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

arXiv:2504.19713 · Physical Review A

Measurement of the total spin angular momentum 〈 F z 〉 of alkali-metal atoms

Runa Yasuda, Kei Ishii, W. Klassen, J. W. Martin, A. Hatakeyama

Published Mar 17, 2025• 0 citations
arXivHTMLPDF

Abstract

It is important to evaluate the total spin angular momentum of alkali-metal atoms if the atoms serve as a reservoir of angular momenta. We use an absorption-monitoring technique to measure $\ensuremath{\langle}{F}_{z}\ensuremath{\rangle}$, i.e., the expectation values of the quantization ($z$) axis components of the total angular momentum of Cs atoms in the electronic ground state in both uncoated and antirelaxation-coated vacuum cells at room temperature. Cs atoms are polarized via optical pumping and probed using their ${D}_{2}$ transitions. The probe laser frequency is varied across the Doppler-broadened ${D}_{2}$ transition; the $\ensuremath{\langle}{F}_{z}\ensuremath{\rangle}$ values are derived using the integrated absorption coefficients. The largest $\ensuremath{\langle}{F}_{z}\ensuremath{\rangle}$ is 2.5 for the coated cell. We then use a simple model of spin flow through vapor cells to estimate the atomic spin relaxation probabilities after a single surface collision.

DOI
10.1103/physreva.111.033111

Related papers

Alkali Atomic Density Detection With Arbitrarily Polarized Light

Xuejing Liu, Menglu Wang, Yuhan Li +3 more

The atomic density of an alkali vapor cell is a critical factor in determining the performance of atomic magnetometers. This paper presents a novel method to detect the density of an alkali atomic ensemble under arbitrary polarization states. By establishing a comprehensive model that correlates the absorption spectrum with the incident light’s polarization, our approach enables real-time and flexible measurements across varying temperatures and polarization angles. Experimental validations are conducted by systematically rotating a quarter-wave plate and controlling the vapor cell temperature, thereby collecting transmission spectra at multiple polarizations. The results demonstrate that the proposed method simplifies density measurements while preserving high accuracy, laying a solid foundation for further research on Spin-Exchange Relaxation-Free (SERF) atomic magnetometers. This technique serves as a versatile and effective tool for in-situ monitoring of alkali metal vapor density in various sensor applications.

IEEE Sensors Journal•Apr 7, 2025•1 citation

Alkali atoms density and spin randomization in antirelaxation coated cells

S. Tsvetkov, S. Gateva, S. Cartaleva

Antirelaxation coatings (ARC) are used in optical cells containing alkali metal vapor to reduce the depolarization of alkali atoms after collisions with the cell walls. The long-lived ground state polarization is a basis for development of atomic clocks, magnetometers, quantum memory, slow light experiments, precision measurements of fundamental symmetries etc. Another application of ARC is with Light-Induced Atomic Desorption (LIAD) for implementation optical dispensers for loading atomic devices as atomic magnetometers, atomic clocks, magneto-optical traps and their miniaturization. In this work, the Rb atomic density and the spin randomization (the number of collisions without spin depolarization) are investigated in PDMS coated vacuum cell when the density is controlled by LIAD, and compared with the results when the density is controlled by temperature. A simple method for measurement of the number of collisions without spin-randomization is used, which comprises recording of the time dependence of the fluorescence intensity of alkali atoms during exposure of the cell to resonant radiation pulses. The obtained results are discussed from point of view of LIAD applications for density control in spectroscopy investigations.

AIP conference proceedings•Jan 1, 2019•1 citation

Experimental investigations of relaxation of spin polarized atoms on coated surfaces

Natarajan D. Bhaskar

The interaction of spin polarized cesium atoms on coated surfaces is examined. Coated surfaces find extensive applications in atomic devices-hydrogen masers and advanced rubidium frequency standards utilize wall coatings to obtain very narrow hyperfine resonances. A Cs atomic beam is hyperfine or spin polarized by optical pumping techniques using a single mode AlGaAs diode laser. The ground state distribution is probed before and after scattering from coated surfaces using laser induced fluorescence spectroscopy. The coatings under investigations are paraffin and organosilanes and these are known to be very weakly relaxing surfaces for polarized alkali atoms. The spin relaxation properties of paraffin and organosilane coatings have been studied in glass cell-vapor environment. In our experiments using polarized atomic beams, our goal is to examine in detail the hyperfine and spin relaxation properties of these coatings in a carefully controlled environment which is not possible in the gas cell environment. We measure the spin relaxation probability per wall collision as a function of temperature of the surface. Results of our studies will be presented.

