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Wyniki wyszukiwania dla: QUANTUM-CHEMICAL CALCULATIONS
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Efficient bounds on quantum-communication rates via their reduced variants
PublikacjaWe investigate one-way communication scenarios where Bob operating on his component can transfer some subsystem to the environment. We define reduced versions of quantum-communication rates and, further, prove upper bounds on a one-way quantum secret key, distillable entanglement, and quantum-channel capacity by means of their reduced versions. It is shown that in some cases they drastically improve their estimation.
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Quantum strategies for rendezvous and domination tasks on graphs with mobile agents
PublikacjaThis paper explores the application of quantum nonlocality, a renowned and unique phenomenon acknowledged as a valuable resource. Focusing on an alternative application, we demonstrate its quantum advantage for mobile agents engaged in specific distributed tasks without communication. The research addresses the significant challenge of rendezvous on graphs and introduces a distributed task for mobile agents grounded in the graph...
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Tip-Based Nanofabrication as a Rapid Prototyping Tool for Quantum Science and Technology
PublikacjaTip-Based Nanofabication as a Rapid Prototyping Tool for Quantum Science and Technology discusses the development of cantilevered nanotips techniques of quantum devices prototyping and how they evolved from scanning probe microscopy. Also covered are the advantages and future prospects of atomic resolution capability and how to use this enabling technology as a rapid prototyping tool for quantum science and technology.
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Quantum-correlation breaking channels, broadcasting scenarios, and finite Markov chains
PublikacjaOne of the classical results concerning quantum channels is the characterization of entanglementbreakingchannels [M. Horodecki et al., Rev. Math. Phys 15, 629 (2003)]. We address the questionwhether there exists a similar characterization on the level of quantum correlations which may gobeyond entanglement. The answer is fully affirmative in the case of breaking quantum correlationsdown to the, so called, QC (Quantum-Classical)...
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The Ellenbogen's “Matter as Software” Concept for Quantum Computer Implementation. C60 and X@C60 Molecules as Available Molecular Building Blocks (MBBs) for Tip-Based Nanofabrication (TBN) of Quantum Computing Devices
PublikacjaThe TBN bottom-up strategy of building quantum devices from C60 and X@C60 MBBs is proposed as an extension of the Ellenbogen's “Matter as Software” idea to quantum information processing. The capped SW or DW CNT STM tip is considered as device for manipulating C60 and X@C60 molecules. In this article, the possibility of using easily available on the market C60 Fullerene and endohedral X@C60 molecules together with commercial CNT...
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Analytical studies of spectrum broadcast structures in quantum Brownian motion
PublikacjaSpectrum broadcast structures are a new and fresh concept in the quantum-to-classical transition, introduced recently in the context of decoherence and the appearance of objective features in quantum mechanics. These are specific quantum state structures, responsible for the objectivization of the decohered state of a system. Recently, they have been demonstrated by means of the well-known quantum Brownian motion model of the recoilless...
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Quantum privacy witness
PublikacjaWhile it is usually known that the mean value of a single observable is enough to detect entanglement or its distillability, the counterpart of such an approach in the case of quantum privacy has been missing. Here we develop the concept of a privacy witness, i.e., a single observable that may detect the presence of the secure key even in the case of bound entanglement. Then we develop the notion of secret-key estimation based...
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Are quantum correlations symmetric?
PublikacjaWe 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...
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A simple test for quantum channel capacity
PublikacjaBased on state and channel isomorphism we point out that semidefiniteprogramming can be used as a quick test for nonzero one-way quantum channelcapacity. This can be achieved by searching for symmetric extensions of statesisomorphic to a given quantum channel. With this method we provide examplesof quantum channels that can lead to high entanglement transmission but stillhave zero one-way capacity, in particular, regions of symmetric...
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Steering is an essential feature of non-locality in quantum theory
PublikacjaA physical theory is called non-local when observers can produce instantaneous effects over distant systems. Non-local 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 well-known class of non-local games known as XOR games. In particular, optimal quantum strategies for XOR games are completely determined...
