Nonclassical effects in a driven atoms/cavity system in the presence of arbitrary driving field and dephasing

We investigate the photon statistics of light transmitted from a driven optical cavity containing one or two atoms interacting with a single mode of the cavity field. We treat arbitrary driving fields with emphasis on departure from previous weak field results. In addition effects of dephasing due to atomic transit through the cavity mode are included using two different models. We find that both models show the nonclassical correlations are quite sensitive to dephasing. The effect of multiple atoms on the system dynamics is investigated by placing two atoms in the cavity mode at different positions, therefore having different coupling strengths.Comment: 8 pages, 10 figures, minor typographical errors corrected, submitted to Phys Rev

Positive Education in the United Arab Emirates: Navigating Through and Beyond the Global Pandemic

Drawing on data from the emirate of Ras Al Khaimah (RAK) in the UAE, this study looks at using Positive Education (PE) to build strengths, competencies, well-being, and toughness in educational communities, to combat learning loss before and during the pandemic. We were interested in understanding how educational leaders, teachers, and students perceive PE and its impact on student well-being, as well as how well-equipped they were to handle the effects of the pandemic after participating in PE. Using qualitative data from semi-structured in-person interviews, focus groups, classroom observations, and document analysis, this study argues that PE supported students in coping with stressors associated with the pandemic. We show three significant findings. First, we found that the pandemic impacted student well-being in numerous academic and nonacademic ways. Second, our results demonstrate that PE was helpful in supporting student resilience and well-being during the pandemic. Third, data show that because PE was rolled out just before the pandemic began, the pandemic curtailed its full implementation. We conclude by recommending a whole school approach to PE that includes family members since the pandemic revealed that when students are engaged in remote learning or otherwise not face-to-face at school, it is critical that parents/families can support youth who may be struggling. Finally, we note the need for school-based support, like PE, to engender student resiliency

Host Centrality in Food Web Networks Determines Parasite Diversity

Background: Parasites significantly alter topological metrics describing food web structure, yet few studies have explored the relationship between food web topology and parasite diversity. Methods/Principal Findings: This study uses quantitative metrics describing network structure to investigate the relationship between the topology of the host food web and parasite diversity. Food webs were constructed for four restored brackish marshes that vary in species diversity, time post restoration and levels of parasitism. Our results show that the topology of the food web in each brackish marsh is highly nested, with clusters of generalists forming a distinct modular structure. The most consistent predictors of parasite diversity within a host were: trophic generality, and eigenvector centrality. These metrics indicate that parasites preferentially colonise host species that are highly connected, and within modules of tightly interacting species in the food web network. Conclusions/Significance: These results suggest that highly connected free-living species within the food web may represent stable trophic relationships that allow for the persistence of complex parasite life cycles. Our data demonstrate that the structure of host food webs can have a significant effect on the establishment of parasites, and on the potential fo

Quantum Noise Limits for Nonlinear, Phase-Invariant Amplifiers

Any quantum device that amplifies coherent states of a field while preserving their phase generates noise. A nonlinear, phase-invariant amplifier may generate less noise, over a range of input field strengths, than any linear amplifier with the same amplification. We present explicit examples of such nonlinear amplifiers, and derive lower bounds on the noise generated by a nonlinear, phase-invariant quantum amplifier.Comment: RevTeX, 6 pages + 4 figures (included in file; hard copy sent on request

A brief mindfulness-based intervention reduces eating disorder symptoms and improves eating self-efficacy and emotion regulation among adults seeking bariatric surgery

Background Up to 64% of bariatric (weight-loss) surgery-seeking adults report eating disorder (ED) symptoms (i.e., binge eating, emotional eating, addictive-like eating, and grazing) that can interfere with surgery outcomes. Well-designed pre-surgical interventions targeting eating behaviours may reduce ED symptoms and protect against suboptimal surgery outcomes. Objectives Provide proof-of-concept data to inform the design and optimization of a pre-surgical mindfulness-based intervention (MBI) for ED symptoms. Evaluate whether the MBI produces meaningful improvements in ED symptoms and clarify the mechanisms-of-action by which the MBI impacts ED symptoms. Methods Twenty-one pre-surgical patients with obesity and ED symptoms referred to a MBI completed self-report measures of addictive-like eating, binge eating, emotional eating, grazing, mindful eating, eating self-efficacy, and emotion regulation pre-(T1) and post-(T2) MBI. Results Repeated-measures ANOVAs revealed improvements in binge eating symptoms (F (1,20) = 30.38, ηp2 = .60, p < .001) and grazing (F (1,20) = 7.57, ηp2 = .28, p = .012), pre- to post-MBI. Adjusting for multiple comparisons, no significant improvements were found for addictive-like eating or emotional eating. Eating self-efficacy (F (1,20) = 29.70, ηp2 = .60, p < .001) and emotion regulation (F (1,20) = 7.18, ηp2 = .26, p = .014) improved, while mindful eating decreased (F (1,20) = 16.25, ηp2 = .45, p = .001), following the MBI. Bivariate correlations found associations between improvements in the mechanism of eating self-efficacy and improvements in the ED symptom of grazing pre- to post-MBI (r = 0.46, p < .05).  As well, improvements in emotion regulation were associated with positive changes in binge and emotional eating and grazing (r = 0.55, p < .001, r = 0.66, p < .001, r = 0.61, p < .05, respectively). Conclusions After participating in the MBI binge eating, grazing, eating self-efficacy, and emotion regulation abilities improved. Further work is needed to understand and mitigate deterioration in mindful eating. Moreover, acceptability and feasibility of the MBI should be assessed prior to testing the MBI in a large-scale efficacy trial. Future research should assess the the impact of this intervention on post-surgery weight-loss, weight-loss maintenance, and maintenance of improvements in ED symptoms

