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New Journal of Physics

Use of the 5 P 3 / 2 → 6 P 3 / 2 electric dipole forbidden transition in Rb as a non-perturbing probe of atom dynamics in an operating magneto-optical trap

L M Hoyos-Campo, F. Ponciano-Ojeda, F. Ramírez-Martínez, J. Flores-Mijangos, Daniel Sahagún, Rocío Jáuregui, J. Jiménez-Mier

Published Oct 1, 2024• 0 citations
Publisher

Abstract

Abstract Results of spectroscopy experiments using the 5 P 3 / 2 → 6 P 3 / 2 electric dipole forbidden transition in cold rubidium atoms are presented. Production of this forbidden transition is detected by observing the emission of the 420 nm fluorescence photons that result from the decay of the 6 P 3 / 2 state into the ground state. The experiments are performed under the steady state operation conditions of a magneto-optical trap (MOT), and thus provide non-perturbing information on the atom-light system. The hyperfine structure of the 6 P 3 / 2 level is completely resolved, and the fluorescence peaks show the expected Autler–Townes (AT) splitting of the emission lines. This hyperfine structure is used to calibrate the frequency scale of all spectra recorded. A combination of this absolute frequency scale and an expression for the AT profile allows an absolute determination of the effective Rabi frequency and detuning of the MOT. The behavior of these AT doublets is studied as a function of frequency detuning and also as a function of the trapping light intensity. The experiments also take full advantage of the strong polarization dependence of the relative intensities of the hyperfine fluorescence components. This study results in a sensitive probe of the relative populations of the magnetic sublevel projections relative to the trapping magnetic field gradient. An almost isotropic population distribution was found, but small deviations from isotropy could be determined with this electric dipole forbidden probe.

DOI
10.1088/1367-2630/ad86e6

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The 5P3/2→6PJ(J=1/2,3/2) Electric Dipole Forbidden Transitions in Rubidium

F. Ponciano-Ojeda, Cristian Mojica-Casique, Santiago Hernández-Gómez +7 more

This paper presents a general review of the results of the experimental and theoretical work carried out by our research group to study the 5P3/2→6PJ electric quadrupole transition in atomic rubidium. The experiments were carried out with room-temperature atoms in an absorption cell. A steady-state population of atoms in the 5P3/2 excited state is produced by a a narrow-bandwidth preparation laser locked to the D2 transition. A second CW laser is used to produce the forbidden transition with resolution of the 6PJ hyperfine states of both rubidium isotopes. The process is detected by recording the 420(422) nm fluorescence that occurs when the atoms in the 6PJ state decay directly into the 5S ground state. The fluorescence spectra show a strong dependence on the relative polarization directions of the preparation laser and the beam producing the forbidden transition. This dependence is directly related to a strong anisotropy in the populations of the 5P3/2 intermediate magnetic substates, and also to the electric quadrupole selection rules over magnetic quantum numbers. A calculation based on the rate equations that includes velocity and detuning dependent transition rates is adequate to reproduce these results. The forbidden transition is also shown to be an ideal probe to measure the Autler–Townes splitting generated in the preparation of the 5P3/2 state. Examples of spectra obtained with cold atoms in a magneto-optical trap (MOT) are also presented. These spectra show the expected Autler–Townes doublet structure with asymmetric line profiles that result as a consequence of the red-detuning of the trapping laser in the MOT.