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The Ellenbogen’s “Matter as Software” Concept for Quantum Computer Implementation: IV. The X@C60 Molecular Building Blocks (MBBs) and Computing System Lifetime Estimation
PublikacjaThe problem of approximate lifetimes of individual X@C60 MBBs and tip-based nanofabricated quantum computing device systems is discussed under the conservative assumption of single-point failure. A single chemical transformation of the C60 cage into high-energy opened o-C60 isomer which forms the communication canal for the low energy transfer of an X atom from X@C60 MBB to the outside environment was studied. According to the...
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Urchin-like TiO2 structures decorated with lanthanide-doped Bi2S3 quantum dots to boost hydrogen photogeneration performance
PublikacjaThe formation of heterojunctions between wide- and narrow-bandgap photocatalysts is commonly employed to boost the efficiency of photocatalytic hydrogen generation. Herein, the photoactivity of urchin-like rutile particles is increased by decorating with pristine as well as Er- or Yb-doped Bi2S3 quantum dots (QDs) at varied QD loadings (1–20 wt%) and doping degrees (1–15 mol%), and the best hydrogen evolution performance is achieved at...
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Quantum corrections to 4 model solutions and applications to Heisenberg chain dynamics
PublikacjaThe Heisenberg spin chain is considered in φ^4 model approximation. Quantum corrections to classical solutions of the one-dimensional φ^4 model within the correspondent physics are valuated with account of rest d − 1 dimensions of a d-dimensional theory. A quantization of the model is considered in terms of space- time functional integral. The generalized zeta-function formalism is used to renormalize and evaluate the functional...
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Cosmic-Time Quantum Mechanics and the Passage-of-Time Problem
PublikacjaA new dynamical paradigm merging quantum dynamics with cosmology is discussed.
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Optical and photocatalytic properties of rare earth metal-modified ZnO quantum dots
PublikacjaA series of novel ZnO quantum dots modified with rare earth metals was successfully prepared by a simple sol-gel approach. The effects of types (Eu, Er, Tb, Yb, Ho, La) and amounts (from 0.09 to 0.45 mmol) of lanthanides on the optical properties, structural characterization and photocatalytic activity of ZnO/RE QDs were systematically investigated. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform...
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Quantum corrections to phi^4 model solutions and applications to Heisenberg chain dynamics
PublikacjaThe Heisenberg spin chain is considered in φ^4 model approximation. Quantum corrections to classical solutions of the one-dimensional φ^4 model within the correspondent physics are evaluated with account of rest d−1 dimensions of a d-dimensional theory. A quantization of the model is considered in terms of spacetime functional integral. The generalized zeta-function formalism is used to renormalize and evaluate the functional integral...
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No-local-broadcasting theorem for multipartite quantum correlations
PublikacjaWe prove that the correlations present in a multipartite quantum state have an operational quantum character even if the state is unentangled, as long as it does not simply encode a multipartite classical probability distribution. Said quantumness is revealed by the new task of local broadcasting, i.e., of locally sharing preestablished correlations, which is feasible if and only if correlations are stricly classical. Our operational...
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Experimental certification of an informationally complete quantum measurement in a device-independent protocol
PublikacjaMinimal informationally complete positive operator-valued measures (MIC-POVMs) are special kinds of measurement in quantum theory in which the statistics of their d2-outcomes are enough to reconstruct any d-dimensional quantum state. For this reason, MIC-POVMs are referred to as standard measurements for quantum information.Here, we report an experiment with entangled photon pairs that certifies, for what we believe is the first...
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Evaluation of ChatGPT Applicability to Learning Quantum Physics
PublikacjaChatGPT is an application that uses a large language model. Its purpose is to generate answers to various questions as well as provide information, help solve problems and participate in conversations on a wide range of topics. This application is also widely used by students for the purposes of learning or cheating (e.g., writing essays or programming codes). Therefore, in this contribution, we evaluate the ability of ChatGPT...
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Multi-criterion, evolutionary and quantum decision making in complex systems
PublikacjaMulti-criterion, evolutionary and quantum decision making supported by the Adaptive Quantum-based Multi-criterion Evolutionary Algorithm (AQMEA) has been considered for distributed complex systems. AQMEA had been developed to the task assignment problem, and then it has been applied to underwater vehicle planning as another benchmark three-criterion optimization problem. For evaluation of a vehicle trajectory three criteria have...
