Download or read book Exploring Single Hole States in InAs GaAs Quantum Dots and Quantum Dot Molecules Under 2 D Electric Fields written by Xiangyu Ma and published by . This book was released on 2019 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: InAs/GaAs quantum dots (QDs) and quantum dot molecules (QDMs) are self-assembled semiconductor nanostructures that can trap a single electron or hole in a 3-D potential-well. Grown by molecular beam epitaxy (MBE), they have excellent optical qualities that can be used in applications for quantum information processing and quantum computing. Specifically, hole spins in a single QD/QDM have longer decoherence time than electron spins due to the lack of hyperfine interaction, making hole spins a great qubit candidate. However, many challenges such as QD growth, device integration, and spin manipulation inhibit the scalability of a hole-spin-based quantum information platform. A deeper understanding of the hole spin physics and the QD/QDM material system is needed to advance device engineering opportunities.
Download or read book Optical and Electrical Properties of Single Self Assembled Quantum Dots in Lateral Electric Fields written by Malte Huck and published by diplom.de. This book was released on 2010-03-25 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inhaltsangabe:Abstract: Chapter 1: In this thesis we investigate the optical properties of self-assembled quantum dots exposed to a lateral electric field. As a result of the electric field the wave functions of electrons and holes inside the quantum dot are manipulated, which makes it possible to tune their energy levels and control the optical properties of the system. The possibility of tuning the emission energy of different few particle states using this method makes this system very promising for the use of a source of polarization entangled photons as discussed in the following sections. In Section 1.1 the concept of entangled states is introduced together with a brief historical overview. The possibility of using the exciton biexciton cascade of a self-assembled quantum dot for the generation of entangled photon pairs is presented in Section 1.2. Chapter 2: In this chapter we introduce the concept of quantum dots and demonstrate their optical emission properties. In Section 2.1 the quantum dot is introduced as a three-dimensional charge carrier trap. Several types of quantum dots are presented in an overview. In Section 2.2 we discuss the physical effects that occur on the way from bulk semiconductor material to the three-dimensional charge carrier confinement in the case of quantum dots. The growth of self-assembled quantum dot samples is the topic of Section 2.3, where the technique of molecular beam epitaxy is introduced (Section 2.3.1). This technique is used to grow the semiconductor quantum dots via heteroepitaxy in the Stranski-Krastanov growth mode (Section 2.3.2). Quantum dots are commonly referred to as artificial atoms due to their atomlike emission features. The origin for this expression is explained in Section 2.4 on the basis of the energetic structure of self-assembled quantum dots. The optical properties of quantum dots are discussed in Section 2.5, beginning with an introduction to the experimental setup that has been used to investigate the quantum dots during this thesis (Section 2.5.1). Different optical excitation modes are presented in Section 2.5.2 and in Section 2.5.3 we discuss, how to achieve a low enough quantum dot density on the analyzed samples. Section 2.5.4 deals with the photoluminescence of different exciton states and in Section 2.5.5 we present how these lines can be identified via power dependent measurements. Finally, the concept of initial charges in self-assembled quantum dots is presented in [...]
Download or read book Optical Spectroscopy of Laterally Spaced InAs GaAs Quantum Dot Molecules written by Shilpa Sanwlani and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, potential device applications have fueled an extensive effort to fabricate lateral arrays of quantum dots (QDs) with specific dot densities, spacings and size distributions. An essential element for the further development of QD devices with new functionalities is the introduction of controllable quantum coupling between two or more QDs in such an array. Tunable quantum coupling between vertically stacked InAs QDs has been demonstrated, with the coupling mediated by coherent tunneling and tunable with a static electric field. While these studies have revealed that the spatial arrangement of QDs can lead to remarkable effects, it will be impossible to scale vertical coupling to a large number of QDs. Investigations of lateral quantum coupling have been slower to develop, however, because special growth protocols are required and the ability to independently tune the luminescence energy of separate QDs is lost. Spectroscopy of single pairs of laterally separated QDs is required to resolve the signatures of quantum coupling from inhomogeneously broadened ensemble spectra. Laterally-coupled quantum dots require modified sample preparation methods to isolate single pairs of QDs and apply electric fields that tune the relative energies of the two dots. The electric field must be applied along the surface of the sample, perpendicular to the growth direction. To apply this lateral field, we use interdigitated electrodes patterned onto the sample surface with photolithography and metal deposition. Electrical connections are made to each of the interdigitated top contacts as well as to an ohmic back contact. This three-terminal arrangement makes it possible to independently control both the relative energies of the dots and the charging of the QDs. We present photoluminescence spectra of laterally coupled QDs whose coupling and charge states are tuned with this three-terminal arrangement. We further discuss the implications and opportunities for control of quantum coupling in laterally-scalable architectures.
