Sharif Digital Repository

Studying the puzzling aspects of quantum phenomenon is quite important subject from different points of view. It must be specially regarded through some major aspects such as: wave-particle dualty, Bell’s theorem no-go theorems, complementarity, entanglement and measurement problem. In this project, we survey subsequently the above topics with a careful attention regarding the measurement problem. One of the most relevant ways claiming to solve measurement problem is the decoherence theory. Scrutinizing the details of formalism and description basis of decoherence, we critically explain and asses the different aspects of this theory  

The relationship between quantum theory and thermodynamics has gained so much attention in recent years. Thermodynamics is indeed a phenomenological science and its theoretical foundations are not clear as well. In the nineteenth century, Boltzmann tried to establish a connection between concepts of thermodynamics and classical mechanics (as a consistent theoretical domain). With development of quantum mechanics in twentieth century, the possibility of analyzing and formulating of the multi-particle systems based on quantum formalism increased. Quantum approach to thermodynamic phenomena has been studied in various ways. Here basic questions are, e.g. how to define Thermodynamic entities... 

Quantum correlations are among most intriguing problems in physics. Bell’s inequality which was proved in 1964 provides with us the possibility of comparing the predictions of quantum theory with what an underlying local realistic theory may reproduce for some given observables in correlated states. The violation of Bell’s inequality in practice prohibits the existance of such underlying theories. Yet, it is not clear which of the assumption, i.e., locality or reality is responsible for explaining the experimentally verified violations. In 2003, a Nobel prizewinner A. J. Leggett proved a new inequality in which the locality assumption was not crucial. Here, we explore different aspects of... 

Although quantum mechanics has thrilled a multitude of successes since its birth, it has also generated puzzles that persist to this day. These puzzles are largely connected with the role of measurement in quantum mechanics. Therefore, we are dealing with individual phenomena and that our possibilities of handling the measuring instruments allow us only to make a choice between the different complementary types of phenomena. Within the framework of delayed-choice experiments, the choice between complementary types of phenomena is postponed to the moments after the preparation of system is a superposition state. Regarding the probability theory, we have concluded that the delayed-choice... 

In this study the concept of the origin of life, as an important question, is investigated and reviewed.Then the possibility of the beginning of life from an extraterrestrial origin is studied via spectroscopy methods to analyze the role of the cosmic waves.Moreover, by considering the similarity between the chirality of the essential amino acids and extraterrestrial amino acids, found in meteors the various methods for studying the structure of molecules, as well as the possibility of the transfer of the central elements of life from space to the earth are reviewed in details.Finally, we suggest how chirality might be emerged due to the interaction of the molecule with the environment,... 

Undoubtedly, the concept of information has an outstanding role in our description of physical systems and biological processes. In the framework of pragmatic approach, information is a useful notion through which any physical event gets its significance. In this approach, information can be understood and recognized while it is capable of producing new information. Thus, the meaning of information depends on our recognition and understanding as conscious beings. Accordingly, the following question may arise: where is the role of conscious being in the emergence of physical properties in Nature? To answer this fundamental question, we first investigate how information enters the physics, in... 

Considering the consistency between the predictions of a theory with what is observed in experience, Quantum Mechanics is the most accurate theory in the history of physics. However, is does not present us an unmbigiuos and realistic description about the nature of the microscopic phenomena. At the heart of these issues is the so-called measurement problem. The formalism of the quantum mechanics is unitary and deterministic. Nevertheles, when one does measurements, the unitary process of the evolution of wave-function breaks due to a stochastic abruption. The results of the measurements are in correspondence with the everyday experience of the observer. Yet, the theory itself does not... 

In order to study the phenomenon of consciousness, many physicists have presented their views. In this thesis, the phenomenon of consciousness is analyzed from Henrry Stapp and Penrose-Hameroffs’ viewpoints. Assuming the subjective reduction of state vector, Stapp considers conscious mind as prerequisite for the reduction of wave function. In his view, consciousness is a selection agent which has a top-level control over brain stimulations,and every conscious experience is the feeling of the top-level event in the brain. He also considers physical world as a structure of tendencies and probabilities. He speaks about creative events which occur among Heisenberg probability distributions. On... 

Regarding the notable progress in communication and competition theories as well as natural sciences, the study of the concepts of information has displayed more attention in recent years.Information, entropy and energy are interrelated concepts. In one hand one can infer that entropy is a quantitation measure of information and on the other hand systems which carry information can accumulated energy.Here, we are going to survey the qualitation as well as quantitation aspects of information with concentration on the behavior of chemical agents as information processors  

In the present era consciousness problem and the relationship between mind and matter as one of the historical and difficult philosophical issues has entered in different scientific fields such as neuroscience, cognitive science and physics. With the introduction of quantum theory and offering its different interpretations, some claimed that understanding the consciousness problem will be possible in the light of quantum theory and some claimed that consciousness is necessary for correct understanding of the quantum theory. Henry Stapp and David Bohm, two prominent physicists with two different approaches to quantum theory try to describe this problem from their point of view. Henry Stapp... 

