Spontaneous Parametric Down Conversion And Quantum Entanglement

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Spontaneous Parametric Down Conversion And Quantum Entanglement

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Author :
language : en
Publisher:
Release Date : 2014

Spontaneous Parametric Down Conversion And Quantum Entanglement written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Quantum entanglement categories.

Quantum entanglement has been a topic of much research in modern physics, and an application in quantum computing is envisioned. This thesis addresses the use of polarization entangled photon pairs produced by spontaneous parametric down-conversion (SPDC) in entanglement transfer process and quantum computing. The simplicity of SPDC entanglement relative to other quantum phenomena is first emphasized by developing a complete classical theory of the photon-crystal interactions characteristic of SPDC. The methods of achieving polarization superposition via the Type-I and Type-II SPDC are described. A combination of superposition and polarization correlation between down-converted photons is shown to violate Bell's inequality, thus revealing the entangled nature of the photon pairs. Finally, the possibility of controlling entangled photons through the manipulation of surface plasmons is highlighted as a way to transfer entanglement from photons to material particles.

Two Photon Quantum Entanglement From Type Ii Spontaneous Parametric Down Conversion

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Author : Todd B. Pittman
language : en
Publisher:
Release Date : 1996

Two Photon Quantum Entanglement From Type Ii Spontaneous Parametric Down Conversion written by Todd B. Pittman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Photons categories.

A Research On The Detection Of The Entangled Red Photons In The Spontaneous Parametric Down Conversion Experiment

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Author : Ting Gu
language : en
Publisher:
Release Date : 2016

A Research On The Detection Of The Entangled Red Photons In The Spontaneous Parametric Down Conversion Experiment written by Ting Gu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.

The spontaneous parametric down-conversion experiment is a quantum optics experiment which demonstrates the very phenomenon of quantum entanglement. The idea of this research project is to conduct this experiment on a self-designed optics system and record observed entangled photon pairs as well as red light cones produced by a non-linear BBO crystal. The BBO crystal is the key component of this experiment and a 405nm laser beam will shine through the crystal to produce down converted 810nm photon pairs. The measuring and data collection tools are a photon counting module and a optics camera. The ultimate goal of this project is to create an optics system and a guide for the spontaneous parametric down-conversion experiment, which will become one of the optics experiments performed in the senior optics lab course. The entire optics system was very successfully built, with the following components aligned in a line: a 405nm laser, a 100mm focus lens, a BBO crystal, a fixed aperture, a red light filter and a camera. The results from the experiment show some indication of the two red light cones produced by the crystal. Further experiments will be carried out to confirm the down-converted light cones and to test the coincidence rate of SPDC.

On Free Space Quantum Key Distribution And Its Implementation With A Polarization Entangled Parametric Down Conversion Source

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Author : Chris Erven
language : en
Publisher:
Release Date : 2007

On Free Space Quantum Key Distribution And Its Implementation With A Polarization Entangled Parametric Down Conversion Source written by Chris Erven and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.

Applied Research Of Quantum Information Based On Linear Optics

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Author : Xiaoye Xu
language : en
Publisher: Springer
Release Date : 2016-03-31

Applied Research Of Quantum Information Based On Linear Optics written by Xiaoye Xu and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-03-31 with Science categories.

This thesis reports on outstanding work in two main subfields of quantum information science: one involves the quantum measurement problem, and the other concerns quantum simulation. The thesis proposes using a polarization-based displaced Sagnac-type interferometer to achieve partial collapse measurement and its reversal, and presents the first experimental verification of the nonlocality of the partial collapse measurement and its reversal. All of the experiments are carried out in the linear optical system, one of the earliest experimental systems to employ quantum communication and quantum information processing. The thesis argues that quantum measurement can yield quantum entanglement recovery, which is demonstrated by using the frequency freedom to simulate the environment. Based on the weak measurement theory, the author proposes that white light can be used to precisely estimate phase, and effectively demonstrates that the imaginary part of the weak value can be introduced by means of weak measurement evolution. Lastly, a nine-order polarization-based displaced Sagnac-type interferometer employing bulk optics is constructed to perform quantum simulation of the Landau-Zener evolution, and by tuning the system Hamiltonian, the first experiment to research the Kibble-Zurek mechanism in non-equilibrium kinetics processes is carried out in the linear optical system.

Sources Of Photonic Entanglement For Applications In Space

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Author : Fabian Steinlechner
language : en
Publisher:
Release Date : 2016

Sources Of Photonic Entanglement For Applications In Space written by Fabian Steinlechner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.