Download or read book Single Quantum Dots written by Peter Michler and published by Springer Science & Business Media. This book was released on 2003-12-09 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Special focus is given to the optical and electronic properties of single quantum dots due to their potential applications in devices operating with single electrons and/or single photons. This includes quantum dots in electric and magnetic fields, cavity-quantum electrodynamics, nonclassical light generation, and coherent optical control of excitons.
Download or read book Spins in Optically Active Quantum Dots written by Oliver Gywat and published by John Wiley & Sons. This book was released on 2010-02-01 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filling a gap in the literature, this up-to-date introduction to the field provides an overview of current experimental techniques, basic theoretical concepts, and sample fabrication methods. Following an introduction, this monograph deals with optically active quantum dots and their integration into electro-optical devices, before looking at the theory of quantum confined states and quantum dots interacting with the radiation field. Final chapters cover spin-spin interaction in quantum dots as well as spin and charge states, showing how to use single spins for break-through quantum computation. A conclusion and outlook round off the volume. The result is a primer providing the essential basic knowledge necessary for young researchers entering the field, as well as semiconductor and theoretical physicists, PhD students in physics and material sciences, electrical engineers and materials scientists.
Download or read book Self Assembled Quantum Dots written by Zhiming M Wang and published by Springer Science & Business Media. This book was released on 2007-11-29 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multidisciplinary book provides up-to-date coverage of carrier and spin dynamics and energy transfer and structural interaction among nanostructures. Coverage also includes current device applications such as quantum dot lasers and detectors, as well as future applications to quantum information processing. The book will serve as a reference for anyone working with or planning to work with quantum dots.
Download or read book Quantum Dots written by Lucjan Jacak and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present an overview of the theoretical background and experimental re sults in the rapidly developing field of semiconductor quantum dots - systems 8 6 of dimensions as small as 10- -10- m (quasi-zero-dimensional) that contain a small and controllable number (1-1000) of electrons. The electronic structure of quantum dots, including the energy quan tization of the single-particle states (due to spatial confinement) and the evolution of these (Fock-Darwin) states in an increasing external magnetic field, is described. The properties of many-electron systems confined in a dot are also studied. This includes the separation of the center-of-mass mo tion for the parabolic confining potential (and hence the insensitivity of the transitions under far infrared radiation to the Coulomb interactions and the number of particles - the generalized Kohn theorem) and the effects due to Coulomb interactions (formation of the incompressible magic states at high magnetic fields and their relation to composite jermions), and finally the spin-orbit interactions. In addition, the excitonic properties of quantum dots are discussed, including the energy levels and the spectral function of a single exciton, the relaxation of confined carriers, the metastable states and their effect on the photoluminescence spectrum, the interaction of an exciton with carriers, and exciton condensation. The theoretical part of this work, which is based largely on original re sults obtained by the authors, has been supplemented with descriptions of various methods of creating quantum-dot structures.
Download or read book Self Assembled InGaAs GaAs Quantum Dots written by and published by Academic Press. This book was released on 1999-03-29 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is concerned with the crystal growth, optical properties, and optical device application of the self-formed quantum dot, which is one of the major current subjects in the semiconductor research field.The atom-like density of states in quantum dots is expected to drastically improve semiconductor laser performance, and to develop new optical devices. However, since the first theoretical prediction for its great possibilities was presented in 1982, due to the difficulty of their fabrication process. Recently, the advent of self-organized quantum dots has made it possible to apply the results in important optical devices, and further progress is expected in the near future.The authors, working for Fujitsu Laboratories, are leading this quantum-dot research field. In this volume, they describe the state of the art in the entire field, with particular emphasis on practical applications.
Download or read book Quantum Dots written by Elena Borovitskaya and published by World Scientific. This book was released on 2002-07-08 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, leading experts on quantum dot theory and technology provide comprehensive reviews of all aspects of quantum dot systems. The following topics are covered: (1) energy states in quantum dots, including the effects of strain and many-body effects; (2) self-assembly and self-ordering of quantum dots in semiconductor systems; (3) growth, structures, and optical properties of III-nitride quantum dots; (4) quantum dot lasers.
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.
Download or read book Programme and The Book of Abstracts Seventh Annual Conference YUCOMAT 2005 written by Dragan P. Uskoković and published by Institute of Technical Sciences of SASA. This book was released on 2005-08-01 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS - Serbia became a member of FEMS (Federation of European Materials Societies).
