  We provide further evidence to support the fact that a four-dimensional
effective field theory description with de Sitter isometries in IIB string
theory, overcoming the no-go and the swampland criteria, can only exist if de
Sitter space is realized as a Glauber-Sudarshan state. We show here that this
result is independent of the choice of de Sitter slicings. The
Glauber-Sudarshan state, constructed by shifting the interacting vacuum in the
M-theory uplift of the scenario, differs from a standard coherent state in QFT
in the sense that the shape and size of the state changes with respect to time,
implying changes in the graviton and the flux quanta. Despite this, the
expectation values of the graviton and flux operators in such a state reproduce
the exact de Sitter background, as long as we are within the temporal bound set
by the onset of the strong coupling in the dual type IIA side, and satisfy the
corresponding Schwinger-Dyson's equations in the presence of hierarchically
controlled perturbative and non-perturbative quantum corrections.
  Additionally, we provide a detailed study of the fluxes supporting the
Glauber-Sudarshan state in the M-theory uplift of the IIB scenario. We show
explicitly how the Bianchi identities, anomaly cancellation and flux
quantization conditions, along-with the constraints from the Schwinger-Dyson's
equations, conspire together to provide the necessary temporal dependences to
support such a state in full M-theory. We also discuss how our analysis points
towards a surprising connection to the four-dimensional null energy condition,
for a Friedman-Lemaitre-Robertson-Walker state in the IIB side, as a
consistency condition for the existence of an effective field theory
description in M-theory.