Photonics•Dec 1, 2023•0 citations

Optical spectroscopy of the 5 p 3/2 → 6 p 1/2 electric dipole-forbidden transition in atomic rubidium

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Abstract We present the first evidence of excitation of the 5 p 3 / 2 → 6 p 1 / 2 electric dipole-forbidden transition in atomic rubidium. The experiments were done in a rubidium vapor cell using Doppler-free optical–optical double resonance spectroscopy with counter-propagating beams, with a similar scheme to the excitation of the other fine transition 6 p 3/2 in the 6 p J manifold reported in Ponciano-Ojeda et al (2015 Phys. Rev. A 92 042511). The 5 p 3 / 2 → 6 p 1 / 2 dipole-forbidden excitation occurs at a wavelength λ ≈ 917.5 nm. The spectra showed the two main hyperfine states of the 6 p 1/2 manifold, and also resolved up to three satellites that appear due to effects of selection of velocities in thermal rubidium atoms. The polarization dependence of the relative intensities of the hyperfine lines of the decay fluorescence is also investigated. The data show that the individual line intensities and also the total cross-section have a strong dependence on the polarization direction. Experimental data for different polarization configurations of the light beams used in this two-photon spectroscopy are compared with the results of calculations that consider a strong atom-field coupling in the preparation step, followed by a weak electric quadrupole excitation and the blue fluorescence decay emission. Good agreement between experiment and this three-step model is found in the case of linear–linear polarizations, which confirms the results found for the 5 p 3 / 2 → 6 p 3 / 2 forbidden transition. The results presented here complete the information about the 5 p 3/2 → 6 p J electric dipole-forbidden transition in rubidium.

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Observation of the 5p3/2→6p3/2 electric-dipole-forbidden transition in atomic rubidium using optical-optical double-resonance spectroscopy

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Direct evidence of excitation of the $5{p}_{3/2}\ensuremath{\rightarrow}6{p}_{3/2}$ electric-dipole-forbidden transition in atomic rubidium is presented. The experiments were performed in a room-temperature rubidium cell with continuous-wave external cavity diode lasers. Optical-optical double-resonance spectroscopy with counterpropagating beams allows the detection of the nondipole transition free of Doppler broadening. The $5{p}_{3/2}$ state is prepared by excitation with a laser locked to the maximum $F$ cyclic transition of the ${D}_{2}$ line, and the forbidden transition is produced by excitation with a 911 nm laser. Production of the forbidden transition is monitored by detection of the 420 nm fluorescence that results from decay of the $6{p}_{3/2}$ state. Spectra with three narrow lines ($\ensuremath{\approx}13$ MHz FWHM) with the characteristic $F\ensuremath{-}1, F$, and $F+1$ splitting of the $6{p}_{3/2}$ hyperfine structure in both rubidium isotopes were obtained. The results are in very good agreement with a direct calculation that takes into account the $5s\ensuremath{\rightarrow}5{p}_{3/2}$ preparation dynamics, the $5{p}_{3/2}\ensuremath{\rightarrow}6{p}_{3/2}$ nondipole excitation geometry, and the $6{p}_{3/2}\ensuremath{\rightarrow}5{s}_{1/2}$ decay. The comparison also shows that the electric-dipole-forbidden transition is a very sensitive probe of the preparation dynamics.

arXiv:1506.06105•Physical Review A•Oct 20, 2015•18 citations

Electric-dipole forbidden transitions for probing atomic state preparation: the case of the Autler–Townes effect

F. Ramírez-Martínez, F. Ponciano-Ojeda, Santiago Hernández-Gómez +7 more

Abstract This work demonstrates an scheme in which a weak electric quadrupole ( E 2) transition with a controlled frequency detuning in a ladder configuration is used as an extremely non-perturbing probe for precisely identifying subtle details of the effects driven by AC fields coupling atomic states and the preparation of quantum states. For this purpose, we provide a precise experimental and theoretical study of the Autler Townes (AT) effect derived from a strong electric dipole transition stimulated by a resonant laser beam and probed by the E 2 interaction. The experiment was carried out for a 87 Rb atomic gas at room temperature in a velocity-selective scheme. The AT effect was monitored via the splitting of the fluorescence spectra associated with the spontaneous decay to the ground state. The theoretical description incorporates the modification of standard few-level schemes introduced by forbidden electric-dipole transitions selection rules. We develop an analytic ladder three-level scheme to approximate the cyclic 5S 1/2 F = 2 → 5P 3/2 F = 3 → 6P 3/2 F = 1, 2, 3 → 5S 1/2 F = 2 path. Other levels that could have effects on the fluorescence are included via a fourth level with effective parameters. Doppler effects and finite bandwidths of the laser beams are included in the theoretical model to closely reproduce the experimental results.

