Quantum Reading of a Classical Digital Memory

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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 nonclassical 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 nontrivial applications in the technology of digital memories, such as optical disks and barcodes.

Original languageEnglish
Article number090504
Number of pages4
JournalPhysical Review Letters
Issue number9
Publication statusPublished - 2 Mar 2011

Bibliographical note

GS citations 31 in one year since publication.
Extensive media coverage.
High-impact 4-page letter plus 21-page Supplementary Materials.


  • Quantum information
  • Quantum technology
  • Quantum entanglement
  • Optical memories
  • Non classical states
  • Quantum optics
  • Hyphotesis testing
  • Data storage
  • Gaussian states
  • Gaussian channels
  • Einstein Podolsky Rosen correlations
  • Non locality

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