Separable states can be used to realize the fair quantum communication

2019 ◽  
Vol 17 (01) ◽  
pp. 1950004
Author(s):  
Dong-Mei Gao ◽  
Ying Xin ◽  
Zai-Liang Ye ◽  
Xiao-Yan Qiao
Keyword(s):  
Channel Coding ◽  
Quantum Communication ◽  
Sufficient Conditions ◽  
Basic Question ◽  
Classical Correlation ◽  
Quantum Communications ◽  
Nonclassical State ◽  
Accessible Information ◽  
Essential Resource ◽  
Classical Means

When Alice and Bob are never entangled with each other, can they share equal amount of information via noiseless channels? When the transfered subsystem B is classical, this basic question concerning communication capacity has a very satisfying answer: the amount of accessible information, as quantified by the classical correlation on B, is always equal. If the subsystem B is in a nonclassical state, the amount of accessible information, like their classical counterparts, is also well quantified by classical correlation, but the similarity ends here: the amount of accessible information from shared states may not be equal, because the subsystem B cannot be accessed perfectly by classical means. In this work, we show how to establish fair quantum communications. Our results give sufficient conditions for fair quantum communications and show that symmetric discord is the essential resource for this task. We further demonstrate that the fair quantum communication is fundamentally the same as the Shannon noisy channel coding theorem.

scholarly journals On the Classical Capacity of General Quantum Gaussian Measurement

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 377
Author(s):  
Alexander Holevo
Keyword(s):  
Dual Problem ◽  
Measurement Channel ◽  
Gaussian Channel ◽  
Quantum Communications ◽  
Classical Capacity ◽  
Optimal Ensemble ◽  
Accessible Information ◽  
Measurement Channels ◽  
Gaussian Ensemble ◽  
Average State

In this paper, we consider the classical capacity problem for Gaussian measurement channels. We establish Gaussianity of the average state of the optimal ensemble in the general case and discuss the Hypothesis of Gaussian Maximizers concerning the structure of the ensemble. Then, we consider the case of one mode in detail, including the dual problem of accessible information of a Gaussian ensemble. Our findings are relevant to practical situations in quantum communications where the receiver is Gaussian (say, a general-dyne detection) and concatenation of the Gaussian channel and the receiver can be considered as one Gaussian measurement channel. Our efforts in this and preceding papers are then aimed at establishing full Gaussianity of the optimal ensemble (usually taken as an assumption) in such schemes.

scholarly journals Proposal for space-borne quantum memories for global quantum networking

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Mustafa Gündoğan ◽  
Jasminder S. Sidhu ◽  
Victoria Henderson ◽  
Luca Mazzarella ◽  
Janik Wolters ◽  
...  
Keyword(s):  
Quantum Communication ◽  
Global Scale ◽  
Space Systems ◽  
Quantum Communications ◽  
Communication Links ◽  
Probabilistic Detection ◽  
Entanglement Distribution ◽  
Near Term ◽  
Quantum Internet ◽  
Memory Characteristics

AbstractGlobal-scale quantum communication links will form the backbone of the quantum internet. However, exponential loss in optical fibres precludes any realistic application beyond few hundred kilometres. Quantum repeaters and space-based systems offer solutions to overcome this limitation. Here, we analyse the use of quantum memory (QM)-equipped satellites for quantum communication focussing on global range repeaters and memory-assisted (MA-) QKD, where QMs help increase the key rate by synchronising otherwise probabilistic detection events. We demonstrate that satellites equipped with QMs provide three orders of magnitude faster entanglement distribution rates than existing protocols based on fibre-based repeaters or space systems without QMs. We analyse how entanglement distribution performance depends on memory characteristics, determine benchmarks to assess the performance of different tasks and propose various architectures for light-matter interfaces. Our work provides a roadmap to realise unconditionally secure quantum communications over global distances with near-term technologies.

scholarly journals Iterative procedure for computing accessible information in quantum communication

