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Quantum Coherent Dynamics Of Excitons And Valley Pseudospins In Atomically Thin Semiconductors
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Book Synopsis Quantum Coherent Dynamics of Excitons and Valley Pseudospins in Atomically Thin Semiconductors by : Kai Hao (Ph. D.)
Download or read book Quantum Coherent Dynamics of Excitons and Valley Pseudospins in Atomically Thin Semiconductors written by Kai Hao (Ph. D.) and published by . This book was released on 2018 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Monolayer transition metal dichalcogenides (TMDCs) are new emerging van der Waals materials. Several TMDC materials go through with a transition from indirect to direct gap semiconductors when reduced to monolayer thickness limit with emission in the visible to near-infrared range, making them attractive materials for optoelectronic applications. Their near-gap optical properties are dominant by excitons (bound electron-hole pairs), charged excitons (known as trions) or higher order bound states (e.g., neutral and charged biexcitons). In this dissertation, we explored the quantum coherent dynamics of exciton, trions and their associated valley index using a powerful ultrafast spectroscopy tool known as the two-dimensional coherent spectroscopy (2DCS). We investigated the underlying mechanisms that determined the valley coherence associated with excitons and trions. In monolayer TMDCs, there are two inequivalent K and K' points in momentum space, where the band extrema are located and the excitons are formed. The excitonic states in the two valleys are selectively coupled to light with opposite helicity. This valley contrasting optical selection rules allow one to address and manipulate the valley index readily, a unique property and advantage of TMDC materials for valleytronic applications. The valley coherence can be quantitatively evaluated in polarization resolved zero-quantum 2D spectra. We found that the exciton valley coherence is limited by the electron-hole exchange interaction in the system. In contrast, for the charged exciton (trion) states, where the inter-valley scattering is suppressed, it is the intra-valley pure dephasing limits the inter-valley coherence time. These results provide the insight of valley coherence dynamics in monolayer TMDCs and suggest possible approaches to improve the valley coherence time. Next, we investigate the coherence coupling between excitons and trions created in one valley. The trions are charged quasiparticles which contribute to the charge transport directly. Thus, the coupling between exciton and trion states can significantly influent the interpretation of transport measurements. We demonstrate that these two types of quasiparticles are coherently coupled to each other by the observation of the quantum beating of the cross-diagonal peaks in one-quantum 2D spectra. The coherence time between them can be extracted by monitoring the amplitude decay of the beating signal. We found that the coherent coupling dephasing rate between the exciton and trion equals to the sum of the exciton and trion dephasing rate, indicating uncorrelated dephasing process for excitons and trions. At longer time scale, the phonon-assisted energy transfer couples the two states incoherently. Finally, we studied the higher order correlated states in monolayer TMDCs. We used polarization resolved 2DCS to reveal bounded inter-valley neutral biexcitons and charged biexcitons as new peaks which spectrally shifted in 2D spectra. The binding energies of these biexcitons are ∼20 and ∼5 meV respectively. Unlike linear optical spectroscopy studies, the 2D spectra separate the different quantum pathways. Hence, these spectra provide unambiguous evidence of the biexciton states. The extracted binding energy of the biexciton states agrees with theoretical calculation and resolves controversies in the literature. Biexciton formation is important for applications such as lasers and generations of entangled photon pairs.
