15 results on '"Nguyen H. Le"'
Search Results
2. Environmental factors influence the local establishment of
- Author
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Nguyen T, Hien, Dang D, Anh, Nguyen H, Le, Nguyen T, Yen, Tran V, Phong, Vu S, Nam, Tran N, Duong, Nguyen B, Nguyen, Duong T T, Huong, Luu Q, Hung, Chau N T, Trinh, Nguyen V, Hoang, Vien Q, Mai, Le T, Nghia, Nguyen T, Dong, Le H, Tho, Simon, Kutcher, Tim P, Hurst, Jacqui L, Montgomery, Megan, Woolfit, Edwige, Rances, Le, Nguyen, Jack, Brown-Kenyon, Angela, Caird, Breeanna J, McLean, Inaki, Iturbe-Ormaetxe, Scott A, Ritchie, Scott L, O'Neill, and Peter A, Ryan
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- 2021
3. The multi-photon induced Fano effect
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Konstantin Litvinenko, B. N. Murdin, C. R. Pidgeon, Britta Redlich, Nickolay Abrosimov, Yury M. Andreev, Nguyen H. Le, and Zhiming Huang
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Nonlinear optics ,Photon ,Science ,многофотонные процессы ,media_common.quotation_subject ,Silicon photonics ,Optical spectroscopy ,General Physics and Astronomy ,02 engineering and technology ,Fano plane ,Interference (wave propagation) ,01 natural sciences ,Asymmetry ,Article ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Mathematics::Algebraic Geometry ,law ,молекулярная спектроскопия ,0103 physical sciences ,Atom ,Bound state ,Physics::Atomic Physics ,Фано эффект ,010306 general physics ,фотоионизация ,media_common ,Physics ,Multidisciplinary ,General Chemistry ,FELIX Infrared and Terahertz Spectroscopy ,атомная спектроскопия ,021001 nanoscience & nanotechnology ,Laser ,Qubit ,Atomic physics ,0210 nano-technology - Abstract
The ordinary Fano effect occurs in many-electron atoms and requires an autoionizing state. With such a state, photo-ionization may proceed via pathways that interfere, and the characteristic asymmetric resonance structures appear in the continuum. Here we demonstrate that Fano structure may also be induced without need of auto-ionization, by dressing the continuum with an ordinary bound state in any atom by a coupling laser. Using multi-photon processes gives complete, ultra-fast control over the interference. We show that a line-shape index q near unity (maximum asymmetry) may be produced in hydrogenic silicon donors with a relatively weak beam. Since the Fano lineshape has both constructive and destructive interference, the laser control opens the possibility of state-selective detection with enhancement on one side of resonance and invisibility on the other. We discuss a variety of atomic and molecular spectroscopies, and in the case of silicon donors we provide a calculation for a qubit readout application., Fano resonances occur in many platforms that have auto-ionizing states. Here the authors show that auto-ionizing states are not required for multi-photon Fano resonance in a Si:P system with significant screening by using a pump-probe method.
- Published
- 2021
4. Position-controlled functionalization of vacancies in silicon by single-ion implanted germanium atoms
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Simona Achilli, Nguyen H. Le, Takashi Tanii, Enrico Prati, Guido Fratesi, Takahiro Shinada, Nicola Manini, Marco Turchetti, Giovanni Onida, and Giorgio Ferrari
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Hubbard model ,Materials science ,Silicon ,chemistry.chemical_element ,FOS: Physical sciences ,Germanium ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Biomaterials ,Delocalized electron ,Ge-vacancy complex ,law ,Electrochemistry ,point defects ,quantum transport ,Condensed Matter - Materials Science ,Dopant ,business.industry ,Transistor ,Materials Science (cond-mat.mtrl-sci) ,single-ion implantation ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Crystallographic defect ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Semiconductor ,chemistry ,Optoelectronics ,0210 nano-technology ,business - Abstract
Special point defects in semiconductors have been envisioned as suitable components for quantum-information technology. The identification of new deep centers in silicon that can be easily activated and controlled is a main target of the research in the field. Vacancy-related complexes are suitable to provide deep electronic levels but they are hard to control spatially. With the spirit of investigating solid state devices with intentional vacancy-related defects at controlled position, here we report on the functionalization of silicon vacancies by implanting Ge atoms through single-ion implantation, producing Ge-vacancy (GeV) complexes. We investigate the quantum transport through an array of GeV complexes in a silicon-based transistor. By exploiting a model based on an extended Hubbard Hamiltonian derived from ab-initio results we find anomalous activation energy values of the thermally activated conductance of both quasi-localized and delocalized many-body states, compared to conventional dopants. We identify such states, forming the upper Hubbard band, as responsible of the experimental sub-threshold transport across the transistor. The combination of our model with the single-ion implantation method enables future research for the engineering of GeV complexes towards the creation of spatially controllable individual defects in silicon for applications in quantum information technologies.
