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SUMMARY:Quantum decoherence during inflation
DTSTART;VALUE=DATE-TIME:20200305T184800Z
DTEND;VALUE=DATE-TIME:20200305T190000Z
DTSTAMP;VALUE=DATE-TIME:20240618T224620Z
UID:indico-contribution-274@mosphys.ru
DESCRIPTION:Speakers: Arina Shtennikova ()\nDuring inflation the universe
rapidly expands and the observed classical distribution of inhomogeneities
originates from the substantially non-classical state. The problem of tra
nsition from quantum to classical behavior is also important outside the c
osmological context in connection with the study of mesoscopic systems. An
d this problem can be viewed in the context of the theory of decoherence i
nduced by environment. In short\, this phenomenon lies in the fact that th
e quantum degrees of freedom of the system are entangled with the degrees
of freedom of the environment\, which leads to the suppression of interfer
ence effects and the classicalisation of the system.\nIn cosmological cont
ext\, the transition to classical behavior is studied within the Wheeler-D
eWitt approach with small inhomogeneous perturbations considered over quan
tized homogeneous background. The Wheeler-DeWitt equation is solved in the
Born-Oppenheimer approximation. Using this approximation\, one can repres
ent the wave function as a product of homogeneous and inhomogeneous parts.
Inhomogeneous wave function is associated with QFT approach on a clas-sic
al curved background and homogeneous part provides probability amplitude f
or different backgrounds. The decoherence process itself is observed by st
udying the corresponding density matrix.\nIn this paper we discuss the dec
oherence of background degrees of freedom due to the loss of information a
bout modes going beyond the cosmological horizon while mantaining the full
information about the short wavelength perturbations. We demonstrate the
classicalization process of the quantum state of inhomogeneities of the un
iverse by observing reduced density matrix of the short wavelength fluctua
tions.\n\nhttps://rich2018.org/indico/event/5/contributions/274/
LOCATION:HSE Study Center “Voronovo”
URL:https://rich2018.org/indico/event/5/contributions/274/
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