The nonlocal correlations of entangled systems are a feature inherent to quantum theory that is fundamentally at odds with our common-sense notions of realism and locality. Additionally, entanglement is an essential resource for numerous quantum communication protocols such as quantum teleportation and quantum dense coding, quantum cryptography, as well as quantum-enhanced metrological schemes and quantum computation. These quantum schemes allow for significant gains in performance over their classical counterparts, and a commercial implementation of protocols utilizing entangled photons thus seems likely in the foreseeable future. A key challenge to be addressed, in order to achieve a global-scale implementation of quantum-enhanced protocols, is the distribution of entanglement over long distances. While photons are in many ways ideal carriers of quantum information, their distribution over long distances is significantly impeded by losses. At present, loss in optical fiber links or atmospheric attenuation and obstructions of the line of sight in terrestrial free-space links limit the distribution of photonic entanglement to several hundred kilometers. Installing sources of photons with quantum correlations on space platforms would allow such distance limitations to be overcome. This would not only lead to the first global-scale implementation of quantum communication protocols, but would also create the opportunity for a completely new class of quantum experiments in a general relativistic framework. State-of-the-art laboratory sources of entangled photons are generally ill-suited for applications in harsh environments such as space, either owing to the use of bulky lasers, the requirement for active interferometric stabilization, or insufficient photon-pair-generation efficiency. Thus, an integral milestone for the experimental implementation of quantum communication protocols over satellite links is the development of robust, space-proof sources of entangled photons with high brightness and entanglement visibility. This thesis is intended to bridge laboratory experiments and real-world applications of quantum entanglement in harsh operational conditions. To this end, the main results of this thesis are: Highly efficient sources of polarization-entangled photons for the distribution of entanglement via long-distance free-space links. The sources are very robust and compact, and incorporate only components which are compliant with the severe requirements of space flight and operation. Optimization of spectral properties and fiber-coupling efficiency of photon pairs generated via spontaneous parametric down-conversion in bulk periodically poled potassium titanyl phosphate. The results of these studies are of great practical relevance for the development of an ultra-stable and efficient entangled photon source. Engineering and characterization of field-deployable polarization-entangled photon sources with high visibility (>99%) and record pair-detection rates (>3 million detected pairs per mW of pump power). As a result of the performance demonstrated, the sources developed have been incorporated into ongoing experiments, for example in quantum nanophotonics and quantum communications, and will provide an enabling tool for future real-world applications.

Quantum Optics Entanglement And Bell S Theorem

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Author : Andrew D Poverman
language : en
Publisher:
Release Date : 2021

Quantum Optics Entanglement And Bell S Theorem written by Andrew D Poverman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Quantum optics categories.

The field of quantum optics provides a wonderful setting in which to study fundamental aspects of quantum mechanics such as entanglement, Bell's theorem, and non-locality. This thesis presents theoretical discussions of qubits, entanglement, and Bell's theorem in addition to experimental discussions on the nature of photons, creating entangled states using Spontaneous Parametric Down-Conversion (SPDC), and a Bell Test with polarization entangled photons. The experimental sections are written to be useful as instructions for one to conduct these experiments on their own. By doing these experiments, one will gain familiarity with quantum optics experiments as well as a firmer grasp on the intricate nature of measurements in quantum mechanics. On the topic of measurement, there is a brief discussion on the von Neumann model of measurement and the concept of decoherence.

Photonic Entanglement New Sources And New Applications

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Author : Jiŕí Svozilík
language : en
Publisher:
Release Date : 2014

Photonic Entanglement New Sources And New Applications written by Jiŕí Svozilík 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.

Non-classical correlations, usually referred as entanglement, are ones of the most studied and discussed features of Quantum Mechanics, since the initial introduction of the concept in the decade of 1930s. Even nowadays, a lot of efforts, both theoretical and experimental, are devoted in this topic, that covers many distinct areas of physics, such as a quantum computing, quantum measurement, quantum communications, solid state physics, chemistry and even biology. The fundamental tasks that one should consider related to the entanglement are: -How to create quantum entangled states. -How to maintain entanglement during propagation against sources of decoherence. -How to effectively detect it. -How to employ the benefits that entanglement offers. This thesis, divided into four chapters, concentrates on the first and last tasks considered above. In Chapter 1, a brief introduction and overview of what it is entanglement is given, starting with the famous paper of Einstein, Podolsky and Rosen, and continuing with John Bell's formulation of the so-called Bell's inequalities. We define here general concepts about entangled quantum states and introduce important entanglement measures, that are later used all over the thesis. In this chapter, sources of entangled particles (namely photons) are also mentioned. The importance is put on sources based on the nonlinear process of spontaneous parametric down-conversion. The last part of this chapter is then dedicated to a list of applications that benefit from the use of engangled states. Chapter 2 is devoted to the systematic study of the generation of entangled and non-entangled photon pairs in semiconductor Bragg reflection waveguides. Firstly, we present a source of photon pairs with a spectrally uncorrelated two-photon amplitude, achieved by a proper tailoring of the geometrical and material dispersions via structural design of waveguides. Secondly, Bragg reflection waveguides are designed in a scuh way, that results in the generation of spectrally broadband paired photons entangled in the polarization degree of freedom. Finally, we present experimental results of entangled photon pairs generation in this type of structures. In Chapter 3, we explore the feasibility of the generation of photon pairs entangled in the spatial degree of freedom, i.e. in the orbital angular momentum (OAM). Firstly, we examine how to create a highly multidimensional Hilbert space using OAM modes obtained in a chipred-poled nonlinear bulk crystals. Here, we show, how an increase of the chirp of the poling can effectively increase the Schmidt number by several orders of magnitude. Secondly, we investigate periodically poled silica glass fibres with a ring-shpaed core, that are capable to support the generation of simple OAM modes. The final Chapter 4 is dedicated to the Anderson localization and quantum random walks. At the beginning of this chapter, we present an experimental proposal for the realization of a discrete quantum random walks using the multi-path Mach-Zehnder interferometer with a spatial light modulator, that allows us to introduce different types of statistical or dynamical disorders. And secondly, we show how the transverse Anderson localization of partially coherent light, with a variable first-order degree of coherence, can be studied making use of entangled photon pairs.

