  We present a model and protocol that enable the generation of extremely
stable computer glasses at minimal computational cost. The protocol consists of
an instantaneous quench in an augmented potential energy landscape, with
particle radii as additional degrees of freedom. We demonstrate how our
glasses' mechanical stability, which is readily tunable in our approach, is
reflected both in microscopic and macroscopic observables. Our observations
indicate that the stability of our computer glasses is at least comparable to
that of computer glasses generated by the celebrated Swap Monte Carlo
algorithm. Strikingly, some key properties support even qualitatively enhanced
stability in our scheme: the density of quasilocalized excitations displays a
gap in our most stable computer glasses, whose magnitude scales with the
polydispersity of the particles. We explain this observation, which is
consistent with the lack of plasticity we observe at small stress. It also
suggests that these glasses are depleted from two-level systems, similarly to
experimental vapor-deposited ultrastable glasses.
