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Wyniki wyszukiwania dla: CUINS2 QUANTUM DOTS
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Electrochemistry from first-principles in the grand canonical ensemble
PublikacjaProgress in electrochemical technologies, such as automotive batteries, supercapacitors, and fuel cells, depends greatly on developing improved charged interfaces between electrodes and electrolytes. The rational development of such interfaces can benefit from the atomistic understanding of the materials involved by first-principles quantum mechanical simulations with Density Functional Theory (DFT). However, such simulations are...
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All Nonclassical Correlations Can Be Activated into Distillable Entanglement
PublikacjaWe devise a protocol in which general nonclassical multipartite correlations produce a physically relevant effect, leading to the creation of bipartite entanglement. In particular, we show that the relative entropy of quantumness, which measures all nonclassical correlations among subsystems of a quantum system, is equivalent to and can be operationally interpreted as the minimum distillable entanglement generated between the system...
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Jahn-Teller and related conical intersections in the benzene radical cation and the monofluoro derivate
PublikacjaThe multi-state multi-mode vibronic interactions in the benzene radical cation and its monofluoro derivative have been investigated theoretically, based on high-level electronic structure calculations for the system parameters and a quantum treatment of the nuclear motion. The available experimental data are well reproduced. The interplay of different vibronic coupling mechanisms is pointed out leading to multiple nonadiabatic...
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Potential energy surfaces of the low-lying electronic states of the Li+LiCs system
PublikacjaAb initio quantum chemistry calculations are performed for the mixed alkali triatomic system. Global minima of the ground and first excited doublet states of the trimer are found and Born-Oppenheimer potential energy surfaces of the Li atom interacting with the LiCs molecule were calculated for these states. The lithium atom is placed at various distances and bond angles from the lithium-caesium dimer. Three-body nonadditive forces...
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Binary-Encounter Model for Direct Ionization of Molecules by Positron-Impact
PublikacjaWe introduce two models for the computation of direct ionization cross sections by positron impact over a wide range of collision energies. The models are based on the binary-encounter-Bethe model and take into account an extension of the Wannier theory. The cross sections computed with these models show good agreement with experimental data. The extensions improve the agreement between theory and experiment for collision energies...
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Entanglement and Nonlocality are Inequivalent for Any Number of Parties
PublikacjaUnderstanding the relation between nonlocality and entanglement is one of the fundamental problems in quantum physics. In the bipartite case, it is known that these two phenomena are inequivalent, as there exist entangled states of two parties that do not violate any Bell inequality. However, except for a single example of an entangled three-qubit state that has a local model, almost nothing is known about such a relation in multipartite...
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Inequivalence of entanglement, steering, and Bell nonlocality for general measurements
PublikacjaEinstein-Podolsky-Rosen steering is a form of inseparability in quantum theory commonly acknowledged to be intermediate between entanglement and Bell nonlocality. However, this statement has so far only been proven for a restricted class of measurements, namely, projective measurements. Here we prove that entanglement, one-way steering, two-way steering, and nonlocality are genuinely different considering general measurements,...
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Free randomness amplification using bipartite chain correlations
PublikacjaA direct analysis of the task of randomness amplification from Santha-Vazirani sources using the violation of the chained Bell inequality is performed in terms of the convex combination of no-signaling boxes required to simulate quantum violation of the inequality. This analysis is used to find the exact threshold value of the initial randomness parameter from which perfect randomness can be extracted in the asymptotic limit of...
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The luminescence study of Bi-doped Cs2AgInCl6 double perovskite.
Dane BadawczeHere, we report a halide precursor acid precipitation method to synthesize Cs2AgIn1−xBixCl6 (x = 0, 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, and 1) microcrystals. Cs2AgInCl6 and Bi derivative double perovskites show broadband white light emission via self-trapped excitons (STEs) and have achieved the highest internal quantum efficiency of up to 52.4% at...
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Low-energy positron scattering from gas-phase uracil
PublikacjaQuantum scattering calculations are presented for the interaction of low energy positrons with the uracil molecule, an important component of biological systems. The rotational elastic and inelastic cross sections and vibrational inelastic cross sections are reported and compared with existing experiments, indicating a general trend of the cross sections different from the experimental findings and in line with what should be expected...