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Connections between Mutually Unbiased Bases and Quantum Random Access Codes
PublikacjaWe present a new quantum communication complexity protocol, the promise--Quantum Random Access Code, which allows us to introduce a new measure of unbiasedness for bases of Hilbert spaces. The proposed measure possesses a clear operational meaning and can be used to investigate whether a specific number of mutually unbiased bases exist in a given dimension by employing Semi--Definite Programming techniques.
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Thermodynamical approach to quantifying quantum correlations
PublikacjaWe consider the amount of work which can be extracted from a heat bath using a bipartite state ρ shared by two parties. In general it is less then the amount of work extractable when one party is in possession of the entire state. We derive bounds for this “work deficit” and calculate it explicitly for a number of different cases. In particuar, for pure states the work deficit is exactly equal to the distillable entanglement of...
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Entangled Histories vs. the Two-State-Vector Formalism - Towards a Better Understanding of Quantum Temporal Correlations
PublikacjaThe Two-State-Vector formalism and the Entangled Histories formalism are attempts to betterunderstand quantum correlations in time. Both formalisms share some similarities, but they are notidentical, having subtle differences in their interpretation and manipulation of quantum temporalstructures. However, the main objective of this paper is to prove that, with appropriately definedscalar products, both formalisms can be...
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Quantum superadditivity in linear optics networks: Sending bits via multiple-access Gaussian channels
PublikacjaSuperadditivity effects of communication capacities are known in the case of discrete variable quantum channels. We describe the continuous variable analog of one of these effects in the framework of Gaussian multiple access channels (MACs). Classically, superadditivity-type effects are strongly restricted: For example, adding resources to one sender is never advantageous to other senders in sending their respective information...
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Remarkable visible-light induced hydrogen generation with ZnIn2S4 microspheres/CuInS2 quantum dots photocatalytic system
PublikacjaA new and active material in the form of ZnIn2S4 microspheres decorated by CuInS2 quantum dots have been obtained by hydrothermal method for the first time. The optimum amount of CuInS2 quantum dots (1.13 wt.%) introduced into rection medium during ZnIn2S4 microspheres synthesis increased the photocatalytic H2 generation rate by 2.5 times than that of bare ZnIn2S4 photocatalysis under visible light irradiation. This sample exhibited...
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Local hidden–variable models for entangled quantum states
PublikacjaWhile entanglement and violation of Bell inequalities were initially thought to be equivalent quantum phenomena, we now have different examples of entangled states whose correlations can be described by local hidden-variable models and, therefore, do not violate any of the Bell inequalities. We provide an up-to-date overview of the existing literature regarding local hidden-variable models for entangled quantum states, in both...
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H2O˙+ and OH+ reactivity versus furan: experimental low energy absolute cross sections for modeling radiation damage
PublikacjaRadiotherapy is one of the most widespread and efficient strategies to fight malignant tumors. Despite its broad application, the mechanisms of radiation-DNA interaction are still under investigation. Theoretical models to predict the effects of a particular delivered dose are still in their infancy due to the difficulty of simulating a real cell environment, as well as the inclusion of a large variety of secondary processes. This...
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Quantum Steering Inequality with Tolerance for Measurement-Setting Errors: Experimentally Feasible Signature of Unbounded Violation
Publikacjauantum steering is a relatively simple test for proving that the values of quantum-mechanical measurement outcomes come into being only in the act of measurement. By exploiting quantum correlations, Alice can influence — steer — Bob ’ s physical system in a way that is impossible in classical mechanics, as shown by the violation of steering inequalities. Demonstrating this and similar quantum effects for systems of increasing size,...
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Grzegorz Boczkaj dr hab. inż.
Osoby -
The photocurrent quantum efficiency dependence on the applied voltage in organic solar cells
PublikacjaWe demonstrate that our recently reported model (Szmytkowski 2007 J. Phys. D: Appl. Phys. 40 3352) of the photocurrent quantum efficiency in organic semiconductors explains the external quantum efficiency dependence on the electric field in organic solar cells. This effect can be explained by taking into account that the photogeneration of charge carriers occurs via the electron-hole pair dissociation and the space charge effects...
