Learning Density Matrix with the help of exercises

Reshma. P, Prasanth. P, Nishanth. P and . K. M. Udayanandan

Former HOD NAS College

In real situations, the systems that we deal with in quantum statistical mechanics, are mainly mixed systems. We will not be able write a single state vector for such systems, which makes finding the average thermodynamic properties impossible. In statistical mechanics what we find or measure is the ensemble average of any thermodynamic property. Density matrix comes to rescue or save physicist from this difficult situation. Hence understanding density matrix and its uses will be of great help for students and teachers and this article aims to clarify the doubts faced by the learners of statistical mechanics, while studying density matrices.