Optimal tracking for pairs of qubit states

In classical control theory, tracking refers to the ability to perform measurements and feedback on a classical system in order to enforce some desired dynamics. In this paper we investigate a simple version of quantum tracking, namely, we look at how to optimally transform the state of a single qubit into a given target state, when the system can be prepared in two different ways, and the target state depends on the choice of preparation. We propose a tracking strategy that is proved to be optimal for any input and target states. Applications in the context of state discrimination, state purification, state stabilization and state-dependent quantum cloning are presented, where existing optimality results are recovered and extended.Comment: 15 pages, 8 figures. Extensive revision of text, optimality results extended, other physical applications include

Entanglement universality of two-qubit X-states

We demonstrate that for every two-qubit state there is a X-counterpart, i.e., a corresponding two-qubit X-state of same spectrum and entanglement, as measured by concurrence, negativity or relative entropy of entanglement. By parametrizing the set of two-qubit X-states and a family of unitary transformations that preserve the sparse structure of a two-qubit X-state density matrix, we obtain the parametric form of a unitary transformation that converts arbitrary two-qubit states into their X-counterparts. Moreover, we provide a semi-analytic prescription on how to set the parameters of this unitary transformation in order to preserve concurrence or negativity. We also explicitly construct a set of X-state density matrices, parametrized by their purity and concurrence, whose elements are in one-to-one correspondence with the points of the concurrence versus purity (CP) diagram for generic two-qubit states.Comment: 24 pages, 6 figures. v2 includes new references and minor changes (accepted version

Heuristic for estimation of multiqubit genuine multipartite entanglement

For every N-qubit density matrix written in the computational basis, an associated "X-density matrix" can be obtained by vanishing all entries out of the main- and anti-diagonals. It is very simple to compute the genuine multipartite (GM) concurrence of this associated N-qubit X-state, which, moreover, lower bounds the GM-concurrence of the original (non-X) state. In this paper, we rely on these facts to introduce and benchmark a heuristic for estimating the GM-concurrence of an arbitrary multiqubit mixed state. By explicitly considering two classes of mixed states, we illustrate that our estimates are usually very close to the standard lower bound on the GM-concurrence, being significantly easier to compute. In addition, while evaluating the performance of our proposed heuristic, we provide the first characterization of GM-entanglement in the steady states of the driven Dicke model at zero temperature.Comment: 19 pages, 5 figure

Wild cards, weak signals and prganizational improvisation

This paper addresses the need for reliable action guidelines that can be used by organisations in turbulent environments. Building on current conceptual and empirical research, we suggest an analytical approach for the management of surprising and potentially damaging events. In order to do so we use the wild card management system. Wild cards refer to sudden and unique incidents that can constitute turning points in the evolution of a certain trend or system. As the first of the two components of such a wild card system we advocate a weak signal methodology to take into account those wild cards that can be anticipated by scanning the decision environment. The second component, the nurture of improvisation capabilities, is designed to deal with ongoing crisis. This paper can be seen as part of a broader agenda on how to manage in conditions of continuous but unpredictable change.wild cards, weak signals, improvisation, minimal structures

Benchmarking Reproductive Efficiency and Transition Cow Health of Kansas Dairy Herds

Comparing key performance indicators across dairy farms may provide insightful information to dairy producers. Differences in management philosophies, facilities, and locations of dairy farms may influence overall performance of dairy operations. An ongoing extension program aims to benchmark reproductive performance and transition cow health of dairy farms located in Kansas and adjacent states. In this report, we compiled data from 2013 to 2015 of herds enrolled in the program and divided the data in warm and cool seasons to evaluate the impact of heat stress on key performance indicators. Annual pregnancy risk and warm to cool ratio of pregnancy risk varied from 20.9 to 22.5% and 75 to 82%, respectively. Annual insemination risk varied from 63.6 to 66.4% and warm to cool ratio of insemination risk varied from 96 to 97%, which suggests that heat stress does not remarkably affect insemination risk. In contrast, conception risk is significantly affected by heat stress because conception risk in the warm season ranged from 26.7 to 29.6% and in the cool season from 34.5 to 35.4% from 2013 to 2015. Percentage of cows that were treated for mastitis within 21 d after calving was below 4% annually. Warm to cool ratio of percentage of cows treated for mastitis ranged from 139 to 170%, indicating that during summer, cows are at increased risk of being affected by early postpartum mastitis. Benchmarking key performance indicators may assist dairy producers to identify areas of opportunity for improvement

Assessing Training Methods to Educate Dairy Workers

Training employees is fundamental for dairy producers to achieve efficiency in order to increase profitability. Training videos offered online are becoming more common and recommended to train employees. The goals of this survey were to evaluate the comfort level of dairy employees in using computers and tablets, and preferred training delivery methods. A total of 71 employees from 6 dairies were interviewed. Interviews were conducted in the preferred language of the interviewee – English or Spanish. Of the respondents, 52 and 65.6% of employees consider computers and tablets easy to use, respectively. More than half of the employees reported that they do not use computers or tablets on a regular basis. The majority of employees (70%) would rather have a training session in a face-to-face format than a computer- or tablet-based format. This survey suggests that dairy employees may not be comfortable using computers in training sessions, which may limit the utility of some specific technologies to educate employees

Estimation of the sugar cane cultivated area from LANDSAT images using the two phase sampling method

A two phase sampling method and the optimal sampling segment dimensions for the estimation of sugar cane cultivated area were developed. This technique employs visual interpretations of LANDSAT images and panchromatic aerial photographs considered as the ground truth. The estimates, as a mean value of 100 simulated samples, represent 99.3% of the true value with a CV of approximately 1%; the relative efficiency of the two phase design was 157% when compared with a one phase aerial photographs sample