Filters
total: 3629

Catalog
 Publications 2557 available results
 Journals 597 available results
 Conferences 235 available results
 Publishing Houses 1 available results
 People 112 available results
 Projects 12 available results
 Research Teams 1 available results
 eLearning Courses 21 available results
 Events 2 available results
 Open Research Data 91 available results
displaying 1000 best results Help
Search results for: QUANTUM INFORMATION THEORY

Superadditivity of two quantum information resources
PublicationEntanglement is one of the most puzzling features of quantum theory and a principal resource for quantum information processing. It is well known that in classical information theory, the addition of two classical information resources will not lead to any extra advantages. On the contrary, in quantum information, a spectacular phenomenon of the superadditivity of two quantum information resources emerges. It shows that quantum...

Structure of the Resource Theory of Quantum Coherence
PublicationQuantum coherence is an essential feature of quantum mechanics which is responsible for the departure between the classical and quantum world. The recently established resource theory of quantum coherence studies possible quantum technological applications of quantum coherence, and limitations that arise if one is lacking the ability to establish superpositions. An important open problem in this context is a simple characterization...

Aspects of multistation quantum information broadcasting
PublicationWe study quantum information transmission over multiparty quantum channel. In particular, we show an equivalence of different capacity notions and provide a multiletter characterization of a capacity region for a general quantum channel with k senders and m receivers. We point out natural generalizations to the case of twoway classical communication capacity. (C) 2010 Elsevier B.V. All rights reserved.

On mixed states entanglement and quantum communication: aspects of quantum channels theory
PublicationDokonano przeglądu związków miedzy stanami kwantowymi oraz kwantowymi kanałami. Wykazano, że istnienie nietypowych korelacji kwantowych (splątanie związane typu NPT) w pewnych sytuacjach pociąga za sobą nieaddytywność pojemności kanałów kwantowych.

Local information as a resource in distributed quantum systems.
PublicationZaproponowano nowy paradygmat dla kwantowego paradygmatu odległych laboratoriów w których informacja jest zasobem. W tym schemacie obserwatorzy dokonują destylacji informacji lokalnych stanów czystych.

Termodynamics of quantum information systems  Hamiltonian description.
PublicationPrzy użyciu podejścia hamiltonowskiego wyprowadzono wzór na pracę dla układów kwantowych zanurzonych w ciepłym otoczeniu.

Product Graph Invariants with Applications in the Theory of Information
PublicationThere are a large number of graph invariants. In the paper, we consider some of them, e.g. the independence and chromatic numbers. It is well know that we cannot efficiently calculate these numbers for arbitrary graphs. In the paper we present relations between these invariants and concepts from the theory of information. Concepts such as source coding and transmission over a noisy channel with zero probability of error are modeled...

npj Quantum Information
Journals 
QUANTUM INFORMATION & COMPUTATION
Journals 
Steering is an essential feature of nonlocality in quantum theory
PublicationA physical theory is called nonlocal when observers can produce instantaneous effects over distant systems. Nonlocal theories rely on two fundamental effects: local uncertainty relations and steering of physical states at a distance. In quantum mechanics, the former one dominates the other in a wellknown class of nonlocal games known as XOR games. In particular, optimal quantum strategies for XOR games are completely determined...

Applications of semidefinite optimization in quantum information protocols
PublicationThis work is concerned with the issue of applications of the semidefinite programming (SDP) in the field of quantum information sci ence. Our results of the analysis of certain quantum information protocols using this optimization technique are presented, and an implementation of a relevant numerical tool is introduced. The key method used is NPA discovered by Navascues et al. [Phys. Rev. Lett. 98, 010401 (2007)]. In chapter...

Quantum morphogenesis: A variation on Thom`s catastrophe theory.
PublicationZaproponowano nowy opis morfogenezy na poziomie kwantowym w oparciu o rozwiązania samo przełączające nieliniowego równania von Neumanna.

IEEE TRANSACTIONS ON INFORMATION THEORY
Journals 
INTERNATIONAL JOURNAL OF QUANTUM INFORMATION
Journals 
Objectivity in a Noisy Photonic Environment through Quantum State Information Broadcasting
PublicationRecently, the emergence of classical objectivity as a property of a quantum state has been explicitly derived for a small object embedded in a photonic environment in terms of a spectrum broadcast form—a specific classically correlated state, redundantly encoding information about the preferred states of the object in the environment. However, the environment was in a pure state and the fundamental problem was how generic and robust...

