  The gravitationally induced entanglement is a type of quantum entanglement
that can be generated between two mesoscopic particles using their Newtonian
gravitational interaction. It has attracted a great deal of attention as a new
platform for studying quantum aspects of gravity. The present paper analyzes
the gravitationally induced entanglement as a pure interference effect and
shows that the entanglement is induced solely by a sign change associated with
the destructive quantum interference. It is also shown that when the
entanglement is non-maximal, the preparation for destructive interference for
one of the particles can recover a maximum visibility interference pattern for
the other particle. Therefore, the non-maximally entangled state can be
extremely effective for experimental testing since it can help in reducing
requirements (on masses of the particles and their interaction duration,
separation distances and sources) and preserve the information about
entanglement at the same time. As a result, the improvement in the
signal-to-noise ratio is demonstrated and a parameter that determines minimal
requirements for experimental testing is defined.
