Quantum-optical phenomena in magnetoelectric crystals

Since Star Wars, lasers have been known from sci-fi movies and more recently from everyday applications such as DVD players and laser pointers. Unlike conventional lamps, lasers produce a coherent beam of light that can be described by a single wavelength and a single wave function of position and time. The laser medium is located between a pair of mirrors, a so - called optical cavity resonator. The cavity length selects the only possible light mode that determines the wavelength of the output beam. However, lasers are sensitive to small changes in the length of the optical cavity resonator, which limits their use in high-precision applications such as atomic clocks. This disadvantage is overcome in quantum optics. The phase memory of the system is stored in the collective quantum state of the laser material and not in the geometric parameters of the resonator. The collective state of the laser material guarantees the high stability of the laser beam when isolated from the environment. Experimental realizations of such systems typically work near absolute zero temperature, limiting their investigation and making practical applications impossible. In our project we plan to realize quantum optical effects at routinely accessible standard laboratory temperatures. Independent up or down directed magnetic moments (spins) o f rare earth metal ions give the ensemble of two-state quantum systems of our study. The wave that couples them is provided by the oscillations (spin waves) of the ordered magnetic iron moments surrounding them. Thus, we concentrate on realizing the magnetic alternative of conventional quantum optics of the electrical domain. Besides the fundamental novelty, the main practical advantages of our approach are the higher, easily accessible characteristic temperatures, and, due to the longer wavelength of the spin waves, the insensitivity to small changes in sample size.