You have one-minute remaining:” What my parents have taught me about distance, loss, and uncertainty

Journal #52 from Media Rise's Quarantined Across Borders Collection by Azeta Hatef. From United States (California). Quarantined in United States (Massachusetts).In this piece, I reflect on how the novel coronavirus has resurfaced conversations around trauma and response to disaster in my family. As the child of refugees, this moment has made clearer how my parents have responded to uncertainty and the ways in which these methods inform my understanding of distance and loss.Media Rise Publications. Quarantined Across Borders Collection. Edited by Dr Srividya "Srivi" Ramasubramanian

Quantum Coherence and Interference in Metallic Photonic Crystals and Hybrid Systems

In the first part of the thesis, we study the absorption coefficient of quantum dots doped in metallic photonic crystals under different circumferences. We study numerically the temporal evolution of the absorption coefficient profile where a probe field is applied to monitor the absorption process in two cases, when quantum dots are embedded lightly and densely. We also studied the effect of a changing plasma frequency on the absorption profile of quantum dots two possible field configurations. We show that the changes in plasma energy can take the system from the absorption region to the transparent and gain region. As the next part, we developed an analytical theory for the photonic band structure and density of states of two-dimensional rectangular metallic photonic crystals. We found that the location of the photonic band gap can be controlled by modifying the plasma energy of either metal. We showed that by changing the plasma energy one can control the spontaneous emission in the metallic photonic crystal. Finally, I studied hybrid systems (quantum dot - metallic nanoparticle). The main advantage of hybrid systems when compared with other nano-optical systems is the possibility for direct energy and quantum information transfer between nanoparticles. In this project, we investigate the control of thermal energy loss in metallic nanoparticles, an effect which could destroy the quality of transformed information if not properly controlled

You have one-minute remaining:” What my parents have taught me about distance, loss, and uncertainty

Journal #52 from Media Rise's Quarantined Across Borders Collection by Azeta Hatef. From United States (California). Quarantined in United States (Massachusetts).In this piece, I reflect on how the novel coronavirus has resurfaced conversations around trauma and response to disaster in my family. As the child of refugees, this moment has made clearer how my parents have responded to uncertainty and the ways in which these methods inform my understanding of distance and loss.Media Rise Publications. Quarantined Across Borders Collection. Edited by Dr Srividya "Srivi" Ramasubramanian

Characteristics of Household Solid Waste Open Burning Emissions

Open burning of household waste is a common phenomenon in many rural areas in developing countries, such as South Africa. Due to limited resources for collecting and proper disposal of the waste, household and municipal solid waste is often dumped in neighborhoods and are open burned in piles to reduce odor and create space for the incoming waste. Uncontrolled, low temperature burning, and smoldering conditions are typical associated with household waste fires. Emissions from these ground level burns cause local and regional air pollution, leading to adverse health effects among community residents. It is known that emissions from waste open burning can increase the risk of heart disease; aggravate respiratory ailments, such as asthma and emphysema; and cause rashes, nausea or headaches. Solid waste burning also produces harmful quantities of pollutants that settle on crops and in waterways, where they eventually wind up in our food and affect our health. In addition, the large amount of greenhouse gases and particles can affect global and regional radiation budget. Despite their significant impact on air quality, human health, and climate, very few studies have characterized emissions from open burning of household waste. In this study, we conducted a systematic laboratory combustion of eight categories of wastes including: paper, rubber, textile, plastic (hard and soft), vegetation (with three different moisture contents), food discards, and combined materials. Key results include emission factors of important pollutants as well as size distribution and optical properties of smoke particles. These data will provide key information for emission inventory, air quality management, climate impact assessment, and health effects evaluation

Optical nonlinear effects and photon pair production in modulated materials

According to quantum field theory an oscillation of boundary conditions in the vacuum can generate real photon pairs, which pop into existence from the zero-point energy. This surprising effect is known as the dynamical Casimir effect (DCE). In this thesis, we focus our attention on using the DCE as a route to experimentally study the quantum vacuum. Initially we explore experimental approaches that rely on an oscillation of vacuum boundary conditions. These require a direct temporal modulation of the boundary condition, which we achieve by temporally modulating the refractive index through the second order nonlinearity of the medium. We show that the key condition for this approach is that the medium is subwavelength in thickness. This leads to a temporal modulation of the refractive index. We use a mechanically exfoliated MoS2 monolayer. We present a detailed study of the second order nonlinearity of 2D (mono-atomic layer) dichalcogenide MoS2, and test its potential for spontaneous parametric down-conversion (SPDC) i.e. amplification of vacuum fluctuations mediated by optical nonlinearity. We present a model of SPDC in MoS2 monolayers and show that our data are compatible with theoretical estimates. We show exciting indications that SPDC may be possible in this material by performing polarization and lifetime measurements. We also discuss and characterise a new photo-luminescence emission around 1500 nm which is enhanced at the edges of multi-layer MoS2. In chapter three we present experimental approaches using spatially modulated third order nonlinear media along the propagation axis. We show that under certain conditions the spatial modulation of the boundary conditions along the nonliner media can be considered as a temporal modulation. Modulated waveguides provide an intensity variation of the pulse along the waveguide. Two different materials are used as substrate material for the waveguides; gallium lanthanum sulphide (GLS), which has a high third order nonlinear susceptibility and fused silica. We present numerical simulation results for photon generation from the modulated waveguides in GLS sample. We also characterise the nonlinear response and effects of the waveguides. In both substrates, we show that the lack of nonlinearity and different sources of losses prevents the creation of photon pairs. Finally, we present an experimental method in which the group velocity dispersion (GVD) is modulated along a photonic crystal fiber. Measurements of the temporal correlations between the newly generated frequencies is presented with a coincident to accidental ratio (CAR) of 7.5: yielding proof of a quantum correlation between the generated photon pairs