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A quantum access network

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https://www.readbyqxmd.com/read/27404561/experimental-realization-of-an-entanglement-access-network-and-secure-multi-party-computation
#1
X-Y Chang, D-L Deng, X-X Yuan, P-Y Hou, Y-Y Huang, L-M Duan
To construct a quantum network with many end users, it is critical to have a cost-efficient way to distribute entanglement over different network ends. We demonstrate an entanglement access network, where the expensive resource, the entangled photon source at the telecom wavelength and the core communication channel, is shared by many end users. Using this cost-efficient entanglement access network, we report experimental demonstration of a secure multiparty computation protocol, the privacy-preserving secure sum problem, based on the network quantum cryptography...
2016: Scientific Reports
https://www.readbyqxmd.com/read/26931131/interface-induced-growth-and-transformation-of-polymer-conjugated-proto-crystalline-phases-in-aluminosilicate-hybrids-a-multiple-quantum-23-na-23-na-mas-nmr-correlation-spectroscopy-study
#2
Jiri Brus, Libor Kobera, Martina Urbanova, Barbora Doušová, Miloslav Lhotka, David Koloušek, Jiří Kotek, Pavel Čuba, Jiri Czernek, Jiří Dědeček
Nanostructured materials typically offer enhanced physicochemical properties because of their large interfacial area. In this contribution, we present a comprehensive structural characterization of aluminosilicate hybrids with polymer-conjugated nanosized zeolites specifically grown at the organic-inorganic interface. The inorganic amorphous Al-O-Si framework is formed by alkali-activated low-temperature transformation of metakaoline, whereas simultaneous copolymerization of organic comonomers creates a secondary epoxide network covalently bound to the aluminosilicate matrix...
March 22, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/26656307/quantum-secured-gigabit-optical-access-networks
#3
Bernd Fröhlich, James F Dynes, Marco Lucamarini, Andrew W Sharpe, Simon W-B Tam, Zhiliang Yuan, Andrew J Shields
Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely...
2015: Scientific Reports
https://www.readbyqxmd.com/read/25914316/high-pressure-synthesis-of-cd-nh%C3%A2-%C3%A2-b%C3%A2-o%C3%A2-nh%C3%A2-%C3%A2-pioneering-the-way-to-the-substance-class-of-ammine-borates
#4
Gerhard Sohr, Nina Ciaghi, Michael Schauperl, Klaus Wurst, Klaus R Liedl, Hubert Huppertz
To date, the access to the substance class of borates containing nitrogen, for example, nitridoborates, oxonitridoborates, or amine borates, was an extreme effort owing to the difficult starting materials and reaction conditions. Although a number of compounds containing boron and nitrogen are known, no adduct of ammonia to an inorganic borate has been observed so far. A new synthetic approach starting from the simple educts CdO, B2O3, and aqueous ammonia under conditions of 4.7 GPa and 800 °C led to the synthesis of Cd(NH3)2[B3O5(NH3)]2 as the first ammine borate...
May 18, 2015: Angewandte Chemie
https://www.readbyqxmd.com/read/25860179/challenges-in-the-interpretation-of-protein-h-d-exchange-data-a-molecular-dynamics-simulation-perspective
#5
Robert G McAllister, Lars Konermann
Many protein structural investigations involve the use of H/D exchange (HDX) techniques. It is commonly thought that amide backbone protection arises from intramolecular H-bonding and/or burial of NH sites. Recently, fundamental HDX-related tenets have been called into question. The current work focuses on ubiquitin for exploring the defining features that distinguish amides in "open" (exchange-competent) and "closed" (exchange-incompetent) environments. Instead of relying on static X-ray structures, we employ all-atom molecular dynamics (MD) simulations for obtaining a dynamic view of the protein ground state and its surrounding solvent...
April 28, 2015: Biochemistry
https://www.readbyqxmd.com/read/25413490/experimental-demonstration-of-graph-state-quantum-secret-sharing
#6
B A Bell, D Markham, D A Herrera-Martí, A Marin, W J Wadsworth, J G Rarity, M S Tame
Quantum communication and computing offer many new opportunities for information processing in a connected world. Networks using quantum resources with tailor-made entanglement structures have been proposed for a variety of tasks, including distributing, sharing and processing information. Recently, a class of states known as graph states has emerged, providing versatile quantum resources for such networking tasks. Here we report an experimental demonstration of graph state-based quantum secret sharing--an important primitive for a quantum network with applications ranging from secure money transfer to multiparty quantum computation...
2014: Nature Communications
https://www.readbyqxmd.com/read/25034014/constrained-geometric-dynamics-of-the-fenna-matthews-olson-complex-the-role-of-correlated-motion-in-reducing-uncertainty-in-excitation-energy-transfer
#7
Alexander S Fokas, Daniel J Cole, Alex W Chin
The trimeric Fenna-Mathews-Olson (FMO) complex of green sulphur bacteria is a well-studied example of a photosynthetic pigment-protein complex, in which the electronic properties of the pigments are modified by the protein environment to promote efficient excitonic energy transfer from antenna complexes to the reaction centres. By a range of simulation methods, many of the electronic properties of the FMO complex can be extracted from knowledge of the static crystal structure. However, the recent observation and analysis of long-lasting quantum dynamics in the FMO complex point to protein dynamics as a key factor in protecting and generating quantum coherence under laboratory conditions...
