F. G. Vagizov

Coherent control of the waveforms of recoilless γ-ray photons

The concepts and ideas of coherent, nonlinear and quantum optics have been extended to photon energies in the range of 10–100 kiloelectronvolts, corresponding to soft γ-ray radiation (the term used when the radiation is produced in nuclear transitions) or, equivalently, hard X-ray radiation (the term used when the radiation is produced by electron motion). The recent experimental achievements in this energy range include the demonstration of parametric down-conversion in the Langevin regime, electromagnetically induced transparency in a cavity, the collective Lamb shift, vacuum-assisted generation of atomic coherences and single-photon revival in nuclear absorbing multilayer structures. Also, realization of single-photon coherent storage and stimulated Raman adiabatic passage were recently proposed in this regime. More related work is discussed in a recent review. However, the number of tools for the coherent manipulation of interactions between γ-ray photons and nuclear ensembles remains limited. Here we suggest and implement an efficient method to control the waveforms of γ-ray photons coherently. In particular, we demonstrate the conversion of individual recoilless γ-ray photons into a coherent, ultrashort pulse train and into a double pulse. Our method is based on the resonant interaction of γ-ray photons with an ensemble of nuclei with a resonant transition frequency that is periodically modulated in time. The frequency modulation, which is achieved by a uniform vibration of the resonant absorber, owing to the Doppler effect, renders resonant absorption and dispersion both time dependent, allowing us to shape the waveforms of the incident γ-ray photons. We expect that this technique will lead to advances in the emerging fields of coherent and quantum γ-ray photon optics, providing a basis for the realization of γ-ray-photon/nuclear-ensemble interfaces and quantum interference effects at nuclear γ-ray transitions.

Suppression of γ-photon absorption via quantum interference

We show that the interference effects (similar to electromagnetically induced transparency, which was widely studied earlier in electronic transitions in optics) may appear in γ-radiation at nuclear transitions under the condition of nuclear level anticrossing. We demonstrate it also experimentally in optically thin samples of FeCO3.

Quantum interference in mössbauer scattering spectra

The role of quantum interference in the formation of the resonance scattering spectra of Mössbauer photons is studied. A resonant rf field mixing the spin levels of the excited state of a nucleus is considered to be the mechanism ensuring the conditions for quantum interference. A considerable intensity redistribution of the elastic and Raman scattering channels is shown to occur as a result of quantum interference.

Experimental search for laser-induced effects in 151Eu and 57Fe doped crystals

We studied the Mössbauer effect in 151Eu and 57Fe doped crystals in the search for laser-induced effects caused by changes in the hyperfine interaction due to electronic excitation. The Mössbauer spectra observed in the presence of laser radiation demonstrated a notable change of the shape of the 151Eu spectrum and the appearance of an additional hyperfine pattern in the case of the 57Fe Mössbauer resonance.

Effects of optical radiation on the Mössbauer spectrum of 151Eu3+: CaF2

We study the changes in the shape of the Mössbauer spectrum for the 21.5 keV transition of 151Eu3+ nuclei in a CaF2 lattice, assuming that a population of the excited electronic state 5 D 0 is maintained by optical pumping. For a population of the excited state 5 D 0 of 10%, we determine the magnitude of the changes in the Mössbauer spectrum as 1.9% of the area of the unperturbed spectrum.

Experimental observation of laser-induced modification of Mössbauer spectra

Abstract The modification of Fe57 Mössbauer spectra of a MgO single crystal under the action of laser radiation was observed. A possible interpretation of the observed effect is proposed.

Conversion of recoillessγradiation into a periodic sequence of short intense pulses in a set of several sequentially placed resonant absorbers

An efficient technique to produce a periodic sequence of ultrashort pulses of recoilless gamma-radiation via its transmission through the optically thick vibrating resonant absorber was demonstrated recently [Nature, 508, 80 (2014)]. In this work we extend the theoretical analysis to the case of a set of multiple absorbers. We consider an analytical model describing the control of spectral content of a frequency modulated gamma-radiation by selective correction of amplitudes and initial phases of some spectral components, using, respectively, the resonant absorption or dispersion of nuclei. On the basis of the analytical solutions we determine the ultimate possibilities of the proposed technique.

Principles of controlling a single-photon radiation state using optically thick resonant media

The propagation of a single-photon wave packet in a thick resonant absorber if it undergoes rapid displacement at a certain instant after the beginning of a wave packet emission is investigated theoretically and experimentally. This displacement was found to yield a radiation burst at the absorber output.

Determination of the Lamb-Mössbauer Factor by the Delayed Coincidence Technique

A method for determining the Lamb-Mössbauer factor by means of the delayed coincidence technique is proposed. The effective thickness of a series of K4Fe(CN)6 · 3H2O samples was measured and recoilless fraction f = 0.339 ± 0.004 was determined.

Radiofrequency stimulated quantum interference on Mössbauer transitions

Redistribution of the elastic and Raman channel intensities in the Mössbauer resonant scattering spectrum can be controlled by the radio frequency (rf) stimulated quantum interference of gamma-transition amplitudes. More general expressions for each channel intensity are written out exactly taking into account the influence of the rf field. Results of calculations for the simple three-level scheme can be easily generalized to the case of 57Fe isotope in magnetic materials.