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The influence of anchoring group position in ruthenium dye molecule on performance of dye-sensitized solar cells
PublikacjaThe effect of anchoring group position and, in consequence, the orientation of the ruthenium dye molecule on titania surface on the performance of dye-sensitized solar cells has been studied intensively. Three model ruthenium sensitizing dyes bearing carboxylic anchoring group in ortho, meta or para position were synthesized and well characterized by spectroscopic, electrochemical, photophysical and photochemical measurements....
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Vibrational excitation of acetylene by positron impact
PublikacjaVibrationally inelastic quantum calculations are carried out at low collision energies for the scattering of a beam of positrons off acetylene gaseous molecules. The normal mode analysis is assumed to be valid and the relative fluxes into the C–C and C–H symmetric vibrational modes are computed within a Body-Fixed (BF) formulation of the dynamics by solving the relevant vibrational Coupled Channels (VCC) equations. The clear dominance...
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Amplifying the Randomness of Weak Sources Correlated With Devices
PublikacjaThe problem of device-independent randomness amplification against no-signaling 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 Santha-Vazirani (SV) source. To do so, we introduce an SV-like condition...
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Entanglement of genuinely entangled subspaces and states: Exact, approximate, and numerical results
PublikacjaGenuinely entangled subspaces (GESs) are those subspaces of multipartite Hilbert spaces that consist only of genuinely multiparty entangled pure states. They are natural generalizations of the well-known notion of completely entangled subspaces, which by definition are void of fully product vectors. Entangled subspaces are an important tool of quantum information theory as they directly lead to constructions of entangled states,...
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Production of singlet oxygen atoms by photodissociation of oxywater
PublikacjaQuantum chemical calculations are reported for the energies of the few lowest electronic singlet states of oxywater along dissociation of the oxygen-oxygen bond into water and singlet oxygen using multistate multireference second-order Møller–Plesset perturbation theory. We compute an energy of 21 kcal/mol to remove one oxygen atom in the lowest singlet state. The two lowest excited singlet states have vertical excitation energies...
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Optical Spectroscopic Studies of Tetrahydrofuran Fragmentation Induced by Collisions with Dihydrogen Cations
PublikacjaCollisions of dihydrogen cations with tetrahydrofuran molecules have been studied. Luminescence spectra and the emission functions of the excited products at projectile energies ranging from 8 to 1000 eV have been measured using collision-induced emission spectroscopy. The recorded spectra are dominated by the atomic lines of the hydrogen Balmer series, whose intensities decrease more quickly than derived by the quantum-theoretical...
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Predicting the viscosity and electrical conductivity of ionic liquids on the basis of theoretically calculated ionic volumes
PublikacjaSelected physical properties of the ionic liquids might be quantitatively predicted based on the volumes of the ions these systems are composed of. It is demonstrated that the ionic volumes calculated using relatively simple theoretical quantum chemistry methods can be utilised to estimate the viscosities and electrical conductivities of various commonly used ionic liquids. The fitting formulas of the exponential form are offered...
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Contra Bellum: Bell's Theorem as a Confusion of Languages
PublikacjaBell's theorem is a conflict of mathematical predictions formulated within an infinite hierarchy of mathematical models. Inequalities formulated at level k ∈ Z are violated by probabilities at level k+1. We are inclined to think that k=0 corresponds to the classical world, while k=1 — to the quantum one. However, as the k=0 inequalities are violated by k=1 probabilities, the same relation holds between k=1 inequalities violated...
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Entanglement-redistribution boxes
PublikacjaWe establish a framework to study the classical-communication properties of primitive local operations assisted by classical communication which realize various redistributions of entanglement, like, e.g., entanglement swapping. On the one hand, we analyze what local operations and how much classical communication are needed to perform them. On the other hand, we investigate whether and to what extent such primitives can help to...
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Hydrogen migration in formation of NH(A3Π) radicals via superexcited states in photodissociation of isoxazole molecules
PublikacjaFormation of the excited NH(A 3Π) free radicals in the photodissociation of isoxazole (C3H3NO) molecules has been studied over the 14-22 eV energy range using photon-induced fluorescence spectroscopy. The NH(A 3Π) is produced through excitation of the isoxazole molecules into higher-lying superexcited states. Observation of the NH radical, which is not a structural unit of the isoxazole molecule, corroborates the hydrogen atom...
