  Quantum systems are inherently dissipation-less, making them excellent
candidates even for classical information processing. We propose to use an
array of large-spin quantum magnets for realizing a device which has two modes
of operation: memory and data-bus. While the weakly interacting low-energy
levels are used as memory to store classical information (bits), the
high-energy levels strongly interact with neighboring magnets and mediate the
spatial movement of information through quantum dynamics. Despite the fact that
memory and data-bus require different features, which are usually prerogative
of different physical systems -- well isolation for the memory cells, and
strong interactions for the transmission -- our proposal avoids the notorious
complexity of hybrid structures. The proposed mechanism can be realized with
different setups. We specifically show that molecular magnets, as the most
promising technology, can implement hundreds of operations within their
coherence time, while adatoms on surfaces probed by a scanning tunneling
microscope is a future possibility.
