An investigation of information loss in black hole spacetimes is performed. We demon- strate that the definition of particles as energy levels of the Harmonic oscillator will not have physical significance in general and is thus not a good instrument to study the ra- diation of black holes. This is due to the ambiguity of the choice of coordinates on the phase space of the quantum field. We demonstrate how to identify quantum states in the functional Schr ̈dinger picture. o We demonstrate that information is truly lost in the case of a Vaidya black hole (a black hole formed from null dust) if we neglect back reaction. This is done by quantizing the constrained classical system of a Klein-Gordon field in a Vaidya background. The interaction picture of quantum mechanics can be applied to this system. We find a physically well motivated vacuum state for a spherically symmetric space- time with an extra conformal Killing vector. We also demonstrate how to calculate the response of a particle detector in the a LeMaitre-Tolman-Bondi spacetime with a self- similarity. Finally, some of the claims and confusion surrounding Unruh radiation, Hawking radiation and the equivalence principle are investigated and shown to be false.

An investigation of information loss in black hole spacetimes is performed. We demon- strate that the definition of particles as energy levels of the Harmonic oscillator will not have physical significance in general and is thus not a good instrument to study the ra- diation of black holes. This is due to the ambiguity of the choice of coordinates on the phase space of the quantum field. We demonstrate how to identify quantum states in the functional Schr ̈dinger picture. o We demonstrate that information is truly lost in the case of a Vaidya black hole (a black hole formed from null dust) if we neglect back reaction. This is done by quantizing the constrained classical system of a Klein-Gordon field in a Vaidya background. The interaction picture of quantum mechanics can be applied to this system. We find a physically well motivated vacuum state for a spherically symmetric space- time with an extra conformal Killing vector. We also demonstrate how to calculate the response of a particle detector in the a LeMaitre-Tolman-Bondi spacetime with a self- similarity. Finally, some of the claims and confusion surrounding Unruh radiation, Hawking radiation and the equivalence principle are investigated and shown to be false.

With diminishing returns in performance with scaling of traditional transistor devices, there is a growing need to understand and improve potential replacements technologies. Sufficient reliability has not been established in these devices and additional redundancy through use of fault tolerance and error correction codes are necessary. There is a price to pay in terms of energy and area, with this additional redundancy. It is of utmost importance to determine this energy cost and relate it to the increased reliability offered by the use of error correction codes. In this thesis, we have determined the lower bound for energy dissipation associated with error correction using a linear (n,k) block code. The bound obtained is implementation independent and is derived from fundamental considerations and it allows for quantum effects in the channel and decoder. We have also developed information theoretic efficacy measures that can quantify the performance of the error correction and their relationship to the corresponding energy cost.

Submitted by Gabriel Cozzella (cozzella@ift.unesp.br) on 2016-08-21T00:22:31Z No. of bitstreams: 1 MSc Dissertation.pdf: 773902 bytes, checksum: a2d2f3173a5f3ec0ab24f201d71929da (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-08-24T16:43:46Z (GMT) No. of bitstreams: 1 cozzella_g_me_ift.pdf: 773902 bytes, checksum: a2d2f3173a5f3ec0ab24f201d71929da (MD5) / Made available in DSpace on 2016-08-24T16:43:46Z (GMT). No. of bitstreams: 1 cozzella_g_me_ift.pdf: 773902 bytes, checksum: a2d2f3173a5f3ec0ab24f201d71929da (MD5) Previous issue date: 2016-07-26 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A teoria quântica de campos em espaços-tempos curvos é o arcabouço teórico mais sólido que temos para estudar a interação entre gravitação e mecânica quântica na ausência de uma teoria completa de gravitação quântica. Neste contexto, um problema que atraiu muita atenção dos físicos teóricos nas últimas décadas é o chamado “paradoxo da perda de informação em buracos negros”, onde a evolução de um estado quântico puro inicial para um estado quântico misto final caracterizaria uma violação das leis da mecânica quântica. Nesta dissertação nós argumentamos que a perda de informação em si não viola as leis da mecânica quântica e é consequência direta da teoria semi-clássica utilizada. Finalmente, argumentamos que a questão da recuperação da informação deve ser tratada utilizando-se uma teoria de gravitação quântica ainda desconhecida. / The quantum theory of fields in curved space-times is the most solid framework for studying the interplay between gravity and quantum mechanics in the absence of a complete theory of quantum gravity. In this scenario, one problem that has drawn much attention from the theoretical physics community in the last decades is the so-called “black hole information loss paradox”, where the evolution from an initial pure quantum state to a final mixed quantum state would constitute a violation of the laws of quantum mechanics. In this dissertation we argue that information loss does not violate quantum mechanics, being simply a consequence of the semi-classical framework adopted and that the question of information recovery needs to be addressed by a yet unknown theory of quantum gravity. / FAPESP: 2014/08684-9

