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

Physical review. B, Condensed matter

Optically detected low-field ESR in the metastable state of Tm2+ : SrF2 . I. ESR signals and cross relaxation

T. Kohmoto, Yukio Fukuda, T. Hashi

Published Nov 1, 1986• 15 citations
Publisher

Abstract

ESR signals of ${\mathrm{Tm}}^{2+}$:${\mathrm{SrF}}_{2}$ are observed in the ground ${(}^{2}$${\mathrm{F}}_{7/2}$,${E}_{5/2}$) and metastable ${(}^{2}$${\mathrm{F}}_{5/2}$,${E}_{5/2}$) states in low magnetic fields (0--300 Oe) at liquid-helium temperatures. We achieved a very high detection sensitivity (\ensuremath{\sim}${10}^{9}$ spins in the ground state) using optical means; the population differences are created by circular dichroism and spin memory, and the change of the Faraday rotation is detected by a polarimeter. Several interesting phenomena were observed. The signals in the ground and metastable states appeared with opposite polarities. The preferential pumping from the metastable state was examined by a double pumping experiment. We also measured the Faraday rotation between 4000 and 7000 A\r{}. The experimental results suggest that the magnetization in the metastable state created by the preferential pumping from the ground state followed by the spin memory is in the opposite direction to that in the ground state. Anomalous behavior of the metastable-state signals was observed both in frequency and time domains. These are explained as an effect of the metastable-state--ground-state cross relaxation enhanced by the ground-state--ground-state cross relaxation.

DOI
10.1103/physrevb.34.6085

Related papers

Anomalous Population Distributions in an Optically Excited Metastable Level in Ca F2 : Tm2+

Charles H. Anderson, Edward S. Sabisky

The population distribution among the magnetic sublevels of the metastable state of Ca${\mathrm{F}}_{2}$: ${\mathrm{Tm}}^{2+}$ is shown to be strongly influenced by spin orientation memory from the ground state. This memory is dependent on the wavelength and polarization of the pump radiation, being quite strong at 5790 \AA{}. The population is also influenced by an optical cross-relaxation or excitation transfer between neighboring ions, particularly so because the hyperfine splittings in the ground and excited states are almost identical. Also, it is shown that there is a high degree of nuclear spin orientation memory.

Physical Review•Feb 10, 1969•20 citations

Quantum-beat free-induction decay in Tm2+ :Sr F2 : Fourier-transform ESR spectroscopy by optical means

T. Kohmoto, Yukio Fukuda, M. Tanigawa +2 more

We demonstrate, for the first time, a nanosecond Fourier-transform ESR experiment in solids achieved by optical means. ESR free-induction-decay signals in 0-100 Oe have been observed in the ground state of ${\mathrm{Tm}}^{2+}$:Sr${\mathrm{F}}_{2}$ as a new type of quantum beat generated by an optical excitation to the absorption band with a circularly polarized light pulse. The Fourier transform of the observed signals gives the ESR spectrum, and the origin of the decay is attributed to the superhyperfine interaction between the ${\mathrm{Tm}}^{2+}$ ion and neighboring fluorine nuclei.

Physical review. B, Condensed matter•Sep 1, 1983•13 citations

Optical Pumping of Helium in the S13 Metastable State

F. D. Colegrove, P. A. Franken

The alignment of ${\mathrm{He}}^{4}$ atoms in the ($n=2$, metastable) $^{3}S_{1}$ state is described. Metastable atoms are produced by an rf discharge in a glass tube containing a few mm of pure helium, and the one micron pumping light ($2^{3}P\ensuremath{-}2^{3}S$) is provided by a helium lamp. A resonance signal is obtained from radio frequency disorientation by monitoring the transmitted pumping light. The double maximum line shape of this signal for strong rf magnetic fields is discussed. Included also is a discussion of the angular dependence of the signal when unpolarized light is used and an explanation of the inversion of the resonance signal for certain densities of the metastable helium atoms.The measured relaxation time of the oriented metastable atoms in the discharge is about 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ second and the pumping time is about a millisecond. A method is proposed and initial measurements are given for the cross section for destruction of metastable helium atoms by collision with foreign gas atoms. The application of optical pumping in helium to the measurement of weak magnetic fields is also discussed.

Physical Review•Jul 15, 1960•118 citations

Spin noise spectroscopy of metastable helium

Shikang Liu, Pascal Neveu, L. Hemmen +4 more

Spin noise spectroscopy (SNS) allows optically detect the fluctuations of a spin ensemble. Such fluctuations induce noise in the birefringence of the medium, which can be probed by recording polarization fluctuations of a laser beam after its propagation through the sample. As spin fluctuations are centered on the zero frequency, a transverse magnetic field is applied: spin precession then shifts the spin noise resonance at the Larmor frequency, so that it is not hidden by technical noises. The first SNS experiment was reported in the early 1980s by Alexandrov and Zapasskii, but it is only in 2004 that advances in narrow linewidth lasers and low noise electronics allow using this technique to probe various systems, such as thermal atomic vapors, semiconductors, or quantum wells. It was also proposed for magnetic field sensing, and possible measurements of correlations beyond the second-order raise a lot of interest, as they can give access to new quantum phenomena. We have performed spin noise spectroscopy in a metastable helium gas cell, and show that we can get two polarization dependent noise peaks when we record the linear instead of the circular birefringence fluctuations. Moreover, the relatively simple structure of helium allows us to show that it depends on the closest optical transition even when we are detuned by more than the Doppler broadening. We can also show that the behavior of the polarization dependence is strongly affected by time dependent B-field fluctuations. We performed simulations using a density matrix time evolution model, with added random fluctuations. It reproduces quite well the experimental results, including the transition dependence and the time dependent B-field noise effect, which have not been reported yet.