Unconditional privacy over channels which cannot convey quantum information
PublicationQuantum cryptography enables one to verify that the state of the quantum system has not been tampered with and thus one can obtain privacy regardless of the power of the eavesdropper. All previous protocols relied on the ability to faithfully send quantum states or equivalently to share pure entanglement. Here we show this need not be the caseone can obtain verifiable privacy even through some channels which cannot be used to...

Quantum information isomorphism: Beyond the dilemma of the Scylla of ontology and the Charybdis of instrumentalism.
PublicationZaprezentowano koncepcję izomorfizmu kwantowej informacji, zgodnie z którym kwantowy opis natury jest izomorficzny z samą naturą.

Distributed correlations and information flows within a hybrid multipartite quantumclassical system
PublicationUnderstanding the nonMarkovian mechanisms underlying the revivals of quantum entanglement in the presence of classical environments is central in the theory of quantum information. Tentative interpretations have been given by either the role of the environment as a control device or the concept of hidden entanglement. We address this issue from an informationtheoretic point of view. To this aim, we consider a paradigmatic tripartite...

Teleportation seen from spacetime: on 2spinor aspects of quantum information processing
PublicationZastosowanie formalizmu 2spinowego do kwantowego przetwarzania informacji zilustrowane przykładem teleportacji i relatywistycznej korelacji błędu.

Twospinors, oscillator algebras, and qubits: aspects of manifestly covariant approach to relativistic quantum information
PublicationThe first part of the paper reviews applications of 2spinor methods to relativistic qubits (analogies between tetrads in Minkowski space and 2qubit states, qubits defined by means of null directions and their role for elimination of the PeresScudoTerno phenomenon, advantages and disadvantages of relativistic polarization operators defined by the PauliLubanski vector, manifestly covariant approach to unitary representations...

Quantum Information Processing
Journals 
Schemes of transmission of classical information via quantum channels with many senders: Discrete and continuousvariable cases
PublicationSuperadditivity effects in the classical capacity of discrete multiaccess channels and continuous variable (CV) Gaussian MACs are analyzed. Several examples of the manifestation of superadditivity in the discrete case are provided, including, in particular, a channel which is fully symmetric with respect to all senders. Furthermore, we consider a class of channels for which input entanglement across more than two copies of the...

Foundations and Trends in Communications and Information Theory
Journals 
Journal of Information Science Theory and Practice
Journals 
Workshop on Quantum Information Processing
Conferences 
ERATO Conference on Quantum Information Science
Conferences 
An approach to constructing genuinely entangled subspaces of maximal dimension
PublicationGenuinely entangled subspaces (GESs) are the class of completely entangled subspaces that contain only genuinely multiparty entangled states. They constitute a particularly useful notion in the theory of entanglement but also have found an application, for instance, in quantum error correction and cryptography. In a recent study (Demianowicz and Augusiak in Phys Rev A 98:012313, 2018), we have shown how GESs can be efficiently...

Information Theory Workshop
Conferences 
Are quantum correlations symmetric?
PublicationWe provide operational definition of symmetry of entanglement: An entangled state contains symmetric entanglement if its subsystems can be exchanged (swapped) by means of local operations and classical communication. We show that in general states have asymmetric entanglement. This allows to construct nonsymmetric measure of entanglement, and a parameter that reports asymmetry of entanglement contents of quantum state. We propose...

Multiacces quantum communication and product higher rank numerical range
PublicationIn the present paper we initiate the study of the product higher rank numerical range. The latter, being a variant of the higher rank numerical range, is a natural tool for study ing a construction of quantum error correction codes for multiple access channels. We review properties of this set and relate it to other numerical ranges, which were recently introduced in the literature. Further, the concept is applied to the construction...

ON THE NONLOCALITY OF TRIPARTITE NONSINGALING BOXES EMERGING FROM WIRINGS
PublicationIt has been recently shown, that some of the tripartite boxes admittin g bilocal decom position, lead to nonlocality under wiring operation applied to t wo of the subsystems [R. Gallego et al. Physical Review Letters 109 , 070401 (2012)]. In the following, we study this phenomenon quantitatively. Basing on the known classes of bo xes closed un der wirings, we introduce multipartite monotones which are count erparts of bipartite ones...

NOBROADCASTING OF NONSIGNALLING BOXES VIA OPERATIONS WHICH TRANSFORM LOCAL BOXES INTO LOCAL ONES
PublicationWe deal with families of probability distributions satisfying nonsignalling condition, called nonsignalling boxes and consider a class of operations that transform local boxes into local ones (the one that admit LHV model). We prove that any operation from this class cannot broadcast a bipartite nonlocal box with 2 binary inputs and outputs. We consider a function called antiRobustness which can not decrease under these operations....

