Displacement-noise-free interferometeric gravitational-wave detector using unidirectional neutrons with four speeds

For further gravitational wave (GW) detections, it is significant to invent a technique reduce all kinds of mirror displacement noise dominant at low frequencies for ground-based detectors. The neutron displacement-noise-free interferometer (DFI) one the tools lower frequencies. In this paper, we describe simplified configuration DFI in terms incidence direction. new configuration, neutrons enter with unidirectional four speeds as opposed two bidirectional incidences opposite directions reported previously. This simplification proof-of-principle experiments.