SPIE Quantum Technologies•Jun 3, 2022•1 citation

Light-induced Frequency Shift and Relaxation of Ground-State 3He via Metastability-Exchange Collisions

L. Y. Wu, H. Yan

Metastability-exchange collisions (MECs) lie at the heart of metastability-exchange optical pumping (MEOP) in 3He, enabling the transfer of polarization from the metastable state to the ground state, as well as the optical detection of nuclear magnetic resonance. Leveraging MECs, optically pumped 3He nuclear magnetometers have been developed since the earliest demonstrations of MEOP. However, it also induces an additional frequency shift and relaxation of the nuclear spin precession, thereby limiting the sensitivity of the magnetometer. In this work, we identify a new source of frequency shift and relaxation in the 3He nuclear spin, arising from the light shift. This effect arises from an MEC-mediated interaction between light and the nucleon spin. We develop a theoretical model to describe this light-induced effect and highlight its significance in low magnetic fields. This effect is experimentally demonstrated, and its dependence on various parameters -- including magnetic field strength, light intensity, and wavelength -- is investigated. Our result provides a better understanding of the frequency shift and relaxation of 3He spin precession under MEOP conditions. Moreover, our experiment reveals an MEC-mediated coupling between the 3He nuclear spin and light, which may indicate the feasibility of MEC-assisted optical manipulation of 3He nuclear spins at the quantum level, as proposed in several theoretical schemes.

quant-pharXiv:2511.01313•Nov 4, 2025

Laser spectroscopy of thulium atoms implanted in liquid and solid 4 He

Kiyoshi Ishikawa, A. Hatakeyama, Koichi Gosyono-o +3 more

The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width $\ensuremath{\sim}0.1$ nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state ${4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}$, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 10${}^{10}$--10${}^{11}$ atoms/cm${}^{3}$. The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the ${4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}$ ${(6,5/2)}_{7/2}$ state of free thulium atoms. The excited state is expected to be a mixed state of the ${4f}^{12}{5d6s}^{2}$ and ${4f}^{13}6s6p$ configurations. The metastable state ${4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}$ is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.

