On the possibility of propagation of gamma-ray photons at a velocity less than 6 m/s at room temperature by means of acoustically induced transparency

In [Y.V. Radeonychev et al., Phys. Rev. Lett. 124, 163602 (2020)], we reported the observation of the acoustically induced transparency of a stainless steel foil for 14.4-keV resonant gamma-ray photons from a $^{57}$Co radioactive Mössbauer source, which is similar to electromagnetically induced transparency and Autler–Townes splitting. In this work, we show that the use of a stainless steel foil with a certain thickness that is enriched in $^{57}$Fe and oscillates at the optimal frequency under the same experimental conditions can slow down a single-photon wave packet of gamma radiation with a duration of about 80 ns from the $^{57}$Co source to a velocity of less than 6 m/s with a delay of about 100 ns at room temperature.