We demonstrate the use of stimulated Raman adiabatic passage (STIRAP) for population transfer from the ground state to the 5D5/2 level (5 5 5 ) S P D / / / 1 2 3 2 5 2 in laser-cooled 87 Rb atoms and examine the influence of the time delay between laser pulses, pulse height, pulse duration and frequency detuning from resonance on the efficiency of Rb atom excitation to the 5D5/2 level. In our experiments, the pulse duration was varied widely (30 - 200 ns), which allowed us to assess the effect of spontaneous decay on the population of the 5D5/2 level (natural lifetime, 300 ns). We per- formed numerical calculations with allowance for spontaneous decay from the 5P3/2 and 5D5/2 levels and compared the results to experimental data, which allowed the population of the 5D5/2 level to be determined. The maximum population of the 5D5/2 level in the region under excitation was 80 % of the total number of rubidium atoms.We demonstrate the use of stimulated Raman adiabatic passage (STIRAP) for population transfer from the ground state to the 5D5/2 level (5 5 5 ) S P D / / / 1 2 3 2 5 2 in laser-cooled 87 Rb atoms and examine the influence of the time delay between laser pulses, pulse height, pulse duration and frequency detuning from resonance on the efficiency of Rb atom excitation to the 5D5/2 level. In our experiments, the pulse duration was varied widely (30 - 200 ns), which allowed us to assess the effect of spontaneous decay on the population of the 5D5/2 level (natural lifetime, 300 ns). We per- formed numerical calculations with allowance for spontaneous decay from the 5P3/2 and 5D5/2 levels and compared the results to experimental data, which allowed the population of the 5D5/2 level to be determined. The maximum population of the 5D5/2 level in the region under excitation was 80 % of the total number of rubidium atoms.

Quantum ElectronicsAug 29, 201211 citations

Interference between different channels in the spontaneous decay of two excited atoms

F. T. Arecchi, Gian Piero Banfi, V. Fossati Bellani

Il Nuovo cimento della Società italiana di fisica. B/Il Nuovo cimento BOct 1, 19721 citation

Simple cases of spontaneous emission from an atom-photon cluster localized in a microcavity

Ashat M. Basharov

The spontaneous emission from an atomic ensemble localized in a microcavity with the participation of microcavity photons and an external broadband quantized electromagnetic field at the Raman resonance of photons with an optically forbidden (two-photon) atomic transition has been studied. The average spontaneous decay intensity has been calculated for simple cases. It is shown that the dynamics of spontaneous emission from this atomic ensemble differs generally from the conventional superradiance (spontaneous emission of an atomic ensemble at a one-photon optically allowed transition from excited to the ground state. When the atomic ensemble is strongly excited, the delay times and the emission pulse shape differ significantly. The parameter ranges where the spontaneous emission from the atomic ensemble under consideration at a two-photon Raman transition can be described as conventional superradiance with renormalized parameters are found. In the case of single excitation the photon emission probability depends on the number of photons and atoms in the microcavity.The spontaneous emission from an atomic ensemble localized in a microcavity with the participation of microcavity photons and an external broadband quantized electromagnetic field at the Raman resonance of photons with an optically forbidden (two-photon) atomic transition has been studied. The average spontaneous decay intensity has been calculated for simple cases. It is shown that the dynamics of spontaneous emission from this atomic ensemble differs generally from the conventional superradiance (spontaneous emission of an atomic ensemble at a one-photon optically allowed transition from excited to the ground state. When the atomic ensemble is strongly excited, the delay times and the emission pulse shape differ significantly. The parameter ranges where the spontaneous emission from the atomic ensemble under consideration at a two-photon Raman transition can be described as conventional superradiance with renormalized parameters are found. In the case of single excitation the photon emission probability depends on the number of photons and atoms in the microcavity.

Optics and SpectroscopyJul 1, 20100 citations

Many-atom spontaneous emission in a damped cavity

JOSIP SEKE

Journal of the Optical Society of America BFeb 1, 19870 citations

Cooperative effects in the spontaneous decay of few atoms

H. Blank, M. Blank, Karl Blum +1 more

Physics Letters AOct 1, 198415 citations

Time Advance and Probability Conservation in PT-Symmetric Quantum Mechanics

Philip D. Mannheim

When excited states decay the time evolution operator $U(t)=e^{-iHt}$ does not obey $U^{\dagger}(t)U(t)=I$ . Nonetheless, probability conservation is not lost if one includes both excitation and decay, though it takes a different form. Specifically, if the eigenspectrum of a Hamiltonian is complete, then due to $CPT$ symmetry, a symmetry that holds for all physical systems, there must exist an operator $V$ that effects $VHV^{-1}=H^{\dagger}$ , so that $V^{-1}U^{\dagger}(t)VU(t)=I$ . In consequence, the time delay associated with decay must be accompanied by an equal and opposite time advance for excitation. Thus when a photon excites an atom the spontaneous emission of a photon from the excited state must occur without any decay time delay at all. An effect of this form together with an associated negative time delay appear to have recently been reported by Sinclair et. al., PRX Quantum \textbf{3}, 010314 (2022) and Angulo et. al., arXiv:2409.03680 [quant-ph].When excited states decay the time evolution operator $U(t)=e^{-iHt}$ does not obey $U^{\dagger}(t)U(t)=I$. Nonetheless, probability conservation is not lost if one includes both excitation and decay, though it takes a different form. Specifically, if the eigenspectrum of a Hamiltonian is complete, then due to $CPT$ symmetry, a symmetry that holds for all physical systems, there must exist an operator $V$ that effects $VHV^{-1}=H^{\dagger}$, so that $V^{-1}U^{\dagger}(t)VU(t)=I$. In consequence, the time delay associated with decay must be accompanied by an equal and opposite time advance for excitation. Thus when a photon excites an atom the spontaneous emission of a photon from the excited state must occur without any decay time delay at all. An effect of this form together with an associated negative time delay appear to have recently been reported by Sinclair et. al., PRX Quantum \textbf{3}, 010314 (2022) and Angulo et. al., arXiv:2409.03680 [quant-ph].

arXiv:2504.12068Apr 16, 20250 citations

When excited states decay the time evolution operator

U(t)=e^{-iHt}

does not obey

U^{\dagger}(t)U(t)=I

. Nonetheless, probability conservation is not lost if one includes both excitation and decay, though it takes a different form. Specifically, if the eigenspectrum of a Hamiltonian is complete, then due to

CPT

symmetry, a symmetry that holds for all physical systems, there must exist an operator

V

that effects

VHV^{-1}=H^{\dagger}

, so that

V^{-1}U^{\dagger}(t)VU(t)=I

. In consequence, the time delay associated with decay must be accompanied by an equal and opposite time advance for excitation. Thus when a photon excites an atom the spontaneous emission of a photon from the excited state must occur without any decay time delay at all. An effect of this form together with an associated negative time delay appear to have recently been reported by Sinclair et. al., PRX Quantum \textbf{3}, 010314 (2022) and Angulo et. al., arXiv:2409.03680 [quant-ph].