Download or read book Quantum memory with atomic ensembles of rubidium and single photons for long distance quantum communication written by Thorsten Strassel and published by . This book was released on 2008 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Broad Bandwidth and High Dimensional Quantum Memory Based on Atomic Ensembles written by Dong-Sheng Ding and published by Springer. This book was released on 2017-12-26 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an experimental study of quantum memory based on cold atomic ensembles and discusses photonic entanglement. It mainly focuses on experimental research on storing orbital angular momentum, and introduces readers to methods for storing a single photon carried by an image or an entanglement of spatial modes. The thesis also discusses the storage of photonic entanglement using the Raman scheme as a step toward implementing high-bandwidth quantum memory. The storage of photonic entanglement is central to achieving long-distance quantum communication based on quantum repeaters and scalable linear optical quantum computation. Addressing this key issue, the findings presented in the thesis are very promising with regard to future high-speed and high-capacity quantum communications.

Download or read book Quantum Network with Multiple Cold Atomic Ensembles written by Bo Jing and published by Springer Nature. This book was released on 2022-03-16 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the novel research in quantum memory networking, especially quantum memories based on cold atomic ensembles. After discussing the frontiers of quantum networking research and building a DLCZ-type quantum memory with cold atomic ensemble, the author develops the ring cavity enhanced quantum memory and demonstrates a filter-free quantum memory, which significantly improves the photon-atom entanglement. The author then realizes for the first time the GHZ-type entanglement of three separate quantum memories, a building block of 2D quantum repeaters and quantum networks. The author also combines quantum memories and time-resolved measurements, and reports the first multiple interference of three single photons with different colors. The book is of good reference value for graduate students, researchers, and technical personnel in quantum information sciences.

Download or read book Quantum Memory Protocols in Large Cold Atomic Ensembles written by Lucile Veissier and published by . This book was released on 2013 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum memories are an essential building block for quantum information science and in particular for the implementation of quantum communications across long distances. A quantum memory is defined as a system capable of storing and retrieving quantum states on-demand, such as quantum bits (qubits). Atomic ensembles are good candidates for this purpose because they enables strong light-matter coupling in case of a large number of atoms. Moreover, the collective effect, enhanced in the regime of large optical depth, can lead to storage efficiency close to unity. Thus, in this thesis, a large magneto-optical trap for cesium atoms is used as a atomic medium in order to implement a quantum memory protocol based on electromagnetically induced transparency (EIT). First, the EIT phenomenon is studied through a criterion for the discrimination between the EIT and the Autler-Townes splitting models. We then report on the implementation of an EIT-based memory for photonic qubits encoded in orbital angular momentum (OAM) of light. A reversible memory for Laguerre-Gaussian modes is implemented, and we demonstrate that the optical memory preserves the handedness of the helical structure at the single-photon level. Then, a full quantum state tomography of the retrieved OAM encoded qubits is performed, giving fidelities above the classical bound. This showed that our optical memory operates in the quantum regime. Finally, we present the implementation of the so-called DLCZ protocol in our ensemble of cold atoms, enabling the generation of heralded single photons. A homodyne detection setup allows us to realize the quantum tomography of the created photonic state.

Download or read book Quantum Frequency Conversion of Single Photons Emitted by Atomic Quantum Memories to Telecom Wavelengths written by Pau Farrera Soler and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In quantum repeater schemes for long distance quantum communication, quantum memories (QMs) play a vital role. For these applications, QMs need to be connected to the fiber optics network. However most QMs operate at wavelengths where the absorption in optical fibers is high. Therefore, their connection to a quantum frequency converter (QFC) to telecom wavelengths is required. In this work we convert an heralded single photon emitted by a rubidium atomic ensemble QM, using a QFC implemented with a non-linear waveguide. The main advantages of this converter setup are its compactness, relative simplicity and wavelength flexibility. We show that after this process the non-classical correlations between the heralding photons and converted heralded photons generated in the QM are preserved. This is the first time that frequency conversion of non-classical light emitted by an atomic QM is performed with a solid state device.