Bulletin of the American Physical Society•May 1, 1993•0 citations

Alignment-to-orientation conversion in the ground state of atomic Cs with linearly polarized laser excitation

Arturs Mozers, Laima Busaite, Dace Osite +1 more

In this study we explored the angular momentum alignment-to-orientation conversion occurring in various alkali metals -- K, Rb, Cs. We used a theoretical model that is based on Optical Bloch equations and uses the density matrix formalism. Our model includes the interaction of all neighboring hyperfine levels, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. Additionally we simulated signals where the ground- or the excited-state coherent processes were switched off allowing us to determine the origins of obtained signals. We also performed experiments on Cs atoms with two laser beams: linearly polarised Cs D1 pump and circularly polarized Cs D2 probe. We used the pump beam to create angular momentum alignment in the ground state and observed the transmission signal of the probe beam as we changed the magnetic field. Full analysis of the experimentally obtained transmission signal from a single circularly polarized probe laser component is provided.

•Dec 16, 2020•0 citations

Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques

Scott J. Seltzer, David J. Michalak, Marcus H. Donaldson +17 more

Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10 000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C[Double Bond]C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.

arXiv:1002.4417•The Journal of Chemical Physics•Oct 11, 2010•63 citations

Optical pumping of alkali-metal vapor in the quasi-high-pressure regime

Kezheng Yan, Jinbo Hu, Nan Zhao

Optical pumping is fundamental to high-precision measurement using thermal alkali-metal atoms in vapor cells. In applications such as atomic magnetometry, buffer gases (e.g., $\mathrm{N}_2$ or $\mathrm{He}$) at specific pressures are introduced to quench fluorescence and mitigate wall relaxation. In the high-pressure limit (e.g., the $\mathrm{N}_2$ pressure $p_{\mathrm{N}_2}> 1$~atm), where collisional broadening exceeds hyperfine splittings of the atoms, optical pumping theory provides a clear description of the angular momentum exchange between photons and atomic spins. However, in many magnetic sensing scenarios, the high-pressure approximation becomes inadequate as its pressure conditions are not strictly satisfied. Consequently, an explicit description of optical pumping under realistic pressures is critical for selecting operating points and enhancing system performance. To address this, we develop a unified theoretical framework of optical pumping in the quasi-high-pressure regime, where collisional broadening is comparable to the ground-state hyperfine splitting. We demonstrate that light absorption, spin polarization, and magnetic-resonance linewidth in this regime differ significantly from those predicted by the high-pressure limit and offer favorable operating conditions. Our study extends conventional modeling and offers critical guidance for atomic magnetometry operating under realistic buffer gas pressures.

