Submitted Papers
| [∗] |
Feedback-based Quantum Algorithm Inspired by Counterdiabatic Driving Rajesh K. Malla, Hiroki Sukeno, Hongye Yu, Tzu-Chieh Wei, Andreas Weichselbaum, and Robert M. Konik arXiv:2401.15303 [quant-ph] |
| [∗] |
Finite-size subthermal regime in disordered SU(N)-symmetric Heisenberg chains Dimitris Saraidaris, Jheng-Wei Li, Andreas Weichselbaum, Jan von Delft, and Dmitry A. Abanin arXiv:2304.03099 [quant-ph] |
| [∗] |
Detecting Multipartite Entanglement Patterns using Single Particle Green's Functions Rajesh K. Malla, Andreas Weichselbaum, Tzu-Chieh Wei, and Robert M. Konik arXiv:2310.05870 [quant-ph] |
| [∗] |
Mass gaps of a Z3 gauge theory with three fermion flavors in 1+1 dimensions Adrien Florio, Andreas Weichselbaum, Semeon Valgushev, and Robert D. Pisarski arXiv:2310.18312 [hep-th] |
Papers Published in Peer-Reviewed Journals
| [84] |
RKKY to Kondo crossover in helical edge of a topological insulator Pol Alonso-Cuevillas Ferrer, Oleg M. Yevtushenko, and Andreas Weichselbaum Phys. Rev. Res. 5, 033016 (2023) |
| [83] |
Emergence of Spinons in Layered Trimer Iridate Ba4Ir3O10 Y. Shen, J. Sears, G. Fabbris, A. Weichselbaum, W. Yin, H. Zhao, D. G. Mazzone, H. Miao, M. H. Upton, D. Casa, R. Acevedo-Esteves, C. Nelson, A. M. Barbour, C. Mazzoli, G. Cao, and M. P. M. Dean Phys. Rev. Lett. 129, 207201 (2022) |
| [82] |
Nonequilibrium spintronic transport through Kondo impurities Anand Manaparambil, Andreas Weichselbaum, Jan von Delft, and Ireneusz Weymann Phys. Rev. B 106, 125413 (2022) |
| [81] |
Quantum spin liquid with emergent chiral order in the triangular-lattice Hubbard model Bin-Bin Chen, Ziyu Chen, Shou-Shu Gong, D. N. Sheng, Wei Li, and Andreas Weichselbaum Phys. Rev. B 106, 094420 (2022) |
| [80] |
Machine learning of Kondo physics using variational autoencoders and symbolic regression Cole Miles, Matthew R. Carbone, Erica J. Sturm, Deyu Lu, Andreas Weichselbaum, Kipton Barros, and Robert M. Konik Phys. Rev. B 104, 235111 (2021) |
| [79] |
Abelian SU(N)1 chiral spin liquids on the square lattice Ji-Yao Chen, Jheng-Wei Li, Pierre Nataf, Sylvain Capponi, Matthieu Mambrini, Keisuke Totsuka, Hong-Hao Tu, Andreas Weichselbaum, Jan von Delft, and Didier Poilblanc Phys. Rev. B 104, 235104 (2021) |
| [78] |
Differentiating Hund from Mott physics in a three-band Hubbard-Hund model: Temperature dependence of spectral, transport, and thermodynamic properties K. M. Stadler, G. Kotliar, S.-S. B. Lee, A. Weichselbaum, and J. von Delft Phys. Rev. B 104, 115107 (2021) |
| [77] |
Predicting impurity spectral functions using machine learning Erica J. Sturm, Matthew R. Carbone, Deyu Lu, Andreas Weichselbaum, and Robert M. Konik Phys. Rev. B 103, 245118 (2021) |
| [76] |
Dimerization and spin decoupling in a two-leg Heisenberg ladder with frustrated trimer rungs Andreas Weichselbaum, Weiguo Yin, and Alexei M. Tsvelik Phys. Rev. B 103, 125120 (2021) |
| [75] |
Study of spin symmetry in the doped t-J model using infinite projected entangled pair states Jheng-Wei Li, Benedikt Bruognolo, Andreas Weichselbaum, and Jan von Delft Phys. Rev. B 103, 075127 (2021) |
| [74] |
A beginner's guide to non-abelian iPEPS for correlated fermions Benedikt Bruognolo, Jheng-Wei Li, Jan von Delft, and Andreas Weichselbaum SciPost Phys. Lect. Notes 25 (2021) |
| [73] |
