Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Modern Optics

Laser-field-induced quantum beats in correlations in cascade emission

Anil K. Patnaik, G. S. Agarwal

Published Oct 1, 1998• 13 citations
Publisher

Abstract

A cascade system involving two closely lying intermediate states can exhibit quantum beats in two-photon correlations provided that the dipole matrix elements satisfy certain conditions which, however, are rarely satisfied by atomic systems. However, if two intermediate states are produced by using ac Stark splitting, then quantum beats will always occur. Detailed analysis of such beats and their physical interpretation is given.

DOI
10.1080/09500349808231749

Related papers

One-photon-cascade spectrum in a two-photon-pumped three-level system

Z Chen, Helen S. Freedhoff

The top level of a three-level atom is populated by resonant two-photon optical pumping from the bottom level by a field intense enough to produce dynamic Stark splitting. The frequencies and intensities are calculated for the one-photon cascade emission to the ground state via a nearly resonant intermediate level. Two strong (shifted) doublets near the atomic frequencies, and a weaker triplet centred at the laser frequency are predicted.

Journal of Physics B Atomic Molecular and Optical Physics•Feb 14, 1990•0 citations

Cascade Zeeman quantum beats produced by stepwise excitation using broad-line laser pulses. I. Theory

Bryan J. Dalton

A theory of stepwise pulsed-laser excitation of cascade Zeeman quantum beats has been developed for a four-level system. The laser pulses are treated in the broad-line approximation and the full optical-pumping equations for the atomic-density matrix of each level have been obtained. These can be used to describe saturation and light shift effects. The weak-pumping theory solutions to the optical pumping equations have been used to obtain expressions for the cascade quantum-beat intensity versus time curves. Larmor precession, spontaneous-emission decay and the populating of the final cascade level during the excitation pulse are all allowed for. A Wiener-Levy phase diffusion model with slowly varying amplitudes is used for the laser pulses, and the final theoretical expressions for the quantum beats depend on the time-dependent intensities of the laser pulses as well as on their polarisations. Hyperfine effects have been ignored. The theory applies to both coincident pulses and to pulses with a time delay between them. An illustrative application to the case of two very short but coincident pulses (during which Larmor precession, spontaneous emission etc. can be ignored) is given. In an accompanying paper the theoretical expressions are further evaluated and successfully applied to the interpretation of cascade Zeeman quantum beat experiments in Fe I.

Journal of Physics B Atomic and Molecular Physics•Jan 28, 1987•6 citations

Quantum Beats in Intensity Correlations of Spontaneous Emission from Two Non-identical Atoms

Z. Ficek, R. Tanaś, S. Kielich

The two-time second-order correlation function of the electric field spontaneously emitted by a system of two non-identical two-level atoms with different transition frequencies and different natural linewidths is calculated from the viewpoint of quantum beats and photon anticorrelation effects. Our analytical solution shows that the intensity correlation exhibits quantum beats. The quantum beats are shown to appear even if the two atoms are independent. For identical atoms, beats appear only if dipole–dipole interaction between the atoms is included, and they are then strongly dependent on the direction of observation with respect to the line connecting the two atoms. The anticorrelation effect between the photons emitted in different directions is also discussed. It is shown that for a single-time correlation function the condition for anticorrelation is independent of interatomic interactions. For a two-time correlation function, interatomic interactions reduce the anticorrelation effect.

Journal of Modern Optics•Jan 1, 1988•7 citations

General theory of laser-induced quantum beats. II. Sequential laser excitation; effects of external static fields

Mark P. Silverman, S. Haroche, M. Groß

A general theory of laser-induced quantum beats introduced in paper I is extended to include the effects of sequential laser excitation by several lasers for atomic systems either free or subjected to external static fields. A detailed study is made of the dependence of the quantum beat signal on the polarizations of the exciting laser pulses and detected spontaneous emission. The theory is applied to the echelon excitation of sodium $\mathrm{nD}$ Rydberg states. An analysis of the Zeeman beats produced by excitation in an external magnetic field suggests new ways to measure the fine-structure interaction constant of the Rydberg levels.

Physical Review A•Oct 1, 1978•18 citations

Quantum beats in photon correlations of spontaneous emission from two nonidentical atoms

Z. Ficek, R. Tanaś, S. Kielich

The appearance of quantum beats in a two-time second-order correlation function is discussed for the case of spontaneous emission from two nonidentical atoms. The atoms are separated by distances comparable with the resonance wavelength and have different transition frequencies and natural line widths. It is shown that quantum beats appear for nonidentical and identical atoms. In the latter case the dipole–dipole interaction between the atoms is a necessary condition for the appearance of quantum beats. Two mechanisms lead to quantum beats in the case of nonidentical atoms and such beats may appear even for independent atoms. The effect is similar to that of interference between independent beams.

