Low Temperature Physics: 36, 671 (2010); https://doi.org/10.1063/1.3490659 (6 pages)
Fizika Nizkikh Temperatur: Volume 36, Number 8-9 (August 2010), p. 846-853 ( to contents , go back )
On possibility to use a Bose-Einstein condensate for the filtration of optical pulses
Y.V. Slyusarenko and A.G. Sotnikov
National Science Center "Kharkov Institute of Physics and Technology" 1 Academicheskaya St., Kharkov 61108, Ukraine
Received November 18, 2009, revised February 4, 2010
A possibility to use the ultraslow-light phenomenon in a Bose–Einstein condensate of alkali-metal atoms for improving the spectral characteristics of optical signals is studied. The main reason for consideration of this problem is a resonant behavior of the slowing of electromagnetic pulses in the system under discussion. In other words, the maximum reduction of the group velocity has a pulse with spectral characteristics that are close to the resonances in the spectrum of alkali-metal atoms. The description of the filtration phenomenon is constructed in the framework of the microscopic theory of response of hydrogenlike atoms gas to weak external electromagnetic field. The possibility to filter optical pulses is illustrated with a signal of normal (Gaussian) spectral distribution that propagates through a dilute gas of alkali-metal atoms in the Bose-condensed state. We study in detail the case that is based on the use of Zeeman splitting of the hyperfine structure of sodium atom levels in external homogeneous static magnetic field and the choice of the corresponding occupation of Zeeman sublevels of the ground state. Conditions are established under which spectral components of well-defined frequencies are distinguished from the initial pulse. The intensity of the transmitted components in the defined frequency range in this case is rather large in comparison with other transmitted components. It is shown that additional filtration of the transmitted pulse through the Bose–Einstein condensate with another value of bias field provides a total noise removal from the initial optical signal.
PACS: 05.30.–d Quantum statistical mechanics;
Key words: alkali-metal atoms, Bose-Einstein condensate, electromagnetic waves, optical range, Green function, group velocity of signal, slowing-down of impulses,filtration of signal.