New extended interpolating operators made of quenched three
dimensional fermions are introduced in the context of lattice QCD. The mass of
the 3D fermions can be tuned in a controlled way to find a better overlap of
the extended operators with the states of interest. The extended operators have
good renormalisation properties and are easy to control when taking the
continuum limit. Moreover the short distance behaviour of the two point
functions built from these operators is greatly improved. The operators have
been numerically implemented and a comparison to point sources and Jacobi
smeared sources has been performed on the new CLS configurations.
