| 21. |
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| 22. |
- Mazur, Mikael, et al.
(författare)
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Real-Time Transmission over 2x55 km All 7-Core Coupled-Core Multi-Core Fiber Link
- 2022
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Ingår i: Optical Fiber Communication Conference, OFC 2022. - 9781557524669 - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- We demonstrate the first transmission experiment using 7-core coupled-core fiber with in-line coupled-core multi-core amplifiers and real-time DSP. The real-time DSP is implemented using a single FPGA that performs MIMO processing across all 7 cores.
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| 23. |
- Miyake, T., et al.
(författare)
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Effects of momentum-dependent self-energy in the electronic structure of correlated materials
- 2013
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 87:11
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Tidskriftsartikel (refereegranskat)abstract
- We study how the k dependence in the self-energy affects the quasiparticle band structure and one-particle spectral functions. It is known that, in electron-gas-like materials, the self-energy depends significantly on k and there is a strong cancellation between the k dependence and the energy dependence of the self-energy. Analysis of the GW self-energy reveals that, even in correlated materials with narrow bands, such as SrVO3, the self-energy significantly depends on k. When the nonlocal effect is neglected, the quasiparticle band structure is over-renormalized, yielding too large mass enhancement compared to the case of k-dependent self-energy. The present result suggests that partial cancellation between the frequency dependence and the k dependence in the self-energy is important when discussing the quasiparticle band structure of correlated materials. DOI: 10.1103/PhysRevB.87.115110
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| 24. |
- Murayama, A., et al.
(författare)
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Propagation dynamics of exciton spins in a high-density semiconductor quantum dot system
- 2009
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Ingår i: physica status solidi c. - : phys. stat. sol. c. - 1862-6351 .- 1610-1642.
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Konferensbidrag (refereegranskat)abstract
- We study propagation dynamics of exciton spins in a system composed of high-density self-assembled quantum dots (QDs) of CdSe and a diluted magnetic semiconductor (DMS) layer of ZnMnSe, where spin-polarized excitons are generated in the DMS layer and are subsequently injected into the QDs. The degree of circular polarization, P, of excitonic photoluminescence at 5 T in the coupled QDs shows a rapid increase with increasing delay time after a linearly polarized pulsed excitation, indicating the exciton-spin injection from the ZnMnSe to CdSe-QDs. The P value tends to decay gradually because of the exciton-spin relaxation in the QDs after the injection. The spin-polarized excitons in the QD ensemble migrate simultaneously from the QDs with higher exciton energies to those with lower exciton energies, where the exciton-spins relax inside each dot during the migration. Therefore, the observed P values in the QD emission band are affected by this feeding of the relaxed spins.
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| 25. |
- Murayama, A, et al.
(författare)
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Transfer dynamics of spin-polarized excitons into semiconductor quantum dots
- 2009
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Ingår i: Journal of Luminescence. - : Elsevier BV. - 0022-2313 .- 1872-7883. ; 129, s. 1927-1930
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Tidskriftsartikel (refereegranskat)abstract
- We study on the transfer dynamics of spin-polarized excitons into self-assembled quantum dots (QDs) of CdSe coupled with a diluted magnetic semiconductor (DMS) layer of ZnMnSe through a ZnSe barrier layer. A variation in the degree of circular polarization P of excitonic photoluminescence in the coupled QDs was observed between samples with different thicknesses (LB) of the non-magnetic barrier. Relatively high values of P (0.3) were obtained in the samples with LB=1 or 2 nm, and the time dependences of the P value indicate the spin-transfer dynamics. From the LB dependence of the spin-transfer time, the spin-transfer mechanism is discussed, namely spin-conserving energy transfer.
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| 26. |
- Ohtani, H., et al.
(författare)
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Equilibrium between fluorite and pyrochlore structures in the ZrO2-Nd2O3 system
- 2005
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Ingår i: Materials transactions. - : Japan Institute of Metals. - 1345-9678 .- 1347-5320. ; 46:6, s. 1167-1174
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Tidskriftsartikel (refereegranskat)abstract
- The phase diagram of the ZrO2-Nd2O3 system has been characterized showing isolated two-phase regions for a cubic fluorite-type ZrO2 solid solution and Nd2Zr2O7 with a pyrochlore-type structure. A thermodynamic analysis was carried out to elucidate the origin of this interesting phase equilibrium. A compound energy model with the formula (Zr4+,Nd3+)(0.5)(Nd3+,Zr4+)(0.5)(O2-,va)(2) was applied to describe the Gibbs energy for these phases in consideration of the ordering of the cation sites in the structure. The ordering arrangement on the anion sites was not taken into account. The Gibbs energy for the liquid was described using an ionic solution model, while the binary compounds, such as tetragonal and monoclinic ZrO2, and cubic and hexagonal Nd2O3, were treated as stoichiometric solid phases. The thermodynamic assessment was based on the experimental phase boundaries as well as the evaluated formation energy for the stoichiometric Nd,2Zr2O7 phase. The phase diagram calculations showed that the peculiar feature of this phase diagram was reproduced well in our work. The results strongly suggest that the two-phase boundaries between the cubic fluorite-type ZrO2 solid solution and the pyrochlore-type structure occur due to the ordering of the Zr4+ and Nd3+ cations.
