Universal emergence of the one-third plateau in the magnetization process of frustrated quantum spin chains

We present a numerical study of the magnetization process of frustrated quantum spin-S chains with S=1, 3/2, 2 as well as the classical limit. Using the exact diagonalization and density-matrix renormalization techniques, we provide evidence that a plateau at one third of the saturation magnetization exists in the magnetization curve of frustrated spin-S chains with S>1/2. Similar to the case of S=1/2, this plateau state breaks the translational symmetry of the Hamiltonian and realizes an up-up-down pattern in the spin component parallel to the external field. Our study further shows that this plateau exists both in the cases of an isotropic exchange and in the easy-axis regime for spin-S=1, 3/2, and 2, but is absent in classical frustrated spin chains with isotropic interactions. We discuss the magnetic phase diagram of frustrated spin-1 and spin-3/2 chains as well as other emergent features of the magnetization process such as kink singularities, jumps, and even-odd effects. A quantitative comparison of the one-third plateau in the easy-axis regime between spin-1 and spin-3/2 chains on the one hand and the classical frustrated chain on the other hand indicates that the critical frustration and the phase boundaries of this state rapidly approach the classical result as the spin S increases.Comment: 15 pages RevTex4, 13 figure

Entangled-Photon Imaging of a Pure Phase Object

We demonstrate experimentally and theoretically that a coherent image of a pure phase object may be obtained by use of a spatially incoherent illumination beam. This is accomplished by employing a two-beam source of entangled photons generated by spontaneous parametric down-conversion. Though each of the beams is, in and of itself, spatially incoherent, the pair of beams exhibits higher-order inter-beam coherence. One of the beams probes the phase object while the other is scanned. The image is recorded by measuring the photon coincidence rate using a photon-counting detector in each beam. Using a reflection configuration, we successfully imaged a phase object implemented by a MEMS micro-mirror array. The experimental results are in accord with theoretical predictions.Comment: 11 pages, 3 figures, submittedto Phys. Rev. Let

Optical and Ionospheric Phenomena at EISCAT under continuous X-mode HF pumping

We present experimental results from multiinstrument observations in the high-latitude ionospheric F2 layer at the EISCAT (European Incoherent Scatter Scientific Association) heating facility. The results come from a set of experiments, when an X-polarized HF pump wave at high heater frequencies (fH > 6.0 MHz) was injected into the F region of the ionosphere toward the magnetic zenith. Experiments were carried out under quiet magnetic conditions with an effective radiated power of 458–548 MW. HF pumping was produced at different heater frequencies, away from electron gyroharmonic frequencies, and different durations of heater pulses. We show the first experimental evidence of the excitation of artificial optical emissions at red (630 nm) and green (557.7 nm) lines in the high-latitude ionospheric F2 layer induced by an X-polarized HF pump wave. Intensities at red and green lines varied in the range 110–950 R and 50–350 R, respectively, with a ratio of green to red line of 0.35–0.5. The results of optical observations are compared with behaviors of the HF-enhanced ion and plasma lines from EISCAT UHF incoherent scatter radar data and small-scale field-aligned artificial irregularities from Cooperative UK Twin Located Auroral Sounding System observations. It was found that the X-mode radio-induced optical emissions coexisted with HF-enhanced ion and plasma lines and strong artificial field-aligned irregularities throughout the whole heater pulse. It is indicative that parametric decay or oscillating two-stream instabilities were not quenched by fully established small-scale field-aligned artificial irregularities excited by an X-mode HF pump wave

Experience of using lumacaftor/ivacaftor in children with cystic fibrosis in the Astrakhan region

Background. Targeted therapy in patients with cystic fibrosis, which aims to restore the function of the cystic fibrosis transmembrane conductance regulator protein, is currently revolutionary in the treatment of the disease. The first drug available in Russia for the treatment of patients with this genetic disease is lumacaftor/ivacaftor (Orkambi®), which was registered on December 2, 2020.The aim. To study the efficacy of lumacaftor/ivacaftor during 12 weeks of administration in children in Astrakhan region.Materials and methods. This article presents the clinical experience of Orkambi medicine use in 3 children with F508del/F508del genotype and a severe course of cystic fibrosis for 12 weeks. According to the study design, such indices as body mass index, indexes of external respiratory function, character of respiratory tract microbiota, level of chloride in sweat fluid and pancreatic elastase in feces, dynamics of biochemical blood indexes were evaluated. The study was performed within the time periods specified in the study protocol, namely, before the start of therapy, 2, 4, and 12 weeks of treatment.Results. Two patients had a decrease in sweat test values by 11 and 19 mmol/l from the baseline, a significant increase in forced vital capacity of lungs. One patient had an adverse event in the form of hepatobiliary disorders manifested by increased liver transaminase activity, which was the reason for discontinuing the drug.Conclusions. The short-term experience of using pathogenetic therapy with lumacaftor/ ivacaftor in children in the Astrakhan region demonstrated both the expected effect on chlorine channel function and the possibility of side effects, including severe ones, that can lead to withdrawal of the drug