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- 2021
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5. Highly efficient THz four-wave mixing in doped silicon
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Nikolay V. Abrosimov, Viktoria Eless, Britta Redlich, B. N. Murdin, K. Saeedi, C. R. Pidgeon, Ian Galbraith, Sergey Pavlov, Nils Dessmann, Gabriel Aeppli, Helge Riemann, Alberto Perez-Delgado, Steven Chick, Nguyen H. Le, Konstantin Litvinenko, and Alexander F. G. van der Meer
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Silicon ,Materials science ,Photon ,Nonlinear optics ,Terahertz radiation ,Silicon photonics ,chemistry.chemical_element ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,Article ,010309 optics ,Four-wave mixing ,0103 physical sciences ,Applied optics. Photonics ,Third-order non-linearities ,Terahertz- und Laserspektroskopie ,Terahertz optics ,business.industry ,Doping ,Free-electron laser ,QC350-467 ,FELIX Infrared and Terahertz Spectroscopy ,Optics. Light ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Photon upconversion ,Electronic, Optical and Magnetic Materials ,TA1501-1820 ,chemistry ,Susceptibility ,Picosecond ,Optoelectronics ,0210 nano-technology ,business ,FELIX Fel Technology - Abstract
Third-order non-linearities are important because they allow control over light pulses in ubiquitous high-quality centro-symmetric materials like silicon and silica. Degenerate four-wave mixing provides a direct measure of the third-order non-linear sheet susceptibility χ(3)L (where L represents the material thickness) as well as technological possibilities such as optically gated detection and emission of photons. Using picosecond pulses from a free electron laser, we show that silicon doped with P or Bi has a value of χ(3)L in the THz domain that is higher than that reported for any other material in any wavelength band. The immediate implication of our results is the efficient generation of intense coherent THz light via upconversion (also a χ(3) process), and they open the door to exploitation of non-degenerate mixing and optical nonlinearities beyond the perturbative regime., Light: Science & Applications, 10 (1), ISSN:2047-7538
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- 2021
6. Environmental factors influence the local establishment of Wolbachia in Aedes aegypti mosquitoes in two small communities in central Vietnam
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Nguyen T. Hien, Dang D. Anh, Nguyen H. Le, Nguyen T. Yen, Tran V. Phong, Vu S. Nam, Tran N. Duong, Nguyen B. Nguyen, Duong T.T. Huong, Luu Q. Hung, Chau N.T. Trinh, Nguyen V. Hoang, Vien Q. Mai, Le T. Nghia, Nguyen T. Dong, Le H. Tho, Simon Kutcher, Tim P. Hurst, Jacqui L. Montgomery, Megan Woolfit, Edwige Rances, Peter Kyrylos, Katherine L. Anders, Le Nguyen, Jack Brown-Kenyon, Angela Caird, Breeanna J. McLean, Inaki Iturbe-Ormaetxe, Scott A. Ritchie, Scott L. O'Neill, and Peter A. Ryan
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Immunology and Microbiology (miscellaneous) ,Health Policy ,Public Health, Environmental and Occupational Health ,Medicine (miscellaneous) ,Biochemistry, Genetics and Molecular Biology (miscellaneous) - Abstract
Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown to reduce transmission of dengue and other pathogens, under both laboratory and field conditions. Here we describe the entomological outcomes of wMel Wolbachia mosquito releases in two small communities in Nha Trang City in central Vietnam. Methods: The wMel strain of Wolbachia was backcrossed into local Aedes aegypti genotype and mosquito releases were undertaken by community members or by staff. Field monitoring was undertaken to track Wolbachia establishment in local Ae. aegypti mosquito populations. Ecological studies were undertaken to assess relationships between environmental factors and the spatial and temporal variability in Wolbachia infection prevalence in mosquitoes. Results: Releases of wMel Wolbachia Ae. aegypti mosquitoes in two small communities in Nha Trang City resulted in the initial establishment of Wolbachia in the local Ae. aegypti mosquito populations, followed by seasonal fluctuations in Wolbachia prevalence. There was significant small-scale spatial heterogeneity in