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:1404.1759 · Physical Review Letters

High-Precision Spectroscopy of the Forbidden 2 S13→2 P11 Transition in Quantum Degenerate Metastable Helium

Remy Notermans, W. Vassen

Published Jun 25, 2014• 36 citations
arXivHTMLPDF

Abstract

We have measured the forbidden $2\text{ }^{3}{S}_{1}\ensuremath{\rightarrow}2\text{ }^{1}{P}_{1}$ transition at 887 nm in a quantum degenerate gas of metastable $^{4}\mathrm{He}$ atoms confined in an optical dipole trap. The determined transition frequency is 338 133 594.4 (0.5) MHz, from which we obtain an ionization energy of the $2\text{ }^{1}{P}_{1}$ state of 814 709 148.6 (0.5) MHz. This ionization energy is in disagreement by $>3\ensuremath{\sigma}$ with the most accurate quantum electrodynamics calculations available. Our measurements also provide a new determination of the lifetime of the $2\text{ }^{1}{P}_{1}$ state of $0.551\text{ }(0.004{)}_{\text{stat}}\text{ }{(}_{\ensuremath{-}0.000}^{+0.013}{)}_{\text{syst}}\text{ }\text{ }\mathrm{ns}$, which is the most accurate determination to date and in excellent agreement with theory.

DOI
10.1103/physrevlett.112.253002

Related papers

Experimental Determination of the Helium 2 P13–1 S01 Transition Rate

R. G. Dall, K. G. H. Baldwin, L. J. Byron +1 more

We present the first experimental determination of the $2\text{ }^{3}P_{1}--1\text{ }^{1}S_{0}$ transition rate in helium and compare this measurement with theoretical quantum-electrodynamic predictions. The experiment exploits the very long ($\ensuremath{\sim}1\text{ }\text{ }\mathrm{\text{minute}}$) confinement times obtained for atoms magneto-optically trapped in an apparatus used to create a Bose-Einstein condensate of metastable ($2\text{ }^{3}S_{1}$) helium. The $2\text{ }^{3}P_{1}--1\text{ }^{1}S_{0}$ transition rate is measured directly from the decay rate of the cold atomic cloud following 1083 nm laser excitation from the $2\text{ }^{3}S_{1}$ to the $2\text{ }^{3}P_{1}$ state, and from accurate knowledge of the $2\text{ }^{3}P_{1}$ population. The value obtained is $177\ifmmode\pm\else\textpm\fi{}8\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, which agrees very well with theoretical predictions, and has an accuracy that compares favorably with measurements for the same transition in heliumlike ions higher in the isoelectronic sequence.

Physical Review Letters•Jan 15, 2008•20 citations

Frequency Metrology in Quantum Degenerate Helium: Direct Measurement of the 2 3 S 1 → 2 1 S 0 Transition

Rob van Rooij, Joseph Steven Borbely, Juliette Simonet +4 more

Precision spectroscopy of simple atomic systems has refined our understanding of the fundamental laws of quantum physics. In particular, helium spectroscopy has played a crucial role in describing two-electron interactions, determining the fine-structure constant and extracting the size of the helium nucleus. Here we present a measurement of the doubly forbidden 1557-nanometer transition connecting the two metastable states of helium (the lowest energy triplet state 2 (3)S(1) and first excited singlet state 2 (1)S(0)), for which quantum electrodynamic and nuclear size effects are very strong. This transition is weaker by 14 orders of magnitude than the most predominantly measured transition in helium. Ultracold, submicrokelvin, fermionic (3)He and bosonic (4)He atoms are used to obtain a precision of 8 × 10(-12), providing a stringent test of two-electron quantum electrodynamic theory and of nuclear few-body theory.

arXiv:1105.4974•Science•Jul 7, 2011•136 citations

The First Measurement of the $2^{3}S_{1} \rightarrow 3^{3}P - 2^{3}P$ Tune-Out Wavelength in He*