Soviet Journal of Quantum Electronics•Jun 30, 1988•1 citation

Quantum correlations and violation of the Bell inequality induced by an external field in a two-photon radiative cascade

Luqi Yuan, Sumanta Das

We study the polarization-dependent second-order correlation of a pair of photons emitted in a four-level radiative cascade driven by an external field. It is found that the quantum correlations of the emitted photons, degraded by the energy splitting of the intermediate levels in the radiative cascade, can be efficiently revived by a far-detuned external field. The physics of this revival is linked to an induced Stark shift and the formation of dressed states in the system by the nonresonant external field. Furthermore, we investigated the competition between the effect of the coherent external field and incoherent dephasing of the intermediate levels. We find that the degradation of quantum correlations due to the incoherent dephasing can be contained for small dephasing with the external field. We also studied the nonlocality of the correlations by evaluating the Bell inequality in the linear polarization basis for the radiative cascade. We find that the Bell parameter decreases rapidly with increase in the intermediate-level energy splitting or incoherent dephasing rate to the extent that there is no violation. However, the presence of an external field leads to control over the degrading mechanisms and preservation of nonlocal correlation among the photons. This in turn can induce a violation of Bell's inequality in the radiative cascade for arbitrary intermediate-level splitting and small incoherent dephasing.

arXiv:1109.4099•Physical Review A•Jun 17, 2011•2 citations
A cascade system involving two closely lying intermediate states can exhibit quantum beats in two-photon correlations provided that the dipole matrix elements satisfy certain conditions which, however, are rarely satisfied by atomic systems. However, if two intermediate states are produced by using ac Stark splitting, then quantum beats will always occur. Detailed analysis of such beats and their physical interpretation is given.
A theory of stepwise pulsed-laser excitation of cascade Zeeman quantum beats has been developed for a four-level system. The laser pulses are treated in the broad-line approximation and the full optical-pumping equations for the atomic-density matrix of each level have been obtained. These can be used to describe saturation and light shift effects. The weak-pumping theory solutions to the optical pumping equations have been used to obtain expressions for the cascade quantum-beat intensity versus time curves. Larmor precession, spontaneous-emission decay and the populating of the final cascade level during the excitation pulse are all allowed for. A Wiener-Levy phase diffusion model with slowly varying amplitudes is used for the laser pulses, and the final theoretical expressions for the quantum beats depend on the time-dependent intensities of the laser pulses as well as on their polarisations. Hyperfine effects have been ignored. The theory applies to both coincident pulses and to pulses with a time delay between them. An illustrative application to the case of two very short but coincident pulses (during which Larmor precession, spontaneous emission etc. can be ignored) is given. In an accompanying paper the theoretical expressions are further evaluated and successfully applied to the interpretation of cascade Zeeman quantum beat experiments in Fe I.
The two-time second-order correlation function of the electric field spontaneously emitted by a system of two non-identical two-level atoms with different transition frequencies and different natural linewidths is calculated from the viewpoint of quantum beats and photon anticorrelation effects. Our analytical solution shows that the intensity correlation exhibits quantum beats. The quantum beats are shown to appear even if the two atoms are independent. For identical atoms, beats appear only if dipole–dipole interaction between the atoms is included, and they are then strongly dependent on the direction of observation with respect to the line connecting the two atoms. The anticorrelation effect between the photons emitted in different directions is also discussed. It is shown that for a single-time correlation function the condition for anticorrelation is independent of interatomic interactions. For a two-time correlation function, interatomic interactions reduce the anticorrelation effect.
A general theory of laser-induced quantum beats introduced in paper I is extended to include the effects of sequential laser excitation by several lasers for atomic systems either free or subjected to external static fields. A detailed study is made of the dependence of the quantum beat signal on the polarizations of the exciting laser pulses and detected spontaneous emission. The theory is applied to the echelon excitation of sodium nD\mathrm{nD}nD Rydberg states. An analysis of the Zeeman beats produced by excitation in an external magnetic field suggests new ways to measure the fine-structure interaction constant of the Rydberg levels.
The appearance of quantum beats in a two-time second-order correlation function is discussed for the case of spontaneous emission from two nonidentical atoms. The atoms are separated by distances comparable with the resonance wavelength and have different transition frequencies and natural line widths. It is shown that quantum beats appear for nonidentical and identical atoms. In the latter case the dipole–dipole interaction between the atoms is a necessary condition for the appearance of quantum beats. Two mechanisms lead to quantum beats in the case of nonidentical atoms and such beats may appear even for independent atoms. The effect is similar to that of interference between independent beams.
We study the polarization-dependent second-order correlation of a pair of photons emitted in a four-level radiative cascade driven by an external field. It is found that the quantum correlations of the emitted photons, degraded by the energy splitting of the intermediate levels in the radiative cascade, can be efficiently revived by a far-detuned external field. The physics of this revival is linked to an induced Stark shift and the formation of dressed states in the system by the nonresonant external field. Furthermore, we investigated the competition between the effect of the coherent external field and incoherent dephasing of the intermediate levels. We find that the degradation of quantum correlations due to the incoherent dephasing can be contained for small dephasing with the external field. We also studied the nonlocality of the correlations by evaluating the Bell inequality in the linear polarization basis for the radiative cascade. We find that the Bell parameter decreases rapidly with increase in the intermediate-level energy splitting or incoherent dephasing rate to the extent that there is no violation. However, the presence of an external field leads to control over the degrading mechanisms and preservation of nonlocal correlation among the photons. This in turn can induce a violation of Bell's inequality in the radiative cascade for arbitrary intermediate-level splitting and small incoherent dephasing.