Journal of Physics B Atomic Molecular and Optical Physics•Mar 24, 2021•8 citations

Use of an electric-dipole forbidden transition to optically probe the Autler Townes effect

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We study the Autler Townes (AT) effect derived from a strong electric dipole transition stimulated by a resonant laser beam and probing it by means of a weak electric quadrupole transition with a controlled frequency detuning in a ladder configuration. The experiment was carried out for a $^{87}$Rb atomic gas at room temperature in a velocity-selective scheme. The AT effect was monitored via the splitting of the fluorescence spectra associated with the spontaneous decay to the ground state. The theoretical description incorporates the modification of standard few-level schemes introduced by forbidden electric-dipole transitions selection rules. We develop an analytic ladder three-level scheme to approximate the cyclic $5\mathrm{S}_{1/2} \mathrm{F}=2\rightarrow 5\mathrm{P}_{3/2} F=3 \rightarrow 6\mathrm{P}_{3/2} \mathrm{F}=1,2,3\rightarrow 5 \mathrm{S}_{1/2}\mathrm{F}=2$ path. Other levels that could have effects on the fluorescence are included via a fourth level with effective parameters. Doppler effects and finite bandwidths of the laser beams are included in the theoretical model to closely reproduce the experimental results.

arXiv:1909.01293•Sep 3, 2019•0 citations

One step beyond the electric dipole approximation: An experiment to observe the 5p → 6p forbidden transition in atomic rubidium

F. Ponciano-Ojeda, Santiago Hernández-Gómez, Cristian Mojica-Casique +8 more

An advanced undergraduate experiment to study the 5P3/2→6P3/2 electric quadrupole transition in rubidium atoms is presented. The experiment uses two external cavity diode lasers, one operating at the D2 rubidium resonance line and the other built with commercial parts to emit at 911 nm. The lasers produce the 5s→5p→6p excitation sequence in which the second step is the forbidden transition. Production of atoms in the 6P3/2 state is observed by detection of the 420 nm fluorescence that results from electric dipole decay into the ground state. Lines whose widths are significantly narrower than the Doppler width are used to study the hyperfine structure of the 6P3/2 state in rubidium. The spectra illustrate characteristics unique to electric dipole forbidden transitions, like the electric quadrupole selection rules; they are also used to show general aspects of two-color laser spectroscopy such as velocity selection and hyperfine pumping.

