| 1. |
- Boström, E. Viñas, et al.
(författare)
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Time-Stretched Spectroscopy by the Quantum Zeno Effect : The Case of Auger Decay
- 2018
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Ingår i: Physical Review Letters. - 0031-9007. ; 121:23
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Tidskriftsartikel (refereegranskat)abstract
- A tenet of time-resolved spectroscopy is "faster laser pulses for shorter timescales". Here, we suggest turning this paradigm around, and slowing down the system dynamics via repeated measurements, to do spectroscopy on longer timescales. This is the principle of the quantum Zeno effect. We exemplify our approach with the Auger process, and find that repeated measurements increase the core-hole lifetime, redistribute the kinetic energy of Auger electrons, and alter entanglement formation. We further provide an explicit experimental protocol for atomic Li, to make our proposal concrete.
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| 2. |
- Moskalenko, Evgenii, et al.
(författare)
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Single InAs/GaAs quantum dot spectroscopy in a lateral electric field
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We report on the comprehensive study of InAs/GaAs single quantum dots subjected to a lateral external electric field by means of micro-photoluminescence (μ-PL) technique. The results obtained on the exciton in the μ-PL spectra of a single dot demonstrate a considerable PL intensity enhancement (up to a factor of 4) of the dot as well as a redistribution of the excitonic lines when an electric field is applied. The latter fact exhibits an effective charge reconfiguration of the dot from a purely negatively charged to a neutral state. The model proposed to explain the charge redistribution is based on an effective hole localization at the potential fluctuations of the wetting layer at low temperature and bias.
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| 3. |
- Hopjan, M., et al.
(författare)
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Molecular junctions and molecular motors : Including Coulomb repulsion in electronic friction using nonequilibrium Green's functions
- 2018
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Ingår i: Physical Review B. - 2469-9950. ; 98:4
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Tidskriftsartikel (refereegranskat)abstract
- We present a theory of molecular motors based on the Ehrenfest dynamics for nuclear coordinates and the adiabatic limit of the Kadanoff-Baym equations for current-induced forces. Electron-electron interactions can be systematically included through many-body perturbation theory, making the nonequilibrium Green's function formulation suitable for first-principles treatments of realistic junctions. The method is benchmarked against simulations via real-time Kadanoff-Baym equations, finding an excellent agreement. Results on a paradigmatic model of a molecular motor show that correlations can change dramatically the physical scenario by, e.g., introducing a sizable damping in self-sustained van der Pol oscillations.
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| 4. |
- Joost, J.-P., et al.
(författare)
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Löwdin's symmetry dilemma within Green functions theory for the one-dimensional Hubbard model
- 2021
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Ingår i: Contributions to Plasma Physics. - : Wiley. - 0863-1042 .- 1521-3986.
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Tidskriftsartikel (refereegranskat)abstract
- The energy gap of correlated Hubbard clusters is well studied for one-dimensional systems using analytical methods and density-matrix-renormalization-group (DMRG) simulations. Beyond 1D, however, exact results are available only for small systems by quantum Monte Carlo. For this reason and, due to the problems of DMRG in simulating 2D and 3D systems, alternative methods such as Green functions combined with many-body approximations (GFMBA), that do not have this restriction, are highly important. However, it has remained open whether the approximate character of GFMBA simulations prevents the computation of the Hubbard gap. Here we present new GFMBA results that demonstrate that GFMBA simulations are capable of producing reliable data for the gap which agrees well with the DMRG benchmarks in 1D. An interesting observation is that the accuracy of the gap can be significantly increased when the simulations give up certain symmetry restriction of the exact system, such as spin symmetry and spatial homogeneity. This is seen as manifestation and generalization of the “symmetry dilemma” introduced by Löwdin for Hartree–Fock wave function calculations.
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