Many-body dynamics of the decay of excitons of different charges in a quantum dot

We calculate the photoluminescence spectrum of a single semiconductor quantum dot strongly coupled to a continuum as a function of light frequency, gate voltage, and magnetic field. The spectrum is dominated by the recombination of several excitonic states which can be considered as quantum quenches in which the many-body nature of the system is suddenly changed between initial and final states. This is associated with an Anderson orthogonality catastrophe with a power-law singularity at the threshold. We explain the main features observed experimentally in the region of stability of the trion X-, the neutral exciton X0, and the gate-voltage-induced transition between them.Fil: Andrade Hoyos, Jhon Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Aligia, Armando Ángel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Cornaglia de la Cruz, Pablo Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentin

A practical guide to density matrix embedding theory in quantum chemistry

Density matrix embedding theory (DMET) provides a theoretical framework to treat finite fragments in the presence of a surrounding molecular or bulk environment, even when there is significant correlation or entanglement between the two. In this work, we give a practically oriented and explicit description of the numerical and theoretical formulation of DMET. We also describe in detail how to perform self-consistent DMET optimizations. We explore different embedding strategies with and without a self-consistency condition in hydrogen rings, beryllium rings, and a sample S$_{\text{N}}$2 reaction. The source code for the calculations in this work can be obtained from \url{https://github.com/sebwouters/qc-dmet}.Comment: 41 pages, 10 figure

Five years of density matrix embedding theory

Density matrix embedding theory (DMET) describes finite fragments in the presence of a surrounding environment. In contrast to most embedding methods, DMET explicitly allows for quantum entanglement between both. In this chapter, we discuss both the ground-state and response theory formulations of DMET, and review several applications. In addition, a proof is given that the local density of states can be obtained by working with a Fock space of bath orbitals

Influence of mesoporous iron based nanoparticles on Chlorella sorokiniana metabolism during photosynthetic biogas upgrading

Producción CientíficaThree different mesoporous iron based nanoparticles (NPs) were added to Chlorella sorokiniana batch cultures devoted to photosynthetic biogas upgrading to enhance CO2 biofixation: Fe2O3, carbon coated zero valent iron NPs containing 7.26 % (wt%) of iron (CALPECH NPs) and carbon coated zero valent iron NPs containing 31.38 % (wt%) of iron (SMALLOPS NPS). The three types of NPs enhanced CO2 adsorption and therefore biogas upgrading in tests conducted in 1.2 L enclosed photobioreactors. However, the addition of 70 mg L−1 of CALPECH NPs resulted in a 2-fold enhancement in the microalgae productivity, and a carbohydrate and lipid content increase by 56 % and 25 %, respectively compared to the control assay. Under UV and visible light irradiation the addition of Fe2O3 NPs resulted in a 5.3-times fold enhancement in carbohydrate content when 70 mg L−1 was added. Similarly, the addition of 20 mg L−1 of SMALLOPS NPs increased the lipid content by 11 % under UV irradiation. Interestingly, CALPECH NPs did not significantly influence C. sorokiniana composition, suggesting that these particular NPs can act as UV scavengers. Therefore, the addition of mesoporous nanoparticles could improve CO2 fixation and microalgae productivity during photosynthetic biogas upgrading.Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (grants CLU 2017-09, CL-EI-2021-07 and UIC 315)Universidad Nacional Autónoma de México (project IN108922

Evaluation of leachate turbidity reduction in sanitary landfills following a coagulation/flocculation process enhanced by vegetable starch and thermal water

This study evaluates the reduction of leachate turbidity in landfills after applying a mixture of banana starch and thermal water. Principal component analysis was applied to study the combined effect with four variables: pH, concentration of starch and thermal water mixture, rapid mixing speed and slow mixing speed. The experimental design involved 16 experiments with repetition in the jar test to obtain the optimum dose while measuring turbidity as a response variable. The results showed that after the oxidation process of organic matter, under optimal conditions determined in the experiment, the mixture of starch and thermal water contributed to the reduction of leachate turbidity by 29.1%