2005 ◽  
Vol 71 (5) ◽  
Author(s):  
Jaroslav Řeháček ◽  
Berthold-Georg Englert ◽  
Dagomir Kaszlikowski
Keyword(s):  
Iterative Procedure ◽  
Quantum Communication ◽  
Accessible Information

scholarly journals Using quantum communications for maritime signal flags

2019 ◽  
Vol XXII (1) ◽  
pp. 151-157
Author(s):  
Plesa M. C.
Keyword(s):  
Quantum Communication ◽  
Quantum Computer ◽  
Quantum Communications ◽  
Maritime Communication ◽  
Quantum Internet ◽  
Made In

Quantum communications are becoming very quickly a reality. There are huge advancement made in the field of quantum internet. Recently, IBM has announced the first commercial quantum computer with 20 qubits. Given all the advancements in the field, in this paper we investigate how quantum technologies can be applied in maritime communications. In this paper we address the problem of international maritime flag signals. More exactly, we proposed some quantum communication schemes for international maritime signal flags. We are also study the efficiency and security boost that quantum communications give in this type of maritime communication.

scholarly journals Informationally restricted quantum correlations

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 332 ◽  
Author(s):  
Armin Tavakoli ◽  
Emmanuel Zambrini Cruzeiro ◽  
Jonatan Bohr Brask ◽  
Nicolas Gisin ◽  
Nicolas Brunner
Keyword(s):  
Hilbert Space ◽  
Lower Bounds ◽  
Quantum Communication ◽  
Space Dimension ◽  
Quantum Correlations ◽  
Strong Correlations ◽  
Classical Communication ◽  
Accessible Information ◽  
Classical Correlations ◽  
The One

Quantum communication leads to strong correlations, that can outperform classical ones. Complementary to previous works in this area, we investigate correlations in prepare-and-measure scenarios assuming a bound on the information content of the quantum communication, rather than on its Hilbert-space dimension. Specifically, we explore the extent of classical and quantum correlations given an upper bound on the one-shot accessible information. We provide a characterisation of the set of classical correlations and show that quantum correlations are stronger than classical ones. We also show that limiting information rather than dimension leads to stronger quantum correlations. Moreover, we present device-independent tests for placing lower bounds on the information given observed correlations. Finally, we show that quantum communication carrying log⁡d bits of information is at least as strong a resource as d-dimensional classical communication assisted by pre-shared entanglement.

The Clinical Use of Antipsychotic Plasma Levels

2021 ◽  
Author(s):  
Jonathan M. Meyer ◽  
Stephen M. Stahl
Keyword(s):  
Mental Health Professionals ◽  
Nurse Practitioners ◽  
New Technologies ◽  
Clinical Care ◽  
Formal Training ◽  
Accessible Information ◽  
Clear Explanation ◽  
Oral Antipsychotic ◽  
Essential Resource ◽  
Trough Levels

Clinicians recognize that monitoring psychotropic levels provides invaluable information to optimize therapy and track treatment adherence, but they lack formal training specifically focused on the use of plasma antipsychotic levels for these purposes. As new technologies emerge to rapidly provide these results, the opportunity to integrate this information into clinical care will grow. This practical handbook clarifies confusing concepts in the literature on use of antipsychotic levels, providing clear explanations for the logic underlying clinically relevant concepts such as the therapeutic threshold and the point of futility, and how these apply to individual antipsychotics. It offers accessible information on the expected correlation between dosages and trough levels, and also provides a clear explanation of how to use antipsychotic levels for monitoring oral antipsychotic adherence, and methods to help clinicians differentiate between poor adherence and variations in drug metabolism. An essential resource for psychiatrists, psychiatric nurse practitioners, and mental health professionals worldwide.

Generating new nonclassical state by repeatedly operating number operator on coherent state

2021 ◽  
pp. 2150167
Author(s):  
Gang Ren ◽  
Jian-Ming Du ◽  
Wen-Hai Zhang
Keyword(s):  
Quantum Optics ◽  
Coherent State ◽  
Quantum State ◽  
Quantum Communication ◽  
Photon Number ◽  
Number Operator ◽  
Squeezing Effect ◽  
Nonclassical State ◽  
Poissonian Statistics ◽  
Photon Number Distribution

In this paper, using the principle of quantum state superposition, we report a nonclassical quantum state which is constructed by repeatedly operating the number operator on the coherent state. Nonclassical effects of this state are discussed by photon-number distribution, sub-Poissonian statistics, anti-bunching and negativity of Wigner function and squeezing effect. Our work provides an important nonclassical resource, which may be used in quantum communication and quantum optics.