Quantum many-body simulations of the two-dimensional Fermi-Hubbard model in ultracold optical lattices Bin-Bin Chen, Chuang Chen, Ziyu Chen, Jian Cui, Yueyang Zhai, Andreas Weichselbaum, Jan von Delft, Zi Yang Meng, and Wei Li Phys. Rev. B 103, L041107 (2021) |
| [72] |
Renormalized Lindblad driving: A numerically exact nonequilibrium quantum impurity solver Matan Lotem, Andreas Weichselbaum, Jan von Delft, and Moshe Goldstein Phys. Rev. Research 2, 043052 (2020) |
| [71] |
Uncovering Non-Fermi-Liquid Behavior in Hund Metals: Conformal Field Theory Analysis of an SU(2)×SU(3) Spin-Orbital Kondo Model E. Walter, K. M. Stadler, S.-S. B. Lee, Y. Wang, G. Kotliar, A. Weichselbaum, and J. von Delft Phys. Rev. X 10, 031052 (2020) |
| [70] |
X-symbols for non-Abelian symmetries in tensor networks Andreas Weichselbaum Phys. Rev. Research 2, 023385 (2020) |
| [69] |
Global Phase Diagram of a Spin-Orbital Kondo Impurity Model and the Suppression of Fermi-Liquid Scale Y. Wang, E. Walter, S.-S. B. Lee, K. M. Stadler, J. von Delft, A. Weichselbaum, and G. Kotliar Phys. Rev. Lett. 124, 136406 (2020) |
| [68] |
Orbital differentiation in Hund metals Fabian B. Kugler, Seung-Sup B. Lee, Andreas Weichselbaum, Gabriel Kotliar, and Jan von Delft Phys. Rev. B 100, 115159 (2019) |
| [67] |
Thermal tensor renormalization group simulations of square-lattice quantum spin models Han Li, Bin-Bin Chen, Ziyu Chen, Jan von Delft, Andreas Weichselbaum, and Wei Li Phys. Rev. B 100, 045110 (2019) |
| [66] |
Hundness versus Mottness in a three-band Hubbard-Hund model: on the origin of strong correlations in Hund metals K.M. Stadler, G. Kotliar, A. Weichselbaum, and J. von Delft Annals of Physics 405, 365 (2019) |
| [65] |
Signatures of Mottness and Hundness in archetypal correlated metals Xiaoyu Deng, Katharina M. Stadler, Kristjan Haule, Andreas Weichselbaum, Jan von Delft, and Gabriel Kotliar Nature Comm. 10, 2721 (2019) |
| [64] |
Two-temperature scales in the triangular-lattice Heisenberg antiferromagnet Lei Chen, Dai-Wei Qu, Han Li, Bin-Bin Chen, Shou-Shu Gong, Jan von Delft, Andreas Weichselbaum, and Wei Li Phys. Rev. B 99, 140404 (2019) |
| [63] |
Nontopological Majorana Zero Modes in Inhomogeneous Spin Ladders Neil J. Robinson, Alexander Altland, Reinhold Egger, Niklas M. Gergs, Wei Li, Dirk Schuricht, Alexei M. Tsvelik, Andreas Weichselbaum, and Robert M. Konik Phys. Rev. Lett. 122, 027201 (2019) |
| [62] |
Nonequilibrium Steady-State Transport in Quantum Impurity Models: A Thermofield and Quantum Quench Approach Using Matrix Product States F. Schwarz, I. Weymann, J. von Delft, and A. Weichselbaum Phys. Rev. Lett. 121, 137702 (2018) |
| [61] |
Exponential Thermal Tensor Network Approach for Quantum Lattice Models Bin-Bin Chen, Lei Chen, Ziyu Chen, Wei Li, and Andreas Weichselbaum Phys. Rev. X 8, 031082 (2018) |
| [60] |
Unified phase diagram of antiferromagnetic SU(N) spin ladders A. Weichselbaum, S. Capponi, P. Lecheminant, A. M. Tsvelik, and A. M. Läuchli Phys. Rev. B 98, 085104 (2018) |
| [59] |
At which magnetic field, exactly, does the Kondo resonance begin to split? A Fermi liquid description of the low-energy properties of the Anderson model Michele Filippone, Cătălin Paşcu Moca, Andreas Weichselbaum, Jan von Delft, and Christophe Mora Phys. Rev. B 98, 075404 (2018) |
| [58] |
