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Nonequilibrium Charge Transport Through Quantum Dots With Electron Phonon Interaction
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Book Synopsis Nonequilibrium Charge Transport Through Quantum Dots with Electron-phonon Interaction by : Klaus Ferdinand Albrecht
Download or read book Nonequilibrium Charge Transport Through Quantum Dots with Electron-phonon Interaction written by Klaus Ferdinand Albrecht and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zusammenfassung: The subject of this thesis is the nonequilibrium charge transport through single-molecular quantum dots. For such nanostructures a single excess charge on the molecule can cause quantized nanomechanical vibrations. In order to understand the effects of such an electron-phonon coupling, we discuss the following important aspects of the nonequilibrium system: For a quantum dot coupled to two metallic leads, we study the time evolution of the system from a given initial preparation towards its nonequilibrium steady state. Here, our focus is on the influence of the electron-phonon coupling on the timescales relevant for the charge dynamics. After the transients die out, the steady-state properties of the system become accessible. For this situation, we calculate the local density of states on the quantum dot using the numerically exact diagrammatic Monte Carlo method. Based on these results, we perform a detailed discussion of the voltage dependence of the spectrum under the influence of the electron-phonon interaction. Besides studying a quantum dot coupled to two metals, a hybrid junction is discussed where the molecule is contacted to a metal and a superconductor. It is shown how the superconducting gap influences the charge transport through the quantum dot with a single vibrational mode
Book Synopsis Nonequilibrium Electron Transport in Quantum Dot and Quantum Point Contact Systems by : Anasuya Erin Krishnaswamy
Download or read book Nonequilibrium Electron Transport in Quantum Dot and Quantum Point Contact Systems written by Anasuya Erin Krishnaswamy and published by . This book was released on 1999 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much experimental research has been performed in the equilibrium regime on individual quantum dots and quantum point contacts (QPCs). The focus of the research presented here is electron transport in the nonequilibrium regime in coupled quantum dot and QPC systems fabricated on AlGaAs/GaAs material using the split gate technique. Near equilibrium magnetoconductance measurements were performed on a quantum dot and a QPC. Oscillations were seen in the conductance of the sensor which corresponded to Aharonov-Bohm oscillations in the quantum dot, to our knowledge the first such observation. Sudden jumps in the conductance of the QPC were observed under certain gate biases and under certain magnetic fields. When the gate biases and magnetic field were held constant and the conductance was observed over time, switching was observed with the form of a random telegraph signal (RTS). RTS switching is usually attributed to charging of a single impurity. However, in this case switching may have been due to tunneling via edge states in the dot. Nonequilibrium transport in single quantum dots was investigated. A knee or kink was observed in the current-voltage characteristics of two dots on different material. The bias conditions under which the knee occurred point to electron heating as the physical mechanism for the observed behavior. However, the data can not be fit accurately over all bias ranges with an energy balance hot electron model. Modifications to the model are needed to accurately represent the devices studied here. Finally, the effect of nonlinear transport through a one dimensional (1D) QPC on the equilibrium conductance of an adjacent OD quantum dot was explored. This was the first attempt to observe Coulomb drag between a OD and 1D system. It was observed that the equilibrium conductance peaks in the quantum dot were broadened as the current in the QPC increased. This apparent electron heating effect in the dot can be explained by a simple ballistic phonon model. However, reasonable phase coherence times can be estimated from peak fitting using a Breit- Wigner formula which points to a Coulomb interaction. More detailed numerical calculations should illuminate the dominant scattering processes.
Book Synopsis Quench Dynamics in Interacting and Superconducting Nanojunctions by : Rubén Seoane Souto
Download or read book Quench Dynamics in Interacting and Superconducting Nanojunctions written by Rubén Seoane Souto and published by Springer Nature. This book was released on 2020-02-05 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of many-body interactions and superconducting correlations have become central questions in the quantum transport community. While most previous works investigating current fluctuations in nanodevices have been restricted to the stationary regime, Seoane's thesis extends these studies to the time domain. It provides relevant information about the time onset of electronic correlations mediated by interactions and superconductivity. This knowledge is essential for the development of fast electronic devices, as well as novel applications requiring fast manipulations, such as quantum information processing. In addition, the thesis establishes contact with issues of broad current interest such as non-equilibrium quantum phase transitions.
Book Synopsis Non-equilibrium Electron Transport Through a Double Quantum Dot System by : Verena Körting
Download or read book Non-equilibrium Electron Transport Through a Double Quantum Dot System written by Verena Körting and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Polarons and Bipolarons by : Ashok Chatterjee
Download or read book Polarons and Bipolarons written by Ashok Chatterjee and published by CRC Press. This book was released on 2018-10-09 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive review of the subject of polaron and a thorough account of the sophisticated theories of the polaron. It explains the concept of the polaron physics in as simple a manner as possible and presents the theoretical techniques and mathematical derivations in great detail. Anybody who follows this book will develop a solid command over the subject both conceptually and technically and will be in a position to contribute to this field.
