Entanglement-Saving Channels

The set of Entanglement Saving (ES) quantum channels is introduced and characterized. These are completely positive, trace preserving transformations which when acting locally on a bipartite quantum system initially prepared into a maximally entangled configuration, preserve its entanglement even when applied an arbitrary number of times. In other words, a quantum channel $\psi$ is said to be ES if its powers $\psi^n$ are not entanglement-breaking for all integers $n$. We also characterize the properties of the Asymptotic Entanglement Saving (AES) maps. These form a proper subset of the ES channels that is constituted by those maps which, not only preserve entanglement for all finite $n$, but which also sustain an explicitly not null level of entanglement in the asymptotic limit~$n\rightarrow \infty$. Structure theorems are provided for ES and for AES maps which yield an almost complete characterization of the former and a full characterization of the latter.Comment: 26 page

A determination of the average up-down, strange and charm quark masses from Nf=2+1+1N_f=2+1+1

We present a lattice QCD determination of the average up-down, strange and charm quark masses based on simulations performed by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ dynamical fermions. We simulated at three different values of the lattice spacing, the smallest being approximately $0.06fm$, and with pion masses as small as $210 \text{MeV}$. Our results are: $m_{ud}(2\text{GeV})=3.70(17)\text{MeV}$, $m_s(2\text{GeV})=99.2(3.9)\text{MeV}$, $m_c(m_c)=1.350(49)\text{GeV}$, $m_s/m_{ud}=26.64(30)$ and $m_c/m_s=11.65(12)$

Mass of the b-quark and B-decay constants from Nf=2+1+1 twisted-mass Lattice QCD

We present precise lattice computations for the b-quark mass, the quark mass ratios mb/mc and mb/ms as well as the leptonic B-decay constants. We employ gauge configurations with four dynamical quark flavors, up/down, strange and charm, at three values of the lattice spacing (a ~ 0.06 - 0.09 fm) and for pion masses as low as 210 MeV. Interpolation in the heavy quark mass to the bottom quark point is performed using ratios of physical quantities computed at nearby quark masses exploiting the fact that these ratios are exactly known in the static quark mass limit. Our results are also extrapolated to the physical pion mass and to the continuum limit and read: mb(MSbar, mb) = 4.26(10) GeV, mb/mc = 4.42(8), mb/ms = 51.4(1.4), fBs = 229(5) MeV, fB = 193(6) MeV, fBs/fB = 1.184(25) and (fBs/fB)/(fK/fpi) = 0.997(17).Comment: Version to appear in PRD. Added comments to simulation setup and error budget discussion. 1+20 pages, 9 figure

Leptonic decay constants fK, fD and fDs with Nf = 2+1+1 twisted-mass lattice QCD

We present a lattice QCD calculation of the pseudoscalar decay constants fK, fD and fDs performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their values in the real world. The simulations are based on a unitary setup for the two light mass-degenerate quarks and on a mixed action approach for the strange and charm quarks. We use data simulated at three different values of the lattice spacing in the range 0.06 - 0.09 fm and at pion masses in the range 210 - 450 MeV. Our main results are: fK+ / fpi+ = 1.184 (16), fK+ = 154.4 (2.0) MeV, which incorporate the leading strong isospin breaking correction due to the up- and down-quark mass difference, and fK = 155.0 (1.9) MeV, fD = 207.4 (3.8) MeV, fDs = 247.2 (4.1) MeV, fDs / fD = 1.192 (22) and (fDs / fD) / (fK / fpi) = 1.003 (14) obtained in the isospin symmetric limit of QCD. Combined with the experimental measurements of the leptonic decay rates of kaon, pion, D- and Ds-mesons our results lead to the following determination of the CKM matrix elements: |Vus| = 0.2269 (29), |Vcd| = 0.2221 (67) and |Vcs| = 1.014 (24). Using the latest value of |Vud| from superallowed nuclear beta decays the unitarity of the first row of the CKM matrix is fulfilled at the permille level.Comment: 20 pp., 4 figures; revised version to appear in PRD; improved calculation of IB effects for fK+; minor changes in the final values. arXiv admin note: text overlap with arXiv:1403.450