Polarization-sensitive quantum-optical coherence tomography

We set forth a polarization-sensitive quantum-optical coherence tomography (PS-QOCT) technique that provides axial optical sectioning with polarization-sensitive capabilities. The technique provides a means for determining information about the optical path length between isotropic reflecting surfaces, the relative magnitude of the reflectance from each interface, the birefringence of the interstitial material, and the orientation of the optical axis of the sample. PS-QOCT is immune to sample dispersion and therefore permits measurements to be made at depths greater than those accessible via ordinary optical coherence tomography. We also provide a general Jones matrix theory for analyzing PS-QOCT systems and outline an experimental procedure for carrying out such measurements.Comment: 15 pages, 5 figures, to appear in Physical Review

Phenomenological theory of phase transitions in highly piezoelectric perovskites

Recently discovered fine structure of the morphotropic phase boundaries in highly piezoelectric mixture compounds PZT, PMN-PT, and PZN-PT demonstrates the importance of highly non-linear interactions in these systems. We show that an adequate Landau-type description of the ferroelectric phase transitions in these compounds is achieved by the use of a twelfth-order expansion of the Landau potential in terms of the phenomenological order parameter. Group-theoretical and catastrophe-theory methods are used in constructing the appropriate Landau potential. A complete phase diagram is calculated in phenomenological parameter space. The theory describes both PZT and PZN-PT types of phase diagrams, including the newly found monoclinic and orthorhombic phases. Anomalously large piezoelectric coefficients are predicted in the vicinity of the phase transition lines.Comment: RevTex4, 8 pages, 2 figures. Dramatically changed after referees' Comments, to appear in Phys. Rev. B, 1 April 200

Role of entanglement in two-photon imaging

The use of entangled photons in an imaging system can exhibit effects that cannot be mimicked by any other two-photon source, whatever the strength of the correlations between the two photons. We consider a two-photon imaging system in which one photon is used to probe a remote (transmissive or scattering) object, while the other serves as a reference. We discuss the role of entanglement versus correlation in such a setting, and demonstrate that entanglement is a prerequisite for achieving distributed quantum imaging.Comment: 15 pages, 2 figure

ASSOCIATION OF CC16 POLYMORPHISM WITH RISK FACTORS OF FORMATION OF BRONCHO-OBSTRUCTIVE SYNDROME IN CHILDREN

Syndrome of bronchial obstruction is a symptomatic complex arising on the background of constriction or occlusion of bronchial tubes of different caliber due to bronchospasm, edema and inflammation of the bronchial mucosa, hypersecretion of mucus or compression by surrounding structures. Bronchoobstructive syndrome (BOS) is one of the most common pathological conditions in pediatric practice. The outcome of BOS can be different: from the complete disappearance of clinical manifestations to the process, disability or even death. Accordingly, the study of this problem and the search for methods for early diagnosis and prediction of the outcome of BOS is a very urgent problem. In order to identify risk factors for BOS and to clarify the association with polymorphism of the CC16 gene, 126 children belonging to the main group and 58 from the comparison group were examined. In the course of the study, the triggers influence on the formation of the BOS of concomitant ENT pathology, burdened personal and family allergic anamnesis, and also the recurrent nature of respiratory infections in the first year of life was proved. The association of polymorphism of AA gene of CC16 with the presence of weighed allergic anamnesis and frequent episodes of ARVI, as well as the influence of this genotype on the early debut of respiratory diseases in children, has been revealed. The relationship of the GG genotype with the concomitant ENT pathology among patients with recurrent BOS has been proved

One-Way Entangled-Photon Autocompensating Quantum Cryptography

A new quantum cryptography implementation is presented that combines one-way operation with an autocompensating feature that has hitherto only been available in implementations that require the signal to make a round trip between the users. Using the concept of advanced waves, it is shown that this new implementation is related to the round-trip implementations in the same way that Ekert's two-particle scheme is related to the original one-particle scheme of Bennett and Brassard. The practical advantages and disadvantages of the proposed implementation are discussed in the context of existing schemes.Comment: 5 pages, 1 figure; Minor edits--conclusions unchanged; accepted for publication in Physical Review

A multi-photon Stokes-parameter invariant for entangled states

We consider the Minkowskian norm of the n-photon Stokes tensor, a scalar invariant under the group realized by the transformations of stochastic local quantum operations and classical communications (SLOCC). This invariant is offered as a candidate entanglement measure for n-qubit states and discussed in relation to measures of quantum state entanglement for certain important classes of two-qubit and three-qubit systems. This invariant can be directly estimated via a quantum network, obviating the need to perform laborious quantum state tomography. We also show that this invariant directly captures the extent of entanglement purification due to SLOCC filters.Comment: 9 pages, 0 figures, Accepted for publication in Physical Review