196 research outputs found
Deterministic generation of large-scale entangled photonic cluster state from interacting solid state emitters
The ability to create large highly entangled `cluster' states is crucial for
measurement-based quantum computing. We show that deterministic multi-photon
entanglement can be created from coupled solid state quantum emitters without
the need for any two-qubit gates and regardless of whether the emitters are
identical. In particular, we present a general method for controlled
entanglement creation by making direct use of the always-on exchange
interaction, in combination with single-qubit operations. This is used to
provide a recipe for the generation of two-dimensional, cluster-state entangled
photons that can be carried out with existing experimental capabilities in
quantum dots
Towards practical linear optical quantum computing
Quantum computing promises a new paradigm of computation where information is processed in a way that has no classical analogue. There are a number of physical platforms conducive to quantum computation, each with a number of advantages and challenges. Single photons, manipulated using integrated linear optics, constitute a promising platform for universal quantum computation. Their low decoherence rates make them particularly favourable, however the inability to perform deterministic two-qubit gates and the issue of photon loss are challenges that need to be overcome.
In this thesis we explore the construction of a linear optical quantum computer based on the cluster state model. We identify the different necessary stages: state preparation, cluster state construction and implementation of quantum error correcting codes, and address the challenges that arise in each of these stages. For the state preparation, we propose a series of linear optical circuits for the generation of small entangled states, assessing their performance under different scenarios. For the cluster state construction, we introduce a ballistic scheme which not only consumes an order of magnitude fewer resources than previously proposed schemes, but also benefits from a natural loss tolerance. Based on this scheme, we propose a full architectural blueprint with fixed physical depth. We make investigations into the resource efficiency of this architecture and propose a new multiplexing scheme which optimises the use of resources. Finally, we study the integration of quantum error-correcting codes in the linear optical scheme proposed and suggest three ways in which the linear optical scheme can be made fault-tolerant.Open Acces
Physical-depth architectural requirements for generating universal photonic cluster states
Most leading proposals for linear-optical quantum computing (LOQC) use
cluster states, which act as a universal resource for measurement-based
(one-way) quantum computation (MBQC). In ballistic approaches to LOQC, cluster
states are generated passively from small entangled resource states using
so-called fusion operations. Results from percolation theory have previously
been used to argue that universal cluster states can be generated in the
ballistic approach using schemes which exceed the critical threshold for
percolation, but these results consider cluster states with unbounded size.
Here we consider how successful percolation can be maintained using a physical
architecture with fixed physical depth, assuming that the cluster state is
continuously generated and measured, and therefore that only a finite portion
of it is visible at any one point in time. We show that universal LOQC can be
implemented using a constant-size device with modest physical depth, and that
percolation can be exploited using simple pathfinding strategies without the
need for high-complexity algorithms.Comment: 18 pages, 10 figure
Fault-tolerance thresholds for the surface code with fabrication errors
The construction of topological error correction codes requires the ability
to fabricate a lattice of physical qubits embedded on a manifold with a
non-trivial topology such that the quantum information is encoded in the global
degrees of freedom (i.e. the topology) of the manifold. However, the
manufacturing of large-scale topological devices will undoubtedly suffer from
fabrication errors---permanent faulty components such as missing physical
qubits or failed entangling gates---introducing permanent defects into the
topology of the lattice and hence significantly reducing the distance of the
code and the quality of the encoded logical qubits. In this work we investigate
how fabrication errors affect the performance of topological codes, using the
surface code as the testbed. A known approach to mitigate defective lattices
involves the use of primitive SWAP gates in a long sequence of syndrome
extraction circuits. Instead, we show that in the presence of fabrication
errors the syndrome can be determined using the supercheck operator approach
and the outcome of the defective gauge stabilizer generators without any
additional computational overhead or the use of SWAP gates. We report numerical
fault-tolerance thresholds in the presence of both qubit fabrication and gate
fabrication errors using a circuit-based noise model and the minimum-weight