Book Synopsis Trion and Exciton Dynamics in Two Dimensional Semiconductors by : Akshay Kumar Singh
Download or read book Trion and Exciton Dynamics in Two Dimensional Semiconductors written by Akshay Kumar Singh and published by . This book was released on 2016 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-dimensional semiconducting systems have become increasingly important for a variety of applications including photo-detectors, high-power transistors and optoelectronics. With the discovery of the indirect-to-direct bandgap transition in atomically thin transition metal dichalcogenide (TMDs') materials, a plethora of further applications and advances await. Optical properties in these materials are especially interesting to measure, due to presence of spin-valley coupling giving rise to valleytronic applications, and enhanced light emission (and absorption) with applications in optoelectronics. Optical studies in semiconductors near the bandgap primarily relate to the fundamental optical excitation of semiconductors, an exciton (a Coulomb-bound electron-hole pair). If the Coulomb interaction is strong enough, excitons may capture an extra electron or hole, forming charged excitons known as trions. Trions have shown to carry longer-lived spin information, and can drift under an electric field. The interaction between excitons and trions, is thus a technologically important issue in optoelectronics. The purpose of this dissertation is to measure the interactions between excitons and trions in a variety of two-dimensional systems, primarily in the new class of semiconducting two-dimensional materials, TMDs'. The interactions are measured for their character (coherent or incoherent) and dynamics. Utilizing a two-color pump-probe setup we uncover coherent coupling, between excitons and trions in monolayer molybdenum diselenide, an order of magnitude larger than traditional semiconductors (like gallium arsenide). Incoherent relaxation pathways towards trions, are measured via resonant excitation of excitons. A mobility edge within the exciton resonance is uncovered, with applications in quantifying transport properties of materials under study. Further, valley sensitive measurements are carried out on monolayer tungsten diselenide, revealing the long-lived trion spin polarization and ultrafast exciton valley relaxation. The possible spectroscopy feature of biexcitons is discussed in monolayer tungsten diselenide. Finally, measurements are extended to high mobility gallium arsenide quantum well systems, and electron-density dependent spin scattering mechanisms are uncovered. We further discuss the possibility to suppress spin relaxation, via gate voltage, in these gallium arsenide quantum wells.
Book Synopsis Exciton Dynamics And Many Body Interactions In Layered Semiconducting Materials Revealed With Non-Linear Coherent Spectroscopy by : Prasenjit Dey
Download or read book Exciton Dynamics And Many Body Interactions In Layered Semiconducting Materials Revealed With Non-Linear Coherent Spectroscopy written by Prasenjit Dey and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomically thin, semiconducting transition metal dichalogenides (TMDs), a special class of layered semiconductors, that can be shaped as a perfect two dimensional material, have garnered a lot of attention owing to their fascinating electronic properties which are achievable at the extreme nanoscale. In contrast to graphene, the most celebrated two-dimensional (2D) material thus far; TMDs exhibit a direct band gap in the monolayer regime. The presence of a non-zero bandgap along with the broken inversion symmetry in the monolayer limit brands semiconducting TMDs as the perfect candidate for future optoelectronic and valleytronics-based device application. These remarkable discoveries demand exploration of different materials that possess similar properties alike TMDs. Recently, III-VI layered semiconducting materials (example: InSe, GaSe etc.) have also emerged as potential materials for optical device based applications as, similar to TMDs, they can be shaped into a perfect two-dimensional form as well as possess a sizable band gap in their nano-regime. The perfect 2D character in layered materials cause enhancement of strong Coulomb interaction. As a result, excitons, a coulomb bound quasiparticle made of electron-hole pair, dominate the optical properties near the bandgap. The basis of development for future optoelectronic-based devices requires accurate characterization of the essential properties of excitons. Two fundamental parameters that characterize the quantum dynamics of excitons are: a) the dephasing rate, 𝛾, which represents the coherence loss due to the interaction of the excitons with their environment (for example- phonons, impurities, other excitons, etc.) and b) excited state population decay rate arising from radiative and non-radiative relaxation processes.
Book Synopsis Quantum Photonics by : Yasuhiko Arakawa
Download or read book Quantum Photonics written by Yasuhiko Arakawa and published by Elsevier. This book was released on 2024-06-28 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum Photonics aims to serve as a comprehensive and systematic reference source for entrants to the field of quantum photonics, including updated topics on quantum photonics for researchers working in this field. The book reviews the fundamental knowledge of modern photonics related quantum technologies, key concepts of quantum photonic devices, and quantum photonics applications. The book is suitable for graduate students, researchers, and engineers who want to learn quantum photonics fundamentals. The editors, who are leaders in this field, have formulated this book as an introduction to the cutting-edge research in quantum photonics. Researchers and students involved in the development of semiconductor optoelectronics and optical communication systems should also find this book helpful. Covers the whole quantum photonics field, including nanostructured materials, physics, modelling, and quantum technology applications ranging from applications of q-bit emitters to quantum dot lasers Comprehensively and systematically reviews fundamentals and applications of quantum photonics for beginners in the field Provides foundational knowledge for modern photonics-related quantum technologies
Book Synopsis Coherent Light-Matter Interactions in Monolayer Transition-Metal Dichalcogenides by : Edbert Jarvis Sie
Download or read book Coherent Light-Matter Interactions in Monolayer Transition-Metal Dichalcogenides written by Edbert Jarvis Sie and published by Springer. This book was released on 2017-11-11 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents optical methods to split the energy levels of electronic valleys in transition-metal dichalcogenides (TMDs) by means of coherent light-matter interactions. The electronic valleys found in monolayer TMDs such as MoS2, WS2, and WSe2 are among the many novel properties exhibited by semiconductors when thinned down to a few atomic layers, and have have been proposed as a new way to carry information in next generation devices (so-called valleytronics). These valleys are, however, normally locked in the same energy level, which limits their potential use for applications. The author describes experiments performed with a pump-probe technique using transient absorption spectroscopy on MoS2 and WS2. It is demonstrated that hybridizing the electronic valleys with light allows one to optically tune their energy levels in a controllable valley-selective manner. In particular, by using off-resonance circularly polarized light at small detuning, one can tune the energy level of one valley through the optical Stark effect. Also presented within are observations, at larger detuning, of a separate contribution from the so-called Bloch--Siegert effect, a delicate phenomenon that has eluded direct observation in solids. The two effects obey opposite selection rules, enabling one to separate the two effects at two different valleys.