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A Note on Fractional Curl Operator
PublikacjaIn this letter, we demonstrate that the fractional curl operator, widely used in electromagnetics since 1998, is essentially a rotation operation of components of the complex Riemann–Silberstein vector representing the electromagnetic field. It occurs that after the wave decomposition into circular polarisations, the standard duality rotation with the angle depending on the fractional order is applied to the left-handed basis vector...
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The luminescence study of SrAl11.88−xGaxO19:0.12Cr3+ coumpounds.
Dane BadawczePortable near-infrared (NIR) light sources are in high demand for applications in spectroscopy, night vision, bioimaging, and many others. Typical phosphor designs feature isolated Cr3+ ion centers, and it is challenging to design broadband NIR phosphors based on Cr3+–Cr3+ pairs. Here, we explore the solid-solution series SrAl11.88–xGaxO19:0.12Cr3+...
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Experimental and theoretical studies on the Sulfamethazine-Urea and Sulfamethizole-Urea solid-liquid equilibria
PublikacjaThe miscibility of active pharmaceutical ingredients with excipients is an important aspect in pharmaceutical technology protocols. In this study, the differential scanning calorimetry (DSC) was used for Sulfamethazine-Urea (SI–U) and Sulfamethizole-Urea (SO–U) solid-liquid phase diagrams determination. Both sulfonamides form simple binary eutectics with Urea. The lack of new co-crystal phase formation was confirmed by inspection...
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Elimination and migration of hydrogen in the vacuum-ultraviolet photodissociation of pyridine molecules
PublikacjaElimination of the excited hydrogen atoms H(n), n = 4–7, and hydrogen migration in formation of the excited NH(A 3Π) free radicals in the photodissociation of pyridine, C5H5N, molecules have been studied over the 17.5–70 eV photon energy range. In the measurements the photon-induced fluorescence spectroscopy technique has been applied. Both fragments are produced through excitation of pyridine molecules into higher-lying superexcited...
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Entropy Production Associated with Aggregation into Granules in a Subdiffusive Environment
PublikacjaWe study the entropy production that is associated with the growing or shrinking of a small granule in, for instance, a colloidal suspension or in an aggregating polymer chain. A granule will fluctuate in size when the energy of binding is comparable to k_{B}T, which is the “quantum” of Brownian energy. Especially for polymers, the conformational energy landscape is often rough and has been commonly modeled as being self-similar...
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Fluorescence of p-hydroxyazobenzocrowns – Tautomeric equilibrium effect
PublikacjaThe spectroscopic properties of a series of para-hydroxyazobenzocrowns, including three novel compounds, were investigated using UV–Vis absorption and emission spectroscopy. This study presents, for the first time, determined quantum yield (QY) values for macrocycles of this category, ranging between 0.122 and 0.195. The highest values were obtained for crowns bearing two phenyl substituents in benzene rings. The impact of aromatic...
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Kagome Lattice Promotes Chiral Spin Fluctuations
PublikacjaDynamical spin fluctuations in magnets can be endowed with a slight bent toward left- or right-handed chirality by Dzyaloshinskii-Moriya interactions. However, little is known about the crucial role of lattice geometry on these chiral spin fluctuations and on fluctuation-related transport anomalies driven by the quantum-mechanical (Berry) phase of conduction electrons. Via thermoelectric Nernst effect and electric Hall effect experiments,...
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Conjectured strong complementary-correlations tradeoff
PublikacjaWe conjecture uncertainty relations that restrict correlations between the results of measurements performed by two separate parties on a shared quantum state. The first uncertainty relation bounds the sum of two mutual informations when one party measures a single observable and the other party measures one of two observables. The uncertainty relation does not follow from the Maassen-Uffink uncertainty relation and is much stronger...
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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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Topological, nonreciprocal, and multiresonant slow light beyond the time-bandwidth limit
PublikacjaTopologically protected transport has recently emerged as an effective means to address a recurring problem hampering the field of slow light for the past two decades: its keen sensitivity to disorders and structural imperfections. With it, there has been renewed interest in efforts to overcome the delay-time-bandwidth limitation usually characterizing slow-light devices, on occasion thought to be a fundamental limit. What exactly...
