  Path integral Monte Carlo (PIMC) simulations are used to calculate the
momentum distribution of the homogeneous electron gas at finite temperature.
This is done by calculating the off-diagonal elements of the real-space density
matrix, represented in PIMC by open paths. It is demonstrated how the
restricted path integral Monte Carlo methods can be extended in order to deal
with open paths in fermionic systems where a sign problem is present. The
computed momentum distribution shows significant deviations for strong
correlation from free fermion results but agrees with predictions from
variational methods.
