186,468 research outputs found
Two electrons in a strongly coupled double quantum dot: from an artificial helium atom to a hydrogen molecule
No full textNRC publication: Ye
Theory of valence-band holes as Luttinger spinors in vertically coupled quantum dots
No full textWe describe the valence-band holes of quantum dot molecules formed by two vertically coupled disks, using a four-band k . p Hamiltonian. It is shown that the strong spin-orbit coupling of the valence band introduces characteristic features in the hole tunneling, which are not captured by the usual single-band heavy-hole approximation. Therefore, a treatment of hole states as multiband Luttinger spinors is required. Within this description the parity symmetry in the vertical direction is lost, and chirality symmetry must be used instead. Effects of spin-orbit coupling on the hole and exciton states, as well as on the optical transitions are discussed. We show that, with increasing interdot distance, the spin-orbit interaction leads to a bonding-antibonding ground-state transition and to quenching of the excitonic emission. These results are relevant to recent experiments
Influence of valence band spin-orbit coupling on the entanglement of excitons in coupled quantum dots
No full textWe study the effect of valence band spin\u2013orbit interaction on the exciton entanglement in vertically stacked quantum dots, using a multi-band k\ub7p theory for holes. It is shown that the spin\u2013orbit interaction reduces the exciton entanglement, establishing an intrinsic upper limit. For usual InGaAs nanostructures, however, this effect is generally small and does not pose a challenge for current attempts for the development of quantum information.Peer reviewed: YesNRC publication: Ye
Role Of Finite Hole Mass In The Negatively Charged Exciton In Two Dimensions
No full textThe role of finite hole mass on the ground and excited state of the negatively charged exciton in two dimensions is discussed. The configuration-interaction is analyzed using exact excitonic states. A variational approach is used to study the ground-state energy to show the interplay of finite hole mass and electron-electron interactions.94716722Brum, J.A., Hawrylak, P., (1997) Comments Condens. Matter Phys., 18, p. 135Narvaez, G.A., Brum, J.A., Hawrylak, P., (1998) Proceedings of the 24th International Conference on the Physics of Semiconductors, , in: D. Gershoni (Ed.) Jerusalem World Scientific, SingaporeHawrylak, P., (1991) Phys. Rev. B, 44, p. 3821Uenoyama, T., Sham, L.J., (1990) Phys. Rev. Lett., 65, p. 1048Kheng, K., (1993) Phys. Rev. Lett., 71, p. 1752Finkelstein, G., Shtrikman, H., Bar-Joseph, I., (1995) Phys. Rev. Lett., 74, p. 976Buhmann, H., (1995) Phys. Rev. B, 51, p. 7969Shields, A.J., (1995) Phys. Rev. B, 51, p. 8049Shields, A.J., Pepper, M., Simmons, M.Y., Ritchie, D.A., (1995) Phys. Rev. B, 52, p. 7841Gekhtman, D., Cohen, E., Ron, A., Pfeiffer, L.N., (1996) Phys. Rev. B, 54, p. 10320Glasberg, S., Finkelstein, G., Shtrikman, H., Bar-Joseph, I., (1999) Phys. Rev. B, 59, p. 10425Hayne, M., Jones, C.L., Bogaerts, R., Riva, C., Usher, A., Peeters, F.M., Herlach, F., Henini, M., (1999) Phys. Rev. B, 59, p. 2927Lampert, M., (1958) Phys. Rev. Lett., 1, p. 450Stébé, B., Ainane, A., (1989) Superlatt. Microstruct., 5, p. 545Thilagam, A., (1997) Phys. Rev. B, 55, p. 7804Usukura, J., Suzuki, Y., Varga, K., (1999) Phys. Rev. B, 59, p. 5652Esser, E., Runge, E., Zimmermann, R., Langbein, W., (2000) Phys. Stat. Sol. a, 178, p. 489Riva, C., Peeters, F.M., Varga, K., (2000) Phys. Rev. B, 61, p. 13873Wojs, A., Hawrylak, P., (1995) Phys. Rev. B, 51, p. 10880Palacios, J.J., Yoshioka, D., MacDonald, A.H., (1996) Phys. Rev. B, 54, p. 2296Whittaker, D.M., Shields, A.J., (1997) Phys. Rev. B, 56, p. 15185Stébé, B., Moradi, A., (2000) Phys. Rev. B, 61, p. 2888Hawrylak, P., Grabowski, M., (1994) Phys. Rev. B, 49, p. 