Entanglement measurement based on two-particle interference

We propose a simple and realizable method using a two-particle interferometer for the experimental measurement of pairwise entanglement, assuming some prior knowledge about the quantum state. The basic idea is that the properties of the density matrix can be revealed by the single- and two-particle interference patterns. The scheme can easily be implemented with polarized entangled photons.Comment: 5 pages, 1 figur

The source structure of 0642+449 detected from the CONT14 observations

The CONT14 campaign with state-of-the-art VLBI data has observed the source 0642+449 with about one thousand observables each day during a continuous observing period of fifteen days, providing tens of thousands of closure delays---the sum of the delays around a closed loop of baselines. The closure delay is independent of the instrumental and propagation delays and provides valuable additional information about the source structure. We demonstrate the use of this new "observable" for the determination of the structure in the radio source 0642+449. This source, as one of the defining sources in the second realization of the International Celestial Reference Frame (ICRF2), is found to have two point-like components with a relative position offset of -426 microarcseconds in right ascension and -66 microarcseconds in declination. The two components are almost equally bright with a flux-density ratio of 0.92. The standard deviation of closure delays for source 0642+449 was reduced from 139 ps to 90 ps by using this two-component model. Closure delays larger than one nanosecond are found to be related to the source structure, demonstrating that structure effects for a source with this simple structure could be up to tens of nanoseconds. The method described in this paper does not rely on a priori source structure information, such as knowledge of source structure determined from direct (Fourier) imaging of the same observations or observations at other epochs. We anticipate our study to be a starting point for more effective determination of the structure effect in VLBI observations.Comment: 14 pages, 13 figures, Accepted by Astronomical Journal on 12 Jul, 201

Changes in endogenous hormone concentrations during inflorescence induction and development in pineapple (Ananas comosus cv. Smooth Cayenne) by ethephon

This study investigated the changes of five endogenous hormones in the shoot apex and the white bases of D-leaf during the inflorescence induction and development of ‘Smooth Cayenne’ pineapple, using 14-month-old pot-grown plants as material and ethephon as flower forcing agent. Results showed that application of ethephon increased the level of endogenous ethylene (C2H4), abscisic acid (ABA) and 2-isopentyl adenine (2-iP) while it decreased the concentration of indole-3-acetic acid (IAA), gibberellic acid (GA3) and zeatin (ZT), and led to the transition of vegetative growth to inflorescence initiation. After inflorescence initiation, the contents of C2H4, ABA and 2-iP declined but the contents of IAA, ABA and ZT increased. These results indicated that low levels of IAA, GA3 and ZT and high levels of C2H4, ABA and 2-iP facilitated inflorescence initiation, while high levels of ZT, IAA and GA3 and low levels of C2H4 and ABA facilitated inflorescence development.Key words: Pineapple, inflorescence initiation, inflorescence development, endogenous hormone

The impacts of source structure on geodetic parameters demonstrated by the radio source 3C371

Closure quantities measured by very long baseline interferometry (VLBI) observations are independent of instrumental and propagation instabilities and antenna gain factors, but are sensitive to source structure. A new method is proposed to calculate a structure index based on the median values of closure quantities rather than the brightness distribution of a source. The results are comparable to structure indices based on imaging observations at other epochs and demonstrate the flexibility of deriving structure indices from exactly the same observations as used for geodetic analysis and without imaging analysis. A three-component model for the structure of source 3C371 is developed by model-fitting closure phases. It provides a real case of tracing how the structure effect identified by closure phases in the same observations as the delay observables affects the geodetic analysis, and investigating which geodetic parameters are corrupted to what extent by the structure effect. Using the resulting structure correction based on the three-component model of source 3C371, two solutions, with and without correcting the structure effect, are made. With corrections, the overall rms of this source is reduced by 1 ps, and the impacts of the structure effect introduced by this single source are up to 1.4 mm on station positions and up to 4.4 microarcseconds on Earth orientation parameters. This study is considered as a starting point for handling the source structure effect on geodetic VLBI from geodetic sessions themselves.Comment: 5 figures, 15 pages, accepted by Journal of Geodesy at 19 Dec., 201

Collapses and revivals of exciton emission in a semiconductor microcavity: detuning and phase-space filling effects

We investigate exciton emission of quantum well embedded in a semiconductor microcavity. The analytical expressions of the light intensity for the cases of excitonic number state and coherent state are presented by using secular approximation. Our results show that the effective exciton-exciton interaction leads to the appearance of collapse and revival of the light intensity. The revival time is twice compared the coherent state case with that of the number state. The dissipation of the exciton-polariton lowers the revival amplitude but does not alter the revival time. The influences of the detuning and the phase-space filling are studied. We find that the effect of the higher-order exciton-photon interaction may be removed by adjusting the detuning.Comment: 7 pages, 3 figure

Correlations in interference and diffraction

Quantum formalism of Fraunhofer diffraction is obtained. The state of the diffraction optical field is connected with the state of the incident optical field by a diffraction factor. Based on this formalism, correlations of the diffraction modes are calculated with different kinds of incident optical fields. Influence of correlations of the incident modes on the diffraction pattern is analyzed and an explanation of the ''ghost'' diffraction is proposed.Comment: 16 pages, 2 figures, Latex, to appear in J. Mod. Op

Class of exactly solvable SO(n) symmetric spin chains with matrix product ground states

We introduce a class of exactly solvable SO(n) symmetric Hamiltonians with matrix product ground states. For an odd $n\geq 3$ case, the ground state is a translational invariant Haldane gap spin liquid state; while for an even $n\geq 4$ case, the ground state is a spontaneously dimerized state with twofold degeneracy. In the matrix product ground states for both cases, we identify a hidden antiferromagnetic order, which is characterized by nonlocal string order parameters. The ground-state phase diagram of a generalized SO(n) symmetric bilinear-biquadratic model is discussed.Comment: 11 pages, 5 figure

Exact Solution of a Yang-Baxter Spin-1/2 Chain Model and Quantum Entanglement

Entanglement is believed to be crucial in macroscopic physical systems for understanding the collective quantum phenomena such as quantum phase transitions. We start from and solve exactly a novel Yang-Baxter spin-1/2 chain model with inhomogeneous and anisotropic short-range interactions. For the ground state, we show the behavior of neighboring entanglement in the parameter space and find that the inhomogeneous coupling strengths affect entanglement in a distinctive way from the homogeneous case, but this would not affect the coincidence between entanglement and quantum criticality.Comment: 7 pages, 3 figure

Two-channel Kondo model as a generalized one-dimensional inverse square long-range Haldane-Shastry spin model

Majorana fermion representations of the algebra associated with spin, charge, and flavor currents have been used to transform the two-channel Kondo Hamiltonian. Using a path integral formulation, we derive a reduced effective action with long-range impurity spin-spin interactions at different imaginary times. In the semiclassical limit, it is equivalent to a one-dimensional Heisenberg spin chain with two-spin, three-spin, etc. long-range interactions, as a generalization of the inverse-square long-range Haldane-Shastry spin model. In this representation the elementary excitations are "semions", and the non-Fermi-liquid low-energy properties of the two-channel Kondo model are recovered.Comment: 4 pages, no figure, to be published in J. Phys.: Condens. Matter, 200