scholarly journals Applications of Lyapunov Functions to Caputo Fractional Differential Equations

Mathematics ◽  
2018 ◽  
Vol 6 (11) ◽  
pp. 229
Author(s):  
Ravi Agarwal ◽  
Snezhana Hristova ◽  
Donal O’Regan
Keyword(s):  
Differential Equations ◽  
Fractional Differential Equations ◽  
Lyapunov Functions ◽  
Sufficient Conditions ◽  
Basic Question ◽  
Caputo Fractional Differential Equations ◽  
Fractional Differential ◽  
Definition Of ◽  
The Given ◽  
Fractional Equation

One approach to study various stability properties of solutions of nonlinear Caputo fractional differential equations is based on using Lyapunov like functions. A basic question which arises is the definition of the derivative of the Lyapunov like function along the given fractional equation. In this paper, several definitions known in the literature for the derivative of Lyapunov functions among Caputo fractional differential equations are given. Applications and properties are discussed. Several sufficient conditions for stability, uniform stability and asymptotic stability with respect to part of the variables are established. Several examples are given to illustrate the theory.

scholarly journals Accessible Information and Constitutional Democracy: Who Counts?

2016 ◽  
Vol 25 (3) ◽  
pp. 67
Author(s):  
Jennifer Raso
Keyword(s):  
Public Law ◽  
Law Reform ◽  
Constitutional Democracy ◽  
The Public ◽  
Meaningful Participation ◽  
Law And Policy ◽  
Accessible Information ◽  
Legislative Branch ◽  
Reform Processes ◽  
Essential Resource

Accessible information is an essential resource for equal, meaningful participation in the public life of a democratic society. Such information is particularly vital for the effective functioning of all three branches of government in our constitutional democracy: the administrative branch, which creates government policy and holds state actors accountable to the public; the legislative branch, which scrutinizes old and creates new legislation; and the judicial branch, which reviews the acts of the legislative and executive branches. For the law-reform processes of each branch to effectively foster the informed creation and critique of public law and policy, we require reliable, accessible data depicting the diversity of individuals who make up the broader Canadian public.Beyond this practical purpose, accessible information plays an expressive role as it constitutes a particular notion of the Canadian public. The data created by national population censuses and assembled in welfare reports has the power to “nominat[e] into existence” certain groups of people and, conversely, to “refus[e] to name” others. Such information not only represents the public, it also creates the public, as it stands in for the public at all levels of government. By communicating who we are as a society and how we are changing, census information and welfare reports shape our understanding of ourselves — our laws, policies, government, and place in the world.

scholarly journals Robust diagnostics of dark counts for quantum networks

2020 ◽  
Author(s):  
Nikolay Perminov ◽  
Maxim Smirnov ◽  
Konstantin Melnik ◽  
Lenar Gilyazov ◽  
Oleg Bannik ◽  
...  
Keyword(s):  
Quantum Communication ◽  
Single Photon ◽  
Signal To Noise Ratio ◽  
Diagnostic System ◽  
Quantum Communications ◽  
Photon Detectors ◽  
Communication Performance ◽  
Quantum Networks ◽  
Dark Noise ◽  
Total Noise

In this work, we study timestamps when registering counts of single-photon detectors in quantum communications. Post-pulse counts are analyzed based on several approaches. Explicit statistical accounting of the noise of quantum detectors allows you to most correctly select the mode of use of the detectors to realize the most efficient quantum communication with the highest signal to noise ratio. Direct statistical analysis and robust diagnostics of the noise of quantum detectors can be done by ranging the time's tags of quantum keys that are available for the online diagnostic system and analysis a significant amount of information about the quantum communication performance (the amount of dark noise and post-pulse counts, line interference, etc.). The conclusion is made about the proportion of dark noise and post-pulse counts in the total noise, and the limits of applicability of the theory are shown using a sequence of the ranged amplitudes. We offer non-parametric robust diagnostic of times tags in keys to increase the security of quantum networks, and also discuss the prospects of commercializing quantum-classical cloud-based security services.

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