  We consider a basic model of digital memory where each cell is composed of a
reflecting medium with two possible reflectivities. By fixing the mean number
of photons irradiated over each memory cell, we show that a non-classical
source of light can retrieve more information than any classical source. This
improvement is shown in the regime of few photons and high reflectivities,
where the gain of information can be surprising. As a result, the use of
quantum light can have non-trivial applications in the technology of digital
memories, such as optical disks and barcodes.