American Journal of Physics•Dec 19, 2017•5 citations
Abstract Results of spectroscopy experiments using the 5 P 3 / 2 → 6 P 3 / 2 electric dipole forbidden transition in cold rubidium atoms are presented. Production of this forbidden transition is detected by observing the emission of the 420 nm fluorescence photons that result from the decay of the 6 P 3 / 2 state into the ground state. The experiments are performed under the steady state operation conditions of a magneto-optical trap (MOT), and thus provide non-perturbing information on the atom-light system. The hyperfine structure of the 6 P 3 / 2 level is completely resolved, and the fluorescence peaks show the expected Autler–Townes (AT) splitting of the emission lines. This hyperfine structure is used to calibrate the frequency scale of all spectra recorded. A combination of this absolute frequency scale and an expression for the AT profile allows an absolute determination of the effective Rabi frequency and detuning of the MOT. The behavior of these AT doublets is studied as a function of frequency detuning and also as a function of the trapping light intensity. The experiments also take full advantage of the strong polarization dependence of the relative intensities of the hyperfine fluorescence components. This study results in a sensitive probe of the relative populations of the magnetic sublevel projections relative to the trapping magnetic field gradient. An almost isotropic population distribution was found, but small deviations from isotropy could be determined with this electric dipole forbidden probe.
This paper presents a general review of the results of the experimental and theoretical work carried out by our research group to study the 5P3/2→6PJ electric quadrupole transition in atomic rubidium. The experiments were carried out with room-temperature atoms in an absorption cell. A steady-state population of atoms in the 5P3/2 excited state is produced by a a narrow-bandwidth preparation laser locked to the D2 transition. A second CW laser is used to produce the forbidden transition with resolution of the 6PJ hyperfine states of both rubidium isotopes. The process is detected by recording the 420(422) nm fluorescence that occurs when the atoms in the 6PJ state decay directly into the 5S ground state. The fluorescence spectra show a strong dependence on the relative polarization directions of the preparation laser and the beam producing the forbidden transition. This dependence is directly related to a strong anisotropy in the populations of the 5P3/2 intermediate magnetic substates, and also to the electric quadrupole selection rules over magnetic quantum numbers. A calculation based on the rate equations that includes velocity and detuning dependent transition rates is adequate to reproduce these results. The forbidden transition is also shown to be an ideal probe to measure the Autler–Townes splitting generated in the preparation of the 5P3/2 state. Examples of spectra obtained with cold atoms in a magneto-optical trap (MOT) are also presented. These spectra show the expected Autler–Townes doublet structure with asymmetric line profiles that result as a consequence of the red-detuning of the trapping laser in the MOT.
Abstract We present the first evidence of excitation of the 5 p 3 / 2 → 6 p 1 / 2 electric dipole-forbidden transition in atomic rubidium. The experiments were done in a rubidium vapor cell using Doppler-free optical–optical double resonance spectroscopy with counter-propagating beams, with a similar scheme to the excitation of the other fine transition 6 p 3/2 in the 6 p J manifold reported in Ponciano-Ojeda et al (2015 Phys. Rev. A 92 042511). The 5 p 3 / 2 → 6 p 1 / 2 dipole-forbidden excitation occurs at a wavelength λ ≈ 917.5 nm. The spectra showed the two main hyperfine states of the 6 p 1/2 manifold, and also resolved up to three satellites that appear due to effects of selection of velocities in thermal rubidium atoms. The polarization dependence of the relative intensities of the hyperfine lines of the decay fluorescence is also investigated. The data show that the individual line intensities and also the total cross-section have a strong dependence on the polarization direction. Experimental data for different polarization configurations of the light beams used in this two-photon spectroscopy are compared with the results of calculations that consider a strong atom-field coupling in the preparation step, followed by a weak electric quadrupole excitation and the blue fluorescence decay emission. Good agreement between experiment and this three-step model is found in the case of linear–linear polarizations, which confirms the results found for the 5 p 3 / 2 → 6 p 3 / 2 forbidden transition. The results presented here complete the information about the 5 p 3/2 → 6 p J electric dipole-forbidden transition in rubidium.
