10: Fundamentals of quantum statistical mechanics
- Page ID
- 5202
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- 10.2: The Density Matrix and Density Operator
- In general, the many-body wave function is far too large to calculate for a macroscopic system. We wish, therefore, to use the concept of ensembles in order to express expectation values of observables ⟨A⟩ without requiring direct computation of the wavefunction. Toward this goal, this section introduces the density matrix and associated density operator.
- 10.3: Time evolution of the density operator
- The time evolution of the operator ρ can be predicted directly from the Schrödinger equation.