The ability to delegate some of ones activities to other organizations is something that has been used for many years by different types of organizations in different areas. This type of delegation to make use of external knowledge has been found to have many benefits such as improved quality of decision making,shorter decision paths and redistribution of resources to improve processes. Unfortunately, it has also been found that in some activities, delegation can lead to problems with, for example, information access. The purpose of this paper was therefore to investigate whether one authority's delegation of activities to another organization affects access to information based on the concept of public documents. The research questions that formed the basis of the investigation were 1) Are there information losses, based on the concept of public documents, that can arise in connection with the delegated activity, and which are they? and 2) What consequences can information loss have when looking at the principle of public access to official records? This paper has had a qualitative approach where interviews and document studies have been used as methods for gathering information regarding the two research questions. The main conclusion drawn from this thesis is that if the Swedish Transport Agency uses certain types of organizations for delegation of activities, extensive information loss can be incurred regarding information linked to certain parts of its activities and as an authority run the risk of being in conflict with the principle of public access to official records.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第25109号 / 理博第5016号 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 橋本 幸士, 教授 杉本 茂樹, 教授 田島 治 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

The communication regarding the new corona-virus raises questions about availability and plain language. In Sweden, approximately 1.5 million people are in need of this communication through written language due to, inter alia, hearing impairment. Although subtitles are considered one of the most read genres today, it has received little focus in Swedish linguistic research, especially when it comes to intralingual subtitles. However, the communication through subtitles is limited and can lead to information loss. In Sweden, SVT as a public service channel has special requirements to maintain good quality in subtitles but nonetheless omissions are a prerequisite. However, this must never affect the loss of important information. Modality is considered within the Systemic-Functional Linguistics as linguistic tools to create opportunities to shift communication in different degrees and directions. A similar shift in degree can occur in expressions of valuation and opinions. Therefore, modality and valuation are interesting and important to study in a well-known TV- show that communicates, informs and debates about a social-crisis like the Corona-virus. This paper examines modality and expressions of valuation in the adaption from speech to subtitles in the Swedish news-program Agenda (SVT) reporting on the Corona-virus in Sweden and the world. Through the subtitling-shift model created by Sahlin (2001), I examine the omissions of modality and the expressions of valuation. The results show that the communication in subtitles have a weaker emphasis of conflicting opinions, are more objectively constructed and that there is a shift in nuances.

A substantial number of works have aimed at modeling the receptive field properties of the primary visual cortex (V1). Their evaluation criterion is usually the similarity of the model response properties to the recorded responses from biological organisms. However, as several algorithms were able to demonstrate some degree of similarity to biological data based on the existing criteria, we focus on the robustness against loss of information in the form of occlusions as an additional constraint for better understanding the algorithmic level of early vision in the brain. We try to investigate the influence of competition mechanisms on the robustness. Therefore, we compared four methods employing different competition mechanisms, namely, independent component analysis, non-negative matrix factorization with sparseness constraint, predictive coding/biased competition, and a Hebbian neural network with lateral inhibitory connections. Each of those methods is known to be capable of developing receptive fields comparable to those of V1 simple-cells. Since measuring the robustness of methods having simple-cell like receptive fields against occlusion is difficult, we measure the robustness using the classification accuracy on the MNIST hand written digit dataset. For this we trained all methods on the training set of the MNIST hand written digits dataset and tested them on a MNIST test set with different levels of occlusions. We observe that methods which employ competitive mechanisms have higher robustness against loss of information. Also the kind of the competition mechanisms plays an important role in robustness. Global feedback inhibition as employed in predictive coding/biased competition has an advantage compared to local lateral inhibition learned by an anti-Hebb rule.

