Yingkai Ouyang: Improved Upper Bounds on the Quantum Capacity of the Depolarizing Channel with Higher Dimension Amplitude Damping Channels

Yingkai Ouyang, Institute for Quantum Computing (IQC)

Abstract

Evaluating the quantum capacity of the (qubit) depolarizing channel is an important problem. However the quantum capacity of the depolarizing channel does not have tight bounds. We improve the upper bound of the
depolarizing channel by the method of Smith and Smolin. We construct a special channel, and show that a two-fold tensor product of the depolarizing channel is equal to convex combinations of this special channel. The special channel is a particular four dimension amplitude damping channel that is degradable. We then evaluate the quantum capacity of the special channel and thereby obtain an improved upper bound on the quantum capacity of the depolarizing channel.