Comment on "modified quantum-speed-limit bounds for open quantum dynamics in quantum channels"

In a recent paper [Phys. Rev. A 95, 052118 (2017)2469-992610.1103/PhysRevA.95.052118], the authors claim that our criticism, in Phys. Rev. A 94, 052125 (2016)2469-992610.1103/PhysRevA.94.052125, to some quantum speed limit bounds for open quantum dynamics that appeared recently in literature are invalid. According to the authors, the problem with our analysis would be generated by an artifact of the finite-precision numerical calculations. We analytically show here that it is not possible to have any inconsistency associated with the numerical precision of calculations. Therefore, our criticism of the quantum speed limit bounds continues to be valid.Fil: Mirkin, Nicolás. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Toscano, Fabricio. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Wisniacki, Diego Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin

Thermal equilibrium in Gaussian dynamical semigroups

We characterize all Gaussian dynamical semigroups in continuous variables quantum systems of n-bosonic modes which have a thermal Gibbs state as a stationary solution. This is performed through an explicit relation between the diffusion and dissipation matrices, which characterize the semigroup dynamic, and the covariance matrix of the thermal equilibrium state. We also show that Alicki's quantum detailed-balance condition, based on a Gelfand-Naimark-Segal inner product, allows the determination of the temperature dependence of the diffusion and dissipation matrices, and the identification of different Gaussian dynamical semigroups which shares the same thermal equilibrium state.Comment: 14 pages; submmited to Phys. Rev.

La sostenibilidad económica de la empresa pública Correos del Ecuador CDE E.P: incidencia de las condiciones técnico-operativas, gestión comercial y líneas de negocio

En el presente trabajo cuyo tema es investigar la sostenibilidad económica de la Empresa Pública Correos del Ecuador CDE E.P: incidencia de las condiciones técnico-operativas, gestión comercial y líneas de negocio, se realizó el adecuado diagnóstico investigando en función de conocer las condiciones Técnico-Operativas, entender la Gestión comercial, mostrar las líneas de negocio y su incidencia en la Sostenibilidad económica de CDE EP. Es muy importante destacar que después de describir los respectivos indicadores se realizó una adecuada propuesta, la misma que está en función del Cuadro de Mando Integral

Determinación de la prevalencia de toxoplasma gondii mediante test de microelisa en gatos domésticos, propietarios y personal de la Clínica Veterinaria Planeta Vida

This research aims to determine the prevalence of Toxoplasma gondii by microELISA test in domestic cats, owners and staff of Planeta Vida Veterinary Clinic for correlation of positive cases. Blood samples were collected by venipuncture, draw 2-3 cc, it is passed in vacutainer tubes steeping, we centrifuged for 10 minutes at 1500 rpm separating the cells from plasma or serum, then take 1-3 drops to put in the chamber of adding Test 1 drop of buffer and waited 5-10 minutes for reading. Getting in the investigation of all domestic cats (20 cats) was negative 75% and 25% presented a reaction to IgG; of all owners (20 owners), it was found that 80% were negative for IgG and 20% presented a chronic infection. Additionally the total staff (10 people) it was found that 30% tested positive for IgG and 70% were negative; in 100% three groups tested negative acute infection (IgM). Demostrating that there is no direct correlation between domestic cats and their owners, showing positive cats are not transmitted the disease to their owners.Esta investigación tuvo por objetivo determinar la prevalencia de Toxoplasma gondii mediante test de microElisa en gatos domésticos, propietarios y personal de la Clínica Veterinaria Planeta Vida para establecer una correlación de los casos positivos. Se recolectaron muestras sanguíneas por venopunción, extraemos 2-3 cc, pasamos en tubos vacutainer dejando reposar, centrifugamos durante 10 minutos a 1500 rpm separando las células del plasma o del suero, luego tomamos 1-3 gotas que colocamos en la cámara del Test añadiendo 1 gota de buffer y esperamos 5-10 minutos para realizar la lectura. Obteniendo en la investigación que del total de gatos domésticos (20 gatos) el 75 % dio negativo y el 25 % presento una reacción a IgG; del total de los propietarios (20 propietarios), se obtuvo que el 80 % fuera negativo a IgG y el 20 % presento una infección crónica. Adicionalmente del total del personal (10 personas) se obtuvo que el 30% dio positivo a IgG y el 70% restante fue negativo; en los tres grupos el 100% dio negativo a una infección aguda (IgM). Demostrando que no existe una correlación directa entre los gatos domésticos y sus propietarios, observándose los gatos positivos no trasmitieron la enfermedad a sus dueños