December 2014: Photosynthesis Research
https://www.readbyqxmd.com/read/25012712/genomic-instantiation-of-consciousness-in-neurons-through-a-biophoton-field-theory
#8
Lleuvelyn A Cacha, Roman R Poznanski
A theoretical framework is developed based on the premise that brains evolved into sufficiently complex adaptive systems capable of instantiating genomic consciousness through self-awareness and complex interactions that recognize qualitatively the controlling factors of biological processes. Furthermore, our hypothesis assumes that the collective interactions in neurons yield macroergic effects, which can produce sufficiently strong electric energy fields for electronic excitations to take place on the surface of endogenous structures via alpha-helical integral proteins as electro-solitons...
June 2014: Journal of Integrative Neuroscience
https://www.readbyqxmd.com/read/24994063/an-opto-magneto-mechanical-quantum-interface-between-distant-superconducting-qubits
#9
Keyu Xia, Michael R Vanner, Jason Twamley
A quantum internet, where widely separated quantum devices are coherently connected, is a fundamental vision for local and global quantum information networks and processing. Superconducting quantum devices can now perform sophisticated quantum engineering locally on chip and a detailed method to achieve coherent optical quantum interconnection between distant superconducting devices is a vital, but highly challenging, goal. We describe a concrete opto-magneto-mechanical system that can interconvert microwave-to-optical quantum information with high fidelity...
2014: Scientific Reports
https://www.readbyqxmd.com/read/24722221/simple-molecules-as-complex-systems
#10
Tibor Furtenbacher, Péter Arendás, Georg Mellau, Attila G Császár
For individual molecules quantum mechanics (QM) offers a simple, natural and elegant way to build large-scale complex networks: quantized energy levels are the nodes, allowed transitions among the levels are the links, and transition intensities supply the weights. QM networks are intrinsic properties of molecules and they are characterized experimentally via spectroscopy; thus, realizations of QM networks are called spectroscopic networks (SN). As demonstrated for the rovibrational states of H2(16)O, the molecule governing the greenhouse effect on earth through hundreds of millions of its spectroscopic transitions (links), both the measured and first-principles computed one-photon absorption SNs containing experimentally accessible transitions appear to have heavy-tailed degree distributions...
2014: Scientific Reports
https://www.readbyqxmd.com/read/24611606/multicolor-tuning-of-lanthanide-doped-nanoparticles-by-single-wavelength-excitation
#11
Feng Wang, Xiaogang Liu
Lanthanide-doped nanoparticles exhibit unique luminescent properties, including large Stokes shift, sharp emission bandwidth, high resistance to optical blinking, and photobleaching, as well as the unique ability to convert long-wavelength stimulation into short-wavelength emission. These attributes are particularly needed for developing luminescent labels as alternatives to organic fluorophores and quantum dots. In recent years, the well-recognized advantages of upconversion nanocrystals as biomarkers have been manifested in many important applications, such as highly sensitive molecular detection and autofluorescence-free cell imaging...
April 15, 2014: Accounts of Chemical Research
https://www.readbyqxmd.com/read/24346339/two-dimensional-carbon-topological-insulators-superior-to-graphene
#12
Mingwen Zhao, Wenzheng Dong, Aizhu Wang
Graphene was the first material predicted to realize a topological insulator (TI), but unfortunately the gap is unobservably small due to carbon's weak spin-orbital coupling (SOC). Based on first-principles calculations, we propose a stable sp-sp(2) hybrid carbon network as a graphene analog whose electronic band structures in proximity of the Fermi level are characterized by Dirac cones. We demonstrate that this unique carbon framework has topologically nontrivial electronic structures with the Z2 topological invariant of v = 1 which is quite promising for hosting the quantum spin Hall effect (QSHE) in an experimentally accessible low temperature regime (<7 K)...
2013: Scientific Reports
https://www.readbyqxmd.com/read/24240277/an-exactly-solvable-model-for-quantum-communications
#13
Graeme Smith, John A Smolin
Information theory establishes the ultimate limits on performance for noisy communication systems. Accurate models of physical communication devices must include quantum effects, but these typically make the theory intractable. As a result, communication capacities-the maximum possible rates of data transmission-are not known, even for transmission between two users connected by an electromagnetic waveguide with Gaussian noise. Here we present an exactly solvable model of communication with a fully quantum electromagnetic field...
