Nanowire Quantum Dots As Sources Of Single And Entangled Photons
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Nanowire Quantum Dots As Sources Of Single And Entangled Photons
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Author : Milad Khoshnegar Shahrestani
language : en
Publisher:
Release Date : 2014
Nanowire Quantum Dots As Sources Of Single And Entangled Photons written by Milad Khoshnegar Shahrestani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Realization of linear quantum computation and establishing secure quantum communication among interacting parties demand for triggered quantum sources delivering genuine single and entangled photons. However, the intrinsic energy level spectrum of nanostructures made by the nature or developed under a random growth process energetically lacks the expected figures of merit to produce such quantized states of photons. Here, I present the semi-empirical modeling and experimental investigation on the spin fine structure of strongly confining quantum dots embedded in III-V nanowires. To this end, the quantum dot is numerically modeled via the Configuration Interaction method at two different levels: 1) single-particle level, where its pure energy level structure is resolved in the presence of strain and spin-orbit interaction. 2) Few-particle level, at which the few-body interactions appear as perturbative energy corrections and orbital correlations. I demonstrate the influence of quantum confinement on the binding energies and spin fine structure of excitons in the absence of hyperfine interaction. Importantly, the high-symmetry character of excitonic orbitals in nanowire quantum dots restore the degeneracy of optically-active ground-state excitons, offering an ideal spectrum for the entangled photon pair generation. To experimentally verify the idea, we design and fabricate defect-free nanowire quantum dots with ultra-clean excitonic spectrum, and construct the time correlation function of emitted photons through performing a series of low-temperature statistical quantum optics measurements. We observe a decent performance in terms of single photon generation under low excitation powers. Moreover, photon pairs emitted from the biexciton-exciton cascade of nanowire quantum dots exhibit color indistinguishability and polarization entanglement owing to the trivial fine structure splitting of the ground-state excitons. We further extend the idea by proposing the hybridized states of a nanowire-based quantum dot molecule as the potential source of higher-order entangled states. Tracing the field-dependent spectrum suggests the appearance of dominant features under the weak localization of electrons and coherent tunneling of holes. In addition to their Coulomb correlation, excitons also remain spatially correlated, opening new transition channels normally forbidden in the ground state of a single dot. The proposed structure can be exploited to create tripartite hybrid, GHZ and W-entangled states.
Characterizing Single Photon Emission From Quantum Dots In Nanowires
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Author : Morgan Mastrovich
language : en
Publisher:
Release Date : 2019
Characterizing Single Photon Emission From Quantum Dots In Nanowires written by Morgan Mastrovich and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Nanowires categories.
Bright sources of highly indistinguishable single photons are desirable for diverse applications in quantum technology, including quantum cryptographic protocols, information processing, and metrology. The most common single photon source for quantum optical experiments is currently spontaneous parametric downconversion (SPDC); quantum dot sources have the potential to greatly exceed the brightness of these current sources, without compromising the quality of the emitted photons. Embedding a quantum dot within a tapered nanowire waveguide greatly increases the photon extraction efficiency. Exciting a two-photon resonant transition decreases the emission time jitter, improving both the multi-photon suppression and indistinguishability. Before this work, these two techniques have not yet been implemented together. We implemented two-photon resonant excitation (TPRE) for the first time in nanowire-embedded quantum dots; we found that it significantly improved the multi-photon suppression. However, we were unable to measure the indistinguishability due to low counts and instabilities in the experimental apparatus. Nevertheless, we have identified the significant improvements that are still required in order to successfully measure the indistinguishability under TPRE; with these improvements, the measurement should be possible for future group members. We successfully measured the indistinguishability under a quasi-resonant excitation, but did not find a significant difference when comparing to the measurement made on a similar quantum dot under above-bandgap excitation. We must also substantially improve the single photon count rate in order to approach the polarization entanglement rates of SPDC sources. Despite these challenges, nanowire-embedded quantum dots remain a promising source of both single and entangled pairs of photons.
Quantum Nano Photonics
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Author : Baldassare Di Bartolo
language : en
Publisher: Springer
Release Date : 2018-09-19
Quantum Nano Photonics written by Baldassare Di Bartolo and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-09-19 with Science categories.