8174Shinada, M., Sugano, S., (1966) J. Phys. Soc. Jpn., 21, p. 1936MacDonald, A.H., Ritchie, D.S., (1986) Phys. Rev. B, 33, p. 8386Gradshteyn, I.M., Ryzhik, I.M., (1994) Tables of Integrals, Series, and Products, , in: A. Jeffrey (Ed.) Academic Press, New YorkChandrasekhar, S., (1944) Astrophys. J., 100, p. 176Sandler, N.P., Proetto, C.R., (1992) Phys. Rev. B, 46, p. 7707Mahan, G.D., (1981) Many-particle Physics, , Plenum Press, New York and references thereinPhelps, D.E., Bajaj, K.K., (1983) Phys. Rev. B, 27, p. 4883Larsen, D.M., McCann, S.Y., (1992) Phys. Rev. B, 45, p. 3485Larsen, D.M., McCann, S.Y., (1992) Phys. Rev. B, 46, p. 396
Multi-charged Acceptor Centers In P-doped Si/si1 -xgex/si Quantum Wells In The Presence Of A Magnetic Field
No full textNeutral (A0) and positively charged (A+) shallow acceptor centers in p-doped SiGe/Si nanostructures are investigated in the presence of an external magnetic field. The band mixing of valence states, the confinement potential and the magnetic field are responsible for an increase in the binding energy of the system. The properties of the lower-energy states of the A+ are studied and their binding energies calculated for a Si0.87Ge0.13 quantum well. It is shown that the ground state of the A+ complex has a singlet-like parity configuration up to magnetic fields as high as 12 T. The effects of hole-hole repulsive interaction and hole-impurity attractive potential on the A+ spectra are considered. © 1998 Published by Elsevier Science B.V. All rights reserved.21-4785788Shields, A.J., Pepper, M., Ritchie, D.A., Simmons, M.Y., Jones, G.A.C., (1995) Phys. Rev. B, 51, p. 18049Ryu, S.R., Jiang, Z.X., Li, W.J., McCombe, B.D., (1996) Phys. Rev. B, 54, pp. R11086MacDonald, A.H., (1992) Solid State Commun., 84, p. 109Hawrylak, P., (1993) Solid State Commun., 88, p. 475Broido, D., Sham, L.J., (1985) Phys. Rev. B, 31, p. 888Bir, G.L., Pikus, G.E., (1974) Symmetry and Strain-Inducted Effects in Semiconductors, , Wiley, New YorkMadelung, O., (1987) Landolt&Bernstein: Semiconductors, Physics of Group IV and III-V Compounds, 3-17 A. , Springer, BerlinRego, L.G.C., Hawrylak, P., Brum, J.A., Wojs, A., (1997) Phys. Rev. B, 55, p. 15694Wagner, M., Merket, U., Chaplik, A.V., (1992) Phys. Rev. B, 45, p. 1951Ashoori, R.C., Stormer, H.L., Weiner, J.S., Pfeiffer, L.N., Baldwin, K.W., West, K.W., (1993) Phys. Rev. Lett., 71, p. 61
Magnetoexcitons And Correlated Electrons In Quantum Dots In A Magnetic Field
No full textMagnetoexcitons interacting with strongly correlated electronic states in quantum dots in a strong magnetic field are studied. Exact calculations relate the absorption and emission of few-electron artificial atoms to magnetic-field-induced phase transitions between "magic" states. For large compact droplets, the coupling of magnetoexcitons to low-energy excitations (edge magnetorotons) leads to a strong enhancement of the oscillator strength at the Fermi level (Fermi edge singularity) both in absorption and in emission on acceptors. The condensation of edge magnetorotons signals the reconstruction of the droplet and is accompanied by different structures in the absorption spectrum.54161139711409Kastner, M., (1993) Phys. Today, 24 (1), p. 24Chakraborty, T., (1992) Comments Condens. Matter Phys., 16, p. 35Petroff, P.M., Denbaars, S.P., (1994) Superlatt. Microstruct., 15, p. 15Drexler, H., Leonard, D., Hansen, W., Kotthaus, J.P., Petroff, P.M., (1994) Phys. Rev. Lett., 73, p. 2252Wojs, A., Hawrylak, P., (1995) Phys. Rev. B, 51, p. 10880Ashoori, R.C., Stormer, H.L., Weiner, J.S., Pfeiffer, L.N., Baldwin, K.W., West, K.W., (1993) Phys. Rev. Lett., 71, p. 613Su, B., Goldman, V.J., Cunningham, J.E., (1992) Science, 255, p. 313Hawrylak, P., (1993) Phys. Rev. Lett., 71, p. 3347De Chamon, C., Wen, X.