Wolbachia infection prevalence in the Tri Nguyen Village site, resulting in the loss of wMel Wolbachia infection in mosquitoes in north and center areas, despite Wolbachia prevalence remaining high in mosquitoes in the south area. In the second site, Vinh Luong Ward, Wolbachia has persisted at a high level in mosquitoes throughout this site despite similar seasonal fluctuations in wMel Wolbachia prevalence. Conclusion: Seasonal variation in Wolbachia infection prevalence in mosquitoes was associated with elevated temperature conditions, and was possibly due to imperfect maternal transmission of Wolbachia. Heterogeneity in Wolbachia infection prevalence was found throughout one site, and indicates additional factors may influence Wolbachia establishment.
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- 2022
7. Topological phases of a dimerized Fermi-Hubbard model for semiconductor nano-lattices
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Eran Ginossar, Nguyen H. Le, Andrew J. Fisher, and Neil J. Curson
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Hubbard model ,Computer Networks and Communications ,FOS: Physical sciences ,Quantum simulator ,02 engineering and technology ,Topology ,01 natural sciences ,lcsh:QA75.5-76.95 ,Condensed Matter - Strongly Correlated Electrons ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Computer Science (miscellaneous) ,010306 general physics ,Spin-½ ,Physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed Matter - Mesoscale and Nanoscale Physics ,Spins ,Dopant ,Statistical and Nonlinear Physics ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,3. Good health ,Computational Theory and Mathematics ,Quantum dot ,Condensed Matter::Strongly Correlated Electrons ,lcsh:Electronic computers. Computer science ,0210 nano-technology ,Ground state ,lcsh:Physics ,Excitation - Abstract
Motivated by recent advances in fabricating artificial lattices in semiconductors and their promise for quantum simulation of topological materials, we study the one-dimensional dimerized Fermi-Hubbard model. We show how the topological phases at half-filling can be characterized by a reduced Zak phase defined based on the reduced density matrix of each spin subsystem. Signatures of bulk-boundary correspondence are observed in the triplon excitation of the bulk and the edge states of uncoupled spins at the boundaries. At quarter-filling we show that owing to the presence of the Hubbard interaction the system can undergo a transition to the topological ground state of the non-interacting Su-Schrieffer-Heeger model with the application of a moderate-strength external magnetic field. We propose a robust experimental realization with a chain of dopant atoms in silicon or gate-defined quantum dots in GaAs where the transition can be probed by measuring the tunneling current through the many-body state of the chain., 11 pages, 7 figures
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- 2019
8. Giant multiphoton absorption for THz resonances in silicon hydrogenic donors
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M. A. W. van Loon, P. T. Greenland, Gabriel Aeppli, K. Saeedi, Nikolaos Stavrias, C. R. Pidgeon, B. N. Murdin, Konstantin Litvinenko, Britta Redlich, and Nguyen H. Le
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rydberg states ,Photon ,Silicon ,Terahertz radiation ,Binding energy ,Physics::Optics ,chemistry.chemical_element ,semiconductors ,02 engineering and technology ,01 natural sciences ,Effective mass (solid-state physics) ,generation ,0103 physical sciences ,coherent control ,FELIX ,010306 general physics ,free-electron-laser ,Physics ,Hydrogen-like atom ,business.industry ,excitation ,021001 nanoscience & nanotechnology ,2-photon spectroscopy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,germanium ,Semiconductor ,chemistry ,atomic-hydrogen ,1s-2s transition ,Atomic physics ,0210 nano-technology ,business ,Bohr radius - Abstract