This book brings together more closely researchers working in the two fields of quantum optics and nano-optics and provides a general overview of the main topics of interest in applied and fundamental research. The contributions cover, for example, single-photon emitters and emitters of entangled photon pairs based on epitaxially grown semiconductor quantum dots, nitrogen vacancy centers in diamond as single-photon emitters, coupled quantum bits based on trapped ions, integrated waveguide superconducting nanowire single-photon detectors, quantum nano-plasmonics, nanosensing, quantum aspects of biophotonics and quantum metamaterials. The articles span the bridge from pedagogical introductions on the fundamental principles to the current state-of-the-art, and are authored by pioneers and leaders in the field. Numerical simulations are presented as a powerful tool to gain insight into the physical behavior of nanophotonic systems and provide a critical complement to experimental investigations and design of devices.
Towards On Demand Generation Of Entangled Photons With Quantum Dots
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Author : Arash Ahmadi
language : en
Publisher:
Release Date : 2020
Towards On Demand Generation Of Entangled Photons With Quantum Dots written by Arash Ahmadi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The biexciton-exciton cascade in quantum dots (QDs) yields entangled photon pairs, and recent developments in engineering photonic structures around the dot for efficient light extraction and proper control of the fine-structure splitting, has led to significant breakthroughs in achieving an ideal entangled photon source -- exhibiting properties such as high extraction efficiency, low multi-photon emission and high entanglement fidelity. This thesis presents our development in enhancing the performance of entangled photon generation of QDs towards near-unity efficiency and fidelity. We study InAsP quantum dots in photonic nanowires for efficient light extraction and to reveal the effect of a quantum dot with high nuclear spin on the entanglement fidelity. Revealing the ultimate limit of entanglement in QDs is still a challenge, and it is generally believed that a sample made of atoms possessing high nuclear spins exhibits limited entanglement due to the dephasing caused by spin-spin interactions. Moreover, it is assumed that the fine-structure splitting of QDs degrades the entanglement fidelity, as it introduces a which-path information in the biexciton-exciton cascade. We have performed two-photon state tomography on InAsP QDs in InP nanowires, comprising of nuclear spin 9/2, and have realized that such a source is capable of generating entangled photon pairs with negligible dephasing during the emission lifetime, with a peak concurrence C = 77% and a count-weighted average concurrence 62%. This result was obtained by comparing the outcome of our measurements with a theoretical model that assumes no dephasing, however, takes into account the details of the detection system, i.e., dark-count rates and timing resolution, as well as, specific features of the QD, e.g., emission lifetime, fine-structure splitting, multi-photon emission probability, etc. Proper engineering of tapered nanowires allows for extraction of the emitted photons with high efficiency, which makes it possible to perform a complete two-photon state tomography and monitoring the evolution of the exciton state, as well as, the entanglement fidelity of the photon-pair, during the emission lifetime. This enabled us to reveal the effect of an imperfect detection system, as well as, multi-photon emission in recording low values for entanglement fidelity. Moreover, our calculations show that proper analysis of the time-energy uncertainty relation provides the necessary means to measure a high entanglement fidelity even in the presence of fine-structure splitting; since, a detection system with high timing resolution can overlook the which-path information, as the uncertainty in measuring the energy of the photons will be larger than the fine-structure splitting. Therefore, realizing near-unity entanglement fidelity using QDs is merely a technical challenge, i.e., resonant excitation of the QD, in order to suppress multi-photon emission, and use of a detection system with low timing jitter and dark-count rates. As a next step to achieve this goal, we have performed the resonant two-photon excitation scheme for the first time on a QD in a photonic nanowire, which resulted in an enhancement of the performance of our source. We managed to improve the single-photon purity of the source, g^(2)(0), by two orders of magnitude; moreover, analysis of the emission spectrum reveals that this scheme increases the pair-production efficiency to values above 93% for the biexciton-exciton cascade. Taking the efficiency of our experimental setup into consideration, the results indicate an approximately eight-fold enhancement of the pair-extraction efficiency as compared to the quasi-resonant excitation scheme (12.55% vs. 1.6%). Based on these results, two-photon state tomography on our source, under resonant two-photon excitation and performed by a detection system with high timing resolution and low dark-count rates, yields near-unity entanglement fidelity. By considering the enhancement in pair-extraction efficiency that we obtained, QDs in photonic nanowires can surpass the performance of spontaneous parametric down conversion sources in terms of entanglement fidelity and pair-extraction efficiency. Even though we have shown a finite fine-structure splitting does not degrade the entanglement fidelity in QDs, for various application in quantum information removing the fine-structure splitting is beneficial. Therefore, we have proposed a universal all-optical approach for removing the fine-structure splitting. In this scheme, the energy of the photons are shifted by using a pair of quarter-wave plates and fast-rotating half-wave plates after they have been emitted; and as a result, the energy difference between the two decay paths in the biexciton-exciton cascade is erased. This method is applicable to any QD source and can be easily implemented using the currently available technology; moreover, no further sample processing will be required in order to achieve zero fine-structure splitting.