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| 27. |
- Okumura, H, et al.
(författare)
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New insights into the role of microheterogeneity of ZP3 during structural maturation of the avian equivalent of mammalian zona pellucida
- 2023
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 18:3, s. e0283087-
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Tidskriftsartikel (refereegranskat)abstract
- The egg coat including mammalian zona pellucida (ZP) and the avian equivalent, i.e., inner-perivitelline layer (IPVL), is a specialized extracellular matrix being composed of the ZP glycoproteins and surrounds both pre-ovulatory oocytes and ovulated egg cells in vertebrates. The egg coat is well known for its potential importance in both the reproduction and early development, although the underlying molecular mechanisms remain to be fully elucidated. Interestingly, ZP3, one of the ZP-glycoprotein family members forming scaffolds of the egg-coat matrices with other ZP glycoproteins, exhibits extreme but distinctive microheterogeneity to form a large number of isoelectric-point isoforms at least in the chicken IPVL. In the present study, we performed three-dimensional confocal imaging and two-dimensional polyacrylamide-gel electrophoresis (2D-PAGE) of chicken IPVLs that were isolated from the ovarian follicles at different growth stages before ovulation. The results suggest that the relative proportions of the ZP3 isoforms are differentially altered during the structural maturation of the egg-coat matrices. Furthermore, tandem mass spectrometry (MS/MS) analyses and ZP1 binding assays against separated ZP3 isoforms demonstrated that each ZP3 isoform contains characteristic modifications, and there are large differences among ZP3 isoforms in the ZP1 binding affinities. These results suggest that the microheterogeneity of chicken ZP3 might be regulated to be associated with the formation of egg-coat matrices during the structural maturation of chicken IPVL. Our findings may provide new insights into molecular mechanisms of egg-coat assembly processes.
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| 28. |
- Sakuma, Rei, et al.
(författare)
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Ab initio study of the downfolded self-energy for correlated systems: Momentum dependence and effects of dynamical screening
- 2014
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 89:23
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of strongly correlated systems is usually calculated by using an effective model Hamiltonian with a small number of states and an effective on-site interaction. The mode, however, neglects the frequency dependence of the interaction, which emerges as a result of dynamical screening processes not included in the model. The self-energy calculated in this kind of model within dynamical mean-field theory (DMFT) is usually assumed to contain on-site components only. To study the validity of model calculations for the simulation of realistic materials, we make a detailed comparison between the downfolded self-energy in a model Hamiltonian with static and dynamic on-site interaction and the full ab initio self-energy for Fe and SrVO3 within the GW approximation. We find that the model GW self-energy shows weaker k (momentum) dependence than the ab initio GW self-energy, which is attributed to the lack of the long-range interaction and of contributions from other electrons not included in the models. This weak k dependence is found to lead to an artificial narrowing of the quasiparticle band structure. Moreover, this band narrowing is stronger for the dynamic (frequency-dependent) interaction, due to a larger renormalization of the quasiparticle states. These findings indicate a crucial role of the k dependence of the self-energy and dynamical screening for the electronic structure of correlated systems. We also discuss the effects beyond the GW approximation for correlated systems by comparing the GW and DMFT results.
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| 29. |
- Sakuma, Rei, et al.
(författare)
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Self-energy and spectral function of Ce within the GW approximation
- 2012
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 86:24
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Tidskriftsartikel (refereegranskat)abstract
- To investigate how far the GW approximation can treat systems with strong on-site correlations, we perform calculations of the self-energies and spectral functions of alpha-and gamma-Ce within the GW approximation. For this strongly correlated material, the screened interaction exhibits a complex and rich structure which is attributed to strong particle-hole transitions involving localized 4f states. This structure in the screened interaction is carried over to the self-energy, which in turn yields spectral functions with multiple peaks. A satellite at around 5 eV above the Fermi level is formed, which is reminiscent of the experimentally observed upper Hubbard band, while the experimentally observed peak structure below the Fermi level at -2 eV and disappearance of the quasiparticle peak in the. phase are not reproduced. DOI: 10.1103/PhysRevB.86.245126
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