Superfluorescent transitions in an external magnetic field

Abstract

Abstract. Polarisation properties of the superfluorescence in the near-infrared regime have been investigated between high-lying levels of Sr and Ba under the influence of a static homogeneous external magnetic field. In some transitions the time-resolved measurements show a change of the polarisation of the superfluorescence depending on the magnetic field strenght. In suitable experimental conditions intensity modulations were observed. These were assigned as Zeeman quantum beats or indirectly observed Zeeman superfluorescent beats. The experimental findings of superfluorescence in two-level, three-level, or multi-level configurations in dependence on the magnetic field strength can be explained well in a semiclassical model of multi-level superfluorescence.

Zeeman effect of superfluorescently populated 6snf 1F3 Ba I levels

“…2). Recently it was shown that the superfluorescence pulse starts with the polarization of the laser pulse in the second excitation step [6,7]. Since in our measurements the linear polarization of the superfluorescence pulse was parallel to the direction of the magnetic field, there was no dependence of the direction of the polarization of the superfluorescence on the magnetic field strength.…”

“…The experimental set up is the same as already presented [6]. Let us briefly recall that the Ba atoms in an atomic beam were excited stepwise via the 6s6p P level into a 6snd D level by two polarized dye laser pulses.…”

“…A change in the time resolved fluorescence intensity was observed as function of the magnetic field strength. With increasing magnetic field strength the intensity of the superfluorescence pulse polarized perpendicular to the direction of the magnetic field strength decreases and of the superfluorescence pulse polarized parallel to the magnetic field increases [6]. In our experimental conditions the superfluorescence pulse starts from the laser excited 6snd D , M"#1 and M"!1 Zeeman levels and populates the M"#1 and M"!1 Zeeman levels of the 6s(n!3) f F level coherently (Fig.…”

“…In some transitions the polarisation changed with the magnetic field strength and in suitable experimental conditions the time resolved recording of the fluorescence of the superfluorescently populated levels showed intensity modulations depending on the magnetic field strength. These were assigned as Zeeman quantum beats of the observed fluorescence transition or as Zeeman superfluorescence beats indirectly detected by the population modulation of the upper level of the observed fluorescence [6]. The superfluorescent beat frequencies are somewhat different from the usual term of quantum beats [8,9] since in this case it may reflect either initial level splittings, final level splittings, or a combination of both [10][11][12][13].…”

“…Recently in systematic investigations it was found that superfluorescent transitions between high lying levels of Sr and Ba react very sensitively to an external electric [4,5] or magnetic field [6,7]. In some transitions the polarisation changed with the magnetic field strength and in suitable experimental conditions the time resolved recording of the fluorescence of the superfluorescently populated levels showed intensity modulations depending on the magnetic field strength.…”