Information Visualisation Theory and Practice
Conferences 
Workshop in Information Security Theory and Practices
Conferences 
IEEE International Symposium on Information Theory
Conferences 
General paradigm for distilling classical key from quantum states
PublicationIn this paper, we develop a formalism for distilling aclassical key from a quantum state in a systematic way, expandingon our previous work on a secure key from bound entanglement(Horodecki et al., 2005). More detailed proofs, discussion, andexamples are provided of the main results. Namely, we demonstratethat all quantum cryptographic protocols can be recast in away which looks like entanglement theory, with the only changebeing...

Quantum key distribution based on private states: Unconditional security over untrusted channels with zero quantum capacity
PublicationIn this paper, we prove unconditional security for a quantum key distribution (QKD) protocol based on distilling pbits (twisted ebits) from an arbitrary untrusted state that is claimed to contain distillable key. Our main result is that we can verify security using only public communicationvia parameter estimation of the given untrusted state. The technique applies even to boundentangled states, thus extending QKD to the regime...

TAI: Algorithmic Information Theory: Kolmogorov Complexity
Conferences 
International Symposium on Information Theory and Its Applications
Conferences 
Amplifying the Randomness of Weak Sources Correlated With Devices
PublicationThe problem of deviceindependent randomness amplification against nosignaling adversaries has so far been studied under the assumption that the weak source of randomness is uncorrelated with the (quantum) devices used in the amplification procedure. In this paper, we relax this assumption, and reconsider the original protocol of Colbeck and Renner using a SanthaVazirani (SV) source. To do so, we introduce an SVlike condition...

Average Redundancy of the Shannon Code for Markov Sources
PublicationIt is known that for memoryless sources, the average and maximal redundancy of fixed–to–variable length codes, such as the Shannon and Huffman codes, exhibit two modes of behavior for long blocks. It either converges to a limit or it has an oscillatory pattern, depending on the irrationality or rationality, respectively, of certain parameters that depend on the source. In this paper, we extend these findings, concerning the Shannon...

A few steps more towards NPT bound entanglement
PublicationIn this paper, existence of bound entangled states with nonpositive partial transpose (NPT) is considered. As one knows, existence of such states would in particular imply nonadditivity of distillable entanglement. Moreover, it would rule out a simple mathematical description of the set of distillable states. The particular state, known to be 1copy nondistillable and supposed to be bound entangled, is considered. The problem of...

Types of Markov Fields and Tilings
PublicationThe method of types is one of the most popular techniques in information theory and combinatorics. However, thus far the method has been mostly applied to onedimensional Markov processes, and it has not been thoroughly studied for general Markov ﬁelds. Markov ﬁelds over a ﬁnite alphabet of size m ≥ 2 can be viewed as models for multidimensional systems with local interactions. The locality of these interactions is represented...

Squashed entanglement for multipartite states and entanglement measures based on the mixed convex roof
PublicationNew measures of multipartite entanglement are constructedbased on two definitions of multipartite information anddifferent methods of optimizing over extensions of the states. Oneis a generalization of the squashed entanglement where one takesthe mutual information of parties conditioned on the state's extensionand takes the infimum over such extensions. Additivity ofthe multipartite squashed entanglement is proved for both versionsof...

On the Limiting Distribution of LempelZiv’78 Redundancy for Memoryless Sources
PublicationWe study the LempelZiv'78 algorithm and show that its (normalized) redundancy rate tends to a Gaussian distribution for memoryless sources. We accomplish it by extending findings from our 1995 paper, in particular, by presenting a new simplified proof of the central limit theorem (CLT) for the number of phrases in the LZ'78 algorithm. We first analyze the asymptotic behavior of the total path length in the associated digital search...

Lowdimensional bound entanglement with oneway distillable cryptographic key
PublicationIn this paper, we provide a class of bound entangled states that have positive distillable secure key rate. The smallest state of this kind is 4 circle times 4, which shows that peculiar security contained in bound entangled states does not need highdimensional systems. We show that for these states a positive key rate can be obtained by oneway DevetakWinter (DW) protocol. Subsequently, the volume of bound entangled keydistillable...

The 3rd ACM International Conference on the Theory of Information Retrieval
Conferences 
International Conference on the Theory and Application of Cryptology and Information Security
Conferences 
IEEE Information Theory Workshop on Detection, Estimation, Classification and Imaging
Conferences 
Quantum Coherence as a Resource
PublicationThe coherent superposition of states, in combination with the quantization of observables, represents one of the most fundamental features that mark the departure of quantum mechanics from the classical realm. Quantum coherence in manybody systems embodies the essence of entanglement and is an essential ingredient for a plethora of physical phenomena in quantum optics, quantum information, solid state physics, and nanoscale thermodynamics....