perfect matching decoder. Our numerical analysis is most applicable to 2D
chip-based technologies, but the techniques presented here can be readily
extended to other topological architectures. We find that in the presence of 8%
qubit fabrication errors, the surface code can still tolerate a computational
error rate of up to 0.1%.Comment: 10 pages, 15 figure
From three-photon GHZ states to ballistic universal quantum computation
Single photons, manipulated using integrated linear optics, constitute a
promising platform for universal quantum computation. A series of increasingly
efficient proposals have shown linear-optical quantum computing to be formally
scalable. However, existing schemes typically require extensive adaptive
switching, which is experimentally challenging and noisy, thousands of photon
sources per renormalized qubit, and/or large quantum memories for
repeat-until-success strategies. Our work overcomes all these problems. We
present a scheme to construct a cluster state universal for quantum
computation, which uses no adaptive switching, no large memories, and which is
at least an order of magnitude more resource-efficient than previous passive
schemes. Unlike previous proposals, it is constructed entirely from
loss-detecting gates and offers a robustness to photon loss. Even without the
use of an active loss-tolerant encoding, our scheme naturally tolerates a total
loss rate of in the photons detected in the gates. This scheme
uses only 3-GHZ states as a resource, together with a passive linear-optical
network. We fully describe and model the iterative process of cluster
generation, including photon loss and gate failure. This demonstrates that
building a linear optical quantum computer need be less challenging than
previously thought.Comment: Minor changes to match published version. 10 pages and 14 figures
including the supplementary materia
Relative multiplexing for minimizing switching in linear-optical quantum computing
Many existing schemes for linear-optical quantum computing (LOQC) depend on
multiplexing (MUX), which uses dynamic routing to enable near-deterministic
gates and sources to be constructed using heralded, probabilistic primitives.
MUXing accounts for the overwhelming majority of active switching demands in
current LOQC architectures. In this manuscript, we introduce relative
multiplexing (RMUX), a general-purpose optimization which can dramatically
reduce the active switching requirements for MUX in LOQC, and thereby reduce
hardware complexity and energy consumption, as well as relaxing demands on
performance for various photonic components. We discuss the application of RMUX
to the generation of entangled states from probabilistic single-photon sources,
and argue that an order of magnitude improvement in the rate of generation of
Bell states can be achieved. In addition, we apply RMUX to the proposal for
percolation of a 3D cluster state in [PRL 115, 020502 (2015)], and we find that
RMUX allows a 2.4x increase in loss tolerance for this architecture.Comment: Published version, New Journal of Physics, Volume 19, June 201
The business digitalization process in SMEs from the implementation of e-commerce: An empirical analysis
©. This manuscript version is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by/4.0/
This document is the Published, version of a Published Work that appeared in final form in [Journal of Theoretical and Applied Electronic Commerce Research]. To access the final edited and published work see[https://doi.org/10.3390/jtaer18040086]The main objective of this research is to carry out a comprehensive analysis of how
e-commerce affects the performance of small and medium-sized enterprises (SMEs) in Mexico.
This study will pay special attention to the role of business digitalization and the optimization of
operational processes in this context. Our research involved creating a partial least squares structural
equation model (PLS-SEM) to examine our hypotheses. According to our research, incorporating
e-commerce, digitalizing business processes, and improving operational efficiency significantly
contribute to corporate performance. Our results show direct effects that, together with indirect
effects of business digitalization and operational efficiency, enhance the positive influence of online
commerce. This research fills a gap in the literature by investigating the relationship between ecommerce, business digitalization, operational efficiency, and business performance. It provides
essential insights into the direct impact of e-commerce on corporate performance and the indirect
impact through the mediation of business digitalization and operational efficiency. The results show
significant implications for business managers, as the findings can help them to invest in technologies
that foster e-commerce, which, by improving business digitalization and operational efficiency, will
result in better corporate performance and the ability to adapt to today’s turbulent environmen
Combination of Cefditoren and N-acetyl-l-Cysteine Shows a Synergistic Effect against Multidrug-Resistant Streptococcus pneumoniae Biofilms