Book Synopsis On the Interactions Between Charges, Phonons and Photons in Electric Field Tunable Quantum Dot Molecules by :
Download or read book On the Interactions Between Charges, Phonons and Photons in Electric Field Tunable Quantum Dot Molecules written by and published by . This book was released on 2001 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on the optical properties of single InAs/GaAs quantum dot molecules. A quantum dot molecule consists of a pair of quantum dots coupled by a nanometer scale tunneling barrier. Compared to single quantum dots, quantum dot molecules provide greatly enhanced versatility - with the ease of an electric field control, one gains broad flexibility to tune electronic energy levels and manipulate particle tunneling within a QDM. As a consequence, individual QDMs are being intensely studied as controllable interfaces of charge, spin and photonic quantum states at the single particle level. On the other hand, phonons - the quantized vibrations of the underlying crystal lattice - have mostly been left outside the realm of coherent control. In the domain of solid-state quantum technologies, the ubiquitous phonons are mainly considered for the limitations they impose. Omnipresent electron-phonon interactions and the predominantly dissipative nature of phonons are typically a major source of decoherence of the atom-like quantum states hosted by low-dimensional solid-state structures, such as QDMs. Here, we report experimental and theoretical results on the interactions between charges, photons and phonons in electric field tunable quantum dot molecules. Using an effective mass perturbation model, we compute the low energy biexciton states of a quantum dot molecule and apply them to provide a theoretical description of the dipole-dipole interaction between two excitons occupying separate dots in a quantum dot molecule. The expected properties of these so called dipolar states are presented, and we highlight their potential application as a switch for manipulating the transition energy and tunneling properties of the ground state neutral exciton. We then present results from a comprehensive investigation of the quantum confined Stark effect in quantum dot molecules, in which we studied the electric-field dependent energy shifts of exciton states as a function of the tunneling barrier width. Our experimental and computational results reveal that molecular wavefunction formation in quantum dot molecules strongly affects the quantum confined Stark effect, even as the dots are tuned far from resonance for particle tunneling. This dissertation culminates with our report of a novel mechanism by which phonons are made non-dissipative and coherent via electric field control and the optically driven formation of a molecular polaron in a quantum dot molecule. The coherent interaction of a single optical phonon with individual electronic states is revealed via a Fano-type quantum interference that produces a phonon-induced transparency in the optical absorption of individual quantum dot molecules. Experimentally, we find that the transparency is widely tunable by electronic and optical means, and provides a mechanism for amplifying weak coupling channels. This work is significant in that it demonstrates a specific mechanism by which typically incoherent and dissipative phonons are made to behave in a coherent and non-dissipative manner. As such, we demonstrate that phonons may enter the realm of mutual control of quantum states on the single particle level, which so far has been dominated by photons, electrons and spins.
Book Synopsis Transport and Decoherence Phenomena in Quantum Dots by : Kai Xi Wang
Download or read book Transport and Decoherence Phenomena in Quantum Dots written by Kai Xi Wang and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The problem of a few electronic level coupling to an environmental heat bath, such as in quantum dots (QDs), is well-known in modern quantum physics. These systems have been widely studied as they can dictate the dephasing properties in many practical opto-electronic devices. In this thesis we focus on the electron-phonon (quantized lattice vibrations) coupling in QDs that are embedded within semiconductor nanowires. For interband optical transitions, the electron-phonon interactions are treated using a cumulant expansion approach which includes the non-Markovian dynamics. Both the longitudinal optical (LO) and longitudinal acoustic (LA) phonons are included, and structural variations of the QDs are investigated, which, typically the LO phonons and structural asymmetry have been neglected in the literature. We find that the linewidth can have variations on three orders of magnitude when changing the QD geometry due to LO phonon interactions, which obviously has significant implications in mitigating phonon-induced dephasing. Comparison to experimental results is shown for validation of the theoretical model. Finally, we elucidate these effects for single photon emitters composed of different materials. In the intersublevel regime, we study the electron transport dynamics in a quantum dot cascade laser (QDCL), which is a promising candidate as the semiconductor gain medium for THz lasing. The quantum kinetics are included by means of an intuitive and accurate density matrix approach, valid for weak to intermediate e-phonon interaction strength. We find that at low temperatures, the LA phonons can help to inject electrons into the upper lasing state. We believe these findings should be considered and utilized in future opto-electronic device designs.
Book Synopsis Non-linear Charge Transport Through Quantum Dots by : Amritpal Singh
Download or read book Non-linear Charge Transport Through Quantum Dots written by Amritpal Singh and published by . This book was released on 2001 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Molecular Electronics: An Introduction To Theory And Experiment (2nd Edition) by : Elke Scheer
Download or read book Molecular Electronics: An Introduction To Theory And Experiment (2nd Edition) written by Elke Scheer and published by World Scientific. This book was released on 2017-05-19 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Electronics is self-contained and unified in its presentation. It can be used as a textbook on nanoelectronics by graduate students and advanced undergraduates studying physics and chemistry. In addition, included in this new edition are previously unpublished material that will help researchers gain a deeper understanding into the basic concepts involved in the field of molecular electronics.
