[en] A method of dynamic control of absorption and dispersion of a two-level quantum system (atoms, ions or quantum dots) doping a photonic band gap (PBG) material via variation of the intensity and frequency of an external laser field is proposed. The frequency of an optical transition should be inside a PBG and located near or at a photonic band edge. In this case the laser field 'dresses' the quantum system (Mollow splitting) while the decay rates of the dressed states become very different due to a photonic band edge and depend on the form of spectral density of electromagnetic modes as well as intensity and frequency of the laser field. This enables us to control absorption and dispersion of a signal laser field, which is near resonant to the quantum transition of a dopant.

[en] We show the possibility of producing a short bunch of nearly bandwidth-limited few-cycle attosecond pulses based on time-dependent resonant interaction of an incident radiation pulse with the bound states of hydrogen-like atoms. Time-dependence of an atomic resonance is provided by a laser pulse far from resonance with an intensity well below the atomic ionization threshold via time-dependent tunnel ionization from the excited states and time-dependent adiabatic Stark splitting of the excited energy levels. Without external matching of the spectral components it is possible to produce pulses with durations up to 80 as at the carrier wavelength of 13.5 nm in Li²⁺-plasma, as well as pulses with durations up to 600 as at the carrier wavelength of 122 nm in atomic hydrogen. (paper)

[en] The transformation of exponentially decaying waveform (the time dependence of detection probability) of a Mössbauer γ-ray photon into a regular sequence of short nearly bandwidth-limited pulses in a vibrating recoilless resonant absorber is studied. The case of dual-tone vibration at the fundamental frequency and its second harmonic under experimentally feasible conditions is considered. We show that this technique allows one to shorten pulses and increase the ratio of pulse separation to pulse length as well as to enlarge pulse amplitude compared to the pulses produced in harmonically vibrating absorber. The obtained results pave the way to the development of the time-resolved Mössbauer γ-ray spectroscopy and manipulation of quantum information in hard x-ray/γ-ray range. (paper)