Filling-driven Mott transition in SU(N) Hubbard models Seung-Sup B. Lee, Jan von Delft, and Andreas Weichselbaum Phys. Rev. B 97, 165143 (2018) |
| [57] |
Emergent spin-1 trimerized valence bond crystal in the spin-1/2 Heisenberg model on the star lattice Shi-Ju Ran, Wei Li, Shou-Shu Gong, Andreas Weichselbaum, Jan von Delft, and Gang Su Phys. Rev. B 97, 075146 (2018) |
| [56] |
Generalized Schrieffer-Wolff transformation of multiflavor Hubbard models Seung-Sup B. Lee, Jan von Delft, and Andreas Weichselbaum Phys. Rev. B 96, 245106 (2017) |
| [55] |
Doublon-Holon Origin of the Subpeaks at the Hubbard Band Edges Seung-Sup B. Lee, Jan von Delft, and Andreas Weichselbaum Phys. Rev. Lett. 119, 236402 (2017) |
| [54] |
Open Wilson chains for quantum impurity models: Keeping track of all bath modes B. Bruognolo, N.-O. Linden, F. Schwarz, S.-S. B. Lee, K. Stadler, A. Weichselbaum, M. Vojta, F. B. Anders, and J. von Delft Phys. Rev. B 95, 121115 (2017) |
| [53] |
Adaptive broadening to improve spectral resolution in the numerical renormalization group Seung-Sup B. Lee, and Andreas Weichselbaum Phys. Rev. B 94, 235127 (2016) |
| [52] |
Lindblad-driven discretized leads for nonequilibrium steady-state transport in quantum impurity models: Recovering the continuum limit F. Schwarz, M. Goldstein, A. Dorda, E. Arrigoni, A. Weichselbaum, and J. von Delft Phys. Rev. B 94, 155142 (2016) |
| [51] |
Dynamic structure factor of the spin-1/2 XXZ chain in a transverse field Benedikt Bruognolo, Andreas Weichselbaum, Jan von Delft, and Markus Garst Phys. Rev. B 94, 085136 (2016) |
| [50] |
Interleaved numerical renormalization group as an efficient multiband impurity solver K. M. Stadler, A. K. Mitchell, J. von Delft, and A. Weichselbaum Phys. Rev. B 93, 235101 (2016) |
| [49] |
Thermalization and dynamics in the single-impurity Anderson model Ireneusz Weymann, Jan von Delft, and Andreas Weichselbaum Phys. Rev. B 92, 155435 (2015) |
| [48] |
Dynamical mean-field theory plus Numerical Renormalization Group study of spin-orbital separation in a three-band Hund metal K. M. Stadler, Z. P. Yin, J. von Delft, G. Kotliar, and A. Weichselbaum Phys. Rev. Lett. 115, 136401 (2015) |
| [47] |
Symmetric minimally entangled typical thermal states Benedikt Bruognolo, Jan von Delft, and Andreas Weichselbaum Phys. Rev. B 92, 115105 (2015) |
| [46] |
Hexagon-singlet solid ansatz for the spin-1 Kagome antiferromagnet Wei Li, Andreas Weichselbaum, Jan von Delft, and Hong-Hao Tu Phys. Rev. B 91, 224414 (2015) |
| [45] |
Simplex valence-bond crystal in the spin-1 Kagome Heisenberg antiferromagnet Tao Liu, Wei Li, Andreas Weichselbaum, Jan von Delft, and Gang Su Phys. Rev. B 91, 060403 (2015) |
| [44] |
Two-bath spin-boson model: Phase diagram and critical properties Benedikt Bruognolo, Andreas Weichselbaum, Cheng Guo, Jan von Delft, Imke Schneider, and Matthias Vojta Phys. Rev. B 90, 245130 (2014) |
| [43] |
Transmission Phase in the Kondo Regime Revealed in a Two-Path Interferometer S. Takada, C. Bäuerle, M. Yamamoto, K. Watanabe, S. Hermelin, T. Meunier, A. Alex, A. Weichselbaum, J. von Delft, A. Ludwig, A. D. Wieck, and S. Tarucha Phys. Rev. Lett. 113, 126601 (2014) |
| [42] |
Non-Fermi-liquid behavior in nonequilibrium transport through Co-doped Au chains connected to fourfold symmetric leads S. Di Napoli, P. Roura-Bas, Andreas Weichselbaum, and A. A. Aligia Phys. Rev. B 90, 125149 (2014) |
