Geometrically certifying non-EB channels without witness

Wan-Guan Chang^1,3*, Huan-Yu Ku^1,3, Chia-Yi Ju², Guan-Yin Chen²

¹Physics, Center for Quantum Frontiers of Research & Technology (QFort), Tainan, Taiwan
²Physics, National Chung Hsing University, Taichung, Taiwan
³Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Wan-Guan Chang, email:11008089@gs.ncku.edu.tw

Quantum channels play important roles in quantum information. We study a special kind of channel called entanglement-breaking channel. Any quantum state passing through these channels become separable states. We found that the collections of the output states through any of these channels form an ellipsoid on the Bloch sphere. In addition, we found the upper limit of the volume of the ellipsoids. That is to say, a channel is not entanglement-breaking if the volume of the corresponding ellipsoid exceeds the upper limit. In the last part of this work, we show some experimental and numerical evidence to confirm our results.

Keywords: QuantumInformation, QuantumComputing, QuantumSteering