Biofilm formation by Streptococcus pneumoniae is associated with colonization of the upper respiratory tract, including the carrier state, and with chronic respiratory infections in patients suffering from chronic obstructive pulmonary disease (COPD). The use of antibiotics alone to treat recalcitrant infections caused by biofilms is insufficient in many cases, requiring novel strategies based on a combination of antibiotics with other agents, including antibodies, enzybiotics, and antioxidants. In this work, we demonstrate that the third-generation oral cephalosporin cefditoren (CDN) and the antioxidant N-acetyl-l-cysteine (NAC) are synergistic against pneumococcal biofilms. Additionally, the combination of CDN and NAC resulted in the inhibition of bacterial growth (planktonic and biofilm cells) and destruction of the biofilm biomass. This marked antimicrobial effect was also observed in terms of viability in both inhibition (prevention) and disaggregation (treatment) assays. Moreover, the use of CDN and NAC reduced bacterial adhesion to human lung epithelial cells, confirming that this strategy of combining these two compounds is effective against resistant pneumococcal strains colonizing the lung epithelium. Finally, administration of CDN and NAC in mice suffering acute pneumococcal pneumonia caused by a multidrug-resistant strain was effective in clearing the bacteria from the respiratory tract in comparison to treatment with either compound alone. Overall, these results demonstrate that the combination of oral cephalosporins and antioxidants, such as CDN and NAC, respectively, is a promising strategy against respiratory biofilms caused by S. pneumoniae. IMPORTANCE Streptococcus pneumoniae is one of the deadliest bacterial pathogens, accounting for up to 2 million deaths annually prior to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Vaccines have decreased the burden of diseases produced by S. pneumoniae, but the rise of antibiotic-resistant strains and nonvaccine serotypes is worrisome. Pneumococcal biofilms are associated with chronic respiratory infections, and treatment is challenging, making the search for new antibiofilm therapies a priority as biofilms become resistant to traditional antibiotics. In this work, we used the combination of an antibiotic (CDN) and an antioxidant (NAC) to treat the pneumococcal biofilms of relevant clinical isolates. We demonstrated a synergy between CDN and NAC that inhibited and treated pneumococcal biofilms, impaired pneumococcal adherence to the lung epithelium, and treated pneumonia in a mouse pneumonia model. We propose the widely used cephalosporin CDN and the repurposed drug NAC as a new antibiofilm therapy against S. pneumoniae biofilms, including those formed by antibiotic-resistant clinical isolates.This work was supported by Ministerio de Ciencia e Innovación (MICINN) (grant PID2020-119298RB-I00) and by Meiji Pharma Spain (grant MVP 119/20). J.Y. has received grants from MSD-USA (MISP Call) and Pfizer that are not related to this work. J.Y. has participated in advisory boards organized by MSD and Pfizer. M.G. and P.C. are members of the Scientific Department of Meiji Pharma Spain. The other authors declare no competing interests.S
Desarrollo e implementación de un controlador multiplataforma para el Scorbot ER-4U.
El significado de la palabra ingeniería engloba todos aquellos conocimientos que puedan orientarse hacia la creación de nuevas herramientas.
Sin embargo, no solo se debe emplear la ingeniería en el desarrollo de nuevos utensilios, sino sobretodo en el desarrollo de métodos que permitan
dar un nuevo uso a tecnologías que hayan quedado obsoletas. Este proyecto defiende este ideal al implementar una primera versión de un programa
de control multiplataforma para un brazo robótico. Como punto de referencia, se ha elegido para el desarrollo de este trabajo un modelo de brazo
robótico cuyas restricciones de uso han hecho que se deje a un lado como
herramienta de trabajo, el Scorbot 4R-EU. El programa de control para este modelo de brazo robótico solo es ejecutable sobre sistemas operativos
Windows XP y su extensión de uso a otras plataformas puede dar gran versatilidad a este tipo de equipos, sobre todo en el ámbito educativo. A lo
largo de este proyecto se expondrá tanto el desarrollo de las funcionalidades como de la parte gráfica del programa.The meaning of the word engineering encompasses all those knowledge that can be oriented towards the creation of new tools. However, engineering should not only be used for the development of new utensils, it
should also be used to the development of methods that make it possible to
give new use to technologies that have become obsolete. This project defends this ideal by implementing a first version of a multi-platform control
program for a robotic arm. As a point of reference, it has been choosen for
the development of this work a robotic arm model in order of its restrictions of use which have led it to be set aside as a working tool, the Scorbot 4R-EU. The control program for this robotic arm is only executable on
Windows XP operating systems and its extension to other platforms can give great versatility to this type of equipment, especially in the educational
field. Throughout this project, both the development of the functionalities
and the graphic part of the program will be exposed
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