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Mutually polarizable QM/MM model with in situ optimized localized basis functions
PublikacjaWe extend our recently developed quantum-mechanical/molecular mechanics (QM/MM) approach [Dziedzic et al., J. Chem. Phys. 145, 124106 (2016)] to enable in situ optimization of the localized orbitals. The quantum subsystem is described with ONETEP linear-scaling density functional theory and the classical subsystem – with the AMOEBA polarizable force field. The two subsystems interact via multipolar electrostatics and are fully...
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1,3-alternate calix[4]arene-bonded silica stationary phases. Effect of calixarene skeleton substituents on the retention mechanism and column selectivity
PublikacjaFour novel 1,3-alternate calix[4]arene-bonded silica gel stationary phases possessing different aromatic and aliphatic substituents at the upper rim (CalixNph, CalixBph, CalixHex and CalixDdc) were prepared and structurally characterized. The comparison and selectivity of these phases was done by using alkylbenzenes, fatty acid p-bromophenacyl esters, aromatic positional isomers and polynuclear aromatic hydrocarbons as analytes....
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Inseparability criteria based on matrices of moments
PublikacjaInseparability criteria for continuous and discrete bipartite quantum states based on moments of annihilationand creation operators are studied by developing the idea of Shchukin-Vogel criterion Phys. Rev. Lett. 95,230502 2005. If a state is separable, then the corresponding matrix of moments is separable too. Thus, wederive generalized criteria based on the separability properties of the matrix of moments. In particular, acriterion...
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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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A study of concentration depolarization and quenching of photoluminescence of solutions
PublikacjaThe concentration-dependence of emission anisotropy r/r0 and quantum yield eta/eta0 of the photoluminescence of glycerol-water solutions of rhodamine B in two systems of viscosities 7.4 P and 0.72 P is investigated. The experimental data are compared with the new theory of concentraticn depolarization (J. Lumin., 5, 413 (1972)) and concentration quenching of photoluminescence (Acta Phys. Hungar., 30, 145 (1972)), which takes...
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Do positrons measure atomic and molecular diameters?
PublikacjaWe report on density functional calculations (DFT) of elastic integral scattering cross-sections for positron collisions with argon, krypton, nitrogen and methane. The long-range asymptotic polarization potential is described using higher-order terms going much beyond an induced dipole potential (−α / r 4) while the short-range interaction is modeled by two different forms of electron – positron correlation potential (Boroński-Nieminen...
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System information propagation for composite structures
PublikacjaWe study in details decoherence process of a spin register, coupled to a spin environment. We use recently developed methods of information transfer study in open quantum systems to analyze information flow between the register and its environment. We show that there are regimes when not only the register decoheres effectively to a classical bit string, but this bit string is redundantly encoded in the environment, making it available...
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Stripe order and magnetic anisotropy in the S=1 antiferromagnet BaMoP2O8
PublikacjaMagnetic behavior of yavapaiite-type BaMoP2O8 with the spatially anisotropic triangular arrangement of the S=1Mo4+ ions is explored using thermodynamic measurements, neutron diffraction, and density-functional band-structure calculations. A broad maximum in the magnetic susceptibility around 46 K is followed by the stripe antiferromagnetic order with the propagation vector k=(12,12,12) formed below TN≃21 K. This stripe phase is...
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Efficiency of exciton splitting in organic photovoltaic cells within EQE spectrum
PublikacjaThe paper presents a procedure of estimating the efficiency of exciton splitting at ED/EA interface. The procedure consists in evaluation of splitting of excitons into electron-hole pairs on the basis of the external quantum efficiency spectra of planar cells and spectra of absorbance of active organic layers. The fitting parameters are the exciton splitting probabilities at ED/EA interface. The presented procedure was applied...
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Relativistic two-dimensional hydrogen-like atom in a weak magnetic field
PublikacjaA two-dimensional (2D) hydrogen-like atom with a relativistic Dirac electron, placed in a weak, static, uniform magnetic field perpendicular to the atomic plane, is considered. Closed forms of the first- and second-order Zeeman corrections to energy levels are calculated analytically, within the framework of the Rayleigh–Schrödinger perturbation theory, for an arbitrary electronic bound state. The second-order calculations are...