Scaling of conductance through quantum dots with magnetic field

Using different techniques, and Fermi-liquid relationships, we calculate the variation with the applied magnetic field (up to second order) of the zero-temperature equilibrium conductance through a quantum dot described by the impurity Anderson model. We focus on the strong-coupling limit U, where U is the Coulomb repulsion and is half the resonant-level width, and consider several values of the dot level energy E d , ranging from the Kondo regime to the intermediate-valence regime F − E d ∼ , where F is the Fermi energy. We have mainly used the density-matrix renormalization group (DMRG) and the numerical renormalization group (NRG) combined with renormalized perturbation theory (RPT). Results for the dot occupancy and magnetic susceptibility from the DMRG and NRG + RPT are compared with the corresponding Bethe ansatz results for U → ∞, showing an excellent agreement once E d is renormalized by a constant Haldane shift. For U low-energy peak in the spectral density of the dot.Fil: Hamad, Ignacio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Gazza, Claudio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Andrade Hoyos, Jhon Alejandro. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aligia, Armando Ángel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cornaglia de la Cruz, Pablo Sebastian. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Roura Bas, Pablo Gines. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Análisis de las propiedades mecánicas del suelo a partir de la mezcla con residuos de la construcción

143 páginasEste trabajo de grado tuvo como propósito realizar un análisis por medio de ensayos de corte directo. Si los residuos de ladrillo (poco contaminado) se pudieran tomar como un material que mejorara las propiedades físicas y mecánicas de un suelo fino. Para poder analizar esto se realizaron 12 ensayos por cada muestra, y cada muestra tenía un porcentaje de ladrillo triturado diferente (0, 4, 8 y 12 %).PregradoIngeniero(a) Civi

Elucidating the role of nanoparticles on photosynthetic biogas upgrading: Influence of biogas type, nanoparticle concentration and light source

Producción CientíficaThree different nanoparticles, namely Fe2O3, carbon coated zero valent iron (CACOI) and SiO2, were added to a mixed microalgae culture in order to improve photosynthetic biogas upgrading. Fe2O3 and CACOI nanoparticles at 10 mg/L supported higher CO2 consumptions compared to their respective controls. The addition of Fe2O3 nanoparticles at 70 mg/L resulted in a 38 % enhanced biomass productivity, and 20 % higher CO2 consumption but delayed exponential growth. The CACOI nanoparticles at 70 mg/L resulted in a shorter lag phase, enhanced CO2 consumption by 13 %, and carbohydrate content enhancement by 64 %, while the addition of SiO2 nanoparticles at this concentration induced an enhanced lipid and carbohydrates production by 47 % and 68 %, respectively. Interestingly, UV light exposure reduced the beneficial effects of nanoparticles, although CACOI nanoparticles still supported a shorter lag phase and higher carbohydrates production at 70 mg/L. In brief, CACOI nanoparticles hold an untapped potential to promote the metabolism of microalgae during photosynthetic biogas upgrading.Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (projects CLU 2017-09, CL-EI-2021-07, UIC 315)Dirección General de Asuntos del Personal Académico - Universidad Nacional Autónoma de México (project IN108922

Ferromagnetic and underscreened Kondo behavior in quantum dot arrays

We analyze the low energy properties of a device with N + 1 quantum dots in a star configuration. A central quantum dot is tunnel coupled to source and drain electrodes and to N quantum dots. Extending previous results for the N = 2 case we show that, in the appropriate parameter regime, the low energy Hamiltonian of the system is a ferromagnetic Kondo model for a S = (N −1)/2 impurity spin. For small enough interdot tunnel coupling, however, a two-stage Kondo effect takes place as the temperature is decreased. The spin 1/2 in the central quantum dot is Kondo screened first and at lower temperatures the antiferromagnetic coupling to the side-coupled quantum dots leads to an underscreened S = N/2 Kondo effect. We present numerical results for the thermodynamic and spectral properties of the system which show a singular behavior at low temperatures and allow to characterize the different strongly correlated regimes of the device.Fil: Andrade Hoyos, Jhon Alejandro. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones No Nucleares. Gerencia de Física (CAB). Grupo de Teoría de Sólidos; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Garcia, Daniel Julio. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones No Nucleares. Gerencia de Física (CAB). Grupo de Teoría de Sólidos; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Cornaglia de la Cruz, Pablo Sebastian. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones No Nucleares. Gerencia de Física (CAB). Grupo de Teoría de Sólidos; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin