  The development of direct probes of entanglement is integral to the rapidly
expanding field of complex quantum materials. Here we test the robustness of
entangled neutrons as a quantum probe by measuring the
Clauser-Horne-Shimony-Holt contextuality witness while varying the beam
properties. Specifically, we prove that the entanglement of the spin and path
subsystems of individual neutrons prepared in two different experiments using
two different apparatuses persists even after varying the entanglement length,
coherence length, and neutron energy difference of the paths. The two
independent apparatuses acting as entangler-disentangler pairs are static-field
magnetic Wollaston prisms and resonance-field radio frequency flippers. Our
results show that the spatial and energy properties of the neutron beam may be
significantly altered without reducing the contextuality witness value below
the Tsirelson bound, meaning that maximum entanglement is preserved. We also
show that two paths may be considered distinguishable even when separated by
less than the neutron coherence length. This work is the key step in the
realization of the new modular, robust technique of entangled neutron
scattering.
