Download or read book Quantum Confined States and Room Temperature Spin Coherence in Semiconductor Nanocrystal Quantum Dots written by Ahmad Khastehdel Fumani and published by . This book was released on 2015 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis we studied the signature of quantum confined electronic structure of CdSe nanocrystal quantum dots (NCQDs) in the electron spin behavior via time resolved Faraday rotation (TRFR) measurement at room temperature. We found that there is a distinction between the optical spin pumping efficiency(SPE) spectrum and the optical absorbance. Although the first peak in the SPE coincides with the band edge absorption peak, the rest of the two spectra show significant distinctions. There is a second peak in the signal from the larger NCQDs 200~meV higher in energy. The SPE diminishes afterwards. In smaller NCQDs there is only one peak in the signal. We model this behavior following a 6-band effective mass approximation spin dependent absorbance calculation. We also investigated the dynamics of the spin signal and the presence of two precessing components in the TRFR signal. We find that the inhomogeneous dephasing is not sufficient to explain the dynamics of both components. We associate one of the components to the spin signal from neutral excitons and the other one to positively charged trions. We describe the data using a magnetic field dependent spin decoherence mechanism that occurs via fluctuation of the exciton energy levels in between the available fine structure states. This model captures the TRFR experiment data on both short and long timescales. Additionally, we developed a NCQD-polymer composite optical waveguide and investigated the optical spin measurement on these structures.
Download or read book Quantum Confined Semiconductor Nanocrystals written by Wesley Chiang and published by American Chemical Society. This book was released on 2023-09-26 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, the fascinating story of colloidal quantum dots has no series finale yet. Instead, there continue to be advancements in our understanding of the fundamental properties of these nanocrystals, each of these advancements catalyzing a spin-off into a new journey toward potential applications. These remarkable advancements include improving the synthesis techniques, characterizing nanocrystals at the single-particle level, and tailoring their properties for specific applications. The quantum-confined colloidal semiconductor nanocrystals field has witnessed a remarkable convergence of nanoscience, materials chemistry, and spectroscopy, resulting in unprecedented control over their properties. With ongoing research efforts, the potential of semiconductor nanocrystals continues to unfold. Scientists are exploring new materials, developing scalable synthesis methods, and pushing the boundaries of their applications in fields such as quantum computing, energy storage, and biological sensing. The authors take the reader into quantum confinement and quantum dots. While the contents of this primer are rather expansive, they merely scratch the surface of the complex voyage that quantum dot sciences have undergone. The authors have identified vital terminology, valuable concepts, techniques, and applications.
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 Semiconductor Quantum Dots written by Ladislaus B nyai and published by World Scientific. This book was released on 1993 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor Quantum Dots presents an overview of the background and recent developments in the rapidly growing field of ultrasmall semiconductor microcrystallites, in which the carrier confinement is sufficiently strong to allow only quantized states of the electrons and holes. The main emphasis of this book is the theoretical analysis of the confinement induced modifications of the optical and electronic properties of quantum dots in comparison with extended materials. The book develops the theoretical background material for the analysis of carrier quantum-confinement effects, introduces the different confinement regimes for relative or center-of-mass motion quantization of the electron-hole-pairs, and gives an overview of the best approximation schemes for each regime. A detailed discussion of the carrier states in quantum dots is presented and surface polarization instabilities are analyzed, leading to the self-trapping of carriers near the surface of the dots. The influence of spin-orbit coupling on the quantum-confined carrier states is discussed. The linear and nonlinear optical properties of small and large quantum dots are studied in detail and the influence of the quantum-dot size distribution in many realistic samples is outlined. Phonons in quantum dots as well as the influence of external electric or magnetic fields are also discussed. Last but not least the recent developments dealing with regular systems of quantum dots are also reviewed. All things included, this is an important piece of work on semiconductor quantum dots not to be dismissed by serious researchers and physicists.
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 Optical Control and Detection of Spin Coherence in Semiconductor Nanostructures written by Jesse A. Berezovsky and published by ProQuest. This book was released on 2007 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the coherent dynamics of electron spins in quantum dots (QDs) is important for potential applications in solid-state, spin-based electronics and quantum information processing. Here, results are presented focusing on optical initialization, manipulation, and readout of spin coherence in various semiconductor nanostructures. Layered semiconductor nanocrystals are fabricated containing a spherical "quantum shell" in which electrons and holes are confined. As in a planar quantum well, the quantized energy levels and g-factors are found to depend on the shell thickness. Taking this idea a step further, nanocrystals with a concentric, tunnel-coupled core and shell are investigated. Based on the energy and g-factor dependences in these structures, spins can be selectively initialized into, and read out from, states in the core and shell. In contrast to these two ensemble measurements, we next turn to measurements of single electron spins in single QDs. First, we demonstrate the detection of a single electron spin in a QD using a nondestructive, continuously averaged magneto-optical Kerr rotation (KR) measurement. This continuous single QD KR technique is then extended into the time domain using pulsed pump and probe lasers, allowing the observation of the coherent evolution of an electron spin state with nanosecond temporal resolution. By sweeping the delay between the pump and probe, the dynamics of the spin in the QD are mapped out in time, providing a direct measurement of the electron g-factor and spin lifetime. Finally, this time-resolved single spin measurement is used to observe ultrafast coherent manipulation of the spin in the QD using an off-resonant optical pulse. Via the optical Stark effect, this optical pulse coherently rotates the spin state through angles up to pi radians, on picosecond timescales.
