Asia Pacific Physics Week 2023 (APPW2023)

Friday, Nov. 10, 2023 

2:40 PM - 3:20 PM  Plenary Talk  Vahid Karimipour (Sharif University of Technology) 

Quantum information, quantum channels and their symmetries

Vahid Karimipour

Department of Physics, Sharif University of Technology, Tehran, Iran

We discuss the mathematical model of classical and quantum communication channels and the way we try to neutralize the errors which occur during communication. The deep difference between classical and quantum errors are explained. In classical communication, we discuss the concept of capacity of the channel and its properties. In the quantum domain, we show that, in contrast to the classical case, there are different concepts of capacities, depending on the available resources (existence or lack of shared entanglement) and the kind of information (classical or quantum) which is to be sent through the channel.

After introducing the mathematical model of a quantum channel, we discuss the symmetry and covariance properties of a channel and the way it affects calculation of its various kind of capacities.

To elucidate these concepts, we consider a few examples, namely the qubit depolarizing channel which has the full unitary group symmetry and then a kind of Pauli channel which has a lower symmetry. Finally, we consider the Landau-Streater channel in three dimensions which again has a full unitary group symmetry and a modification of it which has a lower symmetry.

Needless to say, in this short talk which is intended for a broad audience, we refrain from any mathematical detail and try to present the basic concepts in a language which is accessible to researchers across different disciplines.