Quantum Mechanics

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Author : Mark Beck
language : en
Publisher: Oxford University Press
Release Date : 2012-07-01

Quantum Mechanics written by Mark Beck and has been published by Oxford University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-07-01 with Science categories.

This textbook presents quantum mechanics at the junior/senior undergraduate level. It is unique in that it describes not only quantum theory, but also presents five laboratories that explore truly modern aspects of quantum mechanics. These laboratories include "proving" that light contains photons, single-photon interference, and tests of local realism. The text begins by presenting the classical theory of polarization, moving on to describe the quantum theory of polarization. Analogies between the two theories minimize conceptual difficulties that students typically have when first presented with quantum mechanics. Furthermore, because the laboratories involve studying photons, using photon polarization as a prototypical quantum system allows the laboratory work to be closely integrated with the coursework. Polarization represents a two-dimensional quantum system, so the introduction to quantum mechanics uses two-dimensional state vectors and operators. This allows students to become comfortable with the mathematics of a relatively simple system, before moving on to more complicated systems. After describing polarization, the text goes on to describe spin systems, time evolution, continuous variable systems (particle in a box, harmonic oscillator, hydrogen atom, etc.), and perturbation theory. The book also includes chapters which describe material that is frequently absent from undergraduate texts: quantum measurement, entanglement, quantum field theory and quantum information. This material is connected not only to the laboratories described in the text, but also to other recent experiments. Other subjects covered that do not often make their way into undergraduate texts are coherence, complementarity, mixed states, the density operator and coherent states. Supplementary material includes further details about implementing the laboratories, including parts lists and software for running the experiments. Computer simulations of some of the experiments are available as well. A solutions manual for end-of-chapter problems is available to instructors.

Realization Of Novel Entangled Photon Sources Using Periodically Poled Materials

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Author : Deny R. Hamel
language : en
Publisher:
Release Date : 2010

Realization Of Novel Entangled Photon Sources Using Periodically Poled Materials written by Deny R. Hamel and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.

This thesis deals with the production of entangled photons using spontaneous parametric down-conversion (SPDC). We start with a short overview of some important theoretical concepts. First we provide a brief reminder of the theory of entanglement. We then discuss how the state of quantum systems can be determined using quantum state tomography. We also explain SPDC, the physical process which we use to produce entangled photons. Finally, we give an overview of the methods which have been used to produce entangled photons in the past, both for two- and three-photon entanglement. The first experiment is the design of an efficient source of entangled photon pairs based on a polarizing Sagnac interferometer configuration. With this configuration, we can use quasi-phasematched materials which allow for higher efficiencies than standard bulk nonlinear materials. The source is pumped by a low-power continuous-wave laser diode, and produces degenerate photon pairs at 809nm. It has a spectral brightness of 87,500 pairs/(s mW nm), and the fidelity of the produced quantum states with a Bell state is 98.9%. The source is used for experiments in quantum key distribution, cluster state quantum computing, remote state preparation, state discrimination, and entanglement-enhanced classical communication. The second experiment discussed in this thesis is the generation of photon triplets using cascaded SPDC. In this experiment, a primary SPDC source is pumped with a low-power, continuous-wave laser diode, producing photon pairs. Single photons from these pairs serve as the pump for a second down-conversion, resulting in photon triplets. This is the first demonstration of the direct production of photon triplets, and the first observation of SPDC at the single photon level. This method could potentially be used to produce entangled photon triplets without post-selection, and as a source of triggered Bell pairs.