Semi classical Approximation: Fixed Energy Propagator

This lecture covers the semi classical approximation for the fixed energy propagator in quantum physics, focusing on the Van Vleck-Pauli and Morette formula. The instructor explains the eigenfunctions and eigenvalues of the fixed energy propagator, emphasizing the continuous spectrum of the Hamiltonian. The lecture delves into barrier penetration and the saddle point approximation, providing insights into the density of states and the transmission probability at energy. Various approximations for the fixed energy propagator are discussed, highlighting the importance of saddle points and turning points in the semiclassical approach.