It has been about a century since the introduction of the theory of quantum mechanics. This theory is a branch of physics that describes the behavior of nature in very small scales and microscopic systems . Since no quantum system is entirely isolated from its surroundings , it is necessary to study their interactions with the environment to understand them accurately. The theory of open quantum systems provides the theoretical and conceptual framework needed to consider these interactions. Then using the appropriate quantum operations , the evolution of the combined system can be investigated. Moreover , considering the environmental effects, some quantum features such as dissipation... 

Up to this day, no conflict ever observed between experiments and the predictions of quantum mechanics. Scientists are in the belief that quantum mechanics is a universal theory and all the systems, even the classical ones, are quantum mechanical in their nature. In this regard, modeling the Earth-Sun dynamics using Hydrogen atom Hamiltonian has been addressed. Since we understand the classical systems with trajectories, we used Bohmian mechanics as an alternative way to study the Earth-Sun dynamics in a quantum fashion. Moreover, for better understanding the concept of the quantum to classical transition, we studied quantum thermodynamics. Accordingly, we described open quantum systems in... 

New biological discussions in quantum mechanics that has grown considerably in the past decade. Meanwhile, considering some of interesting problems in biology and chemistry, the use of quantum approach superposition principle and tunneling effect explain some of the phenomena of life more than several. Nowadays, regarding quantum description, provided to explain how we recognize different odors, what the mechanism photosynthesis is, and how bind navigation occurs. Furthermore, the new field of quantum biology sheds light in underestanding the issue of heritance and genetics inforamtion. In this thesis, after reviewing some interesting topics of quantum biology, the data transfer from... 

In quantum mechanics different states of a system can only be found after a measurement is performed and before the measurement the system may not be in any particular state unless it was prepared in a certain manner. Even so there is no telling the state of system. This behavior raised questions such as: why results of a measurements happen to be in certain states and not in others? And also why an apparatus picks one result over the others? The Decoherence and Transition from quantum to classical behavior may hold the answer to this questions. An example of such transition, one can name the wave-particle duality in double slit experiment. Another example is the formation of straight tracks... 

Different information theories have been provided in recent decades because of the numerous applications of information notion in different fields of sciences. Meanwhile, pragmatic theory of information is one of the most common concepts in this field which has been studied remarkably in recent decades. Different aspects of this theory (in J. G. Roederer’s sense of attitude) are critically assessed in this thesis. Roederer considers the information as a relative concept in which interaction plays fundamental role. Moreover, information is an agent which leads to an univocal correspondence between the sender and the recipient, so that the presence of a certain spatial or temporal pattern... 

According to modal interpretations of quantum mechanics, a state possesses definite values even if it is not an eigenstate. On the other hand, Kochen-Specker theorem holds that all possible possessed values by a system can not be definite. Consequently, modal interpretations to block this theorem, take new metaphysics of properties. In this dissertation, I will show that dispositionalism is that metaphysics. According to dispositionalism, causal powers of a property are constituents of the property. As regards this outline, the thesis would be divided into 5 chapters. In chapter one, presuppositions of later arguments are clarified. Chapter two is related to algebra of properties and finally... 

Bohm-de Broglie theory is an alternative for standard quantum mechanics for explaining the bizarreness of micro-phenomena. This theory is casual and deterministic,but endows with nonlocal and contextual characters. Up to now,two different approaches presented: One is known as Bohm-Hiley (BH) formalism and the other is Dürr-Goldstein-Zanghí (DGZ) representation. In BH formalism, quantum potential has a significant role, according to witch peculiar phenomena such as quantum tunneling, two-slit interference and chemical bond are explained. Active information is also another important rotion introduced by quantum potential. In DGZ approach, however, the foundation of Bohm theory is based on... 

Bohm theory is an alternative for standard quantum mechanics which, provides a deterministic description for physical microsystems. In this theory every physical system, describes as a quantum particle which guided by a correspondiente wave. In stationary states every wave-particle, depends on its initial conditions, is at rest in different points. As an example in hydrogen atom, stationary states means electron, with constant radius and polar angle, has a circular motion in planes which is parallel with xy plane. In this thesis the stationary trajectories of hydrogen atom has been reconsidered and new trajectories are sketched. Also by extension the discussion to the macrosystems, we study... 

This project examines time in quantum mechanics, which includes three chapters. The first chapter is about clocks, which first deals with the history and invention of clocks, and then goes on to describe quantum clocks and various theories about them, including Perez and Faraday quantum clocks . The second chapter deals with the two-slit Yang experiments which, as in the preceding chapter, we first give a historical description of the experiment, and we will continue with our description. We consider that for each of these cases the probability of spatial and linear momentum interference is calculated. The third chapter is the final chapter. In this section, we first discuss the concept of... 

In this thesis we are going to explore a new formalism in micro domain which describes quantum phenomena in a realistic casual fashion by introducing an unified concept of matter, energy, and Information. In this theory, a micro-entity, e.g. an electron, is a combination of a particle and its associated field integrated to a new entity called particle-field. The dynamics of such system will be analyzed. Then, some quantum examples which have controversial aspects will be discussed within the new theory. In a generalized form of formalism, the non-linear Schrödinger Equation is introduced, which enables us to predict some experimental data for common Quantum Mechanical stationary systems....