2008: Professor for Theoretical Physics, Universität Hamburg, Germany
Since 2005: Lead Scientist, DESY, Hamburg, Germany
2002–2005: Director of Research, SPhT Saclay, Commissariat Energie Atomique, France
2000–2002: Research Associate, Albert-Einstein-Institute for Gravitational Physics, Golm, Germany
1995–2000: Assistant Professor for Theoretical Physics, Universität Hamburg, Germany
1993–1995: Research Associate, Physics Department, Harvard University, USA

Since 2018: Head of the Award Committee for the Hamburg Prize of Theoretical Physics
Since 2016: Member of the Advisory Board, Hamilton Mathematical Institute, Dublin, Ireland
Since 2016: Spokesperson of the Wolfgang Pauli Centre for Theoretical Physics, Hamburg, Germany
2014–2018: Management Board member of SFB 676 “Particles Strings & the Early Universe”, Universität Hamburg, Germany
Since 2014: Associate Editor, Nuclear Phyics B
2013–2016: Scientific Coordinator of MSC ITN “Gauge Theory as an Integrable System” (GATIS)
Since 2012: Associate Editor, Annales Henri Poincare
2007–2010: Head of DESY Theory Group, DESY, Hamburg, Germany
Since 2005: Member of Editorial Board, Reviews in Mathematical Physics
Since 2001: Member of Editorial Board, Journal of High Energy Physics