**7. Conclusion**

The problem of photon localization is of rather fundamental nature in quantum electrodynamics. Despite of almost 80-year history of the problem – and the related problem of the photon wave function—the interest in the revision of it has quickened in the recent years. One of the stimulus for that might be developments in modern optics, particularly in femtosecond and quantum optics, thanks to which the somewhat academic problem is transforming into a practical one. Indeed, e. g., availability and applications of single- and sub-cycle photon pulses will force a revision of traditional notions in optics based on the narrow-band approximation. In particular, phrases like "localization cannot be better than wavelength" are loosing sense in the case of such pulses.

Ultrawideband by definition are the so-called localized waves—an emerging new field in wave acoustics and physical optics. We have shown that an interdisciplinary "technology transfer"—application of methods and solutions found in the field of localized waves—is productive for the study of photon localization.
