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113 results on '"Eble, B."'

1. Hyperfine interaction in InAs/GaAs self-assembled quantum dots : dynamical nuclear polarization versus spin relaxation

Author

Krebs, O., Eble, B., Lemaître, A., Voisin, P., Urbaszek, B., Marie, X., and Amand, T.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We report on the influence of hyperfine interaction on the optical orientation of singly charged excitons X+ and X- in self-assembled InAs/GaAs quantum dots. All measurements were carried out on individual quantum dots studied by micro-photoluminescence at low temperature. We show that the hyperfine interaction leads to an effective partial spin relaxation, under 50kHz modulated excitation polarization, which becomes however strongly inhibited under steady optical pumping conditions because of dynamical nuclear polarization. This optically created magnetic-like nuclear field can become very strong (up to ~4 T) when it is generated in the direction opposite to a longitudinally applied field, and exhibits then a bistability regime. This effect is very well described by a theoretical model derived in a perturbative approach, which reveals the key role played by the energy cost of an electron spin flip in the total magnetic field. Eventually, we emphasize the similarities and differences between X+ and X- trions with respect to the hyperfine interaction, which turn out to be in perfect agreement with the theoretical description., Comment: 10 pages, 5 figures

Published
2009
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2. Hole spin dephasing time associated to hyperfine interaction in quantum dots

Author

Testelin, C., Bernardot, F., Eble, B., and Chamarro, M.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The spin interaction of a hole confined in a quantum dot with the surrounding nuclei is described in terms of an effective magnetic field. We show that, in contrast to the Fermi contact hyperfine interaction for conduction electrons, the dipole-dipole hyperfine interaction is anisotropic for a hole, for both pure or mixed hole states. We evaluate the coupling constants of the hole-nuclear interaction and demonstrate that they are only one order of magnitude smaller than the coupling constants of the electron-nuclear interaction. We also study, theoretically, the hole spin dephasing of an ensemble of quantum dots via the hyperfine interaction in the framework of frozen fluctuations of the nuclear field, in absence or in presence of an applied magnetic field. We also discuss experiments which could evidence the dipole-dipole hyperfine interaction and give information on hole mixing., Comment: 35 pages, 7 figures and 2 tables

Published
2009
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3. Hole - Nuclear Spin Interaction in Quantum Dots

Author

Eble, B., Testelin, C., Desfonds, P., Bernardot, F., Balocchi, A., Amand, T., Miard, A., Lemaitre, A., Marie, X., and Chamarro, M.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We have measured the carrier spin dynamics in p-doped InAs/GaAs quantum dots by pump-probe photo-induced circular dichroism and time-resolved photoluminescence experiments. We show that the hole spin dephasing is controlled by the hyperfine interaction between hole and nuclear spins. In the absence of external magnetic field, we find a characteristic hole spin dephasing time of 15 ns, in close agreement with our calculations based on dipole-dipole coupling between the hole and the quantum dot nuclei. Finally we demonstrate that a small external magnetic field, typically 10 mT instead of 200 mT for the case of electrons, quenches the hyperfine hole spin dephasing., Comment: 17 pages, 3 figures, submitted to Phys. Rev. Lett

Published
2008
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4. Inversion of the spin polarization of localized electrons driven by dark excitons

Author

Eble, B., Testelin, C., Bernardot, F., Chamarro, M., and Karczewski, G.

Subjects
Condensed Matter - Other Condensed Matter
Abstract

The creation of free excitons by absorption of circularly polarized photons, and their subsequent fast capture by donors, is at the origin of the spin polarization of donor-bound electrons. The sign of the electronic spin polarization at low density of excitation is, as expected, fixed by the helicity of the exciting light; but at high density of excitation we show that the spin polarization is of the opposite sign. This striking inversion is explained, here, by the contribution of dark excitons to mechanisms of spin polarization of localized electrons., Comment: 3 figures

Published
2008

5. Bistability of the Nuclear Polarisation created through optical pumping in InGaAs Quantum Dots

Author

Braun, P. -F., Urbaszek, B., Amand, T., Marie, X., Krebs, O., Eble, B., Lemaitre, A., and Voisin, P.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We show that optical pumping of electron spins in individual InGaAs quantum dots leads to strong nuclear polarisation that we measure via the Overhauser shift (OHS) in magneto-photoluminescence experiments between 0 and 4T. We find a strongly non-monotonous dependence of the OHS on the applied magnetic field, with a maximum nuclear polarisation of 40% for intermediate magnetic fields. We observe that the OHS is larger for nuclear fields anti-parallel to the external field than in the parallel configuration. A bistability in the dependence of the OHS on the spin polarization of the optically injected electrons is found. All our findings are qualitatively understood with a model based on a simple perturbative approach., Comment: Phys Rev B (in press)

Published
2006
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13. Nanosecond spin coherence of excitons bound to acceptors in a CdTe quantum well.

