  This paper proposes a position fixing method for autonomous navigation using
partial gravity gradient solutions from cold atom interferometers. Cold atom
quantum sensors can provide ultra-precise measurements of inertial quantities,
such as acceleration and rotation rates. However, we investigate the use of
pairs of cold atom interferometers to measure the local gravity gradient and to
provide position information by referencing these measurements against a
suitable database. Simulating the motion of a vehicle, we use partial gravity
gradient measurements to reduce the positional drift associated with inertial
navigation systems. Using standard open source global gravity databases, we
show stable navigation solutions for trajectories of over 1000km.
