Investigation of commuting Hamiltonian in quantum Markov network

Graphical Models have various applications in science and engineering which include physics, bioinformatics, telecommunication and etc. Usage of graphical models needs complex computations in order to evaluation of marginal functions,so there are some powerful methods including mean field approximation, belief propagation algorithm and etc. Quantum graphical models have been recently developed in context of quantum information and computation, and quantum statistical physics, which is possible by generalization of classical probability theory to quantum theory. The main goal of this paper is preparing a primary generalization of Markov network, as a type of graphical models, to quantum case and applying in quantum statistical physics.We have investigated the Markov network and the role of commuting Hamiltonian terms in conditional independence with simple examples of quantum statistical physics.Comment: 11 pages, 8 figure

Effects of Interface Recombination on the Performance of SWCNT\GaAs Heterojunction Solar Cell

AbstractThis paper indicated a theoretical model for describing the effects of the interface recombination on the heterojunction solar cell parameters based on single wall carbon nanotube and GaAs as p-n junction. By choosing the zigzag nanotube and GaAs layer, it is shown that by increasing the interface recombination, short circuit current and open circuit voltage decrease. Depletion current, J-V characteristic and ideality factor variation in terms of interface recombination have been calculated

A numerical study on the relationship between the doping and performance in P3HT:PCBM organic bulk heterojunction solar cells

Abstract In this study, we perform a simulation analysis to investigate the influence of p-type and n-type doping concentration in BHJ SCs using the drift-diffusion model. Specifically, we investigate the effect of doping on the charge carrier transport and calculate the above-mentioned device parameters. We show that doping the active layer can increase the cell characteristic parameters, that the results are in an excellent agreement with the experimental results previously reported in the literature. We also show that doping causes space charge effects which subsequently lead to redistribution of the internal electric field in the device. Our results reveal that higher doping levels lead to screening the electrical field in the P3HT:PCBM active region. This in turn forces the charge carrier transport to be solely dominated by the diffusion, consequently decreasing the performance of the device. We also show that doping of the active layer to an optimum level can effectively improve the charge transport. Moreover, we show that doping can create an Ohmic contact between the organic and cathode interface. Additionally, the charge carrier concentration profile shows that by increasing the dopant concentration, the $$J_{sc}$$ J sc can be improved remarkably. Upon doping the active layer, this indicates that illumination can simply reduce the series resistance in the device