Creating excitonic entanglement in quantum dots through the optical Stark effect

We show that two initially non-resonant quantum dots may be brought into resonance by the application of a single detuned laser. This allows for control of the inter-dot interactions and the generation of highly entangled excitonic states on the picosecond timescale. Along with arbitrary single qubit manipulations, this system would be sufficient for the demonstration of a prototype excitonic quantum computer.Comment: 4 pages, 3 figures; published version, figure 3 improved, corrections to RWA derive

Effect of water and air flow on concentric tubular solar water desalting system.

This work reports an innovative design of tubular solar still with a rectangular basin for water desalination with flowing water and air over the cover. The daily distillate output of the system is increased by lowering the temperature of water flowing over it (top cover cooling arrangement). The fresh water production performance of this new still is observed in Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore (11° North, 77° East), India. The water production rate with no cooling flow was 2050ml/day (410ml/trough). However, with cooling air flow, production increased to 3050ml/day, and with cooling water flow, it further increased to 5000ml/day. Despite the increased cost of the water cooling system, the increased output resulted in the cost of distilled water being cut in roughly half. Diurnal variations of a few important parameters are observed during field experiments such as water temperature, cover temperature, air temperature, ambient temperature and distillate output

Separation-dependent localization in a two-impurity spin-boson model

Using a variational approach we investigate the delocalized to localized crossover in the ground state of an Ohmic two-impurity spin-boson model, describing two otherwise non-interacting spins coupled to a common bosonic environment. We show that a competition between an environment-induced Ising spin interaction and externally applied fields leads to variations in the system-bath coupling strength, $\alpha_c$, at which the delocalized-localized crossover occurs. Specifically, the crossover regime lies between $\alpha_c=0.5$ and $\alpha_c=1$ depending upon the spin separation and the strength of the transverse tunneling field. This is in contrast to the analogous single spin case, for which the crossover occurs (in the scaling limit) at fixed $\alpha_c\approx1$. We also discuss links between the two-impurity spin-boson model and a dissipative two-spin transverse Ising model, showing that the latter possesses the same qualitative features as the Ising strength is varied. Finally, we show that signatures of the crossover may be observed in single impurity observables, as well as in the behaviour of the system-environment entanglement.Comment: 12 pages, 9 figures. Published version. Expanded discussion of the distance dependence between the impurities, and added a related figur

Matter collineations of Spacetime Homogeneous G\"odel-type Metrics

The spacetime homogeneous G\"odel-type spacetimes which have four classes of metrics are studied according to their matter collineations. The obtained results are compared with Killing vectors and Ricci collineations. It is found that these spacetimes have infinite number of matter collineations in degenerate case, i.e. det$(T_{ab}) = 0$, and do not admit proper matter collineations in non-degenerate case, i.e. det$(T_{ab}) \ne 0$. The degenerate case has the new constraints on the parameters $m$ and $w$ which characterize the causality features of the G\"odel-type spacetimes.Comment: 12 pages, LaTex, no figures, Class. Quantum.Grav.20 (2003) 216

Rotating Bose gas with hard-core repulsion in a quasi-2D harmonic trap: vortices in BEC

We consider a gas of N(=6, 10, 15) Bose particles with hard-core repulsion, contained in a quasi-2D harmonic trap and subjected to an overall angular velocity $\Omega$ about the z-axis. Exact diagonalization of the $n\times n$ many-body Hamiltonian matrix in given subspaces of the total (quantized) angular momentum L$_{z}$, with $n\sim 10^{5}$(e.g. for L$_{z}$=N=15, n =240782) was carried out using Davidson's algorithm. The many-body variational ground state wavefunction, as also the corresponding energy and the reduced one-particle density-matrix were calculated. With the usual identification of $\Omega$ as the Lagrange multiplier associated with L$_{z}$ for a rotating system, the $L_{z}-\Omega$ phase diagram (or the stability line) was determined that gave a number of critical angular velocities $\Omega_{{\bf c}i}, i=1,2,3,... ,$ at which the ground state angular momentum and the associated condensate fraction undergo abrupt jumps. A number of (total) angular momentum states were found to be stable at successively higher critical angular velocities $\Omega_{{\bf c}i}, \ i=1,2,3,...$for a given N. For$L_{z}>N$, the condensate was strongly depleted. The critical$\Omega_{{\bf c}i}$values, however, decreased with increasing interaction strength as well as the particle number, and were systematically greater than the non-variational Yrast-state values for the single vortex state with L$_{z}$=N. We have also observed that the condensate fraction for the single vortex state (as also for the higher vortex states) did not change significantly even as the 2-body interaction strength was varied over several$(\sim 4)$ orders of magnitude in the moderately to the weakly interacting regime.Comment: Revtex, 11 pages, 1 table as ps file, 4 figures as ps file

