12 research outputs found
Strategies for optimal single-shot discrimination of quantum measurements
In this work we study the problem of single-shot discrimination of von
Neumann measurements, which we associate with measure-and-prepare channels.
There are two possible approaches to this problem. The first one is simple and
does not utilize entanglement. We focus only on the discrimination of classical
probability distributions, which are outputs of the channels. We find necessary
and sufficient criterion for perfect discrimination in this case. A more
advanced approach requires the usage of entanglement. We quantify the distance
between two measurements in terms of the diamond norm (called sometimes the
completely bounded trace norm). We provide an exact expression for the optimal
probability of correct distinction and relate it to the discrimination of
unitary channels. We also state a necessary and sufficient condition for
perfect discrimination and a semidefinite program which checks this condition.
Our main result, however, is a cone program which calculates the distance
between the measurements and hence provides an upper bound on the probability
of their correct distinction. As a by-product, the program finds a strategy
(input state) which achieves this bound. Finally, we provide a full description
for the cases of Fourier matrices and mirror isometries.Comment: 13 pages, 4 figure
Vertices cannot be hidden from quantum spatial search for almost all random graphs
In this paper we show that all nodes can be found optimally for almost all
random Erd\H{o}s-R\'enyi graphs using continuous-time
quantum spatial search procedure. This works for both adjacency and Laplacian
matrices, though under different conditions. The first one requires
, while the seconds requires , where . The proof was made by analyzing the convergence
of eigenvectors corresponding to outlying eigenvalues in the norm. At the same time for , the property does
not hold for any matrix, due to the connectivity issues. Hence, our derivation
concerning Laplacian matrix is tight.Comment: 18 pages, 3 figur
Does Small Ruminant Lentivirus Infection in Goats Predispose to Bacterial Infection of the Mammary Gland? A Preliminary Study
The aim of this study was to determine whether asymptomatic small ruminant lentivirus
seropositive (SRLV-SP) goats were more susceptible to bacterial infection of the udder when lactating
by comparing the presence and species of pathogenic bacteria in their milk with the values for
seronegative goats (SRLV-SN). Milk samples were collected during morning milking on days 20, 40,
60, 150, and 210 of lactation for three consecutive years and subjected to bacteriological examination.
Staphylococcus caprae and S. xylosus were the most frequent strains identified in both SRLV-SP and
SRLV-SN goats. The prevalence of pathogenic bacteria was the highest in the 1st lactation, regardless
of SRLV status. Moreover, the prevalence of pathogenic bacteria was significantly higher in SRLV-SP
goats, but only those in the 5th or further lactation (p = 0.010). This suggests a relationship between
long-lasting SRLV infection and susceptibility to bacterial infections of the udder
On the probabilistic quantum error correction
Probabilistic quantum error correction is an error-correcting procedure which
uses postselection to determine if the encoded information was successfully
restored. In this work, we deeply analyze probabilistic version of the
error-correcting procedure for general noise. We generalized the Knill-Laflamme
conditions for probabilistically correctable errors. We show that for some
noise channels, we should encode the information into a mixed state to maximize
the probability of successful error correction. Finally, we investigate an
advantage of the probabilistic error-correcting procedure over the
deterministic one. Reducing the probability of successful error correction
allows for correcting errors generated by a broader class of noise channels.
Significantly, if the errors are caused by a unitary interaction with an
auxiliary qubit system, we can probabilistically restore a qubit state by using
only one additional physical qubit.Comment: 28 pages, 2 figure
Milk Yield and Composition, Technological Properties and Homeostasis Indices at Different Lactation Stages and Parities of Two Polish Dairy Goat Breeds
The purpose of the research was to determine the effect of breed, lactation number, and lactation stage on milk efficiency and goat milk ingredients, these being indicators of milk technological parameters and homeostasis disturbances. Goat breed and number of lactation affected energy-corrected milk, value-corrected milk yield, fat corrected milk, protein, casein, lactose contents and free fatty acids. Additionally, differences in non-fat solids and urea contents were found between two Polish common dairy breeds White Improved (PWI) and Fawn Improved (PFI) goats. Moreover, parity affected milk yield, its acidity and somatic cell count (SCC). Milk yield and milk components were found to vary according to lactation stage. At the beginning of lactation, milk is richer in ingredients which have effect on cheese and yoghurt production. All the goats undergo similar changes related to the lactation stage that is at the same time and this can affect the yield and quality of the curd. In production focused on liquid milk, the age structure of the herd should be properly managed, as the goats in their third lactation or above have higher milk yields, regardless of breed. For cheese production, the PWI breed would be more suitable than PFI as the PWI goat milk contains less SCC and more components essential for milk processing, including caseins