1. Institute of Physics; Kazan Federal University; 420008 Kazan Russia
2. Centre for Quantum Technologies; Kazan Federal University; 420008 Kazan Russia
3. E.K. Zavoisky Physical-Technical Institute; Russian Academy of Sciences; 420029 Kazan Russia
4. Institute of Applied Physics; Academy of Sciences of Moldova; MD-2028 Chisinau R. Moldova
5. Experimental Physics V; University of Augsburg; 86159 Augsburg Germany