Prospects for personalizing antiviral therapy for hepatitis C virus with pharmacogenetics

Chronic hepatitis C virus (HCV) infection is a major cause of liver disease worldwide. HCV infection is currently treated with IFNα plus ribavirin for 24 to 48 weeks. This demanding therapy fails in up to 50% of patients, so the use of pharmacogenetic biomarkers to predict the outcome of treatment would reduce futile treatment of non-responders and help identify patients in whom therapy would be justified. Both IFNα and ribavirin primarily act by modulating the immune system of the patient, and HCV uses multiple mechanisms to counteract the antiviral effects stimulated by therapy. Therefore, response to therapy is influenced by variations in human genes governing the immune system and by differences in HCV genes that blunt antiviral immune responses. This article summarizes recent advances in understanding how host and viral genetic variation affect outcome of therapy. The most notable human associations are polymorphisms within the IL28B gene, but variations in human leukocyte antigen and cytokine genes have also been associated with treatment outcome. The most prominent viral genetic association with outcome of therapy is that HCV genotype 1 is much less sensitive to treatment than genotypes 2 and 3, but genetic differences below the genotype level also influence outcome of therapy, presumably by modulating the ability of viral genes to blunt antiviral immune responses. Pharmacogenetic prediction of the outcome of IFN-based therapy for HCV will require integrating the efficacies of the immunosuppressive mechanisms of a viral isolate, and then interpreting the viral resistance potential in context of the genetic profile of the patient at loci associated with outcome of therapy. Direct-acting inhibitors of HCV that will be used in combination with IFNα are nearing approval, so genetic prediction for anti-HCV therapy will soon need to incorporate viral genetic markers of viral resistance to the new drugs

Quantum Simulation of Spin Chains Coupled to Bosonic Modes with Superconducting Circuits

We propose the implementation of a digital quantum simulation of spin chains coupled to bosonic field modes in superconducting circuits. Gates with high fidelities allows one to simulate a variety of Ising magnetic pairing interactions with transverse field, Tavis-Cummings interaction between spins and a bosonic mode, and a spin model with three-body terms. We analyze the feasibility of the implementation in realistic circuit quantum electrodynamics setups, where the interactions are either realized via capacitive couplings or mediated by microwave resonators.Comment: Chapter in R. S. Anderssen et al. (eds.), Mathematics for Industry 11 (Springer Japan, 2015

Preparation of decoherence-free, subradiant states in a cavity

The cause of decoherence in a quantum system can be traced back to the interaction with the environment. As it has been pointed out first by Dicke, in a system of N two-level atoms where each of the atoms is individually dipole coupled to the environment, there are collective, subradiant states, that have no dipole coupling to photon modes, and therefore they are expected to decay slower. This property also implies that these type of states, which form an N-1 dimensional subspace of the atomic subsytem, also decohere slower. We propose a scheme which will create such states. First the two-level atoms are placed in a strongly detuned cavity and one of the atoms, called the control atom is excited. The time evolution of the coupled atom-cavity system leads to an appropriately entangled state of the atoms. By applying subsequent laser pulses at a well defined time instant, it is possible to drive the atomic state into the subradiant, i. e., decoherence free subspace. Up to a certain average number of the photons, the result is independent of the state of the cavity. The analysis of the conditions shows that this scheme is feasible with present day techniques achieved in atom cavity interaction experiments.Comment: 5 page

Quantum integrable multi atom matter-radiation models with and without rotating wave approximation

New integrable multi-atom matter-radiation models with and without rotating wave approximation (RWA) are constructed and exactly solved through algebraic Bethe ansatz. The models with RWA are generated through ancestor model approach in an unified way. The rational case yields the standard type of matter-radiaton models, while the trigonometric case corresponds to their q-deformations. The models without RWA are obtained from the elliptic case at the Gaudin and high spin limit.Comment: 9 pages, no figure, talk presented in int. conf. NEEDS04 (Gallipoli, Italy, July 2004