  Athermal systems across a large range of length scales, ranging from foams
and granular bead packings to crumpled metallic sheets, exhibit slow stress
relaxation when compressed. Experimentally they show a non-monotonic stress
response when decompressed somewhat after an initial compression, i.e. under a
two-step, Kovacs-like protocol. It turns out that from this response one can
tell the age of the system, suggesting an interpretation as a memory effect. In
this work we use a model of an athermal jammed solid, specifically a binary
mixture of soft harmonic spheres, to explore this phenomenon through in-silico
experiments. Using extensive simulations under conditions analogous to those in
experiment, we observe identical phenomenology in the stress response under a
two--step protocol. Our model system also recovers the behaviour under a more
recently studied three-step protocol, which consists of a compression followed
by a decompression and then a final compression. We show that the observed
response in both two-step and three-step protocols can be understood using
Linear Response Theory. In particular, a linear scaling with age for the
two-step protocol arises generically for slow linear responses with power law
or logarithmic decay and does not in itself point to any underlying aging
dynamics.
