Sharif Digital Repository

AdS/CFT Correspondence since it origination has found numerous applications in various aspects of Physics such as ion collision in Accelerators, Condensed matter Physics and etc. this orrespondence is a consequence of String Theory. In this project we have tried to analyze some of its applications in Condensed matter Physics and in the controversial phenomenon of superconductivity without resorting to the complexities of String Theory. Having applied this approach we have found a dual for it in Gravity and having calculated some common physical quantities and equations in these two sets such as Energy gap, Conductivity, London Equations and etc, we have tried to show the correspondence,... 

There is an ever increasing trend to apply AdS/CFT to explain physical phenomena and this endeavor has recently begun concerning Superconductivity. Using black holes with differing structures and gravitational content has proved to be uitful in this explanation. In this thesis we try to explain superconductivity for a charged ro-tating black hole with Kerr-Newman-Ads metric in four dimensions. Having calcu-lated condensation for a rotating black hole we obtained diagrams of phase transition in superconductivity with respect to temperature. In addition a brief discussion on calculating the conductivity has been presented  

Holography is a lensless process with a unique characteristic of recording a 3D image on a 2D plate! From the first hologram constructed by Gabor, the development of holography found several techniques. For the aim of fabricating holograms of Sharif University of Technology, International Campus-Kish Island’logo, we have chosen transmission and rainbow techniques because of their accuracy and applicability. A recording material is needed for the process. Photoresist was found more appropriate to work on. Besides He-Cd and He-Ne lasers are mostly in use in general holography. The laboratory work is an inseparable part which is achieved at laser and hologram unit of Atomic Energy... 

In this thesis, we show that conformal Chern–Simons gravity in three dimensions has various holographic descriptions. They depend on the boundary conditions on the conformal equivalence class and the Weyl factor. The boundary conditions on the Weyl factor of the metric lead to three physically distinct scenarios: I. trivial Weyl factor, II. non-trivial but fixed Weyl factor and III. free Weyl factor. The metric is not necessarily asymptotically AdS in cases II and III, but nevertheless a dual CFT appears to emerge. We focus on a particular case III where an affine U(1) algebra related to holomorphic Weyl rescalings shifts one of the central charges by 1. The Weyl factor then behaves as a... 

According to the AdS/CFT correspondance,Gravity in an asymptotically AdS spacetimes has a conformal field theory dual. One of the perplexing concepts in theoretical physics is obtaining a comprehensive understanding of holography. To this end, it is of interest to explore whether holography exists beyond the known example of the AdS/CFT correspondence and for spacetimes other than the AdS. asymptotically flat spacetimes are of great theoretical importance.A correspondence has recentlay been proposed,which is between asymptotically flat spacetimes and a field theory with Galilean conformal symmerty and it is known as BMS/GCA correspondance.In this thsis,we have reviewed this correspondence... 

Recently, millimeter wave imaging (MMWI) technology is given more attention. This is as a result of three facts. First, despite the infrared or optical cameras, these systems can image a target, which is obscured by one or more optically barriers. Second, the electronics circuits in this band have seen great achievements in the current decade, which facilitate the implementation of MMWI structures. Third, there is no known health hazard for the systems operating in this band with moderate power. Therefore, in this project, a MMWI system based on compressed sensing (CS) for the concealed weapon detection application is proposed. This design consists of a linear antenna array, an appropriate... 

New technologies for three-dimensional (3D) sensing and visualization of real-world objects have been pursued by scientists and engineers for many decades. As opposed to traditional two-dimensional (2D) imaging techniques, 3D imaging technologies can potentially capture the 3D structure, range, and texture information of objects. Therefore, it can be developed for many applications, as medical imaging and diagnosis, dentistry, industrial designs, architecture and security. There are many 3D imaging technologies, such as holography, incoherent holography and integral imaging. Since holographic methods are based on the wave interferometry of two coherent beams, they demand high stability of... 

Nowadays active Millimeter Wave Imaging Systems are used in verity of medical and security applications. This widespread application re- sults from the intrinsic characteristic of electromagnetic waves in this rang of frequency that can penetrate through interior body structures and clothing with- out bringing harmful ionizing efects to the body. Millimeterwave systems can be very high resolution due to the relatively short wavelength. The current state-of-the-art in active millimeter-wave imaging systems use a set of transmit/receive antennae. The transmitter antennae illuminated the intended person with millimeter waves while the back scattered signal is recorded by the receiver antennae.... 