The absorption of multiple photons when there is no resonant intermediate state is a well-known nonlinear process in atomic vapours, dyes and semiconductors. The N-photon absorption (NPA) rate for donors in semiconductors scales proportionally from hydrogenic atoms in vacuum with the dielectric constant and inversely with the effective mass, factors that carry exponents 6N and 4N, respectively, suggesting that extremely large enhancements are possible. We observed 1PA, 2PA and 3PA in Si: P with a terahertz free-electron laser. The 2PA coefficient for 1s-2s at 4.25 THz was 400,000,000 GM (= 4 x 10(-42) cm(4) s), many orders of magnitude larger than is available in other systems. Such high cross-sections allow us to enter a regime where the NPA cross-section exceeds that of 1 PA-that is, when the intensity approaches the binding energy per Bohr radius squared divided by the uncertainty time (only 3.84 MW cm(-2) in silicon)-and will enable new kinds of terahertz quantum control.
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- 2018
9. Single‐Ion Implantation: Position‐Controlled Functionalization of Vacancies in Silicon by Single‐Ion Implanted Germanium Atoms (Adv. Funct. Mater. 21/2021)
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Nicola Manini, Nguyen H. Le, Guido Fratesi, Marco Turchetti, Giovanni Onida, Giorgio Ferrari, Enrico Prati, Simona Achilli, Takashi Tanii, and Takahiro Shinada
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Materials science ,Hubbard model ,Silicon ,Single ion ,chemistry.chemical_element ,Germanium ,Condensed Matter Physics ,Molecular physics ,Crystallographic defect ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Quantum transport ,chemistry ,Position (vector) ,Electrochemistry ,Surface modification - Published
- 2021
10. Optically controlled entangling gates in randomly doped silicon
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Eleanor Crane, Andrew J. Fisher, Kristian Stockbridge, Steven Chick, Thomas Crane, Nguyen H. Le, and Alexander Schuckert
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Physics ,Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Monte Carlo method ,FOS: Physical sciences ,Disordered Systems and Neural Networks (cond-mat.dis-nn) ,02 engineering and technology ,Condensed Matter - Disordered Systems and Neural Networks ,021001 nanoscience & nanotechnology ,7. Clean energy ,01 natural sciences ,Computational physics ,Qubit ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Poisson point process ,Quantum information ,Quantum Physics (quant-ph) ,010306 general physics ,0210 nano-technology ,Coherence (physics) ,Spin-½ ,Quantum computer ,Cluster expansion - Abstract
Randomly-doped silicon has many competitive advantages for quantum computation; not only is it fast to fabricate but it could naturally contain high numbers of qubits and logic gates as a function of doping densities. We determine the densities of entangling gates in randomly doped silicon comprising two different dopant species. First, we define conditions and plot maps of the relative locations of the dopants necessary for them to form exchange interaction mediated entangling gates. Second, using nearest neighbour Poisson point process theory, we calculate the doping densities necessary for maximal densities of single and dual-species gates. We find agreement of our results with a Monte Carlo simulation, for which we present the algorithms, which handles multiple donor structures and scales optimally with the number of dopants and use it to extract donor structures not captured by our Poisson point process theory. Third, using the moving average cluster expansion technique, we make predictions for a proof of principle experiment demonstrating the control of one species by the orbital excitation of another. These combined approaches to density optimization in random distributions may be useful for other condensed matter systems as well as applications outside physics., 14 pages, 10 figures
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- 2019
11. Giant non-linear susceptibility of hydrogenic donors in silicon and germanium
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Nguyen H. Le, Ben Murdin, Gabriel Aeppli, and G. V. Lanskii
