Skip to main content

Research Repository

Advanced Search

Activation and superactivation of single-mode Gaussian quantum channels

Lim, Youngrong; Takagi, Ryuji; Adesso, Gerardo; Lee, Soojoon

Activation and superactivation of single-mode Gaussian quantum channels Thumbnail


Youngrong Lim

Ryuji Takagi

Soojoon Lee


Activation of quantum capacity is a surprising phenomenon according to which the quantum capacity of a certain channel may increase by combining it with another channel with zero quantum capacity. Superactivation describes an even more particular occurrence, in which both channels have zero quantum capacity, but their composition has a nonvanishing one. We investigate these effects for all single-mode phase-insensitive Gaussian channels, which include thermal attenuators and amplifiers, assisted by a two-mode positive-partial-transpose channel. Our result shows that activation phenomena are special but not uncommon. We can reveal superactivation in a broad range of thermal attenuator channels, even when the transmissivity is quite low, or the thermal noise is high. This means that we can transmit quantum information reliably through very noisy Gaussian channels with the help of another Gaussian channel, whose quantum capacity is also zero. We further show that no superactivation is possible for entanglement-breaking Gaussian channels in physically relevant circumstances by proving the nonactivation property of the coherent information of bosonic entanglement-breaking channels with finite input energy.


Lim, Y., Takagi, R., Adesso, G., & Lee, S. (2019). Activation and superactivation of single-mode Gaussian quantum channels. Physical Review A, 99(3), Article 032337.

Journal Article Type Article
Acceptance Date Mar 7, 2019
Online Publication Date Mar 25, 2019
Publication Date 2019-03
Deposit Date Mar 28, 2019
Publicly Available Date Mar 28, 2019
Journal Physical Review A
Print ISSN 2469-9926
Electronic ISSN 2469-9934
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 99
Issue 3
Article Number 032337
Public URL
Publisher URL
Additional Information ©2019 American Physical Society


You might also like

Downloadable Citations