Author

Grinberg, P., Bernardot, F., Eble, B., Karczewski, G., Testelin, C., and Chamarro, M.

Subjects
EXCITON theory, QUANTUM theory, QUASIPARTICLES, TRANSITION metal compounds spectra, CADMIUM compounds, QUANTUM wells
Abstract

We have studied the coherent spin dynamics of excitons bound to acceptors, A0X, immersed in a CdTe quantum well by using time resolved photo-induced Faraday rotation. We have also measured the time-resolved differential transmission in order to determine a A0X lifetime of 220 ps, which is independent of the applied magnetic field. We show that at low magnetic field, the spin of A0X is completely frozen during a time, ≅ 4.5 ns, at least twenty times longer than its lifetime. We compare the spin properties of A0X with the spin properties of other charged excitons systems, and we conclude that the hyperfine interaction of the photo-created electron spin with nuclear spins is very likely to be at the origin of the observed spin dephasing times. [ABSTRACT FROM AUTHOR]

Published
2016
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14. Nitrogen vacancy center in cubic silicon carbide: A promising qubit in the 1.5μm spectral range for photonic quantum networks

Author

Zargaleh, Soroush Abbasi, Hameau, S., Eble, B., Margaillan, F., von Bardeleben, H. J., Cantin, J. L., Gao, Weibo, Photons, Magnons et Technologies Quantiques (INSP-E11), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), School of Physical and Mathematical Sciences, The Photonics Institute, and Centre for Disruptive Photonic Technologies (CDPT)

Subjects
[PHYS]Physics [physics], Nitrogen Vacancy Center, Photonic Quantum Networks, Science::Physics [DRNTU], [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS
Abstract

We have investigated the optical properties of the (NV)− center in 3C-SiC to determine the photoluminscence zero phonon line (ZPL) associated with the 3E→3A2 intracenter transition. Combining electron paramagnetic resonance and photoluminescence spectroscopy, we show that the NV−center in 3C-SiC has a ZPL line at 1.468 μm in excellent agreement with theoretical predictions. The ZPL line can be observed up to T=100 K. The negatively charged NV center in 3C-SiC is the structural isomorphe of the NV center in diamond and has equally a spin S=1 ground state and a spin S=1 excited state, long spin lattice relaxation times and presents optically induced groudstate spin polarization. These properties make it already a strong competitor to the NV center in diamond, but as its optical domain is shifted in the near infrared at 1.5μm, the NV center in 3C-SiC is compatible with quantum photonic networks and silicon based microelectronics. Published version

Published
2018

31. Hole–Nuclear Spin Interaction in Quantum Dots

Author

Eble, B., primary, Testelin, C., additional, Desfonds, P., additional, Bernardot, F., additional, Balocchi, A., additional, Amand, T., additional, Miard, A., additional, Lemaître, A., additional, Marie, X., additional, and Chamarro, M., additional

Published
2009
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40. Spin dynamics and hyperfine interaction in InAs semiconductor quantum dots

Author

Eble, B., primary, Braun, P.‐F., additional, Krebs, O., additional, Lombez, L., additional, Marie, X., additional, Urbaszek, B., additional, Amand, T., additional, Lagarde, D., additional, Renucci, P., additional, Voisin, P., additional, Lemaître, A., additional, Kowalik, K., additional, Kudelski, A., additional, Kalevich, V.K., additional, and Kavokin, K. V., additional

Published
2006
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45. Hole spin mode locking and coherent dynamics in a largely inhomogeneous ensemble of p-doped In As quantum dots.

Author

Fras, F., Eble, B., Siarry, B., Bernardot, F., Miard, A., Lemaître, A., Testelin, C., and Chamarro, M.

Subjects
*COHERENCE (Physics), *INHOMOGENEOUS materials, *QUANTUM dots, *PHYSICS experiments, *DISTRIBUTION (Probability theory), *DENSITY matrices, *MAGNETIC fields
Abstract

In this study, we evidence hole spin mode locking in a largely inhomogeneous p-doped InAs quantum dot (QD) ensemble,Δgxh/gxh ≈34%, which allows us to reveal a long spin coherence time of T2h≈0.8 µs. In addition, with a two-pump experiment, we demonstrate, in a low magnetic range 60-120 mT, the possibility to synchronize and tune a single subset of QDs through the distribution. Experiments are supported by an analysis within the density matrix approach. [ABSTRACT FROM AUTHOR]

Published
2012
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47. Left Ventricular Noncompaction Cardiomyopathy in Association with Trisomy 13.