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Low-energy positron scattering from DNA nucleobases: the effects from permanent dipoles
PublikacjaAb initio quantum calculations for low-energy positron scattering from gas-phase isolated molecular nucleobases which are part of the DNA structure are presented and discussed over the range of 1 eV to 25 eV. The calculations report the integral cross sections (ICSs) and the momentum-transfer cross sections (MTCSs) for Adenine, Guanine, Thymine and Cytosine. The calculations show very clearly the important role of the dominant...
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Vibrational Quenching of Optically Pumped Carbon Dimer Anions
PublikacjaCareful control of quantum states is a gateway to research in many areas of science such as quantum information, quantum-controlled chemistry, and astrophysical processes. Precise optical control of molecular ions remains a challenge due to the scarcity of suitable level schemes, and direct laser cooling has not yet been achieved for either positive or negative molecular ions. Using a cryogenic wire trap, we show how the internal...
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Quantum structure in competing lizard communities
PublikacjaAlmost two decades of research on applications of the mathematical formalism of quantum theory as a modeling tool in domains different from the micro-world has given rise to many successful applications in situations related to human behavior and thought, more specifically in cognitive processes of decision-making and the ways concepts are combined into sentences. In this article, we extend this approach to animal behavior, showing...
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Time travel without paradoxes: Ring resonator as a universal paradigm for looped quantum evolutions
PublikacjaA ring resonator involves a scattering process where a part of the output is fed again into the input. The same formal structure is encountered in the problem of time travel in a neighborhood of a closed timelike curve (CTC). We know how to describe quantum optics of ring resonators, and the resulting description agrees with experiment. We can apply the same formal strategy to any looped quantum evolution, in particular to the...
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Multi-criterion decision making in distributed systems by quantum evolutionary algorithms
PublikacjaDecision making by the AQMEA (Adaptive Quantum-based Multi-criterion Evolutionary Algorithm) has been considered for distributed computer systems. AQMEA has been extended by a chromosome representation with the registry of the smallest units of quantum information. Evolutionary computing with Q-bit chromosomes has been proofed to characterize by the enhanced population diversity than other representations, since individuals represent...
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Directed percolation effects emerging from superadditivity of quantum networks
PublikacjaEntanglement-induced nonadditivity of classical communication capacity in networks consisting of quantum channels is considered. Communication lattices consisting of butterfly-type entanglement-breaking channels augmented, with some probability, by identity channels are analyzed. The capacity superadditivity in the network is manifested in directed correlated bond percolation which we consider in two flavors: simply directed and...
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Hybrid quantum-classical approach for atomistic simulation of metallic systems
PublikacjaThe learn-on-the-fly (LOTF) method [G. Csanyi et al., Phys. Rev. Lett. 93, 175503 (2004)] serves to seamlessly embed quantum-mechanical computations within a molecular-dynamics framework by continual local retuning of the potential's parameters so that it reproduces the quantum-mechanical forces. In its current formulation, it is suitable for systems where the interaction is short-ranged, such as covalently bonded semiconductors....
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Complementarity between entanglement-assisted and quantum distributed random access code
PublikacjaCollaborative communication tasks such as random access codes (RACs) employing quantum resources have manifested great potential in enhancing information processing capabilities beyond the classical limitations. The two quantum variants of RACs, namely, quantum random access code (QRAC) and the entanglement-assisted random access code (EARAC), have demonstrated equal prowess for a number of tasks. However, there do exist specific...
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The adiabatic potentials of low-lying electronic states of the NaRb molecule
PublikacjaAdiabatic potential energy curves and spectroscopic constants have been calculated for the NaRb molecule. The results of ten states of the symmetry Σ+, six states of the symmetry Π, and two states of the symmetry Δ are obtained by the nonrelativistic quantum chemical method used with pseudopotentials describing the interaction of valence electrons with atomic cores. Analysis is based on a comparison with the results of other theoretical...