| [41] |
Equilibrium Fermi-liquid coefficients for the fully screened N-channel Kondo model M. Hanl, A. Weichselbaum, J. von Delft, and M. Kiselev Phys. Rev. B 89, 195131 (2014) |
| [40] |
Local susceptibility and Kondo scaling in the presence of finite bandwidth Markus Hanl, and Andreas Weichselbaum Phys. Rev. B 89, 075130 (2014) |
| [39] |
Identifying Symmetry-Protected Topological Order by Entanglement Entropy W. Li, A. Weichselbaum, and J. von Delft Phys. Rev. B 88, 245121 (2013) |
| [38] |
Proposed Rabi-Kondo Correlated State in a Laser-Driven Semiconductor Quantum Dot B. Sbierski, M. Hanl, A. Weichselbaum, H. E. Türeci, M. Goldstein, L. I. Glazman, J. von Delft, and A. Imamoglu Phys. Rev. Lett. 111, 157402 (2013) |
| [37] |
Nonequilibrium dynamics in an optical transition from a neutral quantum dot to a correlated many-body state F. Haupt, S. Smolka, M. Hanl, W. Wüster, J. Miguel-Sanchez, A. Weichselbaum, J. von Delft, and A. Imamoglu Phys. Rev. B 88, 161304 (2013) |
| [36] |
Iron impurities in gold and silver: Comparison of transport measurements to numerical renormalization group calculations exploiting non-Abelian symmetries M. Hanl, A. Weichselbaum, T. A. Costi, F. Mallet, L. Saminadayar, C. Bäuerle, and J. von Delft Phys. Rev. B 88, 075146 (2013) |
| [35] |
Non-Fermi-Liquid Behavior in Transport Through Co-Doped Au Chains S. Di Napoli, A. Weichselbaum, P. Roura-Bas, A. A. Aligia, Y. Mokrousov, and S. Blügel Phys. Rev. Lett. 110, 196402 (2013) |
| [34] |
Tensor networks and the numerical renormalization group Andreas Weichselbaum Phys. Rev. B 86, 245124 (2012) |
| [33] |
Non-abelian symmetries in tensor networks: A quantum symmetry space approach Andreas Weichselbaum Annals of Physics 327, 2972 (2012) |
| [32] |
Full density-matrix numerical renormalization group calculation of impurity susceptibility and specific heat of the Anderson impurity model L. Merker, A. Weichselbaum, and T. A. Costi Phys. Rev. B 86, 075153 (2012) |
| [31] |
Anderson orthogonality in the dynamics after a local quantum quench Wolfgang Münder, Andreas Weichselbaum, Moshe Goldstein, Yuval Gefen, and Jan von Delft Phys. Rev. B 85, 235104 (2012) |
| [30] |
Critical and Strong-Coupling Phases in One- and Two-Bath Spin-Boson Models Cheng Guo, Andreas Weichselbaum, Jan von Delft, and Matthias Vojta Phys. Rev. Lett. 108, 160401 (2012) |
| [29] |
Incommensurate correlations in the anisotropic triangular Heisenberg lattice Andreas Weichselbaum, and Steven R. White Phys. Rev. B 84, 245130 (2011) |
| [28] |
Spin-1/2 Kondo effect in an InAs nanowire quantum dot: Unitary limit, conductance scaling, and Zeeman splitting Andrey V. Kretinin, Hadas Shtrikman, David Goldhaber-Gordon, Markus Hanl, Andreas Weichselbaum, Jan von Delft, Theo Costi, and Diana Mahalu Phys. Rev. B 84, 245316 (2011) |
| [27] |
Discarded weight and entanglement spectra in the numerical renormalization group Andreas Weichselbaum Phys. Rev. B 84, 125130 (2011) |
| [26] |
Anderson orthogonality and the numerical renormalization group Andreas Weichselbaum, Wolfgang Münder, and Jan von Delft Phys. Rev. B 84, 075137 (2011) |
| [25] |
Quantum quench of Kondo correlations in optical absorption Christian Latta, Florian Haupt, Markus Hanl, Andreas Weichselbaum, Martin Claassen, Wolf Wuester, Parisa Fallahi, Stefan Faelt, Leonid Glazman, Jan von Delft, Hakan E. Türeci, and Atac Imamoglu Nature 474, 627 (2011) |