Author

McMahon, C. J., Chang, A. C., Pignatelli, R. H., Miller-Hance, W. C., Eble, B. K., Towbin, J. A., and Denfield, S. W.

Subjects
CARDIOMYOPATHIES, LEFT heart ventricle, HEART diseases, CORONARY arteries, PEDIATRIC cardiology, CARDIOLOGY
Abstract

In recent years, left ventricular noncompaction (LVNC) has been recognized as a distinct form of cardiomyopathy with its own clinical presentation and natural history. More than 100 cases of LVNC have been described in children. Although LVNC has been described in association with metabolic disorders such as Fabry's disease or genetic disorders such as Roifman's syndrome, this case represents the first report of LVNC in a child with trisomy 13. [ABSTRACT FROM AUTHOR]

Published
2005
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48. Multiple topogenic sequences determine the transmembrane orientation of the hepatitis B surface antigen

Author

Eble, B E, MacRae, D R, Lingappa, V R, and Ganem, D

Abstract

To investigate the mechanism by which complex membrane proteins achieve their correct transmembrane orientation, we examined in detail the hepatitis B surface antigen for sequences which determine its membrane topology. The results demonstrated the presence of at least two kinds of topogenic elements: an N-terminal uncleaved signal sequence and an internal element containing both signal and stop-transfer function. Fusion of reporter groups to either end of the protein suggested that both termini are translocated across the membrane bilayer. We propose that this topology is generated by the conjoint action of both elements and involves a specifically oriented membrane insertion event mediated by the internal sequence. The functional properties of each element can be instructively compared with those of simpler membrane proteins and may provide insight into the generation of other complex protein topologies.

Published
1987
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49. Hepatitis B surface antigen: an unusual secreted protein initially synthesized as a transmembrane polypeptide

Author

Eble, B E, Lingappa, V R, and Ganem, D

Abstract

Hepatitis B surface antigen (HBsAg), the major coat protein of hepatitis B virus, is also secreted from cells as a subviral particle, without concomitant cleavage of N-terminal amino acid sequences. We examined this unusual export process in a cell-free system and showed that the initial product of HBsAg biosynthesis is an integral transmembrane protein, with most or all of its C-terminal half on the lumenal side of the endoplasmic reticulum membrane. To study the nature of its topogenic signals, we synthesized fusion proteins between HBsAg and the nonsecreted protein alpha-globin. Fusion proteins in which approximately 100 amino acids of globin preceded all HBsAg sequences were successfully translocated in vitro; the same domain as in the wild-type HBsAg was transported into the vesicle lumen. Fusions in which the entire globin domain was C terminal were able to translocate both the C-terminal region of HBsAg and its attached globin domain. Thus, uncleaved signal sequences in p24s function to direct portions of the molecule across the membrane and are able to perform this function even when positioned in an internal protein domain.

Published
1986
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50. Natural history of restricted synthesis and expression of measles virus genes in subacute sclerosing panencephalitis.

Author

Haase, A T, Gantz, D, Eble, B, Walker, D, Stowring, L, Ventura, P, Blum, H, Wietgrefe, S, Zupancic, M, and Tourtellotte, W

Abstract

Subacute sclerosing panencephalitis (SSPE) is a slow infection caused by measles virus in which several years separate recovery from typical acute measles and the development of a slowly progressive neurological disease. We have investigated replication of measles virus in brain tissue obtained after the onset of neurological disease and in the terminal phase. With a hybridization tomographic technique that combines in situ hybridization with macroradioautographic screening of large areas of tissue, we analyzed the spatial and temporal distribution of virus genes in vivo, using region- and strand-specific probes for the nucleocapsid and matrix genes. We show that early in the course of SSPE there is a global repression in the synthesis and expression of the genome. In the final stage of SSPE most infected cells still have depressed levels of plus- and minus-strand viral RNA and contain nucleocapsid protein but lack matrix protein. These findings provide further evidence for a unified view of slow infections of the nervous system, where the general constraints on virus gene expression provide an explanation for persistence of virus in the face of the host's immune response, and the slow evolution of pathological change. In the final phases of SSPE the more specific block in virus replication accounts for the cell-associated state of the virus and the difficulty in virus isolation.

Published
1985
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