Activation of quantum capacity of Gaussian channels

Understand

Quantum channels can be activated by a kind of channels whose quantum capacity is zero.

• This activation effect might be useful to overcome noise of channels by attaching other channels which can enhance the capacity of a given channel.
• In this work, we show that such an activation is possible by specific positive-partial-transpose channels for Gaussian lossy channels whose quantum capacities are known.
• We also test more general case involving Gaussian thermal attenuator whose the exact value of quantum capacity has been unknown so far.