Recognizing that the complete initial inversion required in superfluorescence (SF) can only be achieved in a finite time, we use two different master equations for two different stages of SF: one describing the initiation of SF during pumping and another one governing the free evolution of SF after pumping. The pumping process is treated as a Poisson process with varying rate to reflect a pump pulse of arbitrary shape. The exact solution to the first master equation is obtained and used as the initial condition for the second master equation. The statistical properties of the tipping angle and the delay time are then calculated explicity. It is shown that the effects of pumping process on these two quantities can be reduced to a parameter called effective head-start time (EHT). Two different expressions for this EHT have been derived: one with saturation effects and another one without.Recognizing that the complete initial inversion required in superfluorescence (SF) can only be achieved in a finite time, we use two different master equations for two different stages of SF: one describing the initiation of SF during pumping and another one governing the free evolution of SF after pumping. The pumping process is treated as a Poisson process with varying rate to reflect a pump pulse of arbitrary shape. The exact solution to the first master equation is obtained and used as the initial condition for the second master equation. The statistical properties of the tipping angle and the delay time are then calculated explicity. It is shown that the effects of pumping process on these two quantities can be reduced to a parameter called effective head-start time (EHT). Two different expressions for this EHT have been derived: one with saturation effects and another one without.

Physical Review AJan 1, 19841 citation

Observation and origin of multi-THz quantum beats in superfluorescent emission from argon

Noa Nambu, Zan Nie, Kenneth A. Marsh +4 more

We report observation of multi-THz quantum beats in the amplitude of superfluorescence in pure argon gas, using a time delayed 780-nm probe beam that interrogates the relevant population densities. The superfluorescence is induced by three-photon absorption of an ultrashort 260.5-nm laser pulse that creates coherent and coupled populations in multiple closely spaced $3d$ and $5s$ Ar levels. Argon pressure and pump laser focusing parameters are seen to modify the frequency of the quantum beats, which is attributed to the absorption of the self-generated, nonresonant third harmonic of the pump from Ar near the zero of the real part of the overlapping linear susceptibilities of the closely spaced $3d$ and $5s$ excited states. The self-absorption of the phase-matched THG photons creates a coherent population of atoms which acts like an atomic excited state ($3\ensuremath{\omega}$-induced state). We have also observed a new two-step superfluorescent cascade that results from the population redistribution enabled by the 780-nm probe pulse between the $3{d}^{\ensuremath{'}}{[5/2]}_{3}$ and the $3\ensuremath{\omega}$-induced state and gives rise to a previously unknown transition that emits on 1587 nm.We report observation of multi-THz quantum beats in the amplitude of superfluorescence in pure argon gas, using a time delayed 780-nm probe beam that interrogates the relevant population densities. The superfluorescence is induced by three-photon absorption of an ultrashort 260.5-nm laser pulse that creates coherent and coupled populations in multiple closely spaced $3d$ and $5s$ Ar levels. Argon pressure and pump laser focusing parameters are seen to modify the frequency of the quantum beats, which is attributed to the absorption of the self-generated, nonresonant third harmonic of the pump from Ar near the zero of the real part of the overlapping linear susceptibilities of the closely spaced $3d$ and $5s$ excited states. The self-absorption of the phase-matched THG photons creates a coherent population of atoms which acts like an atomic excited state ($3\ensuremath{\omega}$-induced state). We have also observed a new two-step superfluorescent cascade that results from the population redistribution enabled by the 780-nm probe pulse between the $3{d}^{\ensuremath{'}}{[5/2]}_{3}$ and the $3\ensuremath{\omega}$-induced state and gives rise to a previously unknown transition that emits on 1587 nm.

Physical Review AJan 27, 20251 citation

Superfluorescence Experiments

Quirin H. F. Vrehen, H. M. Gibbs

Topics in current physicsJan 1, 198217 citations

3d

and

5s

Ar levels. Argon pressure and pump laser focusing parameters are seen to modify the frequency of the quantum beats, which is attributed to the absorption of the self-generated, nonresonant third harmonic of the pump from Ar near the zero of the real part of the overlapping linear susceptibilities of the closely spaced

3d

and

5s

excited states. The self-absorption of the phase-matched THG photons creates a coherent population of atoms which acts like an atomic excited state ($3\ensuremath{\omega}$-induced state). We have also observed a new two-step superfluorescent cascade that results from the population redistribution enabled by the 780-nm probe pulse between the $3{d}^{\ensuremath{'}}{[5/2]}_{3}$ and the $3\ensuremath{\omega}$-induced state and gives rise to a previously unknown transition that emits on 1587 nm.