Book Synopsis Quantum Theory of Exciton-exciton Interactions in Atomically Thin Semiconductors by : Daniel Erkensten
Download or read book Quantum Theory of Exciton-exciton Interactions in Atomically Thin Semiconductors written by Daniel Erkensten and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantum Confined Excitons in 2-Dimensional Materials by : Carmen Palacios-Berraquero
Download or read book Quantum Confined Excitons in 2-Dimensional Materials written by Carmen Palacios-Berraquero and published by Springer. This book was released on 2018-11-02 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the first established experimental results of an emergent field: 2-dimensional materials as platforms for quantum technologies, specifically through the optics of quantum-confined excitons. It also provides an extensive review of the literature from a number of disciplines that informed the research, and introduces the materials of focus – 2d Transition Metal Dichalcogenides (2d-TMDs) – in detail, discussing electronic and chemical structure, excitonic behaviour and response to strain. This is followed by a brief overview of quantum information technologies, including concepts such as single-photon sources and quantum networks. The methods chapter addresses quantum optics techniques and 2d-material processing, while the results section shows the development of a method to deterministically create quantum dots (QDs) in the 2d-TMDs, which can trap single-excitons; the fabrication of atomically thin quantum light-emitting diodes to induce all-electrical single-photon emission from the QDs, and lastly, the use of devices to controllably trap single-spins in the QDs –the first step towards their use as optically-addressable matter qubits.
Book Synopsis Exciton Polaritons in Microcavities by : Daniele Sanvitto
Download or read book Exciton Polaritons in Microcavities written by Daniele Sanvitto and published by Springer Science & Business Media. This book was released on 2012-05-01 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decade, there has been a burst of new and fascinating physics associated to the unique properties of two-dimensional exciton polaritons, their recent demonstration of condensation under non-equilibrium conditions and all the related quantum phenomena, which have stimulated extensive research work. This monograph summarizes the current state of the art of research on exciton polaritons in microcavities: their interactions, fast dynamics, spin-dependent phenomena, temporal and spatial coherence, condensation under non-equilibrium conditions, related collective quantum phenomena and most advanced applications. The monograph is written by the most active authors who have strongly contributed to the advances in this area. It is of great interests to both physicists approaching this subject for the first time, as well as a wide audience of experts in other disciplines who want to be updated on this fast moving field.
Book Synopsis Advances in Condensed-Matter and Materials Physics by : Jagannathan Thirumalai
Download or read book Advances in Condensed-Matter and Materials Physics written by Jagannathan Thirumalai and published by BoD – Books on Demand. This book was released on 2020-05-06 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, Condensed Matter and Material Physics, incorporates the work of multiple authors to enhance the theoretical as well as experimental knowledge of materials. The investigation of crystalline solids is a growing need in the electronics industry. Micro and nano transistors require an in-depth understanding of semiconductors of different groups. Amorphous materials, on the other hand, as non-equilibrium materials are widely applied in sensors and other medical and industrial applications. Superconducting magnets, composite materials, lasers, and many more applications are integral parts of our daily lives. Superfluids, liquid crystals, and polymers are undergoing active research throughout the world. Hence profound information on the nature and application of various materials is in demand. This book bestows on the reader a deep knowledge of physics behind the concepts, perspectives, characteristic properties, and prospects. The book was constructed using 10 contributions from experts in diversified fields of condensed matter and material physics and its technology from over 15 research institutes across the globe.
