Quantum Reading Capacity

Details Quantum Reading Capacity Quantum Reading Capacity

2011-07-18

arxiv.org/abs/1107.3500v1

New J. Phys. 13, 113012 (2011)

Physics

Quantum Physics

REVTeX. 16 pages. 11 figures

Scientific paper

10.1088/1367-2630/13/11/113012

The readout of a classical memory can be modelled as a problem of quantum channel discrimination, where a decoder retrieves information by distinguishing the different quantum channels encoded in each cell of the memory [S. Pirandola, Phys. Rev. Lett. 106, 090504 (2011)]. In the case of optical memories, such as CDs and DVDs, this discrimination involves lossy bosonic channels and can be remarkably boosted by the use of nonclassical light (quantum reading). Here we generalize these concepts by extending the model of memory from single-cell to multi-cell encoding. In general, information is stored in a block of cells by using a channel-codeword, i.e., a sequence of channels chosen according to a classical code. Correspondingly, the readout of data is realized by a process of "parallel" channel discrimination, where the entire block of cells is probed simultaneously and decoded via an optimal collective measurement. In the limit of an infinite block we define the quantum reading capacity of the memory, quantifying the maximum number of readable bits per cell. This notion of capacity is nontrivial when we suitably constrain the physical resources of the decoder. For optical memories (encoding bosonic channels), such a constraint is energetic and corresponds to fixing the mean total number of photons per cell. In this case, we are able to prove a separation between the quantum reading capacity and the maximum information rate achievable by classical transmitters, i.e., arbitrary classical mixtures of coherent states. In fact, we can easily construct nonclassical transmitters that are able to outperform any classical transmitter, thus showing that the advantages of quantum reading persist in the optimal multi-cell scenario.

Affiliated with

Also associated with

No associations

Rating

Quantum Reading Capacity does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Quantum Reading Capacity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quantum Reading Capacity will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-272224