<p dir="ltr">In holographic quantum field theories, a bulk geometric semiclassical spacetime emerges from strongly coupled interacting conformal field theories in one less spatial dimension. This is the celebrated AdS/CFT correspondence. The entanglement entropy of a boundary spatial subregion can be calculated as the area of a codimension two bulk surface homologous to the boundary subregion known as the RT surface. The bulk region contained within the RT surface is known as the entanglement wedge and bulk reconstruction tells us that any operator in the entanglement wedge can be reconstructed as a non-local operator on the corresponding boundary subregion. This notion that entanglement creates geometry is dubbed "ER=EPR'' and has been the driving force behind recent progress in quantum gravity research. In this thesis, we put together two results that use Tomita-Takesaki modular theory and quantum ergodic theory to make progress on contemporary problems in quantum gravity.</p><p dir="ltr">A version of the black hole information loss paradox is the inconsistency between the decay of two-point functions of probe operators in large AdS black holes and the dual boundary CFT calculation where it is an almost periodic function of time. We show that any von Neumann algebra in a faithful normal state that is quantum strong mixing (two-point functions decay) with respect to its modular flow is a type III₁ factor and the state has a trivial centralizer. In particular, for Generalized Free Fields (GFF) in a thermofield double (KMS) state, we show that if the two-point functions are strong mixing, then the entire algebra is strong mixing and a type III₁ factor settling a recent conjecture of Liu and Leutheusser.</p><p dir="ltr">The semiclassical bulk geometry that emerges in the holographic description is a pseudo-Riemannian manifold and we expect a local approximate Poincaré algebra. Near a bifurcate Killing horizon, such a local two-dimensional Poincaré algebra is generated by the Killing flow and the outward null translations along the horizon. We show the emergence of such a Poincaré algebra in any quantum system with modular future and past subalgebras in a limit analogous to the near-horizon limit. These are known as quantum K-systems and they saturate the modular chaos bound. We also prove that the existence of (modular) future/past von Neumann subalgebras also implies a second law of (modular) thermodynamics.</p>

A substantial number of works have aimed at modeling the receptive field properties of the primary visual cortex (V1). Their evaluation criterion is usually the similarity of the model response properties to the recorded responses from biological organisms. However, as several algorithms were able to demonstrate some degree of similarity to biological data based on the existing criteria, we focus on the robustness against loss of information in the form of occlusions as an additional constraint for better understanding the algorithmic level of early vision in the brain. We try to investigate the influence of competition mechanisms on the robustness. Therefore, we compared four methods employing different competition mechanisms, namely, independent component analysis, non-negative matrix factorization with sparseness constraint, predictive coding/biased competition, and a Hebbian neural network with lateral inhibitory connections. Each of those methods is known to be capable of developing receptive fields comparable to those of V1 simple-cells. Since measuring the robustness of methods having simple-cell like receptive fields against occlusion is difficult, we measure the robustness using the classification accuracy on the MNIST hand written digit dataset. For this we trained all methods on the training set of the MNIST hand written digits dataset and tested them on a MNIST test set with different levels of occlusions. We observe that methods which employ competitive mechanisms have higher robustness against loss of information. Also the kind of the competition mechanisms plays an important role in robustness. Global feedback inhibition as employed in predictive coding/biased competition has an advantage compared to local lateral inhibition learned by an anti-Hebb rule.