| [24] |
Chebyshev matrix product state approach for spectral functions Andreas Holzner, Andreas Weichselbaum, Ian P. McCulloch, Ulrich Schollwöck, and Jan von Delft Phys. Rev. B 83, 195115 (2011) |
| [23] |
Many-Body Dynamics of Exciton Creation in a Quantum Dot by Optical Absorption: A Quantum Quench towards Kondo Correlations Hakan E. Türeci, M. Hanl, M. Claassen, A. Weichselbaum, T. Hecht, B. Braunecker, A. Govorov, L. Glazman, A. Imamoglu, and J. von Delft Phys. Rev. Lett. 106, 107402 (2011) |
| [22] |
Asymmetric spin-1/2 two-leg ladders: Analytical studies supported by exact diagonalization, DMRG, and Monte Carlo simulations D. N. Aristov, C. Brünger, F. F. Assaad, M. N. Kiselev, A. Weichselbaum, S. Capponi, and F. Alet Phys. Rev. B 82, 174410 (2010) |
| [21] |
Correlation density matrices for one-dimensional quantum chains based on the density matrix renormalization group W. Münder, A. Weichselbaum, A. Holzner, J. von Delft, and C. L. Henley New J. of Phys. 12, 075027 (2010) |
| [20] |
Matrix product state approach for a two-lead multilevel Anderson impurity model Andreas Holzner, Andreas Weichselbaum, and Jan von Delft Phys. Rev. B 81, 125126 (2010) |
| [19] |
Variational matrix-product-state approach to quantum impurity models A. Weichselbaum, F. Verstraete, U. Schollwöck, J. I. Cirac, and Jan von Delft Phys. Rev. B 80, 165117 (2009) |
| [18] |
Constrained optimization of sequentially generated entangled multiqubit states Hamed Saberi, Andreas Weichselbaum, Lucas Lamata, David Pérez-García, Jan von Delft, and Enrique Solano Phys. Rev. A 80, 022334 (2009) |
| [17] |
Quantum Criticality Perspective on the Charging of Narrow Quantum-Dot Levels V. Kashcheyevs, Christoph Karrasch, Theresa Hecht, Andreas Weichselbaum, Volker Meden, and Avraham Schiller Phys. Rev. Lett. 102, 136805 (2009) |
| [16] |
Interplay of mesoscopic and Kondo effects for transmission amplitude of few-level quantum dots T. Hecht, A. Weichselbaum, Y. Oreg, and J. von Delft Phys. Rev. B 80, 115330 (2009) |
| [15] |
Density matrix renormalization group study of a quantum impurity model with Landau-Zener time-dependent Hamiltonian Cheng Guo, Andreas Weichselbaum, Stefan Kehrein, Tao Xiang, and Jan von Delft Phys. Rev. B 79, 115137 (2009) |
| [14] |
Kondo Decoherence: Finding the Right Spin Model for Iron Impurities in Gold and Silver T. A. Costi, L. Bergqvist, A. Weichselbaum, J. von Delft, T. Micklitz, A. Rosch, P. Mavropoulos, P. H. Dederichs, F. Mallet, L. Saminadayar, and C. Bäuerle Phys. Rev. Lett. 102, 056802 (2009) |
| [13] |
Matrix-product-state comparison of the numerical renormalization group and the variational formulation of the density-matrix renormalization group Hamed Saberi, Andreas Weichselbaum, and Jan von Delft Phys. Rev. B 78, 035124 (2008) |
| [12] |
Numerical renormalization group calculation of near-gap peaks in spectral functions of the Anderson model with superconducting leads Theresa Hecht, Andreas Weichselbaum, Jan von Delft, and Ralph Bulla J. Phys. Cond. Mat. 20, 275213 (2008) |
| [11] |
Modeling of quantum point contacts in high magnetic fields and with current bias outside the linear response regime Sefa Arslan, E. Cicek, D. Eksi, S. Aktas, Andreas Weichselbaum, and Afif Siddiki Phys. Rev. B 78, 125423 (2008) |