Download or read book Semiconductor Quantum Dots written by Y. Masumoto and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor quantum dots represent one of the fields of solid state physics that have experienced the greatest progress in the last decade. Recent years have witnessed the discovery of many striking new aspects of the optical response and electronic transport phenomena. This book surveys this progress in the physics, optical spectroscopy and application-oriented research of semiconductor quantum dots. It focuses especially on excitons, multi-excitons, their dynamical relaxation behaviour and their interactions with the surroundings of a semiconductor quantum dot. Recent developments in fabrication techniques are reviewed and potential applications discussed. This book will serve not only as an introductory textbook for graduate students but also as a concise guide for active researchers.
Download or read book Semiconductor Nanocrystal Quantum Dots written by Andrey Rogach and published by Springer Science & Business Media. This book was released on 2008-09-02 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to specifically focus on semiconductor nanocrystals, and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices. The enormous potential of nanoscience to impact on industrial output is now clear. Over the next two decades, much of the science will transfer into new products and processes. One emerging area where this challenge will be very successfully met is the field of semiconductor nanocrystals. Also known as colloidal quantum dots, their unique properties have attracted much attention in the last twenty years.
Download or read book Quantum Dots written by Peter A. Ling and published by Nova Publishers. This book was released on 2005 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantum dot is a particle of matter so small that the addition or removal of an electron changes its properties in some useful way. All atoms are quantum dots, but multi-molecular combinations can have this characteristic. In biochemistry, quantum dots are called redox groups. In nanotechnology, they are called quantum bits or qubits. Quantum dots typically have dimensions measured in nanometers, where one nanometer is 10-9 meter or a millionth of a millimetre. The fields of biology, chemistry, computer science, and electronics are all of interest to researchers in nanotechnology. Other applications of quantum dots include nanomachines, neural networks, and high-density memory or storage media. Research is being carried out on nano-crystals, self-assembled dots, and gated structures. This book presents leading-edge research from around the world.
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 Capture and Relaxation in Self Assembled Semiconductor Quantum Dots written by Robson Ferreira and published by Morgan & Claypool Publishers. This book was released on 2016-02-23 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an overview of different models and mechanisms developed to describe the capture and relaxation of carriers in quantum-dot systems. Despite their undisputed importance, the mechanisms leading to population and energy exchanges between a quantum dot and its environment are not yet fully understood. The authors develop a first-order approach to such effects, using elementary quantum mechanics and an introduction to the physics of semiconductors. The book results from a series of lectures given by the authors at the Master’s level.
Download or read book Quantum Dots for Quantum Information Processing Controlling and Exploiting the Quantum Dot Environment written by Martin J. A. Schütz and published by Springer. This book was released on 2016-11-15 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis offers a comprehensive introduction to surface acoustic waves in the quantum regime. It addresses two of the most significant technological challenges in developing a scalable quantum information processor based on spins in quantum dots: (i) decoherence of the electronic spin qubit due to the surrounding nuclear spin bath, and (ii) long-range spin-spin coupling between remote qubits. Electron spins confined in quantum dots (QDs) are among the leading contenders for implementing quantum information processing. To this end, the author pursues novel strategies that turn the unavoidable coupling to the solid-state environment (in particular, nuclear spins and phonons) into a valuable asset rather than a liability.
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 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 Quantum Dots written by Peter A. Ling and published by Nova Publishers. This book was released on 2005 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since first developed in the early sixties, silicon chip technology has made vast leaps forward. From a rudimentary circuit with a mere handful of transistors, the chip has evolved into a technological wonder, packing millions of bits of information on a surface no larger that a human thumbnail. And most experts predict that in the near future, we will see chips with over a billion bits. Quantum dots are small devices that contain a tiny droplet of free electrons. They are fabricated in semiconductor materials and have typical dimensions ranging from nanometres to a few microns. The size and shape of these structures and therefore the number of electrons they contain can be precisely controlled; a quantum dot can have anything from a single electron to a collection of several thousands. The physics of quantum dots shows many parallels with the behaviour of naturally occurring quantum systems in atomic and nuclear physics. As in an atom, the energy levels in a quantum dot become quantised due to the confinement of electrons. Unlike atoms however, quantum dots can be easily connected to electrodes and are therefore excellent tools for studying atomic-like properties. This new book brings together leading research from throughout the world in this field of the future which has become the field of today.
Download or read book Photoactive Semiconductor Nanocrystal Quantum Dots written by Alberto Credi and published by Springer. This book was released on 2017-01-20 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.
Download or read book Quantum Dots written by Michael Shur and published by World Scientific. This book was released on 2002 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.