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Negative result about the construction of genuinely entangled subspaces from unextendible product bases
PublikacjaUnextendible product bases (UPBs) provide a versatile tool with various applications across different areas of quantum information theory. Their comprehensive characterization is thus of great importance and has been a subject of vital interest for over two decades now. An open question asks about the existence of UPBs, which are genuinely unextendible, i.e., they are not extendible even with biproduct vectors. In other words,...
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Implementation of high-precision computation capabilities into the open-source dynamic simulation framework YADE
PublikacjaThis paper deals with the implementation of arbitrary precision calculations into the open-source discrete element framework YADE published under the GPL-2+ free software license. This new capability paves the way for the simulation framework to be used in many new fields such as quantum mechanics. The implementation details and associated gains in the accuracy of the results are discussed. Besides the "standard" double (64 bits)...
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A general approach to study molecular fragmentation and energy redistribution after an ionizing event
PublikacjaWe propose to combine quantum chemical calculations, statistical mechanical methods, and photoionization and particle collision experiments to unravel the redistribution of internal energy of the furan cation and its dissociation pathways. This approach successfully reproduces the relative intensity of the different fragments as a function of the internal energy of the system in photoelectron–photoion coincidence experiments and...
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Significance of Dermoscopy in Association with Clinical Features in Differentiation of Basal Cell Carcinoma and Benign Trichoblastic Tumours
PublikacjaBackground: Although basal cell carcinoma (BCC) can, in the majority of cases, be diagnosed based on clinical and dermoscopic assessment, a potential overlap with benign adnexal skin tumours seems to exist, including trichoblastic tumours (TT). Methods: Retrospective analysis of clinical and dermoscopic features of benign TT and BCC cases was performed to develop a diagnostic algorithm with a potential utility in clinical practice....
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Computational methods for calculation of binding free energy for ligand-receptor complexes
PublikacjaAccurate description of the molecular complexes energetic influence is required for understanding of many biological functions carried out by proteins. Therefore, estimation of binding free energy for ligand-receptor complexes is of highest importance for structure-based ligand design and drug discovery approaches.Experimental methods of determination of difference in Gibbs'es free energy have many limitations. Thus, computational...
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Can Communication Power of Separable Correlations Exceed That of Entanglement Resource?
PublikacjaThe scenario of remote state preparation with a shared correlated quantum state and one bit of forward communication [B. Dakić et al., Nat. Phys. 8, 666 (2012)] is considered. Optimization of the transmission efficiency is extended to include general encoding and decoding strategies. The importance of the use of linear fidelity is recognized. It is shown that separable states cannot exceed the efficiency of entangled states by...
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Necessary and Sufficient Condition for State-Independent Contextual Measurement Scenarios
PublikacjaThe problem of identifying measurement scenarios capable of revealing state-independent contextuality in a given Hilbert space dimension is considered. We begin by showing that for any given dimension d and any measurement scenario consisting of projective measurements, (i) the measure of contextuality of a quantum state is entirely determined by its spectrum, so that pure and maximally mixed states represent the two extremes...
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An analysis of solar energy conversion systems based on photon and thermal processes
PublikacjaSolar spectral irradiance covers a fairly broad wavelength range. Solar radiation is part of the electromagnetic spectrum which is described by the concept of wave-particle duality. The corpuscular theory of electromagnetic radiation states that energy is transmitted by photons. Photons carry specific amounts of energy which can be used to convert solar energy into other types of energy, in particular electricity. The internal...
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Redundant information encoding in QED during decoherence
PublikacjaBroadly understood decoherence processes in quantum electrodynamics, induced by neglecting either the radiation [L. Landau, Z. Phys. 45, 430 (1927)] or the charged matter [N. Bohr and L. Rosenfeld, K. Danske Vidensk. Selsk, Math.-Fys. Medd. XII, 8 (1933)], have been studied from the dawn of the theory. However, what happens in between, when a part of the radiation may be observed, as is the case in many real-life situations, has...
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Realistic noise-tolerant randomness amplification using finite number of devices
PublikacjaRandomness is a fundamental concept, with implications from security of modern data systems, to fundamental laws of nature and even the philosophy of science. Randomness is called certified if it describes events that cannot be pre-determined by an external adversary. It is known that weak certified randomness can be amplified to nearly ideal randomness using quantum-mechanical systems. However, so far, it was unclear whether randomness amplification...