Book Synopsis Encyclopedia of Modern Optics by : Bob D. Guenther
Download or read book Encyclopedia of Modern Optics written by Bob D. Guenther and published by Academic Press. This book was released on 2018-02-14 with total page 2253 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Encyclopedia of Modern Optics, Second Edition, Five Volume Set provides a wide-ranging overview of the field, comprising authoritative reference articles for undergraduate and postgraduate students and those researching outside their area of expertise. Topics covered include classical and quantum optics, lasers, optical fibers and optical fiber systems, optical materials and light-emitting diodes (LEDs). Articles cover all subfields of optical physics and engineering, such as electro-optical design of modulators and detectors. This update contains contributions from international experts who discuss topics such as nano-photonics and plasmonics, optical interconnects, photonic crystals and 2D materials, such as graphene or holy fibers. Other topics of note include solar energy, high efficiency LED’s and their use in illumination, orbital angular momentum, quantum optics and information, metamaterials and transformation optics, high power fiber and UV fiber lasers, random lasers and bio-imaging. Addresses recent developments in the field and integrates concepts from fundamental physics with applications for manufacturing and engineering/design Provides a broad and interdisciplinary coverage of specialist areas Ensures that the material is appropriate for new researchers and those working in a new sub-field, as well as those in industry Thematically arranged and alphabetically indexed, with cross-references added to facilitate ease-of-use
Book Synopsis Physics of Semiconductors in High Magnetic Fields by : Noboru Miura
Download or read book Physics of Semiconductors in High Magnetic Fields written by Noboru Miura and published by Oxford University Press. This book was released on 2008 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes most of the fundamental physical phenomena which semiconductors and their modulated structures exhibit in high magnetic fields. Readers can learn not only the basic theoretical background but also the present state of the art from the most advanced data in this rapidly growing research area.
Book Synopsis Nanoscience And Technology: A Collection Of Reviews From Nature Journals by : Peter Rodgers
Download or read book Nanoscience And Technology: A Collection Of Reviews From Nature Journals written by Peter Rodgers and published by World Scientific. This book was released on 2009-08-21 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains 35 review articles on nanoscience and nanotechnology that were first published in Nature Nanotechnology, Nature Materials and a number of other Nature journals. The articles are all written by leading authorities in their field and cover a wide range of areas in nanoscience and technology, from basic research (such as single-molecule devices and new materials) through to applications (in, for example, nanomedicine and data storage).
Book Synopsis Two Dimensional Transition Metal Dichalcogenides by : Narayanasamy Sabari Arul
Download or read book Two Dimensional Transition Metal Dichalcogenides written by Narayanasamy Sabari Arul and published by Springer. This book was released on 2019-07-30 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents advanced synthesis techniques adopted to fabricate two-dimensional (2D) transition metal dichalcogenides (TMDs) materials with its enhanced properties towards their utilization in various applications such as, energy storage devices, photovoltaics, electrocatalysis, electronic devices, photocatalysts, sensing and biomedical applications. It provides detailed coverage on everything from the synthesis and properties to the applications and future prospects of research in 2D TMD nanomaterials.
Book Synopsis Towards Solid-State Quantum Repeaters by : Kristiaan De Greve
Download or read book Towards Solid-State Quantum Repeaters written by Kristiaan De Greve and published by Springer Science & Business Media. This book was released on 2013-04-16 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: Towards Solid-State Quantum Repeaters: Ultrafast, Coherent Optical Control and Spin-Photon Entanglement in Charged InAs Quantum Dots summarizes several state-of-the-art coherent spin manipulation experiments in III-V quantum dots. Both high-fidelity optical manipulation, decoherence due to nuclear spins and the spin coherence extraction are discussed, as is the generation of entanglement between a single spin qubit and a photonic qubit. The experimental results are analyzed and discussed in the context of future quantum technologies, such as quantum repeaters. Single spins in optically active semiconductor host materials have emerged as leading candidates for quantum information processing (QIP). The quantum nature of the spin allows for encoding of stationary, memory quantum bits (qubits), and the relatively weak interaction with the host material preserves the spin coherence. On the other hand, optically active host materials permit direct interfacing with light, which can be used for all-optical qubit manipulation, and for efficiently mapping matter qubits into photonic qubits that are suited for long-distance quantum communication.
