  Non-Gaussian states, and specifically the paradigmatic Schr\"odinger cat
state, are well-known to be very sensitive to losses. When propagating through
damping channels, these states quickly loose their non-classical features and
the associated negative oscillations of their Wigner function. However, by
squeezing the superposition states, the decoherence process can be
qualitatively changed and substantially slowed down. Here, as a first example,
we experimentally observe the reduced decoherence of squeezed optical
coherent-state superpositions through a lossy channel. To quantify the
robustness of states, we introduce a combination of a decaying value and a
rate-of-decay of the Wigner function negativity. This work, which uses
squeezing as an ancillary Gaussian resource, opens new possibilities to protect
and manipulate quantum superpositions in phase space.