In recent years, the biological evolution of molecular detection capabilities based on gene analysis has provided a reliable performance in the diagnosis of a disease before a symptom emerges. Human gene storage requires a large amount of computer memory (about 1.5 GB for each DNA) and the search for a specific pattern within it with electronic computers is time and power consuming. Optical computing uses light parallel processing capabilities to find the pattern in a digital field, which can be used to process large volumes of data in short time and low power consumption, while electronic computers process data in series with high power dissipation. According to the Optalysys report, the... 

Conventional imaging systems composed of two linear arrays of antennas as a transmitter and receiver. These arrays of antennas electronically scan along their antenna elements and are mechanically moved along a second orthogonal direction for scanning large two-dimensional areas quickly. In this thesis, the transmitter antenna elements are Tapered slot-line Antenna operating at 20-30GHz. A multiplexer circuit is used to transmit wideband signals to each antenna in the array. The receiver is composed of Schottky diode and pick up antenna that they are printed onto the radiating end of the antennas on the edge of the transmitter circuit board.In the available imaging systems, for achieving the... 

High-resolution microscopy with the high field of view is necessary for a lot of applications related to medical studies in different areas and to reach this goal, Imaging Systems with high space bandwidth is required. Since CMOS and CCD image sensors are used for capturing digital images, the large amount of studies has been dedicated to optics and signal processing in order to achieve high resolution and the high field of view images.In lens-based imaging systems, large space-bandwidth is achieved through large lenses with higher magnification and larger image sensors with more number of pixels. The drawback of this methods is using larger optic components that lead to increased cost and... 

In this thesis, we investigate some of the quantum information theoretic approaches in gauge-gravity duality and specially AdS/CFT. Our main focus is the entanglement entropy on the boundary of a holographic theory and its dual on bulk which is called Ryu-Takayanagi (RT) surface. We show that a tensor network model of particles, named HaPPY model, can mimic the RT formula. After proving the RT formula in this model, we introduce a new class of multipartite entangled state named Planar Maximally Entangled (PME) states which can be used as an alternative building block in HaPPY model. We classify PME state of four qubits and give some example of these states for general number of particles.... 

Bonding gravity with Quantum mechanics has always been a challenging issue. So that, accomplishing a theory of quantum gravity is one of the most important research topics in High-Energy Physics.Information paradox in black holes is among such issues which connect quantum mechanics with gravity. Black holes as a natural solution of Einstein equations have a distinction, with other solutions, since there exists an event horizon that imparts space-time into two causally disconnected regions.According to Hawking’s calculations, black holes would evaporate over time by the thermal radiation. This resulting thermal radiation has less information than the initial collapsed matter in a pure state.... 

The information paradox is one of the most important questions around black hole physics. The problem is raised since the operators which are responsible for the evolutions in quantum mechanics are unitary while the black hole evaporation seems to be a nonunitary evolution (Since a black hole which has been formed from the collapse of matter in a pure state evaporates to a mixed thermal state eventually). This loss of information during the evaporation process is known as the information paradox.Recently many attempts have been made to investigate this problem holographically, actually to see if the information is really lost and if not how one can recover the information.Our main goal is to... 

In this thesis, we study different aspects of tilted Dirac materials from hydrodynamics and holography approach. Dirac materials are among the most important structures which have been introduced in recent years in condensed matter physics where graphene is the simplest of them. Classification of space groups allows nonsymmorphic structures where the low energy electronic degrees of freedom can be described by tilted Dirac cones. In the long wavelength and time limit, these materials can be effectively described by a metric which is called tilted metric. Dirac materials are usually strongly coupled and cannot be studied using the common perturbative techniques; therefore hydrodynamics and... 

In this survey we explore the black hole information problem, one of the most challenging issues in theoretical physics over the past few decades. According to the theory of general relativity, black holes can form through gravitational collapse of matter. At semiclassical level, however, black holes emit thermal Hawking-radiation and eventually completely evaporate. After evaporation the radiation state cannot retain all the information about the initial matter that underwent gravitational collapse, contradicting the principles of quantum mechanics. Various approaches have been proposed to address this issue. One such approach is the black hole complementarity principle, introduced by... 

The problem of quantum gravity has always posed significant challenges, particularly evident in black hole evaporation and the information paradox. Numerous proposals have been offered. Solutions such as semi-classical gravitational approximations aim to reconcile gravitational collapse and black hole evaporation with unitary quantum evolution. Symmetries, such as conformal symmetry and Anti-de Sitter geometry, Simplify the explanation of information recovery during black hole evaporation. Near the horizon of a spherically symmetric 4D black hole, gravity can be effectively described by a 2D dilaton theory. Studying the problem in 2D magnifies the strength of conformal symmetry. Holography,...