When Does Noise Increase the Quantum Capacity?
Abstract
Superactivation is the property that two channels with zero quantum capacity can be used together to yield a positive capacity. Here we demonstrate that this effect exists for a wide class of inequivalent channels, none of which can simulate each other. We also consider the case where one of two zero-capacity channels is applied, but the sender is ignorant of which one is applied. We find examples where the greater the entropy of mixing of the channels, the greater the lower bound for the capacity. Finally, we show that the effect of superactivation is rather generic by providing an example of superactivation using the depolarizing channel.
Additional Information
© 2012 American Physical Society. (Received 31 July 2011; published 25 January 2012)Attached Files
Published - PhysRevLett.108.040501.pdf
Supplemental Material - SupplemSect.pdf
Supplemental Material - SupplemSect.tex
Supplemental Material - fig2.pdf
Supplemental Material - fig3.pdf
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Additional details
- Eprint ID
- 67721
- Resolver ID
- CaltechAUTHORS:20160607-103621898
- Created
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2016-06-07Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field