Keldysh formalism for multiple parallel worlds
this paper with M. Ansari has appeared on arxiv today: see it here. This is our contribution to the forthcoming Special JETP issue dedicated to 85th anniversary of Prof. L. V. Keldysh.
Abstract:
We present here a compact and self-contained review of recently developed Keldysh formalism for multiple parallel worlds. The formalism has been applied to consistent quantum evaluation of the flows of informational quantities, in particular, to evaluation of Renyi and Shannon entropy flows. We start with the formulation of standard and extended Keldysh technique in single world in a form convenient for our presentation. We explain the use of Keldysh contours encompassing multiple parallel worlds In the end, we shortly summarize the concrete results obtained with the method.
