Noise is resource-contextual in quantum communication

Abstract

Estimating the information transmission capability of a quantum channel remains one of the fundamental problems in quantum information processing. In contrast to classical channels, the information-carrying capability of quantum channels is contextual. One of the most significant manifestations of this is the superadditivity of the channel capacity: the capacity of two quantum channels used together can be larger than the sum of the individual capacities. Here, we present a one-parameter family of channels for which as the parameter increases its one-way quantum and private capacities increase while its two-way capacities decrease. We also exhibit a one-parameter family of states with analogous behavior with respect to the one- and two-way distillable entanglement and secret key. Our constructions demonstrate that noise is context dependent in quantum communication.

16 pages, 6 figures, Updated with additional and elaborated references. Sincere, thanks to Felix Leditzky and Stefano Pirandola for pointing out the appropriate references. Added note on general applicability of results

References in corpus (9)

• Distillation of secret key and entanglement from quantum states
• The structure of degradable quantum channels
• Unbounded number of channel uses are required to see quantum capacity
• The private classical capacity with a symmetric side channel and its application to quantum cryptography
• Extensive nonadditivity of privacy
• Generic nonadditivity of quantum capacity in simple channels
• Exploring super-additivity of coherent information of noisy quantum channels through Genetic algorithms
• Bounding quantum capacities via partial orders and complementarity
• Experimental observation of coherent-information superadditivity in a dephrasure channel