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Study of Coherent Population Trapping State with a Four-Level System

Qiang Li, 云恩学, 顾思洪 Gu Sihong

Chinese Journal of LasersJan 1, 20091 citation

Effect of four-photon interactions on coherent population trapping in Λ-systems

B. A. Grishanin, Victor N. Zadkov, Dieter Meschede

The resonance fluorescence spectrum of a Λ-system excited by two resonant light fields is calculated using a Markov analysis. Analytical formulas are derived in the strong-field limit within and beyond the rotating wave approximation. It is shown that the resonance fluorescence of the system does not vanish during coherent population trapping. Its spectrum consists of two multiplets which are similar to a triplet in the resonance fluorescence spectrum of a two-level atom and lie at the electronic transition frequencies, together with two triplets located at the frequencies of four-photon processes involving the optical excitation fields. The latter are fundamental in character and impose limits on the lower bound of the dephasing rate for the Raman resonance owing to the effect of radiative decay of the dipole transitions on the dynamics of the ground state. The effect of four-photon dephasing on the absorption spectrum of a Λ-system is analyzed and found to lead to a substantial reduction in the depth of a dip in the absorption spectrum which vanishes as the laser field strength is increased.The resonance fluorescence spectrum of a Λ-system excited by two resonant light fields is calculated using a Markov analysis. Analytical formulas are derived in the strong-field limit within and beyond the rotating wave approximation. It is shown that the resonance fluorescence of the system does not vanish during coherent population trapping. Its spectrum consists of two multiplets which are similar to a triplet in the resonance fluorescence spectrum of a two-level atom and lie at the electronic transition frequencies, together with two triplets located at the frequencies of four-photon processes involving the optical excitation fields. The latter are fundamental in character and impose limits on the lower bound of the dephasing rate for the Raman resonance owing to the effect of radiative decay of the dipole transitions on the dynamics of the ground state. The effect of four-photon dephasing on the absorption spectrum of a Λ-system is analyzed and found to lead to a substantial reduction in the depth of a dip in the absorption spectrum which vanishes as the laser field strength is increased.

Journal of Experimental and Theoretical PhysicsJan 1, 19981 citation

Resonance Fluorescence in 3-Level Systems

Carlos R. Stroud, H. R. Gray

Springer eBooksJan 1, 19780 citations

Coherent Population Trapping in Multi-Level Atomic Systems

Laurentius Windholz

Coherent population trapping (CPT) is treated in multi–level systems, excited by two– or four–frequency laser light. The dynamics of filling non–absorbing (dark) states is investigated. In cases where all transitions involved are excited (closed systems), the effect becomes dependent on the relative phase of the light waves. Further electromagnetically induced transparency (EIT) is described in three– and four–level systems and used for effective side band generation.

Physica ScriptaJan 1, 200113 citations

Observation of coherent population trapping in a V-type two-electron system

Alok K. Singh, Vasant Natarajan A

We observe coherent population trapping (CPT) in a two-electron atom— 174 Yb—using the transition. CPT is not possible for such a transition according to one-electron theory because the magnetic sublevels form a V-type system, but in a two-electron atom like Yb, the interaction of the electrons transforms the level structure into a Λ -type system, which allows the formation of a dark state and hence the observation of CPT. Since the two levels involved are degenerate, we use a magnetic field to lift the degeneracy. The single fluorescence dip then splits into five dips—the central unshifted one corresponds to coherent population oscillation, while the outer four are due to CPT. The linewidth of the CPT resonance is about 300 kHz and is limited by the natural linewidth of the excited state, which is to be expected because the excited state is involved in the formation of the dark state.We observe coherent population trapping (CPT) in a two-electron atom— 174 Yb—using the transition. CPT is not possible for such a transition according to one-electron theory because the magnetic sublevels form a V-type system, but in a two-electron atom like Yb, the interaction of the electrons transforms the level structure into a Λ -type system, which allows the formation of a dark state and hence the observation of CPT. Since the two levels involved are degenerate, we use a magnetic field to lift the degeneracy. The single fluorescence dip then splits into five dips—the central unshifted one corresponds to coherent population oscillation, while the outer four are due to CPT. The linewidth of the CPT resonance is about 300 kHz and is limited by the natural linewidth of the excited state, which is to be expected because the excited state is involved in the formation of the dark state.

arXiv:1502.03079New Journal of PhysicsMar 31, 20154 citations

Temperature and intensity investigations of coherent population trapping resonances

Roland Lammegger, Aleksandar J. Krmpot, Ivan Vasari +2 more

Jahrestagung der Österreichischen Physikalischen GesellschaftJan 1, 20050 citations

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