  Although different architectures of quantum perceptrons have been recently
put forward, the capabilities of such quantum devices versus their classical
counterparts remain debated. Here, we consider random patterns and targets
independently distributed with biased probabilities and investigate the storage
capacity of a continuous quantum perceptron model that admits a classical
limit, thus facilitating the comparison of performances. Such a more general
context extends a previous study of the quantum storage capacity where using
statistical mechanics techniques in the limit of a large number of inputs, it
was proved that no quantum advantages are to be expected concerning the storage
properties. This outcome is due to the fuzziness inevitably introduced by the
intrinsic stochasticity of quantum devices. We strengthen such an indication by
showing that the possibility of indefinitely enhancing the storage capacity for
highly correlated patterns, as it occurs in a classical setting, is instead
prevented at the quantum level.
