Journal article

Extracting spectral properties from Keldysh Green functions

  • Dirks, Andreas Department of Physics, University of Göttingen, Germany - Department of Physics, Georgetown University, Washington, USA
  • Eckstein, Martin Max Planck Research Department for Structural Dynamics, University of Hamburg-CFEL, Germany
  • Pruschke, Thomas Department of Physics, University of Göttingen, Germany
  • Werner, Philipp Department of Physics, University of Fribourg, Switzerland
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Published in:
  • Physical Review E. - 2013, vol. 87, no. 2, p. 023305
English We investigate the possibility to assist the numerically ill-posed calculation of spectral properties of interacting quantum systems in thermal equilibrium by extending the imaginary-time simulation to a finite Schwinger-Keldysh contour. The effect of this extension is tested within the standard maximum entropy approach to analytic continuation. We find that the inclusion of real-time data improves the resolution of structures at high energy, while the imaginary-time data are needed to correctly reproduce low-frequency features such as quasiparticle peaks. As a nonequilibrium application, we consider the calculation of time-dependent spectral functions from retarded Green function data on a finite time interval, and compare the maximum entropy approach to direct Fourier transformation and a method based on Padé approximants.
Faculté des sciences et de médecine
Département de Physique
  • English
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