Quantifying channels output similarity with applications to quantum   control
  In this work we aim at quantifying quantum channel output similarity. In order to achieve this, we introduce the notion of quantum channel superfidelity, which gives us an upper bound on the quantum channel fidelity. This quantity is expressed in a clear form using the Kraus representation of a quantum channel. As examples, we show potential applications of this quantity in the quantum control field. 
{\L}ukasz Pawela and Zbigniew Pucha{\l}a
quant-ph