Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This thesis investigates the structure and behaviour of entanglement, the purely quantum mechanical part of correlations, in many-body systems, employing both numerical and analytical techniques at the interface of condensed matter theory and quantum information theory. Entanglement can be seen as a precious resource which, for example, enables the noiseless and instant transmission of quantum information, provided the communicating parties share a sufficient "amount" of it. Furthermore, measures of entanglement of a quantum mechanical state are perceived as useful probes of collective properties of many-body systems. For instance, certain measures are capable of detecting and classifying ground-state phases and, particularly, transition (or critical) points separating such phases. Chapters 2 and 3 focus on entanglement in many-body systems and its use as a potential resource for communication protocols. They address the questions of how a substantial amount of entanglement can be established between distant subsystems, and how efficiently this entanglement could be "harvested" by way of measurements. The subsequent chapters 4 and 5 are devoted to universality of entanglement between large collections of particles undergoing a quantum phase transition, where, despite the enormous complexity of these systems, collective properties including entanglement no longer depend crucially on the microscopic details.    

Quantum mechanics. Quantumfield theory --- quantumfysica

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

In recent years, remarkable progress in the fabrication of novel mesoscopic devices has produced a revival of interest in quantum Hall physics.  New types of measurements, more precise and efficient than ever, have made it possible to focus closely on the electronic properties of quantum Hall edge states. This is achieved by applying charge and heat currents at mesoscopic length scales, attaching metallic gates and Ohmic contacts, and splitting edge channels with the help of quantum point contacts. The experiments reveal fascinating new phenomena, such as the interference, statistics, and topological phase shifts of fractionally charged quasi-particles, strong interaction and correlation effects, and phase transitions induced by non-Gaussian fluctuations. The thesis discusses some puzzling results of these experiments and presents a coherent picture of mesoscopic effects in quantum Hall systems, which accounts for integer and fractional filling factors and ranges from microscopic theory to effective models, and covers both equilibrium and non-equilibrium phenomena.

Quantum mechanics. Quantumfield theory --- quantumfysica

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

In the processes studied in contemporary physics one encounters the most diverse conditions: temperatures ranging from absolute zero to those found in the cores of stars, and densities ranging from those of gases to densities tens of times larger than those of a solid body. Accordingly, the solution of many problems of modern physics requires an increasingly large volume of information about the propertiesofmatterundervariousconditions,includingextremeones. Atthesame time, there is a demand for an increasing accuracy of these data, due to the fact thatthereliabilityandcomputationalsubstantiationofmanyuniquetechnological devices and physical installations depends on them. The relatively simple models ordinarily described in courses on theoretical physics are not applicable when we wish to describe the properties of matter in a su?ciently wide range of temperatures and densities. On the other hand, expe- ments aimed at generating data on properties of matter under extreme conditions usually face considerably technical di?culties and in a number of instances are exceedingly expensive. It is precisely for these reasons that it is important to - velop and re?ne in a systematic manner quantum-statistical models and methods for calculating properties of matter, and to compare computational results with data acquired through observations and experiments. At this time, the literature addressing these issues appears to be insu?cient. If one is concerned with opacity, which determines the radiative heat conductivity of matter at high temperatures, then one can mention, for example, the books of D. A. Frank-Kamenetskii [67], R. D. Cowan [49], and also the relatively recently published book by D.

Quantum mechanics. Quantumfield theory --- quantumfysica

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This book is the seventh in a series of lectures of the S´ eminaire Poincar´ e,which is directed towards a large audience of physicists and of mathematicians. The goal of this seminar is to provide up-to-date information about general topics of great interest in physics. Both the theoretical and experimental aspects are covered, with some historical background. Inspired by the Bourbaki seminar in mathematics in its organization, hence nicknamed Bourbaphi , the Poincar´ e Seminar is held twice a year at the Institut Henri Poincar´ e in Paris, with cont- butions prepared in advance. Particular care is devoted to the pedagogical nature of the presentations so as to ful?ll the goal of being readable by a large audience of scientists. This volume contains the tenth such seminar, held on April 30, 2007. It is devoted to the application of non-commutative geometry and quantum groups to physics. The book starts with a pedagogical introduction to Moyal geometry by V- cent Pasquier, with special emphasis on the quantum Hall e?ect. It is followed by a detailed review of Vincent Rivasseau on non-commutative ?eld theory and the recent advances which lead to its renormalizability and asymptotic safety. The description of the quantum Hall e?ect as a non-commutative ?uid is then treated in detail by Alexios Polychronakos. Integrable spin chains can be studied through quantum groups; their striking agreement with neutron scattering experiments is reviewed by Jean-MichelMaillet.

Quantum mechanics. Quantumfield theory --- quantumfysica

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Quantum mechanics. Quantumfield theory --- quantumfysica