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lcsh:Applied optics. Photonics ,Nonlinear optics ,Materials science ,Silicon ,Silicon photonics ,chemistry.chemical_element ,Hyperpolarizability ,FOS: Physical sciences ,Physics::Optics ,Germanium ,02 engineering and technology ,01 natural sciences ,Article ,generation ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,lcsh:QC350-467 ,010306 general physics ,Absorption (electromagnetic radiation) ,Terahertz optics ,Quantum well ,Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,business.industry ,Resonance ,Materials Science (cond-mat.mtrl-sci) ,lcsh:TA1501-1820 ,021001 nanoscience & nanotechnology ,states ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Semiconductor ,chemistry ,multiphoton absorption ,Atomic physics ,0210 nano-technology ,business ,lasers ,lcsh:Optics. Light - Abstract
Implicit summation is a technique for the conversion of sums over intermediate states in multiphoton absorption and the high-order susceptibility in hydrogen into simple integrals. Here, we derive the equivalent technique for hydrogenic impurities in multi-valley semiconductors. While the absorption has useful applications, it is primarily a loss process; conversely, the non-linear susceptibility is a crucial parameter for active photonic devices. For Si:P, we predict the hyperpolarizability ranges from χ(3)/n3D = 2.9 to 580 × 10−38 m5/V2 depending on the frequency, even while avoiding resonance. Using samples of a reasonable density, n3D, and thickness, L, to produce third-harmonic generation at 9 THz, a frequency that is difficult to produce with existing solid-state sources, we predict that χ(3) should exceed that of bulk InSb and χ(3)L should exceed that of graphene and resonantly enhanced quantum wells., Semiconductor physics: Giant nonlinearity Lightly doped semiconductors may provide a mean for highly efficient third-harmonic generation (THG) of terahertz radiation. That’s the hopeful prediction of some theoretical analysis performed by scientists in the UK, Switzerland and Russia. Nguyen Le and coworkers calculated that silicon and germanium featuring hydrogenic impurities should possess a giant nonlinear susceptibility in the terahertz region. The finding potentially opens the door to efficient nonlinear processes, such as THG, in the terahertz region. In principle this means that these semiconductors could be used to frequency triple the emission from 2 to 4 THz quantum cascade lasers, resulting in sources in the 6–12 THz gap. At present, no compact, low-cost sources currently exist in this region and researchers are forced to rely on free-electron lasers and difference frequency generators instead.
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- 2018
12. Radii of Rydberg states of isolated silicon donors
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Yu. A. Astrov, C. R. Pidgeon, Zaiping Zeng, Andrew J. Fisher, V. B. Shuman, Leonid М. Portsel, Аnatoly N. Lodygin, Heinz-Wilhelm Hübers, S.G. Pavlov, B. N. Murdin, Konstantin Litvinenko, Nikolai V. Abrosimov, Juerong Li, Steven Clowes, Yann-Michel Niquet, Nguyen H. Le, Hans Engelkamp, Laboratory of Atomistic Simulation (LSIM ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
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Silicon ,Magnetooptical spectroscopy ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,symbols.namesake ,Effective mass (solid-state physics) ,Soft Condensed Matter and Nanomaterials ,0103 physical sciences ,010306 general physics ,Wave function ,ComputingMilieux_MISCELLANEOUS ,Physics ,Zeeman effect ,Radius ,021001 nanoscience & nanotechnology ,Donor state radius ,Magnetic field ,chemistry ,symbols ,Rydberg formula ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Atomic physics ,0210 nano-technology ,Ground state - Abstract
We have performed high field magnetoabsorption spectroscopy on silicon doped with a variety of single and double donor species. The magnetic field provides access to an experimental magnetic length, and the quadratic Zeeman effect, in particular, may be used to extract the wave-function radius without reliance on previously determined effective mass parameters. We were, therefore, able to determine the limits of validity for the standard one-band anisotropic effective mass model. We also provide improved parameters and use them for an independent check on the accuracy of effective mass theory. Finally, we show that the optically accessible excited-state wave functions have the attractive property that interactions with neighbors are far more forgiving of position errors than (say) the ground state.