| [10] |
Sum-Rule Conserving Spectral Functions from the Numerical Renormalization Group Andreas Weichselbaum, and Jan von Delft Phys. Rev. Lett. 99, 076402 (2007) |
| [9] |
Phase lapses in transmission through interacting two-level quantum dots Christoph Karrasch, Theresa Hecht, Andreas Weichselbaum, Jan von Delft, Yval Oreg, and Volker Meden New J. of Phys. 9, 123 (2007) |
| [8] |
Mesoscopic to Universal Crossover of the Transmission Phase of Multilevel Quantum Dots Christoph Karrasch, Theresa Hecht, Andreas Weichselbaum, Yval Oreg, Jan von Delft, and Volker Meden Phys. Rev. Lett. 98, 186802 (2007) |
| [7] |
Tunability of qubit Coulomb interaction: Numerical analysis of top-gate depletion in two-dimensional electron systems A. Weichselbaum, and S. E. Ulloa Phys. Rev. B 74, 085318 (2006) |
| [6] |
Aharonov-Bohm phase as quantum gate in two-electron charge qubits A. Weichselbaum, and S. E. Ulloa Phys. Rev. B 70, 195332 (2004) |
| [5] |
Spatially Resolved Manipulation of Single Electrons in Quantum Dots Using a Scanned Probe A. Pioda, S. Kičin, T. Ihn, M. Sigrist, A. Fuhrer, K. Ensslin, A. Weichselbaum, S. E. Ulloa, M. Reinwald, and W. Wegscheider Phys. Rev. Lett. 93, 216801 (2004) |
| [4] |
Charge qubits and limitations of electrostatic quantum gates A. Weichselbaum, and S. E. Ulloa Phys. Rev. A 70, 032328 (2004) |
| [3] |
Potential landscapes and induced charges near metallic islands in three dimensions A. Weichselbaum, and S. E. Ulloa Phys. Rev. E 68, 056707 (2003) |
| [2] |
Electron Dynamics near a Metallic Island Array Andreas Weichselbaum, and Sergio E. Ulloa Phys. Stat. Sol. B 230, 325 (2002) |
| [1] |
Polarization-dependent intersubband absorption and normal-incidence infrared detection in p-type Si/SiGe quantum wells P. Kruck, A. Weichselbaum, M. Helm, T. Fromherz, G. Bauer, J. F. Nützel, and G. Abstreiter Superlattices and Microstructures 23, 61 (1998) |
Conference Proceedings
| [3] |
Charge qubits and limitations of electrostatic quantum gates A. Weichselbaum, and S.E. Ulloa Physica E: Low-dimensional Systems and Nanostructures 26, 342 proceedings 3rd International Conference on Quantum Dots (QD 2004, Banff) (2005) |
| [2] |
Decoherence of charge qubit systems A. Weichselbaum, and S.E. Ulloa Physics of Semiconductors, Pts A and B (AIP conference proceedings) 772, 1467 proceedings 27th International Conference on the Physics of Semiconductors (ICPS-27, Flagstaff) (2005) |
| [1] |
IR studies of p-type Si/SiGe quantum wells: intersubband absorption, IR detectors, and second-harmonic generation M. Helm, P. Kruck, T. Fromherz, A. Weichselbaum, M. Seto, G. Bauer, Z. Moussa, P. Boucaud, F. H. Julien, J. -M. Lourtioz, J. F. Nützel, and G. Abstreiter Thin Solid Films 294, 330 proceedings European-Materials-Research-Society 1996 Spring Meeting, Strasbourg (1997) |
Thesis
| [3] |
Tensor networks and the numerical renormalization group Andreas Weichselbaum, Habilitation thesis, Ludwig Maximilians University, Munich, Germany (2012) |
| [2] |
Nanoscale quantum dynamics and electrostatic coupling Andreas Weichselbaum, Ph. D. thesis, Ohio University, Athens, OH, US (2004) Advisor: Sergio E. Ulloa |
| [1] |
Infrared Detectors on the Basis of Si/SiGe Heterostructures Andreas Weichselbaum, Diploma thesis (in German), Johannes Kepler Univerität, Linz, Austria (1997) Supervisor: Manfred Helm |