Direct evidence of excitation of the $5{p}_{3/2}\ensuremath{\rightarrow}6{p}_{3/2}$ electric-dipole-forbidden transition in atomic rubidium is presented. The experiments were performed in a room-temperature rubidium cell with continuous-wave external cavity diode lasers. Optical-optical double-resonance spectroscopy with counterpropagating beams allows the detection of the nondipole transition free of Doppler broadening. The 5p3/25{p}_{3/2}5p3/2​ state is prepared by excitation with a laser locked to the maximum FFF cyclic transition of the D2{D}_{2}D2​ line, and the forbidden transition is produced by excitation with a 911 nm laser. Production of the forbidden transition is monitored by detection of the 420 nm fluorescence that results from decay of the 6p3/26{p}_{3/2}6p3/2​ state. Spectra with three narrow lines ($\ensuremath{\approx}13$ MHz FWHM) with the characteristic $F\ensuremath{-}1, F$, and F+1F+1F+1 splitting of the 6p3/26{p}_{3/2}6p3/2​ hyperfine structure in both rubidium isotopes were obtained. The results are in very good agreement with a direct calculation that takes into account the $5s\ensuremath{\rightarrow}5{p}_{3/2}$ preparation dynamics, the $5{p}_{3/2}\ensuremath{\rightarrow}6{p}_{3/2}$ nondipole excitation geometry, and the $6{p}_{3/2}\ensuremath{\rightarrow}5{s}_{1/2}$ decay. The comparison also shows that the electric-dipole-forbidden transition is a very sensitive probe of the preparation dynamics.
Abstract This work demonstrates an scheme in which a weak electric quadrupole ( E 2) transition with a controlled frequency detuning in a ladder configuration is used as an extremely non-perturbing probe for precisely identifying subtle details of the effects driven by AC fields coupling atomic states and the preparation of quantum states. For this purpose, we provide a precise experimental and theoretical study of the Autler Townes (AT) effect derived from a strong electric dipole transition stimulated by a resonant laser beam and probed by the E 2 interaction. The experiment was carried out for a 87 Rb atomic gas at room temperature in a velocity-selective scheme. The AT effect was monitored via the splitting of the fluorescence spectra associated with the spontaneous decay to the ground state. The theoretical description incorporates the modification of standard few-level schemes introduced by forbidden electric-dipole transitions selection rules. We develop an analytic ladder three-level scheme to approximate the cyclic 5S 1/2 F = 2 → 5P 3/2 F = 3 → 6P 3/2 F = 1, 2, 3 → 5S 1/2 F = 2 path. Other levels that could have effects on the fluorescence are included via a fourth level with effective parameters. Doppler effects and finite bandwidths of the laser beams are included in the theoretical model to closely reproduce the experimental results.
We study the Autler Townes (AT) effect derived from a strong electric dipole transition stimulated by a resonant laser beam and probing it by means of a weak electric quadrupole transition with a controlled frequency detuning in a ladder configuration. The experiment was carried out for a 87^{87}87Rb atomic gas at room temperature in a velocity-selective scheme. The AT effect was monitored via the splitting of the fluorescence spectra associated with the spontaneous decay to the ground state. The theoretical description incorporates the modification of standard few-level schemes introduced by forbidden electric-dipole transitions selection rules. We develop an analytic ladder three-level scheme to approximate the cyclic 5S1/2F=2→5P3/2F=3→6P3/2F=1,2,3→5S1/2F=25\mathrm{S}_{1/2} \mathrm{F}=2\rightarrow 5\mathrm{P}_{3/2} F=3 \rightarrow 6\mathrm{P}_{3/2} \mathrm{F}=1,2,3\rightarrow 5 \mathrm{S}_{1/2}\mathrm{F}=25S1/2​F=2→5P3/2​F=3→6P3/2​F=1,2,3→5S1/2​F=2 path. Other levels that could have effects on the fluorescence are included via a fourth level with effective parameters. Doppler effects and finite bandwidths of the laser beams are included in the theoretical model to closely reproduce the experimental results.
An advanced undergraduate experiment to study the 5P3/2→6P3/2 electric quadrupole transition in rubidium atoms is presented. The experiment uses two external cavity diode lasers, one operating at the D2 rubidium resonance line and the other built with commercial parts to emit at 911 nm. The lasers produce the 5s→5p→6p excitation sequence in which the second step is the forbidden transition. Production of atoms in the 6P3/2 state is observed by detection of the 420 nm fluorescence that results from electric dipole decay into the ground state. Lines whose widths are significantly narrower than the Doppler width are used to study the hyperfine structure of the 6P3/2 state in rubidium. The spectra illustrate characteristics unique to electric dipole forbidden transitions, like the electric quadrupole selection rules; they are also used to show general aspects of two-color laser spectroscopy such as velocity selection and hyperfine pumping.