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- 2018
13. Extended Hubbard model for mesoscopic transport in donor arrays in silicon
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Andrew J. Fisher, Eran Ginossar, and Nguyen H. Le
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Physics ,Mesoscopic physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Hubbard model ,Condensed matter physics ,Silicon ,FOS: Physical sciences ,Quantum simulator ,chemistry.chemical_element ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry ,Quantum dot ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,Exponential decay ,010306 general physics ,0210 nano-technology ,Quantum tunnelling - Abstract
Arrays of dopants in silicon are promising platforms for the quantum simulation of the Fermi-Hubbard model. We show that the simplest model with only on-site interaction is insufficient to describe the physics of an array of phosphorous donors in silicon due to the strong intersite interaction in the system. We also study the resonant tunneling transport in the array at low temperature as a mean of probing the features of the Hubbard physics, such as the Hubbard bands and the Mott gap. Two mechanisms of localization which suppresses transport in the array are investigated: The first arises from the electron-ion core attraction and is significant at low filling; the second is due to the sharp oscillation in the tunnel coupling caused by the intervalley interference of the donor electron's wave function. This disorder in the tunnel coupling leads to a steep exponential decay of conductance with channel length in one-dimensional arrays, but its effect is less prominent in two-dimensional ones. Hence, it is possible to observe resonant tunneling transport in a relatively large array in two dimensions.
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- 2017
14. Excited states of defect lines in silicon: A first-principles study based on hydrogen cluster analogues
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Nguyen H. Le, Ben Murdin, Steve Chick, P. T. Greenland, Andrew J. Fisher, and Wei Wu
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Ionic bonding ,FOS: Physical sciences ,02 engineering and technology ,Electron ,01 natural sciences ,Condensed Matter - Strongly Correlated Electrons ,Condensed Matter::Materials Science ,Effective mass (solid-state physics) ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Cluster (physics) ,Molecule ,Physics - Atomic and Molecular Clusters ,Physics::Chemical Physics ,010306 general physics ,Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Chemistry ,Materials Science (cond-mat.mtrl-sci) ,Hydrogen atom ,021001 nanoscience & nanotechnology ,Excited state ,Atomic physics ,0210 nano-technology ,Ground state ,Atomic and Molecular Clusters (physics.atm-clus) ,Physics - Optics ,Optics (physics.optics) - Abstract
Excited states of a single donor in bulk silicon have previously been studied extensively based on effective mass theory. However, a proper theoretical description of the excited states of a donor cluster is still scarce. Here we study the excitations of lines of defects within a single-valley spherical band approximation, thus mapping the problem to a scaled hydrogen atom array. A series of detailed full configuration-interaction and time-dependent hybrid density-functional theory calculations have been performed to understand linear clusters of up to 10 donors. Our studies illustrate the generic features of their excited states, addressing the competition between formation of inter-donor ionic states and intra-donor atomic excited states. At short inter-donor distances, excited states of donor molecules are dominant, at intermediate distances ionic states play an important role, and at long distances the intra-donor excitations are predominant as expected. The calculations presented here emphasise the importance of correlations between donor electrons, and are thus complementary to other recent approaches that include effective mass anisotropy and multi-valley effects. The exchange splittings between relevant excited states have also been estimated for a donor pair and for a three-donor arrays; the splittings are much larger than those in the ground state in the range of donor separations between 10 and 20 nm. This establishes a solid theoretical basis for the use of excited-state exchange interactions for controllable quantum gate operations in silicon., Comment: 14 pages, 6 figures
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- 2017
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15. Vietnam's Emerging National Parks: War, Resource Exploitation, and Recent Struggles to Protect Biodiversity
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Thomas A. Wikle and Nguyen H. Le
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Geography ,business.industry ,Geography, Planning and Development ,Environmental resource management ,Biodiversity ,business ,Environmental planning ,Exploitation of natural resources - Published
- 2013
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