Download or read book Quantum Dots for Quantum Information Technologies written by Peter Michler and published by Springer. This book was released on 2017-06-01 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the most recent developments in quantum dot spin physics and the generation of deterministic superior non-classical light states with quantum dots. In particular, it addresses single quantum dot spin manipulation, spin-photon entanglement and the generation of single-photon and entangled photon pair states with nearly ideal properties. The role of semiconductor microcavities, nanophotonic interfaces as well as quantum photonic integrated circuits is emphasized. The latest theoretical and experimental studies of phonon-dressed light matter interaction, single-dot lasing and resonance fluorescence in QD cavity systems are also provided. The book is written by the leading experts in the field.
Download or read book Quantum Dots written by Elena Borovitskaya and published by World Scientific Publishing Company Incorporated. This book was released on 2002-01-01 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, leading experts on quantum dot theory and technology provide comprehensive reviews of all aspects of quantum dot systems. The following topics are covered: (1) energy states in quantum dots, including the effects of strain and many-body effects; (2) self-assembly and self-ordering of quantum dots in semiconductor systems; (3) growth, structures, and optical properties of III-nitride quantum dots; (4) quantum dot lasers.
Download or read book International Conference on Simulation of Semiconductor Processes and Devices written by and published by . This book was released on 2005 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Dots written by T. Chakraborty and published by Elsevier. This book was released on 1999-11-30 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the electronic and optical properties of two low-dimensional systems: quantum dots and quantum antidots and is divided into two parts. Part one is a self-contained monograph which describes in detail the theoretical and experimental background for exploration of electronic states of the quantum-confined systems. Starting from the single-electron picture of the system, the book describes various experimental methods that provide important information on these systems. Concentrating on many-electron systems, theoretical developments are described in detail and their experimental consequences are also discussed. The field has witnessed an almost explosive growth and some of the future directions of explorations are highlighted towards the end of the monograph. The subject matter is dealt with in such a way that it is both accessible to beginners and useful for expert researchers as a comprehensive review of most of the developments in the field.Furthermore the book contains 37 reprinted articles which have been selected to provide a first-hand picture of the overall developments in the field. The early papers have been arranged to portray the developments chronologically, and the more recent papers provide an overview of future direction in the research.
Download or read book Quantum Dots Fundamentals Applications and Frontiers written by Bruce A. Joyce and published by Springer Science & Business Media. This book was released on 2006-03-30 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains papers delivered at a NATO Advanced Research Workshop and provides a broad introduction to all major aspects of quantum dot structures. Such structures have been produced for studies of basic physical phenomena, for device fabrication and, on a more speculative level, have been suggested as components of a solid-state realization of a quantum computer. The book is structured so that the reader is introduced to the methods used to produce and control quantum dots, followed by discussions of their structural, electronic, and optical properties. It concludes with examples of how their optical properties can be used in practical devices, including lasers and light-emitting diodes operating at the commercially important wavelengths of 1.3 Am and 1.55 Am."
Download or read book Spin Coherence and Vibrational Tunneling in Coupled Quantum Dot Pairs written by Cameron Lamar Jennings and published by . This book was released on 2020 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum dots (QDs) are semiconductor nanoparticles that trap electrons and holes in all three dimensions, resulting in discrete energy levels with strong optical transitions. InAs/GaAs QDs are grown by molecular beam epitaxy of lattice-mismatched InAs on a GaAs substrate, resulting in strain-induced island formation on a two-dimensional wetting layer. In addition to optoelectronic applications such as lasing, infrared detection, and photovoltaics, QDs are capable of hosting optically-controlled spin qubits and emitting photonic qubits for quantum communication and quantum computation. This dissertation focuses on InAs/GaAs coupled quantum dot pairs (CQDs) formed by strain-induced alignment of QDs in nearby layers, resulting in interdot charge tunneling that can be controlled with an applied electric field. We use a combination of theoretical modeling and optical spectroscopy to understand dynamical processes of bound photoexcited charges, aiming to enhance their usefulness for quantum information and sensing technologies and help overcome difficulties preventing their implementation. We develop a model of electron and hole confinement in CQDs, including Coulomb and spin interactions, phonon coupling, and optical transitions. This model is used to simulate relaxation dynamics during neutral molecular biexciton cascades, identifying parameter regimes where two-photon polarization entanglement can be expected. While this process has been demonstrated in single QDs, we find that charge separation in interdot states of CQDs allows for tunable emission energies and a higher tolerance to anisotropic electron-hole exchange splitting. Using low-temperature optical photoluminescence spectrosopy, we identify charge and spin states in single CQDs and investigate their interactions. Two-laser photoluminescence excitation spectroscopy demonstrates two-photon excitation into the molecular biexciton state via a stepwise process, while calculations identify conditions required for efficient simultaneous two-photon absorption. Further investigations find decoherence by electric field fluctuations from charged lattice defects, and identify a novel enhancement of acoustic phonon coupling at hole tunneling resonances from piezoelectric interactions.
