  During inflation, scalar fields, including the Higgs boson, may acquire a
nonzero vacuum expectation value, which must later relax to the equilibrium
value during reheating. In the presence of the time-dependent condensate, the
vacuum state can evolve into a state with a nonzero particle number. We show
that, in the presence of lepton number violation in the neutrino sector, the
particle production can explain the observed matter-antimatter asymmetry of the
universe. We find that this form of leptogenesis is particularly effective when
the Higgs condensate decays rapidly and at low reheat scale. As part of the
calculation, we present some exact results for the Bogoliubov transformations
for Majorana fermions with a nonzero time-dependent chemical potential, in
addition to a time-dependent mass.