Download or read book Advanced Quantum Communications written by Sandor Imre and published by John Wiley & Sons. This book was released on 2012-11-27 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides an overview of the most advanced quantum informational geometric techniques, which can help quantum communication theorists analyze quantum channels, such as security or additivity properties. Each section addresses an area of major research of quantum information theory and quantum communication networks. The authors present the fundamental theoretical results of quantum information theory, while also presenting the details of advanced quantum ccommunication protocols with clear mathematical and information theoretical background. This book bridges the gap between quantum physics, quantum information theory, and practical engineering.

Download or read book A Fast and Robust Approach to Long Distance Quantum Communication With Atomic Ensembles written by and published by . This book was released on 2007 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum repeaters create long-distance entanglement between quantum systems while overcoming difficulties such as the attenuation of single photons in a fiber. Recently, an implementation of a repeater protocol based on single qubits in atomic ensembles and linear optics has been proposed [Duan et al., Nature (London) 414, 413 (2001)]. Motivated by rapid experimental progress towards implementing that protocol, here we develop a more efficient scheme compatible with active purification of arbitrary errors. Using similar resources as the earlier protocol, our approach intrinsically purifies leakage out of the logical subspace and all errors within the logical subspace, leading to greatly improved performance in the presence of experimental inefficiencies. Our analysis indicates that our scheme could generate approximately one pair per 3 min over 1280 km distance with fidelity (F> or = 78%) sufficient to violate Bell's inequality.

Download or read book Long Distance Entanglement Between Quantum Memories written by Yong Yu and published by Springer Nature. This book was released on 2023-01-01 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights novel research work done on cold atom-based quantum networks. Given that one of the main challenges in building the quantum network is the limited entanglement distribution distance, this book presents some state-of-the-art experiments in tackling this challenge and, for the first time, establishes entanglement between quantum memories via metropolitan-scale fiber transmission. This achievement is accomplished by cooperating high-efficiency cold quantum memories, low-loss quantum frequency conversion modules, and long-fiber phase-locking techniques. In the book, the scheme design, experimental setup, data analyses, and numerous technical details are given. Therefore, it suits a broad readership that includes all students, researchers, and technicians who work in quantum information sciences.

Download or read book Development of a Quantum Repeater for Long Distance Quantum Communication Using Photonic Information Storage written by and published by . This book was released on 2007 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this project, we have carried out the pioneering work for long-distance quantum communication using atomic ensembles for photon-state storage and for implementation of quantum repeaters. This work was followed by many groups and is now considered as one of the most promising approaches to overcoming photon losses in long-distance quantum communication. Specific highlights include theoretical proposals for quantum repeaters based on atomic ensembles (Nature, 414, 413, 2001), atom-atom correlations mediated by dark-state polaritons (Phys. Rev. Lett., 88, 243602, 2002), generation of stationary pulses of light (Phys. Rev. Lett, 89, 143602, 2002); experimental demonstrations of atomic memory for correlated photon states (Science, 301, 196, 2003), stationary pulses of light (Nature 426, 638, 2003), shaping quantum pulses via atomic memory (Phys. Rev. Lett. 93, 233602, 2004)), and finally realization of two-node quantum network involving generation and storage of single photon pulses in two remote ensembles (Nature, 438, 837, 2005). Finally, we proposed and analyzed a novel method that uses fixed, minimal physical resources to achieve generation and nested purification of quantum entanglement for quantum communication over arbitrarily long distances. In this method, solid-state single photon emitters with two internal degrees of freedom formed by an electron spin and a nuclear spin are used to build intermediate nodes in a quantum channel (Phys. Rev. Lett. 96,070504, 2006). Recently, we have experimentally demonstrated such a node using Nitrogen-Vacancy centers in room temperature diamond lattice (submitted to Science, 2007).