Bending and Base-Stacking Interactions in Double-Stranded Semiflexible Polymer

Simple expressions for the bending and the base-stacking energy of double-stranded semiflexible biopolymers (such as DNA and actin) are derived. The distribution of the folding angle between the two strands is obtained by solving a Schr\"{o}dinger equation variationally. Theoretical results based on this model on the extension versus force and extension versus degree of supercoiling relations of DNA chain are in good agreement with the experimental observations of Cluzel {\it et al.} [Science {\bf 271}, 792 (1996)], Smith {\it et al.} [{\it ibid.} {\bf 271}, 795 (1996)], and Strick {\it et al.} [{\it ibid.} {\bf 271}, 1835 (1996)].Comment: 8 pages in Revtex format, with 4 EPS figure

Opportunities and Challenges of Tobacco Control Policy at District Level in Indonesia: A Qualitative Analysis

Introduction: Comprehensive tobacco control policies are lacking in Indonesia where smoking prevalence in males is among the highest in the world. This study aims to explore the knowledge, attitude, opportunities and challenges to tobacco control among local stakeholders. Methods: This is a qualitative study using in-depth interviews. Four study areas included Bengkulu Province, Bengkulu City, Seluma District, and Kaur District. Eighteen participants interviewed were from policymakers, legislators, and civil societies during November-December 2020. Thematic data analysis was used. Results: While knowledge and support of the existing Smoke Free Policy (SFP) were high, that of other policies such as outdoor tobacco advertising (OTA) ban and tobacco product display ban were low. Among others, one opportunity was there is already SFP regulation in each study area, to which such bans can be added. Among others, three major challenges were: (a) lack of enforcement of the existing SFP, (b) lack of national regulation to ban OTA and product display, and (c) counter actions by the tobacco industry. Conclusion: The opportunities and challenges identified could be lessons learnt for more comprehensive tobacco control especially by local governments in Indonesia and other countries with similar settings

Income Disparity and Healthcare Utilization: Lessons from Indonesia’s National Health Insurance Claim Data

Background: Indonesia’s National Health Insurance Program, known as Jaminan Kesehatan Nasional (JKN), has a variety of membership pathways for those wishing to gain access. Claim data from JKN offers a cost-effective way of observing who is accessing healthcare services and what types of services are being used. This study is a novel attempt to measure disparities amongst JKN users in their engagement with services, providing an opportunity to reflect on patterns of use. Methods: Using claims data collected from JKN users between 2015–2016, we used the Ordinary Least Square estimation model to compare health services utilization among subsidized and non-subsidized users. We focused primarily on the individual use of the hospital for outpatient and inpatient treatment. Results: Analysis reveals that subsidized users access primary healthcare services more frequently than non-subsidized users. Conversely, non-subsidized users access secondary and tertiary health care services more frequently than other users. Subsidized users who utilize secondary and tertiary health care tend to suffer more severe health illnesses than non-subsidized members. Conclusions: This study concludes that income disparity affects healthcare utilization. Non-subsidized members are more likely than subsidized members to access secondary and tertiary health care services. Our study offers evidence of the potential underutilization of secondary and tertiary healthcare (STHC) by subsidized members, which could lead to inefficiency since subsidized members seeking STHC treatment had severe health conditions, thus needing to be treated longer and requiring higher healthcare expenditures

Nuclear structure and reaction studies at SPIRAL

The SPIRAL facility at GANIL, operational since 2001, is described briefly. The diverse physics program using the re-accelerated (1.2 to 25 MeV/u) beams ranging from He to Kr and the instrumentation specially developed for their exploitation are presented. Results of these studies, using both direct and compound processes, addressing various questions related to the existence of exotic states of nuclear matter, evolution of new "magic numbers", tunnelling of exotic nuclei, neutron correlations, exotic pathways in astrophysical sites and characterization of the continuum are discussed. The future prospects for the facility and the path towards SPIRAL2, a next generation ISOL facility, are also briefly presented.Comment: 48 pages, 27 figures. Accepted for publication in Journal of Physics

Ground state and dynamics of the biased dissipative two-state system: Beyond variational polaron theory

We propose a ground-state ansatz for the Ohmic spin-boson model that improves upon the variational treatment of Silbey and Harris for biased systems in the scaling limit. In particular, it correctly captures the smooth crossover behaviour expected for the ground-state magnetisation when moving between the delocalised and localised regimes of the model, a feature that the variational treatment is unable to properly reproduce, while it also provides a lower ground-state energy estimate in the crossover region. We further demonstrate the validity of our intuitive ground-state by showing that it leads to predictions in excellent agreement with those derived from a non-perturbative Bethe-ansatz technique. Finally, recasting our ansatz in the form of a generalised polaron transformation, we are able to explore the dissipative two-state dynamics beyond weak system-environment coupling within an efficient time-local master equation formalism.Comment: 12 pages, 5 figures, comments welcome. Published version, including revised dynamics section and new discussion on the Toulouse poin