Dissipative Quantum Mechanics of Nanostructures: Electron Transport, Fluctuations, and Interactions
Continuing miniaturization of electronic devices, together with the quickly growing number of nanotechnological applications, demands a profound understanding of the underlying physics. Most of the fundamental problems of modern condensed matter physics involve various aspects of quantum transport and fluctuation phenomena at the nanoscale. In nanostructures, electrons are usually confined to a limited volume and interact with each other and lattice ions, simultaneously suffering multiple scattering events on impurities, barriers, surface imperfections, and other defects. Electron interaction with other degrees of freedom generally yields two major consequences, quantum dissipation and quantum decoherence. In other words, electrons can lose their energy and ability for quantum interference even at very low temperatures. These two different, but related, processes are at the heart of all quantum phenomena discussed in this book.This book presents copious details to facilitate the understanding of the basic physics behind a result and the learning to technically reproduce the result without delving into extra literature. The book subtly balances the description of theoretical methods and techniques and the display of the rich landscape of the physical phenomena that can be accessed by these methods. It is useful for a broad readership ranging from master's and PhD students to postdocs and senior researchers.
We consider the optical conductivity of a clean two-dimensional metal near a quantum spin-density-wave transition. Critical magnetic fluctuations are known to destroy fermionic coherence at “hot spots” of the Fermi surface but coherent quasiparticles survive in the rest of the Fermi surface. A large part of the Fermi surface is not really “cold” but rather “lukewarm” in a sense that coherent quasiparticles in that part survive but are strongly renormalized compared to the noninteracting case. We discuss the self-energy of lukewarm fermions and their contribution to the optical conductivity σ(), focusing specifically on scattering off composite bosons made of two critical magnetic fluctuations. Recent study [S. A. Hartnoll et al., Phys. Rev. B 84, 125115 (2011)] found that composite scattering gives the strongest contribution to the self-energy of lukewarm fermions and suggested that this may give rise to a non-Fermi-liquid behavior of the optical conductivity at the lowest frequencies. We show that the most singular term in the conductivity coming from self-energy insertions into the conductivity bubble σ(Omega) ∝ ln^3(Omega) /(Omega)^(1/3) is canceled out by the vertex-correction and Aslamazov-Larkin diagrams. However, the cancellation does not hold beyond logarithmic accuracy, and the remaining conductivity still diverges as 1/(Omega)^(1/3). We further argue that the 1/(Omega)^(1/3) behavior holds only at asymptotically low frequencies, well inside the frequency range affected by superconductivity. At larger Omega, up to frequencies above the Fermi energy, σ(Omega) scales as 1/(Omega), which is reminiscent of the behavior observed in the superconducting cuprates.
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The Conference reflects the modern state of innovation in education, science, industry and social-economic sphere, from the standpoint of introducing new information technologies.
It is interesting for a wide range of researchers, teachers, graduate students and professionals in the field of innovation and information technologies.
We present a detailed theoretical description of quantum coherent electron transport in voltage-biased crosslike Andreev interferometers.Making use of the charge conjugation symmetry encoded in the quasiclassical formalism, we elucidate a crucial role played by geometric and electron-hole asymmetries in these structures. We argue that a nonvanishing Aharonov-Bohm-like contribution to the current IS flowing in the superconducting contour may develop only in geometrically asymmetric interferometers making their behavior qualitatively different from that of symmetric devices. The current I_N in the normal contour—along with I_S—is found to be sensitive to phase-coherent effects thereby also acquiring a 2π-periodic dependence on the Josephson phase. In asymmetric structures this current develops an odd-in-phase contribution originating from electron-hole asymmetry. We demonstrate that both phase-dependent currents I_S and I_N can be controlled and manipulated by tuning the applied voltage, temperature, and system topology, thus rendering Andreev interferometers particularly important for future applications in modern electronics.
In this manuscript, we study the electrically induced breathing of Metal-Organic Framework (MOF) within a 2D lattice model. The Helmholtz free energy of the MOF in electric eld consists of two parts: the electrostatic energy of the dielectric body in the external electric eld and elastic energy of the framework. The rst contribution is calculated from the rst principles of statistical mechanics with an account of MOF symmetry. By minimizing the obtained free energy and solving the resulting system of equations, we obtain the local electric eld and the parameter of the unit cell (angle ). The paper also studies the cross-section area of the unit cell and the polarization as functions of the external electric eld. We obtain the hysteresis in the region of the structural transition of the framework. Our results are in qualitative agreement with the literature data of the molecular dynamics (MD) simulation of MIL-53(Cr).
International Conference on Micro- and Nano-Electronics 2016
The quantum behavior of superconducting nanowires may essentially depend on the employed experimental setup. Here we investigate a setup that enables passing equilibrium supercurrent across an arbitrary segment of the wire without restricting fluctuations of its superconducting phase. The low temperature physics of the system is determined by a combined effect of collective soundlike plasma excitations and quantum phase slips. At T=0 the wire exhibits two quantum phase transitions, both being controlled by the dimensionless wire impedance g. While thicker wires with g>16 stay superconducting, in the thinnest wires with g<2 the supercurrent is totally destroyed by quantum fluctuations. The intermediate phase 2<g>16 is characterized by two different correlation lengths demonstrating superconductinglike behavior at shorter scales combined with vanishing superconducting response in the long scale limit.
This volume contains the papers presented at the session "Data Science" within the V International Conference on Information Technology and Nanotechnology (ITNT-2019). The conference was held in Samara, Russia, during May 21-24, 2019 (itnt-conf.org). The conference is a forum for leading researchers from all over the world aimed to discuss the latest advances in the basic and applied research in the field of Information Technology and Nanotechnology. It is also aimed to attract young people to advanced scientific research and share the latest trends in training and research programs for future ITNT specialists . In addition to the session "Data Science", ITNT-2019 also included three other sessions: "Computer Optics and Nanophotonics", "Image Processing and Earth Remote Sensing" and "Mathematical Modeling of Physico-Technical Processes and Systems". The whole forum brought together more than 450 scientists from United Kindom, Japan, Switzerland, Iran, Poland, Bulgaria, Finland, China, Kazakhstan and Russia, as well as representatives of global high-tech corporations, developers of modern electronics – Huawei, Nvidia, Intel, and Azimuth Photonics, and more than 60 cities in the world. 436 talks enabled discussion on a wide range of topics. The topics of the session "Data Science" were grouped into the following key directions: Data Mining (Big data, Systems and platforms, Methods); Machine Learning (Neural networks, Statistical methods, Feature-based classification, Applications); Security, Cryptography (Cryptosystems design and analysis, Mathematical and algorithmic aspects, Efficient implementations of algorithms, Network security); High Performance Computing (Parallel programming models and languages, Highperformance implementations, Complex systems simulation).
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.