2,388 research outputs found
Quantum mutual information and quantumness vectors for multi-qubit systems
We introduce a new information theoretic measure of quantum correlations for
multiparticle systems. We use a form of multivariate mutual information -- the
interaction information and generalize it to multiparticle quantum systems.
There are a number of different possible generalizations. We consider two of
them. One of them is related to the notion of quantum discord and the other to
the concept of quantum dissension. This new measure, called dissension vector,
is a set of numbers -- quantumness vector. This can be thought of as a
fine-grained measure, as opposed to measures that quantify some average quantum
properties of a system. These quantities quantify/characterize the correlations
present in multiparticle states. We consider some multiqubit states and find
that these quantities are responsive to different aspects of quantumness, and
correlations present in a state. We find that different dissension vectors can
track the correlations (both classical and quantum), or quantumness only. As
physical applications, we find that these vectors might be useful in several
information processing tasks. We consider the role of dissension vectors -- (a)
in deciding the security of BB84 protocol against an eavesdropper and (b) in
determining the possible role of correlations in the performance of Grover
search algorithm. Especially, in the Grover search algorithm, we find that
dissension vectors can detect the correlations and show the maximum
correlations when one expects.Comment: 18 pages 8 figures. Updated. Comments are welcom
Resource state structure for controlled quantum key distribution
Quantum entanglement plays a pivotal role in many communication protocols,
like secret sharing and quantum cryptography. We consider a scenario where more
than two parties are involved in a protocol and share a multipartite entangled
state. In particular, we considered the protocol of Controlled Quantum Key
Distribution (CoQKD), introduced in the Ref. Chin. Phys. Lett. 20, 183-185
(2003), where, two parties, Alice and Bob establish a key with the cooperation
of other parties. Other parties control/supervise whether Alice and Bob can
establish the key, its security and key rate. We discuss the case of three
parties in detail and find suitable resource states. We discuss the controlling
power of the third party, Charlie. We also examine the usefulness of the new
resource states for generating conference key and for cooperative
teleportation. We find that recently introduced Bell inequalities can be useful
to establish the security of the conference key. We also generalize the
scenario to more than three parties.Comment: 11 pages, 7 figures. Close to published versio
Local, nonlocal quantumness and information theoretic measures
It has been suggested that there may exist quantum correlations that go
beyond entanglement. The existence of such correlations can be revealed by
quantum discord, but not by the conventional measure of entanglement. We argue
that a state displays quantumness that can be of local and nonlocal origin. The
physical quantity such as the quantum discord probes not only the nonlocal
quantumness but also the local quantumness, such as the "local superposition".
This can be a reason why such measures are non-zero when there is no
entanglement. We consider a generalized version of the Werner state to
demonstrate the interplay of local quantumness, nonlocal quantumness, and
classical mixedness of a state.Comment: 7 pages, 8 figures. Title changed. Accepted for publication in IJQ
Automatic eduction and statistical analysis of coherent structures in the wall region of a confine plane
This paper describes a vortex detection algorithm used to expose and statistically characterize the
coherent flow patterns observable in the velocity vector fields measured by Particle Image
Velocimetry (PIV) in the impingement region of air curtains. The philosophy and the architecture of
this algorithm are presented. Its strengths and weaknesses are discussed. The results of a
parametrical analysis performed to assess the variability of the response of our algorithm to the 3
user-specified parameters in our eduction scheme are reviewed. The technique is illustrated in the
case of a plane turbulent impinging twin-jet with an opening ratio of 10. The corresponding jet
Reynolds number, based on the initial mean flow velocity U0 and the jet width e, is 14000. The
results of a statistical analysis of the size, shape, spatial distribution and energetic content of the
coherent eddy structures detected in the impingement region of this test flow are provided.
Although many questions remain open, new insights into the way these structures might form,
organize and evolve are given. Relevant results provide an original picture of the plane turbulent
impinging jet
A general framework for handling commitment in online throughput maximization
We study a fundamental online job admission problem where jobs with deadlines
arrive online over time at their release dates, and the task is to determine a
preemptive single-server schedule which maximizes the number of jobs that
complete on time. To circumvent known impossibility results, we make a standard
slackness assumption by which the feasible time window for scheduling a job is
at least times its processing time, for some .
We quantify the impact that different provider commitment requirements have on
the performance of online algorithms. Our main contribution is one universal
algorithmic framework for online job admission both with and without
commitments. Without commitment, our algorithm with a competitive ratio of
is the best possible (deterministic) for this problem. For
commitment models, we give the first non-trivial performance bounds. If the
commitment decisions must be made before a job's slack becomes less than a
-fraction of its size, we prove a competitive ratio of
, for .
When a provider must commit upon starting a job, our bound is
. Finally, we observe that for scheduling with commitment
the restriction to the `unweighted' throughput model is essential; if jobs have
individual weights, we rule out competitive deterministic algorithms
Global Strategy of Asian Market Enterprises
Emerging Markets have recently been attracting increasing attention in investors’ minds as the post financial meltdown of 2008 and the series of Euro crises have been casting a deep shadow of gloom and uncertainty on the economic performance of the developed economies. Specifically, two important issues are associated with the internationalization of Asian market enterprises (AMEs), namely free-flow of investment at ease of exchange norms and the recent global financial crisis. In addition, availability of free-cash-flows and limited expansion of local markets are the other major factors that push many AMEs to choose internationalization as a growth strategy. Thus, all the papers are original contributions in this special issue and it is our view that they will lead to better understanding of the implications of managing global strategy from a cross section of Asian companies and a richer understanding of the theoretical issues in global strategic management
Antimicrobial resistance in neonates with suspected sepsis
SettingNobel Medical College and Teaching Hospital, Biratnagar, Nepal.ObjectiveTo determine the pattern of antimicrobial resistance and hospital exit outcomes in neonates with suspected sepsis in a tertiary neonatal intensive care unit (NICU).DesignThis hospital-based cohort study was conducted to follow patients from January to December 2019. All identified cases of suspected sepsis were enlisted from hospital records.ResultsSepsis was suspected in 177 (88%) of the 200 cases admitted in the NICU; 52 (29%) were culture-positive. Pseudomonas was the predominant organism isolated (n = 40; 78%), followed by coagulase negative staphylococcus (n = 12, 23%). Nine (17%) of the 52 isolates were resistant to the Access and Watch group of antibiotics, including some resistance to Reserve group drugs such as imipenem and linezolid. Most treated cases (n = 170, 96%) improved, although 7 (4%) left against medical advice.ConclusionMost of the pathogens were resistant to WHO Access and Watch antibiotics and occasional resistance was observed to Reserve group drugs. Most sepsis was caused by Gram-negative bacilli. Improving turnaround times for antibiotic sensitivity testing using point-of-care testing, and a greater yield of culture-positive results are needed to enhance the management of neonatal sepsis
Global Strategy of Asian Market Enterprises
Emerging Markets have recently been attracting increasing attention in investors’ minds as the post financial meltdown of 2008 and the series of Euro crises have been casting a deep shadow of gloom and uncertainty on the economic performance of the developed economies. Specifically, two important issues are associated with the internationalization of Asian market enterprises (AMEs), namely free-flow of investment at ease of exchange norms and the recent global financial crisis. In addition, availability of free-cash-flows and limited expansion of local markets are the other major factors that push many AMEs to choose internationalization as a growth strategy. Thus, all the papers are original contributions in this special issue and it is our view that they will lead to better understanding of the implications of managing global strategy from a cross section of Asian companies and a richer understanding of the theoretical issues in global strategic management
- …