physics.atom-phCross-listedarXiv:2603.05859•Physical Review A•Mar 9, 2026•0 citations
It is important to evaluate the total spin angular momentum of alkali-metal atoms if the atoms serve as a reservoir of angular momenta. We use an absorption-monitoring technique to measure \ensuremath⟨Fz\ensuremath⟩\ensuremath{\langle}{F}_{z}\ensuremath{\rangle}\ensuremath⟨Fz​\ensuremath⟩, i.e., the expectation values of the quantization (zzz) axis components of the total angular momentum of Cs atoms in the electronic ground state in both uncoated and antirelaxation-coated vacuum cells at room temperature. Cs atoms are polarized via optical pumping and probed using their D2{D}_{2}D2​ transitions. The probe laser frequency is varied across the Doppler-broadened D2{D}_{2}D2​ transition; the \ensuremath⟨Fz\ensuremath⟩\ensuremath{\langle}{F}_{z}\ensuremath{\rangle}\ensuremath⟨Fz​\ensuremath⟩ values are derived using the integrated absorption coefficients. The largest \ensuremath⟨Fz\ensuremath⟩\ensuremath{\langle}{F}_{z}\ensuremath{\rangle}\ensuremath⟨Fz​\ensuremath⟩ is 2.5 for the coated cell. We then use a simple model of spin flow through vapor cells to estimate the atomic spin relaxation probabilities after a single surface collision.
The atomic density of an alkali vapor cell is a critical factor in determining the performance of atomic magnetometers. This paper presents a novel method to detect the density of an alkali atomic ensemble under arbitrary polarization states. By establishing a comprehensive model that correlates the absorption spectrum with the incident light’s polarization, our approach enables real-time and flexible measurements across varying temperatures and polarization angles. Experimental validations are conducted by systematically rotating a quarter-wave plate and controlling the vapor cell temperature, thereby collecting transmission spectra at multiple polarizations. The results demonstrate that the proposed method simplifies density measurements while preserving high accuracy, laying a solid foundation for further research on Spin-Exchange Relaxation-Free (SERF) atomic magnetometers. This technique serves as a versatile and effective tool for in-situ monitoring of alkali metal vapor density in various sensor applications.
Antirelaxation coatings (ARC) are used in optical cells containing alkali metal vapor to reduce the depolarization of alkali atoms after collisions with the cell walls. The long-lived ground state polarization is a basis for development of atomic clocks, magnetometers, quantum memory, slow light experiments, precision measurements of fundamental symmetries etc. Another application of ARC is with Light-Induced Atomic Desorption (LIAD) for implementation optical dispensers for loading atomic devices as atomic magnetometers, atomic clocks, magneto-optical traps and their miniaturization. In this work, the Rb atomic density and the spin randomization (the number of collisions without spin depolarization) are investigated in PDMS coated vacuum cell when the density is controlled by LIAD, and compared with the results when the density is controlled by temperature. A simple method for measurement of the number of collisions without spin-randomization is used, which comprises recording of the time dependence of the fluorescence intensity of alkali atoms during exposure of the cell to resonant radiation pulses. The obtained results are discussed from point of view of LIAD applications for density control in spectroscopy investigations.
The interaction of spin polarized cesium atoms on coated surfaces is examined. Coated surfaces find extensive applications in atomic devices-hydrogen masers and advanced rubidium frequency standards utilize wall coatings to obtain very narrow hyperfine resonances. A Cs atomic beam is hyperfine or spin polarized by optical pumping techniques using a single mode AlGaAs diode laser. The ground state distribution is probed before and after scattering from coated surfaces using laser induced fluorescence spectroscopy. The coatings under investigations are paraffin and organosilanes and these are known to be very weakly relaxing surfaces for polarized alkali atoms. The spin relaxation properties of paraffin and organosilane coatings have been studied in glass cell-vapor environment. In our experiments using polarized atomic beams, our goal is to examine in detail the hyperfine and spin relaxation properties of these coatings in a carefully controlled environment which is not possible in the gas cell environment. We measure the spin relaxation probability per wall collision as a function of temperature of the surface. Results of our studies will be presented.
In this study we explored the angular momentum alignment-to-orientation conversion occurring in various alkali metals -- K, Rb, Cs. We used a theoretical model that is based on Optical Bloch equations and uses the density matrix formalism. Our model includes the interaction of all neighboring hyperfine levels, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. Additionally we simulated signals where the ground- or the excited-state coherent processes were switched off allowing us to determine the origins of obtained signals. We also performed experiments on Cs atoms with two laser beams: linearly polarised Cs D1 pump and circularly polarized Cs D2 probe. We used the pump beam to create angular momentum alignment in the ground state and observed the transmission signal of the probe beam as we changed the magnetic field. Full analysis of the experimentally obtained transmission signal from a single circularly polarized probe laser component is provided.
Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10 000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C[Double Bond]C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.
Optical pumping is fundamental to high-precision measurement using thermal alkali-metal atoms in vapor cells. In applications such as atomic magnetometry, buffer gases (e.g., N2\mathrm{N}_2N2​ or He\mathrm{He}He) at specific pressures are introduced to quench fluorescence and mitigate wall relaxation. In the high-pressure limit (e.g., the N2\mathrm{N}_2N2​ pressure pN2>1p_{\mathrm{N}_2}> 1pN2​​>1~atm), where collisional broadening exceeds hyperfine splittings of the atoms, optical pumping theory provides a clear description of the angular momentum exchange between photons and atomic spins. However, in many magnetic sensing scenarios, the high-pressure approximation becomes inadequate as its pressure conditions are not strictly satisfied. Consequently, an explicit description of optical pumping under realistic pressures is critical for selecting operating points and enhancing system performance. To address this, we develop a unified theoretical framework of optical pumping in the quasi-high-pressure regime, where collisional broadening is comparable to the ground-state hyperfine splitting. We demonstrate that light absorption, spin polarization, and magnetic-resonance linewidth in this regime differ significantly from those predicted by the high-pressure limit and offer favorable operating conditions. Our study extends conventional modeling and offers critical guidance for atomic magnetometry operating under realistic buffer gas pressures.