The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
S Tarucha - One of the best experts on this subject based on the ideXlab platform.
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Ground State Transitions beyond the singlet triplet Transition for a two electron quantum dot
Physical Review B, 2007Co-Authors: Yoshifumi Nishi, Y Tokura, J A Gupta, Guy Austing, S TaruchaAbstract:We studied electrostatic confinement effects on correlated electronic States in vertical quantum dots in high magnetic fields. We prepared vertical quantum dots with different lateral confinement strengths and investigated the magnetic field evolution of the electronic States. We observed that the formation of the maximum density droplet State corresponding to filling factor $\ensuremath{\nu}=1$ shifts to lower magnetic field as the lateral confinement energy becomes weaker. In addition, we found a Ground-State Transition in the $\ensuremath{\nu}l1$ regime for the most weakly laterally confined two-electron quantum dot that is predicted to appear beyond an easily accessible magnetic field in standard vertical quantum dots more typically investigated.
L. Canete - One of the best experts on this subject based on the ideXlab platform.
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measurement of the 2 0 Ground State Transition in the β decay of f 20
Physical Review C, 2019Co-Authors: Oliver S. Kirsebom, M. Hukkanen, A. Kankainen, W. H. Trzaska, K. Andersen, D F Stromberg, G Martinezpinedo, E Bodewits, B A Brown, L. CaneteAbstract:We report the first detection of the second-forbidden, nonunique, 2+→0+, Ground-State Transition in the β decay of F20. A low-energy, mass-separated F+20 beam produced at the IGISOL facility in Jyvaskyla, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10-5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β Transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne20 is now known to within better than 25% at the relevant temperatures and densities. (Less)
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First detection of the $2^+\rightarrow 0^+$ Ground-State Transition in the $\beta$ decay of $^{20}$F
arXiv: Nuclear Experiment, 2018Co-Authors: Oliver S. Kirsebom, M. Hukkanen, A. Kankainen, W. H. Trzaska, K. Andersen, L. Canete, J. Cederkäll, T. Enqvist, T. Eronen, H. O. U. FynboAbstract:We report the first detection of the second-forbidden, non-unique, $2^+\rightarrow 0^+$, Ground-State Transition in the $\beta$ decay of $^{20}$F. A low-energy, mass-separated $^{20}\rm{F}$ beam produced at the IGISOL facility in Jyvaskyla, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The branching ratio inferred from the observed $\beta$ yield is $[ 1.10\pm 0.21\textrm{(stat)}\pm 0.17\textrm{(sys)}^{+0.00}_{-0.11}\textrm{(theo)}] \times 10^{-5}$ corresponding to $\log ft = 10.47(11)$, making this the strongest known second-forbidden, non-unique Transition. The experimental result is supported by shell-model calculations and has important astrophysical implications.
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Measurement of the $2^+\rightarrow 0^+$ Ground-State Transition in the $\beta$ decay of $^{20}$F
arXiv: Nuclear Experiment, 2018Co-Authors: Oliver S. Kirsebom, M. Hukkanen, A. Kankainen, W. H. Trzaska, K. Andersen, L. Canete, D F Stromberg, E Bodewits, Gabriel Martínez-pinedo, J. CederkällAbstract:We report the first detection of the second-forbidden, non-unique, $2^+\rightarrow 0^+$, Ground-State Transition in the $\beta$ decay of $^{20}$F. A low-energy, mass-separated $^{20}\rm{F}^+$ beam produced at the IGISOL facility in Jyv\"askyl\"a, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The $\beta$-decay branching ratio inferred from the measurement is $b_{\beta} = [ 0.41\pm 0.08\textrm{(stat)}\pm 0.07\textrm{(sys)}] \times 10^{-5}$ corresponding to $\log ft = 10.89(11)$, making this one of the strongest second-forbidden, non-unique $\beta$ Transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on $^{20}$Ne is now known to within better than 25% at the relevant temperatures and densities.
Oliver S. Kirsebom - One of the best experts on this subject based on the ideXlab platform.