Book Synopsis Two-Dimensional Transition-Metal Dichalcogenides by : Alexander V. Kolobov
Download or read book Two-Dimensional Transition-Metal Dichalcogenides written by Alexander V. Kolobov and published by Springer. This book was released on 2016-07-26 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the current status of theoretical and experimental progress in 2 dimensional graphene-like monolayers and few-layers of transition metal dichalcogenides (TMDCs). Semiconducting monolayer TMDCs, due to the presence of a direct gap, significantly extend the potential of low-dimensional nanomaterials for applications in nanoelectronics and nano-optoelectronics as well as flexible nano-electronics with unprecedented possibilities to control the gap by external stimuli. Strong quantum confinement results in extremely high exciton binding energies which forms an interesting platform for both fundamental studies and device applications. Breaking of spatial inversion symmetry in monolayers results in strong spin-valley coupling potentially leading to their use in valleytronics. Starting with the basic chemistry of transition metals, the reader is introduced to the rich field of transition metal dichalcogenides. After a chapter on three dimensional crystals and a description of top-down and bottom-up fabrication methods of few-layer and single layer structures, the fascinating world of two-dimensional TMDCs structures is presented with their unique atomic, electronic, and magnetic properties. The book covers in detail particular features associated with decreased dimensionality such as stability and phase-transitions in monolayers, the appearance of a direct gap, large binding energy of 2D excitons and trions and their dynamics, Raman scattering associated with decreased dimensionality, extraordinarily strong light-matter interaction, layer-dependent photoluminescence properties, new physics associated with the destruction of the spatial inversion symmetry of the bulk phase, spin-orbit and spin-valley couplings. The book concludes with chapters on engineered heterostructures and device applications such as a monolayer MoS2 transistor. Considering the explosive interest in physics and applications of two-dimensional materials, this book is a valuable source of information for material scientists and engineers working in the field as well as for the graduate students majoring in materials science.
Book Synopsis Cavity Polaritons by : Alexey Kavokin
Download or read book Cavity Polaritons written by Alexey Kavokin and published by Elsevier. This book was released on 2003-11-26 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 32 of the series addresses one of the most rapidly developing research fields in physics: microcavities. Microcavities form a base for fabrication of opto-electronic devices of XXI century, in particular polariton lasers based on a new physical principle with respect to conventional lasers proposed by Einstein in 1917. This book overviews a theory of all major phenomena linked microcavities and exciton-polaritons and is oriented to the reader having no background in solid state theory as well as to the advanced readers interested in theory of exciton-polaritons in microcavities. All major experimental discoveries in the field are addressed as well. · The book is oriented to a general reader and is easy to read for a non-specialist.· Contains an overview of the most essential effects in physics of microcavities experimentally observed and theoretically predicted during the recent decade such as:. · Bose-Einstein condensation at room temperature.· Lasers without inversion of population.· Microcavity boom: optics of the XXI century!· Frequently asked questions on microcavities and responses without formulas. · Half-light-half-matter quasi-particles: base for the future optoelectronic devices
Book Synopsis Defects in Two-Dimensional Materials by : Rafik Addou
Download or read book Defects in Two-Dimensional Materials written by Rafik Addou and published by Elsevier. This book was released on 2022-02-14 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Defects in Two-Dimensional Materials addresses the fundamental physics and chemistry of defects in 2D materials and their effects on physical, electrical and optical properties. The book explores 2D materials such as graphene, hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMD). This knowledge will enable scientists and engineers to tune 2D materials properties to meet specific application requirements. The book reviews the techniques to characterize 2D material defects and compares the defects present in the various 2D materials (e.g. graphene, h-BN, TMDs, phosphorene, silicene, etc.). As two-dimensional materials research and development is a fast-growing field that could lead to many industrial applications, the primary objective of this book is to review, discuss and present opportunities in controlling defects in these materials to improve device performance in general or use the defects in a controlled way for novel applications. Presents the theory, physics and chemistry of 2D materials Catalogues defects of 2D materials and their impacts on materials properties and performance Reviews methods to characterize, control and engineer defects in 2D materials
