Single-Pulse Superfluorescence in Cesium
Superfluorescence has been observed at 2931 nm from the 7P3/2, to 7S1/2, transition in cesium. It is shown that a completely inverted two-level system can be prepared in a magnetic field. Experimental results on the superfluorescent output are reported for a range of sample lengths (1.0 cm to 5.0cm)and densities (8 × 109 cm−3 to 2 × 1011 cm−3 ) and for several values of the inhomogeneous dephasing time (5 ns, 18 ns, and 32 ns). For sufficiently long delay times the emission from the pencil-shaped volume of Fresnel number one consists of a single pulse for all sample lengths, both in an atomic beam and in a cell. Neither homogeneous relaxation nor inhomogeneous dephasing can explain the absence of ringing. For increased densities and reduced delay times, depending on the length of the sample,multiple-pulse output occurs. The occurrence of single and multiple pulses, the delay times, and the pulsewidths are discussed.
KeywordsDelay Time Pulse Shape Single Pulse Atomic Beam Sample Length
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- (3).R. Bonifacio, P. Schwendimann, and F. Haake, Phys. Rev. A 4,302 and 854 (1971) and references therein.Google Scholar
- (10).R. E. Honig, RCA Review 23, 567 (1962); D. R. Stull inAmerican Institute of Physics Handbook, D. E. Gray,editor (McGraw-Hill, N.Y., 1972), p. 4–298.Google Scholar
- (11).N. F. Ramsey, Molecular Beams (Oxford University Press,Oxford, 1956).Google Scholar
- (12).The collision cross-section for Cs-Ar collisions is as large as 572 × 10−16 cm2 (ref. 11, p. 34). In view of the larger polarizability of Cs as compared to Ar, the cross-section for Cs-Cs collisions can be estimated at 1 × 10−13 cm2. Apressure of 10 torr, corresponding to a density of 1.3 × 1017 cm−3, then yields a mean free path of 0.6 × 10−4 cm.Google Scholar
- (13).J. B. Anderson in Molecular Beams and Low Density Gas Dynamics, P. P. Wegner, editor (Marcel Dekker, N.Y., 1974).Google Scholar
- (16).Following Rehler and Eberly, ref. 2, Banfi and Bonifacio have used the relation τd = τR lnμN, where μ is the geometrical shape factor of ref. 2. Inclusion of the factor μ in the logarithm reduces the delay time by roughly a factor of 2 in the present experiment. G. Banfi and R. Bonifacio, Phys. Rev. A. 12, 2068 (1975).Google Scholar