B. M. Henson

The workhorse of atomic physics, quantum electrodynamics, is one of the best-tested theories in physics. However recent discrepancies have shed doubt on its accuracy for complex atomic systems. To facilitate the development of the theory further we aim to measure transition dipole matrix elements of metastable helium (He*) (the ideal 3 body test-bed) to the highest accuracy thus far. We have undertaken a measurement of the `tune-out wavelength' which occurs when the contributions to the dynamic polarizability from all atomic transitions sum to zero; thus illuminating an atom with this wavelength of light then produces no net energy shift. This provides a strict constraint on the transition dipole matrix elements without the complication and inaccuracy of other methods. Using a novel atom-laser based technique we have made the first measurement of the tune-out wavelength in metastable helium between the $3^{3}P_{1,2,3}$ and $2^{3}P_{1,2,3}$ states at 413.07(2) nm which compares well with the predicted value\cite{Mitroy2013} of 413.02(9) nm. We have additionally developed many of the methods necessary to improve this measurement to the 100 fm level of accuracy where it will form the most accurate determination of transition rate information ever made in He* and provide a stringent test for atomic QED simulations. We believe this measurement to be one of the most sensitive ever made of an optical dipole potential, able to detect changes in potentials of $\sim$200 pK and is widely applicable to other species and areas of atom optics.

•Aug 28, 2017•0 citations

The First Measurement of the $2^{3\!}S_1 - 2^{3\!}P / 3^{3\!}P$ Tune-Out Wavelength in He*

B. M. Henson

The workhorse of atomic physics, quantum electrodynamics, is one of the best-tested theories in physics. However recent discrepancies have shed doubt on its accuracy for complex atomic systems. To facilitate the development of the theory further we aim to measure transition dipole matrix elements of metastable helium (He*) (the ideal 3 body test-bed) to the highest accuracy thus far. We have undertaken a measurement of the `tune-out wavelength' which occurs when the contributions to the dynamic polarizability from all atomic transitions sum to zero; thus illuminating an atom with this wavelength of light then produces no net energy shift. This provides a strict constraint on the transition dipole matrix elements without the complication and inaccuracy of other methods. Using a novel atom-laser based technique we have made the first measurement of the tune-out wavelength in metastable helium between the $3^{3}P_{1,2,3}$ and $2^{3}P_{1,2,3}$ states at 413.07(2) nm which compares well with the predicted value [PhysRevA.88.052515] of 413.02(9) nm. We have additionally developed many of the methods necessary to improve this measurement to the 100 fm level of accuracy where it will form the most accurate determination of transition rate information ever made in He* and provide a stringent test for atomic QED simulations. We believe this measurement to be one of the most sensitive ever made of an optical dipole potential, able to detect changes in potentials of $\sim$200 pK and is widely applicable to other species and areas of atom optics.

arXiv:1708.08200•Aug 28, 2017•0 citations

Accurate Determination of the Scattering Length of Metastable Helium Atoms Using Dark Resonances between Atoms and Exotic Molecules

Steven Moal, M. Portier, J. Kim +4 more

We present a new measurement of the $s$-wave scattering length $a$ of spin-polarized helium atoms in the $2\text{ }^{3}S_{1}$ metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy ${E}_{v=14}=\ensuremath{-}91.35\ifmmode\pm\else\textpm\fi{}0.06\text{ }\text{ }\mathrm{MHz}$ of the least-bound state $v=14$ in the interaction potential of the two atoms. We deduce a value of $a=7.512\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{nm}$, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of $1\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$.

arXiv:cond-mat/0509286•Physical Review Letters•Jan 20, 2006•92 citations

Metastable Helium: A New Determination of the Longest Atomic Excited-State Lifetime

Sean S. Hodgman, R. G. Dall, L. J. Byron +3 more

Exited atoms may relax to the ground state by radiative decay, a process which is usually very fast (of order nanoseconds). However, quantum-mechanical selection rules can prevent such rapid decay, in which case these "metastable" states can have lifetimes of order seconds or longer. In this Letter, we determine experimentally the lifetime of the longest-lived neutral atomic state-the first excited state of helium (the 2(3)S1 metastable state)-to the highest accuracy yet measured. We use laser cooling and magnetic trapping to isolate a cloud of metastable helium (He*) atoms from their surrounding environment, and measure the decay rate to the ground 1(1)S0 state via extreme ultraviolet (XUV) photon emission. This is the first measurement using a virtually unperturbed ensemble of isolated helium atoms, and yields a value of 7870(510) seconds, in excellent agreement with the predictions of quantum electrodynamic theory.

