Quantum optics and vacuum confinement of modes in a microscopic cavity

A description is given of several novel experimental methods for quantum-electrodynamic vacuum confinement of emission modes close to a single electromagnetic boundary and in a microscopic Fabry–Perot optical cavity of length of the same order of magnitude as the wavelength of the recorded radiation. Strong anomalies (Purcell effect) of the spontaneous emission process and of a phase transition with spontaneous–stimulated decay of states in the stimulated emission process are demonstrated experimentally. It is shown that in the context of the phase transition theory an active microscopic cavity behaves as a superconductor with an extremely high critical transition temperature. This unusual behavior can be interpreted as a manifestation of a perturbation induced in a quantum system by "measurement apparatus" of dimensions comparable with the de Broglie wavelength of a test particle.