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Natural carbon-based quantum dots and their applications in drug delivery: A review
PublikacjaNatural carbon based quantum dots (NCDs) are an emerging class of nanomaterials in the carbon family. NCDs have gained immense acclamation among researchers because of their abundance, eco-friendly nature, aqueous solubility, the diverse functionality and biocompatibility when compared to other conventional carbon quantum dots (CDs).The presence of different functional groups on the surface of NCDs such as thiol, carboxyl, hydroxyl,...
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Distributed correlations and information flows within a hybrid multipartite quantum-classical system
PublikacjaUnderstanding the non-Markovian 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 information-theoretic point of view. To this aim, we consider a paradigmatic tripartite...
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Intramolecular transformation of an antifungal antibiotic nystatin A1 into its isomer, iso-nystatin A1 - structural and molecular modeling studies
PublikacjaNystatin A1, a polyene macrolide antifungal antibiotic, in a slightly basic or acidic solution undergoes an intramolecular transformation, yielding a structural isomer, the translactonization product, iso-nystatin A1 with lactone ring diminished by two carbon atoms. Structural evidence is provided by advanced NMR and Mass Spectrometry (MS) studies. Molecular dynamics simulations and quantum mechanics calculations gave the insight...
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Quantum corrections to quasi-periodic solution of Sine-Gordon model and periodic solution of phi^4 model
PublikacjaAnalytical form of quantum corrections to quasi-periodic solution of Sine-Gordon model and periodic solution of phi^4 model is obtained through zeta function regularisation with account of all rest variables of a d-dimensional theory. Qualitative dependence of quantum corrections on parameters of the classical systems is also evaluated for a much broader class of potentials u(x) = b^2 f(bx) + C with b and C as arbitrary real constants
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Positron-electron correlation-polarization potentials for the calculation of positron collisions with atoms and molecules
PublikacjaWe present correlation-polarization potentials for the calculation of scattering cross sections of positrons with atoms and molecules. The potentials are constructed from a short-range correlation term and a long-range polarization term. For the short-range correlation term we present four different potentials that are derived from multi-component density functionals. For the long-range polarization term we employ a multi-term...
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Quantum-state transfer in spin chains via isolated resonance of terminal spins
PublikacjaWe propose a quantum-state transfer protocol in a spin chain that requires only the control of the spins at the ends of the quantum wire. The protocol is to a large extent insensitive to inhomogeneity caused by local magnetic fields and perturbation of exchange couplings. Moreover, apart from the free evolution regime, it allows one to induce an adiabatic spin transfer, which provides the possibility of performing the transfer...
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Experimental certification of more than one bit of quantum randomness in the two inputs and two outputs scenario
PublikacjaOne of the striking properties of quantum mechanics is the occurrence of the Bell-type non-locality. They are a fundamental feature of the theory that allows two parties that share an entangled quantum system to observe correlations stronger than possible in classical physics. In addition to their theoretical significance, non-local correlations have practical applications, such as device-independent randomness generation, providing...
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Objectivity in a Noisy Photonic Environment through Quantum State Information Broadcasting
PublikacjaRecently, 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...
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A Comprehensive Experimental and Theoretical Study on the[{(η5-C5H5)2Zr[P(µ-PNEt2)2P(NEt2)2P]}2O Crystalline System
PublikacjaThe structure of tetraphosphetane zirconium complex C52H100N8OP10Zr21 was determined by single crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c, with a = 19.6452(14), b = 17.8701(12), c = 20.7963(14)Å, α = γ = 90°, β = 112.953(7)°, V = 6722.7(8)Å3, Z = 4. The electronic structure of the organometallic complex has been characterized within the framework of Quantum Chemical Topology....
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Dynamics of quantum entanglement
PublikacjaA model of discrete dynamics of entanglement of a bipartite quantum state is considered. It involves a global unitary dynamics of the system and periodic actions of local bistochastic or decaying channel. For initially pure states the decay of entanglement is accompanied by an increase of von Neumann entropy of the system. We observe and discuss revivals of entanglement due to unitary interaction of subsystems. For some mixed states...
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Multiacces quantum communication and product higher rank numerical range
PublikacjaIn 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...