Physical Review Letters•Jul 30, 2009•121 citations
We have measured the forbidden 2 3S1\ensuremath→2 1P12\text{ }^{3}{S}_{1}\ensuremath{\rightarrow}2\text{ }^{1}{P}_{1}2 3S1​\ensuremath→2 1P1​ transition at 887 nm in a quantum degenerate gas of metastable 4He^{4}\mathrm{He}4He atoms confined in an optical dipole trap. The determined transition frequency is 338 133 594.4 (0.5) MHz, from which we obtain an ionization energy of the 2 1P12\text{ }^{1}{P}_{1}2 1P1​ state of 814 709 148.6 (0.5) MHz. This ionization energy is in disagreement by >3\ensuremathσ>3\ensuremath{\sigma}>3\ensuremathσ with the most accurate quantum electrodynamics calculations available. Our measurements also provide a new determination of the lifetime of the 2 1P12\text{ }^{1}{P}_{1}2 1P1​ state of 0.551 (0.004)stat (\ensuremath−0.000+0.013)syst  ns0.551\text{ }(0.004{)}_{\text{stat}}\text{ }{(}_{\ensuremath{-}0.000}^{+0.013}{)}_{\text{syst}}\text{ }\text{ }\mathrm{ns}0.551 (0.004)stat​ (\ensuremath−0.000+0.013​)syst​  ns, which is the most accurate determination to date and in excellent agreement with theory.
We present the first experimental determination of the 2 3P1−−1 1S02\text{ }^{3}P_{1}--1\text{ }^{1}S_{0}2 3P1​−−1 1S0​ transition rate in helium and compare this measurement with theoretical quantum-electrodynamic predictions. The experiment exploits the very long ($\ensuremath{\sim}1\text{ }\text{ }\mathrm{\text{minute}}$) confinement times obtained for atoms magneto-optically trapped in an apparatus used to create a Bose-Einstein condensate of metastable (2 3S12\text{ }^{3}S_{1}2 3S1​) helium. The 2 3P1−−1 1S02\text{ }^{3}P_{1}--1\text{ }^{1}S_{0}2 3P1​−−1 1S0​ transition rate is measured directly from the decay rate of the cold atomic cloud following 1083 nm laser excitation from the 2 3S12\text{ }^{3}S_{1}2 3S1​ to the 2 3P12\text{ }^{3}P_{1}2 3P1​ state, and from accurate knowledge of the 2 3P12\text{ }^{3}P_{1}2 3P1​ population. The value obtained is $177\ifmmode\pm\else\textpm\fi{}8\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, which agrees very well with theoretical predictions, and has an accuracy that compares favorably with measurements for the same transition in heliumlike ions higher in the isoelectronic sequence.
Precision spectroscopy of simple atomic systems has refined our understanding of the fundamental laws of quantum physics. In particular, helium spectroscopy has played a crucial role in describing two-electron interactions, determining the fine-structure constant and extracting the size of the helium nucleus. Here we present a measurement of the doubly forbidden 1557-nanometer transition connecting the two metastable states of helium (the lowest energy triplet state 2 (3)S(1) and first excited singlet state 2 (1)S(0)), for which quantum electrodynamic and nuclear size effects are very strong. This transition is weaker by 14 orders of magnitude than the most predominantly measured transition in helium. Ultracold, submicrokelvin, fermionic (3)He and bosonic (4)He atoms are used to obtain a precision of 8 × 10(-12), providing a stringent test of two-electron quantum electrodynamic theory and of nuclear few-body theory.
The First Measurement of the 23S1→33P−23P2^{3}S_{1} \rightarrow 3^{3}P - 2^{3}P23S1​→33P−23P Tune-Out Wavelength in He*
The workhorse of atomic physics, quantum electrodynamics, is one of the best-tested theories in physics. However recent discrepancies have shed doubt on its accuracy for complex atomic systems. To facilitate the development of the theory further we aim to measure transition dipole matrix elements of metastable helium (He*) (the ideal 3 body test-bed) to the highest accuracy thus far. We have undertaken a measurement of the `tune-out wavelength' which occurs when the contributions to the dynamic polarizability from all atomic transitions sum to zero; thus illuminating an atom with this wavelength of light then produces no net energy shift. This provides a strict constraint on the transition dipole matrix elements without the complication and