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Claudius Hubig

Postdoc in the group of Ignacio Cirac at the Max Planck Institute of Quantum Optics in Garching, working on the development, implementation and application of tensor network algorithms.

Contact Details

Max-Planck-Institut für Quantenoptik
Hans-Kopfermann-Str. 1
85748 Garching
arXiv author page · at MPQ
Formerly: at the Schollwöck Chair · at ExQM

Research Interests

Research is focused on numerical and algorithmic improvements to tensor network methods in condensed matter physics such as the DMRG, time evolution algorithms on MPS and generalisations of these methods to non-one-dimensional networks. Of particular interest is also further interlinking with the numerical linear algebra community as well as the application of DMRG in novel contexts as inner solvers of other methods (such as DMFT or DMET).

Work on a very versatile tensor network toolkit SyTen, capable of handling arbitrary-rank tensors with nonabelian symmetries such as SU(2)-Spin and a high degree of parallelisation was started in early 2015 with C++11. Currently supported are ground-state search with MPS-DMRG (single-site and two-site), various time evolution methods (Krylov, Taylor, TEBD, TDVP) and associated tooling for MPS and MPO generation and arithmetic. Some basic support (DMRG, Krylov time evolution etc.) for binary tree tensor networks and MPS with a local basis optimisation also exists.

The latest addition to the SyTen toolkit is a set of Python bindings which allow for a very fast and flexible definition of new physical systems in a few lines of interpreted, not compiled, code. Additionally, by also exposing the entire tensor network library, it becomes possible to quickly develop and implement new tensor algorithms.


  1. arXiv:1808.10804: Claudius Hubig: Abelian and non-abelian symmetries in infinite projected entangled pair states
  2. Phys. Rev. B 97, 045125 [arXiv]: Claudius Hubig, Jutho Haegeman, Ulrich Schollwöck: Error estimates for extrapolations with matrix-product states
  3. PNAS 2018, 201719374 [arXiv]: Ilia Khait, Patrick Azaria, Claudius Hubig, Ulrich Schollwöck, Assa Auerbach: Doped Kondo chain, a heavy Luttinger liquid
  4. Phys. Rev. B 96, 054423 [arXiv]: Anup K. Bera, Bella Lake, Fabian H. L. Essler, Laurens Vanderstraeten, Claudius Hubig, Ulrich Schollwöck, A. T. M. Nazmul Islam, Astrid Schneidewind, Diana L. Quintero-Castro: Spinon confinement in a quasi one dimensional anisotropic Heisenberg magnet
  5. Phys. Rev. B 95, 035129 [arXiv]: Claudius Hubig, Ian P. McCulloch and Ulrich Schollwöck: Generic construction of efficient matrix product operators
  6. Phys. Rev. B 96, 054303 [arXiv]: Zi Cai, Claudius Hubig and Ulrich Schollwöck: Universal long-time behavior of stochastically driven interacting quantum systems
  7. Phys. Rev. B 91, 155115 [arXiv]: Claudius Hubig, Ian P. McCulloch, Ulrich Schollwöck and F. Alexander Wolf: Strictly single-site DMRG algorithm with subspace expansion


  1. PhD Thesis [at LMU]: Symmetry-Protected Tensor Networks; submitted to the Faculty of Physics at LMU Munich on 2017-08-31, defended on 2017-10-30, refereed by Ulrich Schollwöck and Norbert Schuch
  2. BSc Thesis: Spin Dynamics in Adiabatic Transport through Quantum Dots; submitted to the Faculty of Physics at TU Berlin on 2012-07-03, supervised by Anja Metelmann, refereed by Tobias Brandes and Andreas Knorr



Teaching Experience

Summer 2017
Supervision of Bachelor thesis project: Study of a Sampling Method for Singular Values
Summer 2016
Tutoring for Numerische Mathematik (BSc, LMU)
Summer 2016
Supervision of Bachelor thesis project: Parallelized Time Evolution on the Heisenberg Spin Chain with Matrix Product States
Summer 2015
Tutoring for Advanced Statistical Physics (MSc, LMU)
Winter 2014/15
Tutoring for Thermodynamik und Statistische Physik (BSc, LMU)
Summer 2014
Tutoring for Advanced Statistical Physics (MSc, LMU)



since 11/2017
Postdoc in the group of Ignacio Cirac, Max Planck Institute of Quantum Optics, Garching, Germany.
10/2013 - 10/2017
PhD Student at the Chair of Uli Schollwöck, LMU Munich, Germany. Funded by the ExQM Graduate School and the Nanosystems Initiative Munich. Title of thesis: Symmetry-Protected Tensor Networks.
09/2012 - 07/2013
Read Applied Mathematics (Part III) at Hughes Hall, University of Cambridge, United Kingdom. Graduated with Masters of Advanced Studies in Applied Mathematics.
10/2009 - 07/2012
Read Physics at TU Berlin. Graduated with Bachelor of Science in Physics, title of thesis: Spin Dynamics in Adiabatic Transport through Quantum Dots. Partially funded by Deutschlandstipendium in 2011/2012.