Download or read book Pushing The Frontiers Of Atomic Physics Proceedings Of The Xxi International Conference On Atomic Physics written by Winthrop W Smith and published by World Scientific. This book was released on 2009-03-12 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book highlights the state of the art of the booming field of atomic physics in the early 21st century. It contains the majority of the invited papers from an ongoing series of conferences, held every two years, devoted to forefront research and fundamental studies in basic atomic physics, broadly defined. This conference, held at the University of Connecticut in July 2008, is part of a series of conferences, which began in 1968 and had its historical origins in the molecular beam conferences of the I. I. Rabi group. It provides an archival and up-to-date summary of current research on atoms and simple molecules as well as their interactions with each other and with external fields, including degenerate Bose and Fermi quantum gases and interactions involving ultrafast lasers, strong field control of X-ray processes, and nanoscale and mesoscopic quantum systems. The work of three recent Nobel Laureates in atomic physics is included, beginning with a lecture by Eric Cornell on “When Is a Quantum Gas a Quantum Liquid?”. There are also papers by Laureates Steven Chu and Roy Glauber. The volume also contains the IUPAP Young Scientist Prize lecture by Cheng Chin on “Exploring Universality of Few-Body Physics Based on Ultracold Atoms Near Feshbach Resonances”.

Download or read book Long distance Quantum Communication with Neutral Atoms written by Mohsen Razavi and published by . This book was released on 2006 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) We propose a non-adiabatic mechanism for driving off-resonant Raman transitions that can be used in loading trapped-atom quantum memories. Our method is more flexible than its adiabatic counterpart in that it allows use of larger cavities and a larger class of driving sources. We also describe two proposed implementations for long-distance quantum communication-one that uses trapped atoms as quantum memories and another that employs atomic ensembles for quantum storage. We provide, for the first time, a detailed quantitative performance analysis of the latter system, which enables us to compare these two systems in terms of the fidelity and the throughput that they achieve for entanglement distribution, repeater operation, and quantum teleportation. Finally, we study quantum computing systems that use the cross-Kerr nonlinearity between single-photon qubits and a coherent mode of light. The coherent beam serves a mediating role in coupling two weak single-photon beams. We analytically study this structure using a continuous-time formalism for the cross-Kerr effect in optical fibers. Our results establish stringent conditions that must be fulfilled for the system's proper operation.

Download or read book Quantum Frecuency Conversion for Hybrid Quantum Networks written by Nicolas Maring and published by . This book was released on 2018 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to control the optical frequency of quantum state carriers (i.e. photons) is an important functionality for future quantum networks. It allows all matter quantum systems - nodes of the network - to be compatible with the telecommunication C-band, therefore enabling long distance fiber quantum communication between them. It also allows dissimilar nodes to be connected with each other, thus resulting in heterogeneous networks that can take advantage of the different capabilities offered by the diversity of its constituents. Quantum memories are one of the building blocks of a quantum network, enabling the storage of quantum states of light and the entanglement distribution over long distances. In our group, two different types of memories are investigated: a cold atomic ensemble and an ion-doped crystal. In this thesis I investigate the quantum frequency conversion of narrow-band photons, emitted or absorbed by optical quantum memories, with two different objectives: the first one is to connect quantum memories emitting or absorbing visible single photons with the telecommunication wavelengths, where fiber transmission loss is minimum. The second and main goal is to study the compatibility between disparate quantum nodes, emitting or absorbing photons at different wavelengths. More precisely the objective is to achieve a quantum connection between the two optical memories studied using quantum frequency conversion techniques. The main core of this work is the quantum frequency conversion interface that bridges the gap between the cold ensemble of Rubidium atoms, emitting photons at 780nm, and the Praseodymium ion doped crystal, absorbing photons at 606nm. This interface is composed of two different frequency conversion devices, where a cascaded conversions takes place: the first one converts 780nm photons to the telecommunication C-band, and the second one converts them back to visible, at 606nm. This comes with several challenges such as conversion efficiency, phase stability and parasitic noise reduction, which are important considerations to show the conservation of quantum behaviors through the conversion process. This work can be divided in three parts. In a first one, we built a quantum frequency conversion interface between 606nm and the C-band wavelength, capable of both up and down-conversion of single photon level light. We also characterized the noise processes involved in this specific conversion. In the down-conversion case we showed that memory compatible heralded single photons emitted from a photon pair source preserve their non-classical properties through the conversion process. In the up-conversion case, we showed the storage of converted telecom photons in the praseodymium doped crystal, and their retrieval with high signal to noise ratio. The second part of the work was devoted to the conversion of photons from an emissive Rubidium atomic quantum memory to the telecom C band. In this work we converted the heralding photons from the atomic ensemble and measured non-classical correlations between a stored excitation and a C-band photon, necessary for quantum repeater applications. In the last part of the thesis, we setup the full frequency conversion interface and showed that heralded photons emitted by the atomic ensemble are converted, stored in the solid state memory and retrieved with high signal to noise ratio. We demonstrated that a single collective excitation stored in the atomic ensemble is transfered to the crystal by mean of a single photon at telecom wavelength. We also showed time-bin qubit transfer between the two quantum memories. This work represents the first proof of principle of a photonic quantum connection between disparate quantum memory nodes. The results presented in this thesis pave the way towards the realization of modular and hybrid quantum networks.