inaccuracy of other methods. Using a novel atom-laser based technique we have made the first measurement of the tune-out wavelength in metastable helium between the 33P1,2,33^{3}P_{1,2,3}33P1,2,3​ and 23P1,2,32^{3}P_{1,2,3}23P1,2,3​ states at 413.07(2) nm which compares well with the predicted value\cite{Mitroy2013} of 413.02(9) nm. We have additionally developed many of the methods necessary to improve this measurement to the 100 fm level of accuracy where it will form the most accurate determination of transition rate information ever made in He* and provide a stringent test for atomic QED simulations. We believe this measurement to be one of the most sensitive ever made of an optical dipole potential, able to detect changes in potentials of $\sim$200 pK and is widely applicable to other species and areas of atom optics.
The First Measurement of the 23 ⁣S1−23 ⁣P/33 ⁣P2^{3\!}S_1 - 2^{3\!}P / 3^{3\!}P23S1​−23P/33P Tune-Out Wavelength in He*
The workhorse of atomic physics, quantum electrodynamics, is one of the best-tested theories in physics. However recent discrepancies have shed doubt on its accuracy for complex atomic systems. To facilitate the development of the theory further we aim to measure transition dipole matrix elements of metastable helium (He*) (the ideal 3 body test-bed) to the highest accuracy thus far. We have undertaken a measurement of the `tune-out wavelength' which occurs when the contributions to the dynamic polarizability from all atomic transitions sum to zero; thus illuminating an atom with this wavelength of light then produces no net energy shift. This provides a strict constraint on the transition dipole matrix elements without the complication and inaccuracy of other methods. Using a novel atom-laser based technique we have made the first measurement of the tune-out wavelength in metastable helium between the 33P1,2,33^{3}P_{1,2,3}33P1,2,3​ and 23P1,2,32^{3}P_{1,2,3}23P1,2,3​ states at 413.07(2) nm which compares well with the predicted value [PhysRevA.88.052515] of 413.02(9) nm. We have additionally developed many of the methods necessary to improve this measurement to the 100 fm level of accuracy where it will form the most accurate determination of transition rate information ever made in He* and provide a stringent test for atomic QED simulations. We believe this measurement to be one of the most sensitive ever made of an optical dipole potential, able to detect changes in potentials of $\sim$200 pK and is widely applicable to other species and areas of atom optics.
We present a new measurement of the sss-wave scattering length aaa of spin-polarized helium atoms in the 2 3S12\text{ }^{3}S_{1}2 3S1​ metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy ${E}_{v=14}=\ensuremath{-}91.35\ifmmode\pm\else\textpm\fi{}0.06\text{ }\text{ }\mathrm{MHz}$ of the least-bound state v=14v=14v=14 in the interaction potential of the two atoms. We deduce a value of $a=7.512\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{nm}$, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of $1\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$.
Exited atoms may relax to the ground state by radiative decay, a process which is usually very fast (of order nanoseconds). However, quantum-mechanical selection rules can prevent such rapid decay, in which case these "metastable" states can have lifetimes of order seconds or longer. In this Letter, we determine experimentally the lifetime of the longest-lived neutral atomic state-the first excited state of helium (the 2(3)S1 metastable state)-to the highest accuracy yet measured. We use laser cooling and magnetic trapping to isolate a cloud of metastable helium (He*) atoms from their surrounding environment, and measure the decay rate to the ground 1(1)S0 state via extreme ultraviolet (XUV) photon emission. This is the first measurement using a virtually unperturbed ensemble of isolated helium atoms, and yields a value of 7870(510) seconds, in excellent agreement with the predictions of quantum electrodynamic theory.