Expression of the Gene d1 in the Scutellum of Maize

There have been many descriptions of the morphological expression of mutant genes in the mature plant body, but relatively little has been done on gene expression in early stages of ontogeny in higher plants. The fact that many genes have marked expression in older plants raises the question of the extent to which they are manifested at earlier stages of development. In the present study an embryonic structure of maize, the scutellum, is investigated for evidence of expression of a simple Mendelian recessive, dwarf-one (d1). Four different inbreds were used because it was anticipated that quantitative expression of the gene would be modified by association with different genotypes. The scutellum was chosen as the specific subject of study since preliminary investigations indicated that scutellum shape varied from one inbred to another. It seemed possible, then, that a single gene difference might also show some expression in this organ

Expression of the Gene d1 in the First Three Leaves of Zea Mays L.

The present study is a continuation of investigations of expression of the gene dwarf-one (d1) in the early stages of ontogeny in maize. An earlier study indicated no visible influence of the gene at the mature embryo stage, although expression appears as early after germination as the first stages of development of the mesocotyl. The objective of the present study is to explore the expression of d1 in those stages of seedling development which include maturation of the first three leaves

Growth Responses of Alpine Potentilla diversifolia and Achillea lanulosa to Gibberellic Acid

Applications of gibberellic acid have been shown to alter the growth patterns of genetic dwarfs in mize and in peas. Since the dwarf alpine habits of some native species have been demonstrated also to be genetically conditioned, among which are included certain species of Potentilla and Achillea, the present study was an attempt to investigate the possibility of growth alterations of alpine Achillea lanulosa alpicola Keck and Potentilla diversifolia Lehm. when treated with gibberellic acid. Voucher specimens of these species are in the personal herbarium of the author

Time gating of heralded single photons for atomic memories

We demonstrate a method for time gating the standard heralded continuous- wave (cw) spontaneous parametric down-converted (SPDC) single photon source by using pulsed pumping of the optical parametric oscillator (OPO) below threshold. The narrow bandwidth, high purity, high spectral brightness and the pseudo-deterministic character make the source highly suitable for light-atom interfaces with atomic memories.Comment: Accepted for publication in Optics Letter

High performance guided-wave asynchronous heralded single photon source

We report on a guided wave heralded photon source based on the creation of non-degenerate photon pairs by spontaneous parametric down conversion in a Periodically Poled Lithium Niobate waveguide. Using the signal photon at 1310 nm as a trigger, a gated detection process permits announcing the arrival of single photons at 1550 nm at the output of a single mode optical fiber with a high probability of 0.38. At the same time the multi-photon emission probability is reduced by a factor of 10 compared to poissonian light sources. Relying on guided wave technologies such as integrated optics and fiber optics components, our source offers stability, compactness and efficiency and can serve as a paradigm for guided wave devices applied to quantum communication and computation using existing telecom networks

Theory and experiment of entanglement in a quasi-phase-matched two-crystal source

We report new results regarding a source of polarization entangled photon-pairs created by the process of spontaneous parametric downconversion in two orthogonally oriented, periodically poled, bulk KTiOPO4 crystals (PPKTP). The source emits light colinearly at the non-degenerate wavelengths of 810 nm and 1550 nm, and is optimized for single-mode optical fiber collection and long-distance quantum communication. The configuration favors long crystals, which promote a high photon-pair production rate at a narrow bandwidth, together with a high pair-probability in fibers. The quality of entanglement is limited by chromatic dispersion, which we analyze by determining the output state. We find that such a decoherence effect is strongly material dependent, providing for long crystals an upper bound on the visibility of the coincidence fringes of 41% for KTiOPO4, and zero for LiNbO3. The best obtained raw visibility, when canceling decoherence with an extra piece of crystal, was 91 \pm 0.2%, including background counts. We confirm by a violation of the CHSH-inequality (S = 2.679 \pm 0.004 at 55 s^{-1/2} standard deviations) and by complete quantum state tomography that the fibers carry high-quality entangled pairs at a maximum rate of 55 x 10^3 s^{-1}THz^{-1}mW^{-1}.Comment: 12 pages, 10 figures, REVTeX

Spin Pumping in Lateral Double Quantum Dot Systems

Electron transport in single lateral quantum dot (QD) and parallel lateral double quantum dot (DQD) systems is modeled using semiclassical rate equations. The Zeeman effect, in conjunction with resonant tunneling, is used to select the spin of electrons involved in transport. We show adiabatic spin pumping by periodic variation of the systems\u27 confining parameters, namely the quantum point contacts (QPCs) dictating the boundaries of the dots, and the gate voltage applied to each dot. The limitations of adiabatic spin pumping are subsequently examined by counting the average spin pumped per cycle when frequency and interdot capacitance are adjusted

Quantum key distribution over 30km of standard fiber using energy-time entangled photon pairs: a comparison of two chromatic dispersion reduction methods

We present a full implementation of a quantum key distribution system using energy-time entangled photon pairs and functioning with a 30km standard telecom fiber quantum channel. Two bases of two orthogonal states are implemented and the setup is quite robust to environmental constraints such as temperature variation. Two different ways to manage chromatic dispersion in the quantum channel are discussed.Comment: 10 pages, 4 figure

Practical quantum repeaters with linear optics and double-photon guns

We show how to create practical, efficient, quantum repeaters, employing double-photon guns, for long-distance optical quantum communication. The guns create polarization-entangled photon pairs on demand. One such source might be a semiconducter quantum dot, which has the distinct advantage over parametric down-conversion that the probability of creating a photon pair is close to one, while the probability of creating multiple pairs vanishes. The swapping and purifying components are implemented by polarizing beam splitters and probabilistic optical CNOT gates.Comment: 4 pages, 4 figures ReVTe