282 citations · 4k across the 98 of their papers we have counts for
4 papers · 1 filter
Wigner function and decoherence
C. Kiefer
I briefly review the role of the Wigner function in the study of the quantum-to-classical transition through interaction with the environment (decoherence).
Wheeler-DeWitt equation and Feynman diagrams
A. O. Barvinsky, C. Kiefer
We present a systematic expansion of all constraint equations in canonical quantum gravity up to the order of the inverse Planck mass squared. It is demonstrated that this method g…
Boundary Conditions in Quantum String Cosmology
Mariusz P. Dabrowski, Claus Kiefer
We discuss in detail how to consistently impose boundary conditions in quantum string cosmology. Since a classical time parameter is absent in quantum gravity, such conditions must…
Semiclassical quantum states for black holes
Claus Kiefer
I discuss the semiclassical approximation for the Wheeler-DeWitt equation when applied to the CGHS model and spherically symmetric gravity. Special attention is devoted to the issu…