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Analogies in fluid dynamics: vortex as a black hole
Staňo, Šimon ; Štigler, Jaroslav (referee) ; Illík, Jakub (advisor)
This bachelor thesis discusses the various analogous connections of fluid dynamics with the fields of electricity, electromagnetism, quantum mechanics and gravity. Par- ticular attention has been focused on a certain similarity between rotating black holes and the draining bathtub vortex. At first sight different phenomena that can be ex- plored by simulating known phenomena. The behaviour around real black holes can, with some simplification, be studied within the hydraulic laboratory. The pioneer of this idea is W. G. Unruh, whose work was followed up and continued with research by Silke Weinfurtner. Her research served as the inspiration for the exploration of this field in this bachelor thesis. It is possible to visualize the event horizon of a black hole or the boundaries of the ergosphere, it is also possible to observe more complex phenomena such as superradiance, backreaction or ringdown. The analogy is not completely precise, but it allows a very complex system to be studied with a simple experiment and can lead to a better understanding of these phenomena. A simple experimental setup was created in the laboratory of Victor Kaplan’s Department of Fluid Engineering.
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Quantum description of superradiance of emitters with plasmon-mediated interaction
Olivíková, Gabriela ; Chvátal, Lukáš (referee) ; Křápek, Vlastimil (advisor)
Superradiance is an enhanced decay of an excited system of emitters resulting from their mutual coupling. This thesis is focused on superradiance of the emitters coupled via their interaction with a plasmonic nanoparticle. So-called plasmon-mediated superradiance results in even stronger enhancement of the decay rate as the nanoparticle serves as an additional decay chanel. We have developed a quantum model of the system of emitters coupled to a plasmonic nanoparticle, which allows us to differentiate between a pure dephasing and decay processes. We show that the pure dephasing can destroy the cooperative effect leading to superradiance. Furthermore, we have studied how the direct mutual coupling between emitters affects time evolution of the system in dependence on its configuration, and we show conditions when a decay of the system is dramatically decreased by direct coupling.
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Analogies in fluid dynamics: vortex as a black hole
Staňo, Šimon ; Štigler, Jaroslav (referee) ; Illík, Jakub (advisor)
This bachelor thesis discusses the various analogous connections of fluid dynamics with the fields of electricity, electromagnetism, quantum mechanics and gravity. Par- ticular attention has been focused on a certain similarity between rotating black holes and the draining bathtub vortex. At first sight different phenomena that can be ex- plored by simulating known phenomena. The behaviour around real black holes can, with some simplification, be studied within the hydraulic laboratory. The pioneer of this idea is W. G. Unruh, whose work was followed up and continued with research by Silke Weinfurtner. Her research served as the inspiration for the exploration of this field in this bachelor thesis. It is possible to visualize the event horizon of a black hole or the boundaries of the ergosphere, it is also possible to observe more complex phenomena such as superradiance, backreaction or ringdown. The analogy is not completely precise, but it allows a very complex system to be studied with a simple experiment and can lead to a better understanding of these phenomena. A simple experimental setup was created in the laboratory of Victor Kaplan’s Department of Fluid Engineering.
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Artificial light-harvesting antenna based on an aggregation of bacteriochlorophyll c with selected pigments
Malina, Tomáš ; Pšenčík, Jakub (advisor) ; Litvín, Radek (referee)
Title: Artificial light-harvesting antenna based on an aggregation of bacteriochlorophyll c with selected pigments Author: Tomáš Malina Department: Department of Chemical Physics and Optics Supervisor of the master thesis: doc. RNDr. Jakub Pšenčík, Ph.D., KCHFO MFF UK Abstract: Solar energy is one of the most important energy sources for all living organisms. The light harvesting takes place in specialised photosynthetic complexes called antennas; they typically contain pigments held by a protein scaffold. Antennas of green bacteria, chlorosomes, are unique in this respect, for they do not need proteins to organise the pigments. The pigments contained in chlorosomes, bacteriochlorophyll (BChl) c, d or e, aggregate spontaneously. This self-aggregation can be used to form an artificial light-harvesting antenna the absorption spectrum of which can be extended by addition of other pigments. Antennas based on aggregation of BChl c with β-carotene and BChl a were prepared by a fast and slow method. The excitation energy transfer efficiency between these pigments was studied. The efficiency of energy transfer from BChl c to BChl a reached up to 95 %, the efficiency of energy transfer from β-carotene to BChl c was lower. An important role of β- carotene in artificial aggregates as well as in chlorosomes is its...
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Dynamic elektromagnetic fields in the Kerr spacetime
Skoupý, Viktor ; Ledvinka, Tomáš (advisor) ; Kofroň, David (referee)
In this thesis we study a test electromagnetic field in the vicinity of Kerr black hole and with methods of extraction of its rotational energy. We are investigating a process in which a particle moves in an electromagnetic resonator around Kerr black hole. The energy of the particle is transferred to the electromagnetic field and the particle falls into the black hole with negative energy. We begin with the derivation of Maxwell's and Teukolsky equations and their numerical solutions. We derive a boundary condition for an electromagnetic field on a spherical mirror around the black hole, find the field that satisfies this condition, and describe the procedure for numerical calculation. Next, we calculate the trajectories of charged test particles in such a field and find particles that fall into the black hole with negative energy. We have found that it is possible for the particle to fall into the black hole with the energy of −124% of its rest mass, and the parameters of the electromagnetic field and trajectory of the particle need to be carefully selected.
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Electromagnetic rotational superradiance
Bára, Václav ; Ledvinka, Tomáš (advisor) ; Kofroň, David (referee)
We show the scattering of electromagnetic radiation on a rotating cylinder and a rotating sphere using formalism of the vector spherical harmonics in this thesis. If a specific condition is satisfied then we can observe the rotational superradiance, phenomena originally discovered by Y. B. Zel'dovich in 1970s saying that the radiation can gain power by scattering on a rotating body. In this particular case there is an underlying principle of the rotational superradiance, the energy dissipation in the form of Joule heating created due to the induction of surface currents on the conductor. Superradiance can occur in the radiation scattering on the rotating black hole background, although there is no dissipation present. We summarize the results of scattering on the Kerr black hole from the literature, including an application called Black hole bomb, when the black hole is enclosed into a perfectly reflecting mirror. We show that for the lowest modes of the radiation at specific intervals the general relativity results can be approximated by scattering on the flat spacetime.
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Quantum description of superradiance of emitters with plasmon-mediated interaction
Olivíková, Gabriela ; Chvátal, Lukáš (referee) ; Křápek, Vlastimil (advisor)
Superradiance is an enhanced decay of an excited system of emitters resulting from their mutual coupling. This thesis is focused on superradiance of the emitters coupled via their interaction with a plasmonic nanoparticle. So-called plasmon-mediated superradiance results in even stronger enhancement of the decay rate as the nanoparticle serves as an additional decay chanel. We have developed a quantum model of the system of emitters coupled to a plasmonic nanoparticle, which allows us to differentiate between a pure dephasing and decay processes. We show that the pure dephasing can destroy the cooperative effect leading to superradiance. Furthermore, we have studied how the direct mutual coupling between emitters affects time evolution of the system in dependence on its configuration, and we show conditions when a decay of the system is dramatically decreased by direct coupling.
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