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measurement of the 2 0 Ground State Transition in the β decay of f 20
Physical Review C, 2019Co-Authors: Oliver S. Kirsebom, M. Hukkanen, A. Kankainen, W. H. Trzaska, K. Andersen, D F Stromberg, G Martinezpinedo, E Bodewits, B A Brown, L. CaneteAbstract:We report the first detection of the second-forbidden, nonunique, 2+→0+, Ground-State Transition in the β decay of F20. A low-energy, mass-separated F+20 beam produced at the IGISOL facility in Jyvaskyla, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10-5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β Transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne20 is now known to within better than 25% at the relevant temperatures and densities. (Less)
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First detection of the $2^+\rightarrow 0^+$ Ground-State Transition in the $\beta$ decay of $^{20}$F
arXiv: Nuclear Experiment, 2018Co-Authors: Oliver S. Kirsebom, M. Hukkanen, A. Kankainen, W. H. Trzaska, K. Andersen, L. Canete, J. Cederkäll, T. Enqvist, T. Eronen, H. O. U. FynboAbstract:We report the first detection of the second-forbidden, non-unique, $2^+\rightarrow 0^+$, Ground-State Transition in the $\beta$ decay of $^{20}$F. A low-energy, mass-separated $^{20}\rm{F}$ beam produced at the IGISOL facility in Jyvaskyla, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The branching ratio inferred from the observed $\beta$ yield is $[ 1.10\pm 0.21\textrm{(stat)}\pm 0.17\textrm{(sys)}^{+0.00}_{-0.11}\textrm{(theo)}] \times 10^{-5}$ corresponding to $\log ft = 10.47(11)$, making this the strongest known second-forbidden, non-unique Transition. The experimental result is supported by shell-model calculations and has important astrophysical implications.
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Measurement of the $2^+\rightarrow 0^+$ Ground-State Transition in the $\beta$ decay of $^{20}$F
arXiv: Nuclear Experiment, 2018Co-Authors: Oliver S. Kirsebom, M. Hukkanen, A. Kankainen, W. H. Trzaska, K. Andersen, L. Canete, D F Stromberg, E Bodewits, Gabriel Martínez-pinedo, J. CederkällAbstract:We report the first detection of the second-forbidden, non-unique, $2^+\rightarrow 0^+$, Ground-State Transition in the $\beta$ decay of $^{20}$F. A low-energy, mass-separated $^{20}\rm{F}^+$ beam produced at the IGISOL facility in Jyv\"askyl\"a, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The $\beta$-decay branching ratio inferred from the measurement is $b_{\beta} = [ 0.41\pm 0.08\textrm{(stat)}\pm 0.07\textrm{(sys)}] \times 10^{-5}$ corresponding to $\log ft = 10.89(11)$, making this one of the strongest second-forbidden, non-unique $\beta$ Transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on $^{20}$Ne is now known to within better than 25% at the relevant temperatures and densities.
J A Gupta - One of the best experts on this subject based on the ideXlab platform.
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Ground State Transitions beyond the singlet triplet Transition for a two electron quantum dot
Physical Review B, 2007Co-Authors: Yoshifumi Nishi, Y Tokura, J A Gupta, Guy Austing, S TaruchaAbstract:We studied electrostatic confinement effects on correlated electronic States in vertical quantum dots in high magnetic fields. We prepared vertical quantum dots with different lateral confinement strengths and investigated the magnetic field evolution of the electronic States. We observed that the formation of the maximum density droplet State corresponding to filling factor $\ensuremath{\nu}=1$ shifts to lower magnetic field as the lateral confinement energy becomes weaker. In addition, we found a Ground-State Transition in the $\ensuremath{\nu}l1$ regime for the most weakly laterally confined two-electron quantum dot that is predicted to appear beyond an easily accessible magnetic field in standard vertical quantum dots more typically investigated.