Self Assembled Quantum Dots
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Author : Zhiming M Wang
language : en
Publisher: Springer Science & Business Media
Release Date : 2007-11-29
Self Assembled Quantum Dots written by Zhiming M Wang and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-11-29 with Technology & Engineering categories.
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.
Single Photon Manipulation
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Author : Keyu Xia
language : en
Publisher: BoD – Books on Demand
Release Date : 2020-11-11
Single Photon Manipulation written by Keyu Xia and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-11-11 with Technology & Engineering categories.
This short book aims to present basic information about single photons in a quick read but with not many details. For this purpose, it only introduces the basic concept of single photons, the most important method of generating single photons in experiments, and a specific emerging field.
Toward On Demand Generation Of Entangled Photon Pairs With A Quantum Dot
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Author : Arash Ahmadi
language : en
Publisher:
Release Date : 2020
Toward On Demand Generation Of Entangled Photon Pairs With A Quantum Dot written by Arash Ahmadi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Technology & Engineering categories.
The generation of on-demand, optimally entangled photon pairs remains one of the most formidable challenges in the quantum optics and quantum information community. Despite the fact that recent developments in this area have opened new doors leading toward the realization of sources exhibiting either high brightness or near-unity entanglement fidelity, the challenges to achieve both together persist. Here, we will provide a historical review on the development of quantum dots (QDs) for entangled photon generation, with a focus on nanowire QDs, and address the latest research performed on nanowire QDs, including measuring entanglement fidelity, light-extraction efficiency, dephasing mechanisms, and the detrimental effects of detection systems on the measured values of entanglement fidelity. Additionally, we will discuss results recently observed pertaining to resonant excitation of a nanowire QD, revealing the potential of such sources to outperform spontaneous parametric down-conversion (SPDC) sources, providing a viable solution to the current challenges in quantum optics and quantum information.
Single Photon Generation And Detection
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Author :
language : en
Publisher: Academic Press
Release Date : 2013-11-29
Single Photon Generation And Detection written by and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-29 with Science categories.
Single-photon generation and detection is at the forefront of modern optical physics research. This book is intended to provide a comprehensive overview of the current status of single-photon techniques and research methods in the spectral region from the visible to the infrared. The use of single photons, produced on demand with well-defined quantum properties, offers an unprecedented set of capabilities that are central to the new area of quantum information and are of revolutionary importance in areas that range from the traditional, such as high sensitivity detection for astronomy, remote sensing, and medical diagnostics, to the exotic, such as secretive surveillance and very long communication links for data transmission on interplanetary missions. The goal of this volume is to provide researchers with a comprehensive overview of the technology and techniques that are available to enable them to better design an experimental plan for its intended purpose. The book will be broken into chapters focused specifically on the development and capabilities of the available detectors and sources to allow a comparative understanding to be developed by the reader along with and idea of how the field is progressing and what can be expected in the near future. Along with this technology, we will include chapters devoted to the applications of this technology, which is in fact much of the driver for its development. This is set to become the go-to reference for this field. Covers all the basic aspects needed to perform single-photon experiments and serves as the first reference to any newcomer who would like to produce an experimental design that incorporates the latest techniques Provides a comprehensive overview of the current status of single-photon techniques and research methods in the spectral region from the visible to the infrared, thus giving broad background that should enable newcomers to the field to make rapid progress in gaining proficiency Written by leading experts in the field, among which, the leading Editor is recognized as having laid down the roadmap, thus providing the reader with an authenticated and reliable source
Engineering The Atom Photon Interaction
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Author : Ana Predojević
language : en
Publisher: Springer
Release Date : 2015-07-16
Engineering The Atom Photon Interaction written by Ana Predojević and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-07-16 with Science categories.
This book provides a comprehensive view of the contemporary methods for quantum-light engineering. In particular, it addresses different technological branches and therefore allows the reader to quickly identify the best technology - application match. Non-classical light is a versatile tool, proven to be an intrinsic part of various quantum technologies. Its historical significance has made it the subject of many text books written both from theoretical and experimental point of view. This book takes another perspective by giving an insight to modern technologies used to generate and manipulate quantum light.
Quantum Dots For Quantum Information Technologies
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Author : Peter Michler
language : en
Publisher: Springer
Release Date : 2017-06-01
Quantum Dots For Quantum Information Technologies written by Peter Michler and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-06-01 with Science categories.
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.