Book Synopsis Electron Transport in Quantum Dots by : Jonathan P. Bird
Download or read book Electron Transport in Quantum Dots written by Jonathan P. Bird and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the debate of critical issues in this still developing field. In this matter, I have been assisted greatly by the excellent series of articles provided by the different authors, who are widely recognized as some of the leaders in this vital area of research.
Book Synopsis Tailored Electron-phonon Interactions in Semiconductor Double Quantum Dots by : Thomas Richard Hartke
Download or read book Tailored Electron-phonon Interactions in Semiconductor Double Quantum Dots written by Thomas Richard Hartke and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis demonstrates the construction of a double quantum dot (DQD) in an Indium Arsenide (InAs) nanowire that is mechanically suspended in vacuum between metal contacts and capacitively coupled to a superconducting microwave resonator. This mechanical suspension scheme places the DQD at the center of an effective 380 nm long phonon cavity created by the contacts supporting the ends of the suspended nanowire. Because electron-phonon coupling mechanisms lead to electron transport through the DQD, measurements of current can be used as a probe of the phonon density of states in the nanostructure. Current measurements reveal strong signatures of electron-phonon coupling at energies corresponding to the guitar string vibrational modes of the suspended nanowire. In addition, photon emission has recently been observed in InAs nanowire DQDs coupled to superconducting cavities. However, it has been proposed that a phonon must simultaneously be emitted with each photon to ensure energy conservation. Therefore the photon emission rate should be enhanced when the emitted phonons couple strongly to electrons in the DQD. We quantitatively confirm this hypothesis by independently measuring both the photon emission into the cavity and the electron-phonon coupling strength as a function of the DQD energy splitting.
Book Synopsis Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices by : Benjamin Lingnau
Download or read book Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices written by Benjamin Lingnau and published by Springer. This book was released on 2015-12-14 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis sheds light on the unique dynamics of optoelectronic devices based on semiconductor quantum-dots. The complex scattering processes involved in filling the optically active quantum-dot states and the presence of charge-carrier nonequilibrium conditions are identified as sources for the distinct dynamical behavior of quantum-dot based devices. Comprehensive theoretical models, which allow for an accurate description of such devices, are presented and applied to recent experimental observations. The low sensitivity of quantum-dot lasers to optical perturbations is directly attributed to their unique charge-carrier dynamics and amplitude-phase-coupling, which is found not to be accurately described by conventional approaches. The potential of quantum-dot semiconductor optical amplifiers for novel applications such as simultaneous multi-state amplification, ultra-wide wavelength conversion, and coherent pulse shaping is investigated. The scattering mechanisms and the unique electronic structure of semiconductor quantum-dots are found to make such devices prime candidates for the implementation of next-generation optoelectronic applications, which could significantly simplify optical telecommunication networks and open up novel high-speed data transmission schemes.
Book Synopsis Molecular Electronics by : Ioan Baldea
Download or read book Molecular Electronics written by Ioan Baldea and published by CRC Press. This book was released on 2016-01-05 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular electronics, an emerging research field at the border of physics, chemistry, and material sciences, has attracted great interest in the last decade. To achieve the ultimate goal of designing molecular electronic devices with the desired functionality and experimental manipulation at the single-molecule level, theoretical understanding of
Book Synopsis Quantum Foundations And Open Quantum Systems: Lecture Notes Of The Advanced School by : Theo M Nieuwenhuizen
Download or read book Quantum Foundations And Open Quantum Systems: Lecture Notes Of The Advanced School written by Theo M Nieuwenhuizen and published by World Scientific. This book was released on 2014-10-03 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advanced School on Quantum Foundations and Open Quantum Systems was an exceptional combination of lectures. These comprise lectures in standard physics and investigations on the foundations of quantum physics.On the one hand it included lectures on quantum information, quantum open systems, quantum transport and quantum solid state. On the other hand it included lectures on quantum measurement, models for elementary particles, sub-quantum structures and aspects on the philosophy and principles of quantum physics.The special program of this school offered a broad outlook on the current and near future fundamental research in theoretical physics.The lectures are at the level of PhD students.
Book Synopsis Transport Properties of Molecular Junctions by : Natalya A. Zimbovskaya
Download or read book Transport Properties of Molecular Junctions written by Natalya A. Zimbovskaya and published by Springer. This book was released on 2013-09-07 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts--a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers and professionals.
Book Synopsis Nonequilibrium Quantum Transport and Confinement Effects in Interacting Nanoscale Conductors by : Stephan Weiss
Download or read book Nonequilibrium Quantum Transport and Confinement Effects in Interacting Nanoscale Conductors written by Stephan Weiss and published by . This book was released on 2008 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantum Dots by : Alexander Tartakovskii
Download or read book Quantum Dots written by Alexander Tartakovskii and published by Cambridge University Press. This book was released on 2012-07-19 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review of cutting-edge solid state research, focusing on quantum dot nanostructures, for graduate students and researchers.