-G., (1994) Phys. Rev. B, 49, p. 8227Palacios, J.J., (1993) Europhys. Lett., 23, p. 495(1995) Phys. Rev. B, 51, p. 2363MacDonald, A.H., Eric Yang, S.R., Johnson, M.D., (1993) Aust. J. Phys., 46, p. 345Klein, O., (1995) Phys. Rev. Lett., 74, p. 785Kane, C.L., Fisher, M.P.A., Polchinski, J., (1994) Phys. Rev. Lett., 72, p. 4129Maksym, P.A., (1993) Physica B, 184, p. 385Maksym, P.A., Chakraborty, T., (1990) Phys. Rev. Lett., 65, p. 108(1992) Phys. Rev. B, 45, p. 1947Palacios, J.J., Martin-Moreno, L., Chiappe, G., Louis, E., Tejedor, C., (1994) Phys. Rev. B, 50, p. 5760(1995) Phys. Rev. Lett., 74, p. 5120Apalkov, V.M., Rashba, E.I., (1995) Solid State Commun., 93, p. 193Chen, X.M., Quinn, J.J., (1994) Phys. Rev. B, 50, p. 2354MacDonald, A.H., (1992) Phys. Rev. Lett., 68, p. 1939Buchmann, H., (1990) Phys. Rev. Lett., 65, p. 1056Turb-erfield, A.J., (1990) Phys. Rev. Lett., 65, p. 637Goldberg, B.B., (1990) Phys. Rev. Lett., 65, p. 641Hawrylak, P., (1991) Phys. Rev. B, 44, p. 3821Uneyama, T., Sham, L.J., (1990) Phys. Rev. Lett., 65, p. 1048Hawrylak, P., Pfannkuche, D., (1993) Phys. Rev. Lett., 70, p. 485Pfannkuche, D., (1994) Solid State Electron., 37, p. 1221Apalkov, V.M., Rashba, E.I., (1991) Pis'ma Zh. Éksp. Teor. Fiz., 53, p. 420(1991) JETP Lett., 53, p. 442Hawrylak, P., (1992) Phys. Rev. B, 45, p. 4237Hawrylak, P., Pulsford, N., Ploog, K., (1993) Phys. Rev. B, 46, p. 15593(1992) Solid State Commun., 81, p. 525Petrou, A., Smith, M.C., Perry, C.H., Worlock, J.M., Aggarwal, R.L., (1984) Solid State Commun., 52, p. 93Kukushkin, I.V., Klitzing, K.V., Ploog, K., Timofeev, V.B., (1990) Phys. Rev. B, 40, p. 7788Plaut, A.S., Lage, H., Grambow, P., Heitmann, D., Von Klitzing, K., Ploog, K., (1991) Phys. Rev. Lett., 67, p. 1642Buhmann, H., Joss, W., Von Klitzing, K., Kukushkin, I.V., Martinez, G., Plaut, A.S., Ploog, K., Timofeev, V.B., (1990) Phys. Rev. Lett., 65, p. 1056Buhmann, H., Joss, W., Von Klitzing, K., Kukushkin, I.V., Plaut, A.S., Martinez, G., Ploog, K., Timofeev, V.B., (1991) Phys. Rev. Lett., 66, p. 926Kukushkin, I.V., Pulsford, N.J., Von Klitzing, K., Ploog, K., Haug, R.J., Koch, S., Timofeev, V.B., (1992) Phys. Rev. B, 45, p. 4532Stone, M.D., Wyld, H.W., Schult, R.L., (1992) Phys. Rev. B, 45, p. 14156Stone, M.D., (1990) Int. J. Mod. Phys., 5, p. 503Kallin, C., Halperin, B.I., (1985) Phys. Rev. B, 31, p. 3635Wu, J.-W., Hawrylak, P., Quinn, J.J., (1985) Phys. Rev. B, 31, p. 6592Hawrylak, P., (1995) Phys. Rev. B, 51, p. 1770
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Chitosan elicitation enhances biomass and secondary metabolite production in Carlina acaulis L.
No full textCarlina acaulis L. (Asteraceae) is a medicinal plant with a long history of use as an herbal remedy. Recently, this species attracted the interest of agrochemical companies due to the presence of valuable biopesticides among which the most promising is carlina oxide (COx). To stimulate the biosynthesis of its specialised metabolites by elicitation, a polysaccharide – chitosan was supplemented as chitosan lactate (ChL). The aim was to evaluate the effects of ChL soil and foliar application on the C. acaulis biomass, photosynthetic efficiency, and levels of the COx, chlorogenic acids, protocatechuic acid, schaftosides, and triterpenic acids. ChL has been shown to have no effect on shoot growth while considerably increasing root biomass. It improved photosynthetic efficiency and enhanced levels of specialised metabolites. Soil application of ChL significantly increased chlorogenic and neochlorogenic acid content in leaves, by approximately 330% and 70%, respectively compared to controls. In contrast, foliar application more strongly increased COx levels in roots (55% for foliar vs. 16% for soil treatment). This study has demonstrated that the application of ChL can be used as an inexpensive and accessible way to boost the production of valuable compounds in C. acaulis
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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