1. Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
2. Institute of Radio Astronomy of National Academy of Sciences of Ukraine, Chervonopraporna 4, 61002 Kharkov, Ukraine
3. Quantum Radiophysics Department of V. N. Karazin Kharkiv National University, Svobody Square 4, 61022 Kharkov, Ukraine
4. Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8441, USA
5. Department of Physics and Centre for Laser, Atomic, and Molecular Sciences, University of New Brunswick, Saint John, New Brunswick E2L 4L5, Canada