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contactless electroreflectance of ganyas1 y gaas multi quantum wells the conduction band offset and electron effective mass issues
Solid State Communications, 2006Co-Authors: R Kudrawiec, J A Gupta, M Gladysiewicz, M Motyka, J Misiewicz, G C AersAbstract:Abstract Interband Transitions in GaNyAs1−y/GaAs multi quantum well (MQW) samples with y=0.012 and 0.023 have been studied by contactless electroreflectance spectroscopy (CER). Optical Transitions related to absorption in the GaAs barriers and in the GaNyAs1−y/GaAs QWs have been observed and analyzed. The GaAs related Transition exhibits clear Franz-Keldysh oscillations with the period corresponding to the built-in electric field of 14 and 17 kV/cm for samples with y=0.012 and 0.023, respectively. The portion of the CER spectrum related to absorption in the GaNyAs1−y/GaAs QW exhibits two clear resonances which are attributed to optical Transitions between the Ground and excited States confined in the QWs. The resonance attributed to the Ground State Transition is associated with absorption between the first light- and heavy-hole subbands and the first electron subband (11L and 11H) while the resonance attributed to the excited State Transition is associated with absorption between the second heavy-hole subband and the second electron subband (22H). The energies of the 11H and 22H Transitions have been matched with those obtained from theoretical calculations performed within the effective mass approximation. Thus, the GaNyAs1−y/GaAs QWs are type-I structures with a conduction band offset, QC, between 70 and 80%. Moreover, the incorporation of N atoms into GaAs is found to cause a significant increase in the electron effective mass. The determined values of electron effective mass for GaNyAs1−y/GaAs QW with y=0.012 and 0.023 are 0.105m0 and 0.115m0, respectively.
Pierre M. Petroff - One of the best experts on this subject based on the ideXlab platform.
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Temperature-dependent linewidth of charged excitons in semiconductor quantum dots: Strongly broadened Ground State Transitions due to acoustic phonon scattering
Physical Review B, 2004Co-Authors: Bernhard Urbaszek, Pierre M. Petroff, E. J. Mcghee, M. Krüger, Richard J. Warburton, Khaled Karrai, Thierry Amand, Brian D. Gerardot, Jorge M. GarciaAbstract:We report temperature-dependent photoluminescence on neutral and charged excitons in individual InAs quantum dots. We find narrow emission lines for temperatures up to 30 K for exciton Transitions where only the electron Ground State is occupied. In contrast, for doubly charged excitons where the excited electron State is occupied, we observe a drastic increase of the Ground State Transition linewidth even at 30 K. We interpret this as evidence that the excited electron State is degenerate with the low energy tail of continuum States.
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Nonclassical radiation from a single quantum dot
Physica Status Solidi (B) Basic Research, 2002Co-Authors: Peter Michler, P. J. Carson, A. Kiraz, M. D. Mason, Atac Imamoglu, Steven K. Buratto, Christoph Becher, Winston V. Schoenfeld, Geoffrey F Strouse, Pierre M. PetroffAbstract:We report the experimental observation of photon antibunching in fluorescence from a single self-assembled InAs quantum dot. The nonclassical photon statistics proves the atomlike nature of a single quantum dot at cryogenic temperatures. Pump-power-dependent measurements of the correlation function g^(2)(T) providea method to determine the recombination time of the single exciton Ground-State Transition that does not require pulsed lasers. Using this method, we investigate the influence of photonic environment on a single quantum dot exciton lifetime.
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Tuning of electronic States in self-assembled InAs quantum dots using an ion implantation technique
Journal of Electronic Materials, 1998Co-Authors: P. J. Wellmann, Winston V. Schoenfeld, J. M. Garcia, Pierre M. PetroffAbstract:We report the tunability of up to 150 meV of the Ground State Transition of self-assembled InAs quantum dots (QDs) using Mn ion implantation and subsequent annealing. Because of the exciton localization in the quantum dots, the photoluminescence efficiency (T=12K) of the quantum dot Transition remains at 80% of its original value after implantation with a Mn dose of 1×10^13 cm^−2ions. Strong luminescence still remains at room temperature. At a high implantation dose (1×10^15 cm^−2) and rapid thermal annealing (700°C for 60s) about 25% of the QD luminescence intensity is recovered at T=12K.