Gaussian quantum resource theories

© 2018 American Physical Society. We develop a general framework to assess capabilities and limitations of the Gaussian toolbox in continuous-variable quantum information theory. Our framework allows us to characterize the structure and properties of quantum resource theories specialized to Gaussian states and Gaussian operations, establishing rigorous methods for their description and yielding a unified approach to their quantification. We show in particular that, under a few intuitive and physically motivated assumptions on the set of free states, no Gaussian quantum resource can be distilled with free Gaussian operations, even when an unlimited supply of the resource state is available. This places fundamental constraints on state manipulations in all such Gaussian resource theories. We discuss in particular the applications to quantum entanglement, where we extend previously known results by showing that Gaussian entanglement cannot be distilled even with Gaussian operations preserving the positivity of the partial transpose, as well as to other Gaussian resources such as steering and optical nonclassicality. A comprehensive semidefinite programming representation of all these resources is explicitly provided

INTEGRASI PROTOKOL MQTT DAN HTTP UNTUK OTOMASI BERBASIS IOT PADA PERTANIAN LAHAN KERING

The availability of telecommunication infrastructure and services has not been evenly distributed throughout the NTT region. This problem becomes the basis of this research  to develop a communication system that capable of reaching areas without a telecommunications network. Through the LORA gateway on the raspberry pi, information from areas that are not covered by telecommunications services is sent to another gateway using a working frequency of 915MHz. The plant in this study is the regulation of soil moisture with the input of 2 sensors and 1 relay for controlling land irrigation activities. An esp8266 sensor node collects the sensing results of the YL-69 and DS18B20 sensors to control the pump motor operation. The process of sending data between the sensor node and the gateway uses the mqtt protocol. Users in areas served by the internet network can access all published data on the test website. The results of controlling the plant area in the test area fluctuated and tended to be stable at between 60% and 80%

Entanglement-Breaking Indices

We study a set of new functionals (called entanglement--breaking indices) which characterize how many local iterations of a given (local) quantum channel are needed in order to completely destroy the entanglement between the system of interest over which the transformation is defined and an external ancilla. The possibility of contrasting the noisy effects introduced by the channel iterations via the action of intermediate ({\it filtering}) transformations is analyzed. We provide some examples in which our functionals can be exactly calculated. The differences between unitary and non-unitary filtering operations are analyzed showing that, at least for systems of dimension $d$ larger than or equal to 3, the non-unitary choice is preferable (the gap between the performances of the two cases being divergent in some cases). For $d=2$ (qubit case) on the contrary no evidences of the presence of such gap is revealed: we conjecture that for this special case unitary filtering transformations are optimal. The scenario in which more general filtering protocols are allowed is also discussed in some detail. The case of a depolarizing noise acting on a two--qubit system is exactly solved in a general case.Comment: 17 pages, 2 figures. A new section on generalized filtering protocols has been adde

Ground-dwelling arthropods as biodiversity indicators in maize agroecosystems of Northern Italy

Reliable monitoring of arthropod diversity in a given agroecosystem is essential for the conservation of the related ecosystem services, such as biological control. The often daunting complexity of arthropod collection and identification, however, highlights the need for surrogate taxa that can be easily sampled and be representative of a number of other taxa in term of diversity, general community features and specific composition. In this study, we used pitfall traps to sample three ground-dwelling arthropod taxa important as biocontrol agents (ground beetles, rove beetles and spiders) in 9 conventionally managed maize agroecosystems of Northern Italy over the course of two years, with the goal of characterizing their assemblages and evaluating their reciprocal potential as indicators of activity density, species richness, community turnover and species co-occurrence. Although dominated by few generalist species, sampled arthropod communities were relatively species-rich, and included the first Italian record of the spider Zelotes metellus (Roewer) (Araneae: Gnaphosidae). Ground beetles as a group were confirmed as promising indicators for the species richness and community composition turnover of rove beetles and spiders. Additionally, several abundant arthropod species acted as indicators of the species richness of their respective groups, and the ground beetle Pterostichus macer (Marsham) also worked as an indicator of overall rove beetle activity density. While the co-occurrence of individual arthropod species was limited for the studied taxa, a few species such as the ground beetle Parophonus maculicornis (Duftschmid) did show promise as species-specific bioindicators. Our results could be useful in improving the monitoring and management of these important natural enemies in maize-growing regions