Download or read book Narrowband Single Photons for Light Matter Interfaces written by Markus Rambach and published by Springer. This book was released on 2018-08-28 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a step-by-step guide on how to construct a narrowband single photon source for the integration with atom-based memory systems. It combines the necessary theoretical background with crucial experimental methods and characterisations to form a complete handbook for readers at all academic levels. The future implementation of large quantum networks will require the hybridisation of photonic qubits for communication with quantum memories in the context of information storage. Such an interface requires carefully tailored single photons to ensure compatibility with the chosen memory. The source itself is remarkable for a number of reasons, including being the spectrally narrowest and brightest source of its kind; in addition, it offers a novel technique for frequency stabilisation in an optical cavity, together with exceptional portability. Starting with a thorough analysis of the current literature, this book derives the essential parameters needed to design the source, describes its individual components in detail, and closes with the characterisation of a single photon source.

Download or read book Optical Quantum Memories with Cold Atomic Ensembles written by Adrien Nicolas and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present an experimental study of two optical quantum memory systems based on electromagnetically induced transparency (EIT) in cold cesium atoms.We explain the relevance of quantum memories for the development of large-scale quantum networks, we give a comprehensive theory of the EIT phenomenon and underline the role of relevant parameters regarding the implementation of quantum memories.The first system under study is prepared in a free-space magneto-optical trap. The main result of this thesis is the demonstration of the spatial multimode capability of this system at the quantum level. For this, we used Laguerre-Gaussian (LG) light beams, i.e. beams possessing a non-zero value of orbital angular momentum (OAM). In a first step, we showed that the orbital angular momentum of stored light pulses is preserved by the memory, deep in the single photon regime. In a second step, we encoded information in the orbital angular momentum state of a weak light pulse and defined a qubit using two LG beams of opposite helicities. We developed an original setup for the measurement of this OAM qubit and used it to characterize the action of the memory during the storage of such a light pulse. Our results show that the memory performs the quantum storage of such a qubit.The second system under study, also a cloud of cold atoms, has the specificity that the atoms are trapped optically in the vicinity of a nano-waveguide. This innovative design ensures a higher light-matter interaction and facilitates the interfacing of photons into and out of the memory. We describe the building of this setup and the first steps towards quantum memory implementations.

