Quantum Beat Experiments Using a Cold Neutron Spin Interferometer.

Easy quantum beat experiments have been developed using a new cold neutron spin interferometer, which brings us easy observation of quantum beat phenomena. The quantum beat is created by the coherent superposition of the spin eigenstates of cold neutron with different energy states, which are produced with two radio-frequency flippers. We observed quantum beat phenomena with a range of frequency from 4 kHz to 10 -5  Hz, which correspond to the energy differences from 1.66 ×10 -11  eV to 4.1 ×10 -20  eV. The principle and the arrangement of the quantum beat experiment are discussed, and typical measurement data are presented. Some applications of the quantum beat experiments are briefly proposed.