benefit to consumers and add a degree of complication for CLSC members; government organizations need to inspect carefully among attributes, mainly product type, power of CLSC members, and investment efficiency for the manufacturer, before implementing any subsidy policies so that it can lead to an environmentally and economically viable outcome

Rayleigh-Taylor instability in a phase-separated three-component Bose-Einstein condensate

We investigate the Rayleigh-Taylor instability at the two interfaces in a phase-separated three-component Bose-Einstein condensate in the mean-field framework. The subsequent dynamics in the immiscible three-component condensate has been studied in detail for different cases of instigating the instability in the system. The rotational symmetry of the system breaks when the atom-atom interaction is tuned in such a way that the interface between the components becomes unstable giving rise to non-linear patterns of mushroom shapes which grow exponentially with time. We also identify these non-linear patterns as the solutions of the angular Mathieu equation, representing the normal modes.Comment: 12 pages, 11 figure