  Each end of a Kitaev chain in topological phase hosts a Majorana fermion.
Zero bias conductance peak is an evidence of Majorana fermion when the two
Majorana fermions are decoupled. These two Majorana fermions are separated in
space and this nonlocal aspect can be probed when the two are coupled. Crossed
Andreev reflection is the evidence of the nonlocality of Majorana fermions.
Nonlocality of Majorana fermions has been proposed to be probed by noise
measurements since simple conductance measurements cannot probe it due to the
almost cancellation of currents from electron tunneling and crossed Andreev
reflection. Kitaev ladders on the other hand host subgap Andreev states which
can be used to control the relative currents due to crossed Andreev reflection
and electron tunneling. We propose to employ Kitaev ladder in series with
Kitaev chain and show that the transconductance in this setup can be used as a
probe of nonlocality of Majorana fermions by enhancing crossed Andreev
reflection over electron tunneling.
