 Joint quantum entropy

Joint quantum entropy is a concept in quantum information theory that extends the classical notion of entropy to describe the uncertainty or information content of quantum systems composed of multiple subsystems. Specifically, it relates to the entropy of a joint state of two or more quantum systems, capturing the correlations and entanglements that may exist between them. ### Key Concepts: 1. **Quantum State**: A quantum system is described by a density matrix \(\rho\), which represents the statistical state of the system.