Off-Diagonal Density Matrix Elements

In this chapter, we are going to describe the sampling of off-diagonal
matrix elements using the path-integral formalism. Instead of
calculating diagonal density matrix elements
, for which the paths return to their starting
point, we now include the possibility of open paths. Opening one path
allows one the sampling of the *single-particle reduced density matrix* defined
by,

which will be used to study

Burkhard Militzer 2003-01-15