Novel Collective Effects in Integrated Photonics

Superradiance, the enhanced collective emission of energy from a coherent ensemble of quantum systems, has been typically studied in atomic ensembles. In this work we study theoretically the enhanced emission of energy from coherent ensembles of harmonic oscillators. We show that it should be possible to observe harmonic oscillator superradiance for the first time in waveguide arrays in integrated photonics. Furthermore, we describe how pairwise correlations within the ensemble can be measured with this architecture. These pairwise correlations are an integral part of the phenomenon of superradiance and have never been observed in experiments to date.Comment: 7 pages, 3 figure

Quantum walk on distinguishable non-interacting many-particles and indistinguishable two-particle

We present an investigation of many-particle quantum walks in systems of non-interacting distinguishable particles. Along with a redistribution of the many-particle density profile we show that the collective evolution of the many-particle system resembles the single-particle quantum walk evolution when the number of steps is greater than the number of particles in the system. For non-uniform initial states we show that the quantum walks can be effectively used to separate the basis states of the particle in position space and grouping like state together. We also discuss a two-particle quantum walk on a two- dimensional lattice and demonstrate an evolution leading to the localization of both particles at the center of the lattice. Finally we discuss the outcome of a quantum walk of two indistinguishable particles interacting at some point during the evolution.Comment: 8 pages, 7 figures, To appear in special issue: "quantum walks" to be published in Quantum Information Processin

Disability design and innovation in computing research in low resource settings

80% of people with disabilities worldwide live in low resourced settings, rural areas, informal settlements and in multidimensional poverty. ICT4D leverages technological innovations to deliver programs for international development. But very few do so with a focus on and involving people with disabilities in low resource settings. Also, most studies largely focus on publishing the results of the research with a focus on the positive stories and not the learnings and recommendations regarding research processes. In short, researchers rarely examine what was challenging in the process of collaboration. We present reflections from the field across four studies. Our contributions are: (1) an overview of past work in computing with a focus on disability in low resource settings and (2) learnings and recommendations from four collaborative projects in Uganda, Jordan and Kenya over the last two years, that are relevant for future HCI studies in low resource settings with communities with disabilities. We do this through a lens of Disability Interaction and ICT4D

Quantum walks: a comprehensive review

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

The O-16(gamma,p) reaction at E-gamma=60 and 72-MeV

Angular distributions within the range 25°-125° are presented for the 160(gamma,p) reaction populating low-lying states in 15N at E_gamma = 60 and 72 MeV. A comparison of the data with self-consistent Hartree-Fock RPA calculations shows the importance of meson-exchange currents in the photon-absorption process

Effects of Age and Illumination on Night Driving: A Road Test

OBJECTIVE: This study investigated the effects of drivers' age and low light on speed, lane keeping, and visual recognition of typical roadway stimuli. BACKGROUND: Poor visibility, which is exacerbated by age-related changes in vision, is a leading contributor to fatal nighttime crashes. There is little evidence, however, concerning the extent to which drivers recognize and compensate for their visual limitations at night. METHOD: Young, middle-aged, and elder participants drove on a closed road course in day and night conditions at a "comfortable" speed without speedometer information. During night tests, headlight intensity was varied over a range of 1.5 log units using neutral density filters. RESULTS: Average speed and recognition of road signs decreased significantly as functions of increased age and reduced illumination. Recognition of pedestrians at night was significantly enhanced by retroreflective markings of limb joints as compared with markings of the torso, and this benefit was greater for middle-aged and elder drivers. Lane keeping showed nonlinear effects of lighting, which interacted with task conditions and drivers' lateral bias, indicating that older drivers drove more cautiously in low light. CONCLUSION: Consistent with the hypothesis that drivers misjudge their visual abilities at night, participants of all age groups failed to compensate fully for diminished visual recognition abilities in low light, although older drivers behaved more cautiously than the younger groups. APPLICATION: These findings highlight the importance of educating all road users about the limitations of night vision and provide new evidence that retroreflective markings of the limbs can be of great benefit to pedestrians' safety at night

Collective wellbeing and posttraumatic growth during COVID-19: how positive psychology can help families, schools, workplaces and marginalized communities

Published online: 13 Jul 2021Positive psychology approaches have been shown to play a vital role in protecting mental health in times of challenge and are, therefore, an important area to include when studying the psychological outcomes of COVID-19. While existing research has focused on individual psychological health, this paper focuses on collective wellbeing and collective posttraumatic growth, with the aim of more clearly identifying the positive experiences and positive growth for families, schools, and workplaces during the pandemic. A range of positive psychology interventions for families, schools, workplaces, and psychology clinics are presented. The paper then considers how three broad-reaching phenomena existing in our wider society (i.e., arts and culture, eco-connection, and wellbeing literacy) can be used to boost collective wellbeing. Finally, the use of a positive systems approach to understand civilian responses across different countries, together with an examination of the role that positive psychology can play in supporting marginalized groups, is discussed.Lea Waters, Kim Cameron, S. Katherine Nelson-Coffey, Damien L. Crone, Margaret L. Kern, Tim Lomas, Lindsay Oades, Rhea L. Owens, James O. Pawelski, Tayyab Rashid, Meg A. Warren, Mathew A. White and Paige William