Download or read book Special Topics in Quantum Optics written by Weiping Zhang and published by Springer Nature. This book was released on with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantum Memory Protocols for Photonic Solid state Devices written by Kutlu Kutluer and published by . This book was released on 2018 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: A photonic quantum memory (QM) is a device that has the capability of storing a quantum state of light and retrieving back after a controlled time. It is an important element in quantum information science and is, among other applications, a crucial device for quantum repeater architectures which have been proposed to overcome the loss and the decoherence issues in long distance transmission of photons. Rare earth ion doped solid state systems are promising candidates for QMs which combine the advantages of solid state systems, such as scalability and reduced experimental complexity, with the long coherence time typically found in atomic systems. In this thesis, I investigated three different QM protocols in a Pr3+:Y2SiO5 crystal. The first part describes here the first demonstration of the spectral hole memory (SHoMe) protocol which was proposed theoretically in 2009. This protocol relies on slowing down the light in a long-lived spectral hole and transferring the excitations to the spin state. We first prepare a spectral hole, then send an input pulse whose bandwidth is comparable with the hole and stop the compressed light in the crystal by transferring the off-resonant coherence to the spin state with an optical p pulse. Later a second p pulse transfers the coherence back and leads to the emission of the stored light. We reached a storage and retrieval efficiency of around 40% in the classical regime, and of 31% in the single photon level, with a signal-to-noise ratio of 33 ± 4 for a mean input photon number of 1. These results demonstrate the most efficient and noiseless spin-wave solid-state optical memory at the single photon level to date. The second part of the thesis describes new experiments using the well-known atomic frequency comb (AFC) protocol. It is based on tailoring the inhomogeneously broadened absorption profile of the rare earth with periodic absorptive peaks, which induces the re-emission of the absorbed light field after a certain time determined by the separation between the peaks. In this chapter I describe several AFC experiments. First I present the storage of frequency converted telecom photons into our crystal where we obtained a total efficiency of 1.9 ± 0.2 % for a storage time of 1.6 μs storage time and signal-to-noise ratio of more than 200 for a mean input photon number of 1. Then I discuss the results of improved excited state storage efficiency values for long storage times where we achieved 30% at short storage times and up to 17% at 10 μs storage time. And finally I present a spin-wave AFC experiment where we obtained a signal-to-noise ratio value of 28 ± 8 for a mean input photon number of 1, the highest value achieved so far for this kind of experiment. Finally, in the last part, I describe the first demonstration of a solid-state photon pair source with embedded multimode quantum memory. The aim of the protocol is to combine a single photon source and a QM in one ensemble as in the well-known Duan-Lukin-Zoller-Cirac (DLCZ) scheme however this time not in a cold atomic ensemble but in a solid-state crystal. The protocol takes advantage of the AFC protocol for rephasing the ions and obtaining efficient read-out. The use of AFC also makes the protocol temporally multi-mode. In the experiment, after the AFC preparation we send an on-resonant write pulse and detect the decayed Stokes photons which herald single spin excitations. At a later time a read pulse transfers the spin excitation back to the excited state and we detect the anti-Stokes photons. We show strong non-classical second order cross-correlations between the Stokes and anti-Stokes photons and demonstrate storage of 11 temporal modes. The results presented in this thesis represent a significant contribution to the field of solid-state quantum memories and an important steps towards the realization of scalable quantum network architectures with solid state systems.

Download or read book Polarization Entanglement Storage in Ensemble based Atomic Memories written by Bhaskar Mookerji and published by . This book was released on 2011 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum networks enable the long-distance communication of quantum states through teleportation, but require, in advance, the robust distribution of entanglement between relevant parties. Engineering these networks requires quantum interconnects, which convert quantum states in one physical system to those of another reversibly, and with high fidelity. In this thesis, we describe implementations of long-distance quantum communication networks using polarization entanglement and atomic ensembles. We concisely describe the interactions of a quantum optical field with a heralding atomic ensemble, accounting for multiple-pair events at entanglement generation, as well as finite transmission and photodetection efficiencies under number-resolving and non-resolving photodetection schemes. Using these results, we perform a detailed quantitative performance analysis of quantum networks that distribute and swap entanglement.