Physical review. B, Condensed matter•Jul 1, 1997•36 citations
ESR signals of Tm2+{\mathrm{Tm}}^{2+}Tm2+:SrF2{\mathrm{SrF}}_{2}SrF2​ are observed in the ground {(}^{2}$${\mathrm{F}}_{7/2},E5/2{E}_{5/2}E5/2​) and metastable {(}^{2}$${\mathrm{F}}_{5/2},E5/2{E}_{5/2}E5/2​) states in low magnetic fields (0--300 Oe) at liquid-helium temperatures. We achieved a very high detection sensitivity (\ensuremath{\sim}109{10}^{9}109 spins in the ground state) using optical means; the population differences are created by circular dichroism and spin memory, and the change of the Faraday rotation is detected by a polarimeter. Several interesting phenomena were observed. The signals in the ground and metastable states appeared with opposite polarities. The preferential pumping from the metastable state was examined by a double pumping experiment. We also measured the Faraday rotation between 4000 and 7000 A\r{}. The experimental results suggest that the magnetization in the metastable state created by the preferential pumping from the ground state followed by the spin memory is in the opposite direction to that in the ground state. Anomalous behavior of the metastable-state signals was observed both in frequency and time domains. These are explained as an effect of the metastable-state--ground-state cross relaxation enhanced by the ground-state--ground-state cross relaxation.
The population distribution among the magnetic sublevels of the metastable state of CaF2{\mathrm{F}}_{2}F2​: Tm2+{\mathrm{Tm}}^{2+}Tm2+ is shown to be strongly influenced by spin orientation memory from the ground state. This memory is dependent on the wavelength and polarization of the pump radiation, being quite strong at 5790 \AA{}. The population is also influenced by an optical cross-relaxation or excitation transfer between neighboring ions, particularly so because the hyperfine splittings in the ground and excited states are almost identical. Also, it is shown that there is a high degree of nuclear spin orientation memory.
We demonstrate, for the first time, a nanosecond Fourier-transform ESR experiment in solids achieved by optical means. ESR free-induction-decay signals in 0-100 Oe have been observed in the ground state of Tm2+{\mathrm{Tm}}^{2+}Tm2+:SrF2{\mathrm{F}}_{2}F2​ as a new type of quantum beat generated by an optical excitation to the absorption band with a circularly polarized light pulse. The Fourier transform of the observed signals gives the ESR spectrum, and the origin of the decay is attributed to the superhyperfine interaction between the Tm2+{\mathrm{Tm}}^{2+}Tm2+ ion and neighboring fluorine nuclei.
The alignment of He4{\mathrm{He}}^{4}He4 atoms in the (n=2n=2n=2, metastable) 3S1^{3}S_{1}3S1​ state is described. Metastable atoms are produced by an rf discharge in a glass tube containing a few mm of pure helium, and the one micron pumping light ($2^{3}P\ensuremath{-}2^{3}S$) is provided by a helium lamp. A resonance signal is obtained from radio frequency disorientation by monitoring the transmitted pumping light. The double maximum line shape of this signal for strong rf magnetic fields is discussed. Included also is a discussion of the angular dependence of the signal when unpolarized light is used and an explanation of the inversion of the resonance signal for certain densities of the metastable helium atoms.The measured relaxation time of the oriented metastable atoms in the discharge is about 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ second and the pumping time is about a millisecond. A method is proposed and initial measurements are given for the cross section for destruction of metastable helium atoms by collision with foreign gas atoms. The application of optical pumping in helium to the measurement of weak magnetic fields is also discussed.
Spin noise spectroscopy (SNS) allows optically detect the fluctuations of a spin ensemble. Such fluctuations induce noise in the birefringence of the medium, which can be probed by recording polarization fluctuations of a laser beam after its propagation through the sample. As spin fluctuations are centered on the zero frequency, a transverse magnetic field is applied: spin precession then shifts the spin noise resonance at the Larmor frequency, so that it is not hidden by technical noises. The first SNS experiment was reported in the early 1980s by Alexandrov and Zapasskii, but it is only in 2004 that advances in narrow linewidth lasers and low noise electronics allow using this technique to probe various systems, such as thermal atomic vapors, semiconductors, or quantum wells. It was also proposed for magnetic field sensing, and possible measurements of correlations beyond the second-order raise a lot of interest, as they can give access to new quantum phenomena. We have performed spin noise spectroscopy in a metastable helium gas cell, and show that we can get two polarization dependent noise peaks when we record the linear instead of the circular birefringence fluctuations. Moreover, the relatively simple structure of helium allows us to show that it depends on the closest optical transition even when we are detuned by more than the Doppler broadening. We can also show that the behavior of the polarization dependence is strongly affected by time dependent B-field fluctuations. We performed simulations using a density matrix time evolution model, with added random fluctuations. It reproduces quite well the experimental results, including the transition dependence and the time dependent B-field noise effect, which have not been reported yet.
Metastability-exchange collisions (MECs) lie at the heart of metastability-exchange optical pumping (MEOP) in 3He, enabling the transfer of polarization from the metastable state to the ground state, as well as the optical detection of nuclear magnetic resonance. Leveraging MECs, optically pumped 3He nuclear magnetometers have been developed since the earliest demonstrations of MEOP. However, it also induces an additional frequency shift and relaxation of the nuclear spin precession, thereby limiting the sensitivity of the magnetometer. In this work, we identify a new source of frequency shift and relaxation in the 3He nuclear spin, arising from the light shift. This effect arises from an MEC-mediated interaction between light and the nucleon spin. We develop a theoretical model to describe this light-induced effect and highlight its significance in low magnetic fields. This effect is experimentally demonstrated, and its dependence on various parameters -- including magnetic field strength, light intensity, and wavelength -- is investigated. Our result provides a better understanding of the frequency shift and relaxation of 3He spin precession under MEOP conditions. Moreover, our experiment reveals an MEC-mediated coupling between the 3He nuclear spin and light, which may indicate the feasibility of MEC-assisted optical manipulation of 3He nuclear spins at the quantum level, as proposed in several theoretical schemes.
The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width $\ensuremath{\sim}0.1$ nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state 4f13(2F7/2o)6s2{4f}^{13}{(}^{2}{F}_{7/2}^{o}{)6s}^{2}4f13(2F7/2o​)6s2, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 1010{}^{10}10--1011{}^{11}11 atoms/cm3{}^{3}3. The lifetime of the excited state was measured to be $7.09\ifmmode\pm\else\textpm\fi{}0.04$ $\ensuremath{\mu}$s, which was longer than that of the 4f12(3H6)5d5/26s2{4f}^{12}{(}^{3}{H}_{6}{)5d}_{5/2}{6s}^{2}4f12(3H6​)5d5/2​6s2 (6,5/2)7/2{(6,5/2)}_{7/2}(6,5/2)7/2​ state of free thulium atoms. The excited state is expected to be a mixed state of the 4f125d6s2{4f}^{12}{5d6s}^{2}4f125d6s2 and 4f136s6p{4f}^{13}6s6p4f136s6p configurations. The metastable state 4f13(2F5/2o)6s2{4f}^{13}{(}^{2}{F}_{5/2}^{o}{)6s}^{2}4f13(2F5/2o​)6s2 is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be $75\ifmmode\pm\else\textpm\fi{}3$ ms.