Husimi-Wigner representation of chaotic eigenstates

Just as a coherent state may be considered as a quantum point, its restriction to a factor space of the full Hilbert space can be interpreted as a quantum plane. The overlap of such a factor coherent state with a full pure state is akin to a quantum section. It defines a reduced pure state in the cofactor Hilbert space. The collection of all the Wigner functions corresponding to a full set of parallel quantum sections defines the Husimi-Wigner reresentation. It occupies an intermediate ground between drastic suppression of nonclassical features, characteristic of Husimi functions, and the daunting complexity of higher dimensional Wigner functions. After analysing these features for simpler states, we exploit this new representation as a probe of numerically computed eigenstates of chaotic Hamiltonians. The individual two-dimensional Wigner functions resemble those of semiclassically quantized states, but the regular ring pattern is broken by dislocations.Comment: 21 pages, 7 figures (6 color figures), submitted to Proc. R. Soc.

Uncertainty Relations for coarse-grained measurements: an overview

Uncertainty relations involving complementary observables are one of the cornerstones of quantum mechanics. Aside from their fundamental significance, they play an important role in practical applications, such as detection of quantum correlations and security requirements in quantum cryptography. In continuous variable systems, the spectra of the relevant observables form a continnuum and this necessitates the coarse graining of measurements. However, these coarse-grained observables do not necessarily obey the same uncertainty relations as the original ones, a fact that can lead to false results when considering applications. That is, one cannot naively replace the original observables in the uncertainty relation for the coarse-grained observables and expect consistent results. As such, a number of uncertainty relations that are specifically designed for coarse-grained observables have been developed. In recognition of the 90$^{th}$ anniversary of the seminal Heisenberg uncertainty relation, celebrated last year, and all the subsequent work since then, here we give a review of the state of the art of coarse-grained uncertainty relations in continuous variable quantum systems, as well as their applications to fundamental quantum physics and quantum information tasks. Our review is meant to be balanced in its content, since both theoretical considerations and experimental perspectives are put on an equal footing.Comment: Review article, 35 page

Quantum work for sudden quenches in Gaussian random Hamiltonians

In the context of nonequilibrium quantum thermodynamics, variables like work behave stochastically. A particular definition of the work probability density function (pdf) for coherent quantum processes allows the verification of the quantum version of the celebrated fluctuation theorems, due to Jarzynski and Crooks, that apply when the system is driven away from an initial equilibrium thermal state. Such a particular pdf depends basically on the details of the initial and final Hamiltonians, on the temperature of the initial thermal state, and on how some external parameter is changed during the coherent process. Using random matrix theory we derive a simple analytic expression that describes the general behavior of the work characteristic function G(u), associated with this particular work pdf for sudden quenches, valid for all the traditional Gaussian ensembles of Hamiltonians matrices. This formula well describes the general behavior of G(u) calculated from single draws of the initial and final Hamiltonians in all ranges of temperatures.Fil: Arrais, Eric G.. Universidade Federal do Rio de Janeiro; BrasilFil: Wisniacki, Diego Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Céleri, Lucas C.. Universidade Federal de Goiás; BrasilFil: De Almeida, Norton G.. Universidade Federal de Goiás; BrasilFil: Roncaglia, Augusto Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Toscano, Fabricio. Universidade Federal do Rio de Janeiro; Brasi

Optimal quantum teleportation protocols for fixed average fidelity

We demonstrate that among all quantum teleportation protocols giving rise to the same average fidelity, those with aligned Bloch vectors between input and output states exhibit the minimum average trace distance. This defines optimal protocols. Furthermore, we show that optimal protocols can be interpreted as the perfect quantum teleportation protocol under the action of correlated one-qubit channels. In particular, we focus on the deterministic case, for which the final Bloch vector length is equal for all measurement outcomes. Within these protocols, there exists one type that corresponds to the action of uncorrelated channels: these are depolarizing channels. Thus, we established the optimal quantum teleportation protocol under a very common experimental noise.Comment: 9 pages, 1 figur