November 17, 2013: Nature
https://www.readbyqxmd.com/read/24104677/low-polarization-sensitive-asymmetric-multi-quantum-well-semiconductor-amplifier-for-next-generation-optical-access-networks
#14
Julie E Nkanta, Ramón Maldonado-Basilio, Kaiser Khan, Abdessamad Benhsaien, Sawsan Abdul-Majid, Jessica Zhang, Trevor J Hall
A broadband and low-polarization-sensitive multi-quantum well semiconductor optical amplifier with an asymmetric structure is reported for operation in the E-band wavelength range. A gain peak of 20 dB for a bandwidth of more than 50 nm is measured for both TE and TM polarizations. A maximum polarization sensitivity of 3 dB is measured for a broad wavelength range from 1340 to 1440 nm.
August 15, 2013: Optics Letters
https://www.readbyqxmd.com/read/24005413/a-quantum-access-network
#15
Bernd Fröhlich, James F Dynes, Marco Lucamarini, Andrew W Sharpe, Zhiliang Yuan, Andrew J Shields
The theoretically proven security of quantum key distribution (QKD) could revolutionize the way in which information exchange is protected in the future. Several field tests of QKD have proven it to be a reliable technology for cryptographic key exchange and have demonstrated nodal networks of point-to-point links. However, until now no convincing answer has been given to the question of how to extend the scope of QKD beyond niche applications in dedicated high security networks. Here we introduce and experimentally demonstrate the concept of a 'quantum access network': based on simple and cost-effective telecommunication technologies, the scheme can greatly expand the number of users in quantum networks and therefore vastly broaden their appeal...
September 5, 2013: Nature
https://www.readbyqxmd.com/read/23860488/quantum-internet-using-code-division-multiple-access
#16
Jing Zhang, Yu-xi Liu, Sahin Kaya Ozdemir, Re-Bing Wu, Feifei Gao, Xiang-Bin Wang, Lan Yang, Franco Nori
A crucial open problem inS large-scale quantum networks is how to efficiently transmit quantum data among many pairs of users via a common data-transmission medium. We propose a solution by developing a quantum code division multiple access (q-CDMA) approach in which quantum information is chaotically encoded to spread its spectral content, and then decoded via chaos synchronization to separate different sender-receiver pairs. In comparison to other existing approaches, such as frequency division multiple access (FDMA), the proposed q-CDMA can greatly increase the information rates per channel used, especially for very noisy quantum channels...
2013: Scientific Reports
https://www.readbyqxmd.com/read/23386977/renormalization-and-small-world-model-of-fractal-quantum-repeater-networks
#17
Zong-Wen Wei, Bing-Hong Wang, Xiao-Pu Han
Quantum networks provide access to exchange of quantum information. The primary task of quantum networks is to distribute entanglement between remote nodes. Although quantum repeater protocol enables long distance entanglement distribution, it has been restricted to one-dimensional linear network. Here we develop a general framework that allows application of quantum repeater protocol to arbitrary quantum repeater networks with fractal structure. Entanglement distribution across such networks is mapped to renormalization...
2013: Scientific Reports
https://www.readbyqxmd.com/read/23115129/an-accurate-and-efficient-method-to-predict-the-electronic-excitation-energies-of-bodipy-fluorescent-dyes
#18
Jia-Nan Wang, Jun-Ling Jin, Yun Geng, Shi-Ling Sun, Hong-Liang Xu, Ying-Hua Lu, Zhong-Min Su
Recently, the extreme learning machine neural network (ELMNN) as a valid computing method has been proposed to predict the nonlinear optical property successfully (Wang et al., J. Comput. Chem. 2012, 33, 231). In this work, first, we follow this line of work to predict the electronic excitation energies using the ELMNN method. Significantly, the root mean square deviation of the predicted electronic excitation energies of 90 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives between the predicted and experimental values has been reduced to 0...
March 15, 2013: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/23006193/transconductance-fluctuations-as-a-probe-for-interaction-induced-quantum-hall-states-in-graphene
#19
Dong Su Lee, Viera Skákalová, R Thomas Weitz, Klaus von Klitzing, Jurgen H Smet
Transport measurements normally provide a macroscopic, averaged view of the sample so that disorder prevents the observation of fragile interaction-induced states. Here, we demonstrate that transconductance fluctuations in a graphene field effect transistor reflect charge localization phenomena on the nanometer scale due to the formation of a dot network which forms near incompressible quantum states. These fluctuations give access to fragile broken symmetry and fractional quantum Hall states even though these states remain hidden in conventional magnetotransport quantities...
August 3, 2012: Physical Review Letters
https://www.readbyqxmd.com/read/22522259/elucidation-of-the-timescales-and-origins-of-quantum-electronic-coherence-in-lhcii
#20
Gabriela S Schlau-Cohen, Akihito Ishizaki, Tessa R Calhoun, Naomi S Ginsberg, Matteo Ballottari, Roberto Bassi, Graham R Fleming
Photosynthetic organisms harvest sunlight with near unity quantum efficiency. The complexity of the electronic structure and energy transfer pathways within networks of photosynthetic pigment-protein complexes often obscures the mechanisms behind the efficient light-absorption-to-charge conversion process. Recent experiments, particularly using two-dimensional spectroscopy, have detected long-lived quantum coherence, which theory suggests may contribute to the effectiveness of photosynthetic energy transfer...
May 2012: Nature Chemistry
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