Seminar "The light-induced inter-Coulombic decay in quantum dots: a one- and twodimensional study" by Anika Haller, Helmholtz-Zentrum Berlin, Germany

Date

2018年9月4日 (火) 15:00

Location

C016, Level C, Lab 1

Description

Title: The light-induced inter-Coulombic decay in quantum dots: a one- and twodimensional
study

Speaker: Anika Haller (Helmholtz-Zentrum Berlin, Germany)

Abstract:

We theoretically study the electron dynamics for systems consisting of two singlycharged
and non-coupled quantum dots (QD) in terms of the so-called inter-Coulombic
decay (ICD) [1]. It can be observed as the efficient and dominant decay of a resonance
state into the ground state, in which the Coulomb interaction induces an ultrafast
energy transfer between both sites. This causes the excitation of an electron from one
QD into the continuum, while the relaxation of another electron into a lower bound
state of the second QD can be observed.
It has been shown so far for QDs that share a single continuum direction and strong
confinement in the other two spatial dimensions [2-5]. Lately, we added a second
continuum direction that opens up the applicability in a further group of material
systems, namely laterally arranged self-assembled QDs.
The crucial step is the efficient preparation of the resonance state, which we realize by
resonant excitation with laser pulses [3-5]. We studied the competition of ICD and
direct ionization including multiphoton processes in dependence of the field-strength
and laser focus in one dimension. In the two-dimensional continuum the effect of
electric field polarization on the efficiency of ICD can now be analyzed [6].
The antisymmetrized multiconfiguration time-dependent Hartree method (MCTDH) [7]
serves as a space-resolved wavefunction ansatz and grid-based calculations are
performed utilizing the Heidelberg MCTDH program [8]. The standard POTFIT method
[9] that transforms general potential energy surfaces into product form as needed for
MCTDH has turned out to be too memory demanding when calculating in two
dimensions. Instead, we adopt the Multigrid POTFIT method [10] that yields
satisfactory results within decent computation times.
References
1. L. S. Cederbaum, J. Zobeley, and F. Tarantelli. Phys. Rev. Lett. 79, 4778 (1997).
2. A. Bande, K. Gokhberg, and L. S. Cederbaum, J. Chem. Phys. 135, 144112 (2011).
3. A. Bande, J. Chem. Phys. 138, 214104 (2013).
4. A. Haller, Y.-C. Chiang, M. Menger, E. F. Aziz, and A. Bande, Chem. Phys. 482, 135 (2017).
5. A. Haller and A. Bande, under review in J. Chem. Phys.
6. A. Haller, D. Peláez, and A. Bande, in preparation.
7. U. Manthe, H.-D. Meyer, and L. S. Cederbaum, J. Chem. Phys. 97, 3199 (1992).
8. M. H. Beck, A. Jäckle, G. A. Worth, and H.-D. Meyer, Phys. Rep. 324, 1 (2000).
9. A. Jäckle and H.-D. Meyer, J. Chem. Phys. 104, 7974 (1996).
10. D. Peláez and H.-D. Meyer, J. Chem. Phys. 138, 014108 (2013).

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