  Quantum superpositions can be used for parallel information processing, but
only if protected against decoherence. A two-particle four-state system may
have two-dimensional subspaces that are partially or completely
decoherence-free, e.g., the symmetric triplet state as an example of the
former, the anti-symmetric singlet state of the latter. By extension, a
multiparticle system that in the laboratory basis is plagued by decoherence may
in some other basis exhibit the symmetries that yield such decoherence-free
subspaces (DFS's). Fully-interacting many-fermion spin 1/2 networks may be
mathematically transformed to a more tractable many-to-one (or -to-some)
variant. This paper applies such a transformation to a hypothetical network of
boson-like operators and then argues that a fully-interacting particle
number-preserving network of bosons plus fermions with supersymmetric degrees
of freedom may be more plausibly exploited so as to contain DFS's. Physical
systems that in some basis are inherently anti-symmetric are already known to
be useful for quantum information processing. Supersymmetric systems may be
likewise.
