We propose a method to transform a single-photon field into bunches of pulses with controllable timing and number of pulses in a bunch. The method is based on transmission of a photon through an optically thick single-line absorber vibrated with a frequency appreciably exceeding the width of the absorption line. The narrow spectrum of the incoming photon is “seen” by the vibrated absorber as a comb of equidistant spectral components separated by the vibration frequency. Tuning the absorber in resonance with $m\mathrm{th}$ spectral component transforms the output radiation into bunches of pulses with $m$ pulses in each bunch. We provide a simple analytical solution clearly describing this effect and experimentally demonstrate the proposed technique with a single 14.4-keV photon and an ensemble of vibrated ${}^{57}\mathrm{Fe}$ nuclei. This method opens an alternate way to the production of time-bin qubits.

The ground state band structure, magnetic moments, charges and population numbers of electronic shells of Cu and Fe atoms have been calculated for chalcopyrite CuFeS₂ using density functional theory. The comparison between our calculation results and experimental data (X-ray photoemission, X-ray absorption and neutron diffraction spectroscopy) has been made. Our calculations predict a formal oxidation state for chalcopyrite as Cu¹⁺Fe³⁺S ₂ ²⁻ . However, the assignment of formal valence state to transition metal atoms appears to be oversimplified. It is anticipated that the valence state can be confirmed experimentally by nuclear magnetic and nuclear quadrupole resonance and Mössbauer spectroscopy methods.

The radiation burst from a single $\gamma$-photon field interacting with a dense resonant absorber is studied theoretically and experimentally. This effect was discovered for the fist time by P. Helisto et al. [ Phys. Rev. Lett. 66, 2037 (1991)] and it was named the “gamma echo.” The echo is generated by a 180${}^{\circ }$ phase shift of the incident radiation field, attained by an abrupt change of the position of the absorber with respect to the radiation source during the coherence time of the photon wave packet. Three distinguishing cases of the gamma echo are considered; i.e., the photon is in exact resonance with the absorber, close to resonance (on the slope of the absorption line), and far from resonance (on the far wings of the resonance line). In resonance the amplitude of the radiation burst is two times larger than the amplitude of the input radiation field just before its phase shift. This burst was explained by Helisto et al. as a result of constructive interference of the coherently scattered field with the phase-shifted input field, both having almost the same amplitude. We found that out of resonance the scattered radiation field acquires an additional component with almost the same amplitude as the amplitude of the incident radiation field. The phase of the additional field depends on the optical thickness of the absorber and resonant detuning. Far from resonance this field interferes destructively with the phase-shifted incident radiation field and radiation quenching is observed. Close to resonance the three fields interfere constructively and the amplitude of the radiation burst is three times larger than the amplitude of the input radiation field.

The pulsed radiation field propagating in a thick resonant absorber induces the polarization (quantified by the induced atomic dipoles in optical domain or the induced nuclear transition moments in gamma domain), which is distributed oscillatorily along the absorber forming a sandwich of polarization layers with opposite phases. As a result, the reemitted, scattered fields in different layers interfere with the incident input field destructively or constructively, giving rise to the well-known dynamical beats of the output radiation. We propose a method how to force these layers in the sandwich to reemit in phase with the incident field, which results in a strong radiation burst of short duration at the output of the absorber. We demonstrate this method experimentally for the 14.4 keV nuclear transition in ${}^{57}$Fe.