densitymatrise
The density matrix is a mathematical object used in quantum mechanics to describe the state of a quantum system. It is a generalization of the state vector, allowing for the description of mixed states, which are probabilistic mixtures of pure states, as well as pure states themselves. A pure state can be represented by a state vector, but a mixed state cannot.
The density matrix, often denoted by the Greek letter rho ($\rho$), is a positive semi-definite Hermitian operator
The density matrix is useful for calculating expectation values of observables. The expectation value of an