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

Applied Physics B

Ultracold metastable helium: Ramsey fringes and atom interferometry

W. Vassen, Remy Notermans, Robert J. Rengelink, Rudolf F.H.J. van der Beek

Published Nov 25, 2016• 11 citations
Publisher

Abstract

We report on interference studies in the internal and external degrees of freedom of metastable triplet helium atoms trapped near quantum degeneracy in a $$1.5 \,\upmu {\mathrm{m}}$$ optical dipole trap. Applying a single $$\pi /2$$ rf pulse we demonstrate that 50% of the atoms initially in the $$m=+1$$ state can be transferred to the magnetic field insensitive $$m=0$$ state. Two $$\pi /2$$ pulses with varying time delay allow a Ramsey-type measurement of the Zeeman shift for a high precision measurement of the $$2\,^3S_1$$ – $$2\,^1S_0$$ transition frequency. We show that this method also allows strong suppression of mean-field effects on the measurement of the Zeeman shift, which is necessary to reach the accuracy goal of 0.1 kHz on the absolute transition frequencies. Theoretically the feasibility of using metastable triplet helium atoms in the $$m=0$$ state for atom interferometry is studied demonstrating favorable conditions, compared to the alkali atoms that are used traditionally, for a non-QED determination of the fine structure constant.

DOI
10.1007/s00340-016-6563-0

Related papers

Ultracold Metastable Helium: Ramsey Fringes and Atom Interferometry

W. Vassen, Remy Notermans, Robert J. Rengelink +1 more

Abstract We report on interference studies in the internal and external degrees of freedom of metastable triplet helium atoms trapped near quantum degeneracy in a $$ 1.5\kern0.166667em \upmu \mathrm{m} $$ 1.5 μ m optical dipole trap. Applying a single $$ \pi /2 $$ π / 2 rf pulse we demonstrate that 50% of the atoms initially in the $$ m=+1 $$ m = + 1 state can be transferred to the magnetic field insensitive $$ m=0 $$ m = 0 state. Two $$ \pi /2 $$ π / 2 pulses with varying time delay allow a Ramsey-type measurement of the Zeeman shift for a high precision measurement of the $$ {2}^3{S}_1 $$ 2 3 S 1 – $$ {2}^1{S}_0 $$ 2 1 S 0 transition frequency. We show that this method also allows strong suppression of mean-field effects on the measurement of the Zeeman shift, which is necessary to reach the accuracy goal of 0.1 kHz on the absolute transition frequencies. Theoretically the feasibility of using metastable triplet helium atoms in the $$ m=0 $$ m = 0 state for atom interferometry is studied demonstrating favorable conditions, compared to the alkali atoms that are used traditionally, for a non-QED determination of the fine structure constant.

Springer eBooks•Jan 1, 2018•2 citations

Optical traps for Ultracold Metastable Helium atoms

Juliette Simonet

The thematics treated in this manuscript illustrate two specificities of ultracold metastable Helium gases: the ability to compare experimental measurement with precise theoretical evaluations (simplicity of the atomic structure) and to easily detect products of Penning ionisations. We present the building and the characterisation of a novel magnetic trap with large optical access, allowing to combine the production of a Bose-Einstein condensate with its in situ loading into a 3D optical lattice. The theoretical fundaments of the experiments planned in those optical potentials are then detailed. In a crossed dipole trap, the influence of the magnetic field, now a free parameter, on the Penning collision rates can be measured and compared to a new theoretical evaluation. Concerning Helium in optical lattices, two subjects are developped: the effect of the confinement on the inelastic Penning collisions (1D optical lattice) and the modelisation of the Penning losses via a dissipative Bose-Hubbard model (3D lattice). Finally we present the first direct measurement of the dipolar magnetic transition 23S1 to 23P2, linking the singlet and triplet families in Helium 4. This spectroscopy experiment, realised in collaboration with the group of W. Vassen (LaserLab - Amsterdam), combines cold atoms knowledge with the frequency comb technique, in order to reach an accuracy of 5 kHz.

•Mar 14, 2011•4 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

Matter-wave interferometry with helium atoms in low- l Rydberg states

J. D. R. Tommey, S. D. Hogan

Electric Rydberg-atom interferometry has been performed with helium atoms in coherent superpositions of the $1s56s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ and $1s57s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ Rydberg levels. The experiments were carried out in a longitudinal geometry with the atoms traveling at 2000 m/s in pulsed supersonic beams. After laser photoexcitation from the $1s2s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ metastable level, coherent manipulation of the population of the Rydberg states was achieved using sequences of microwave pulses. The difference in the static electric dipole polarizabilities of the $1s56s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ and $1s57s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ levels allowed superpositions of external momentum states to be generated when inhomogeneous electric fields were used to exerted forces on the atoms prepared in superpositions of these internal states. Interference fringes, with contributions arising from the spatial separation of these Rydberg-atom wave packets in the direction of propagation of the atomic beam, were identified through changes in the internal-state populations as the magnitudes and durations of the time-dependent electric-field gradient pulses were adjusted. The maximal displacement of the atomic wave packets for which interference fringes were observed was $\ensuremath{\sim}0.75\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$, limited by the longitudinal velocity spread in the atomic beam and the characteristics of the inhomogeneous electric-field distribution in the apparatus. The experimental data are in good quantitative agreement with the results of numerical calculations of the time evolution of the atomic states under the experimental conditions.

Physical Review A•Sep 3, 2021•8 citations

Bloch Oscillations of Metastable Helium in an optical lattice

Rudolf F.H.J. van der Beek

The main subject of this thesis is to demonstrate that helium is a promising candidate for matter wave interferometry, with the goal of providing an improved value for the fine-structure constant, α. In particular, fast and efficient momentum transfer via Bloch oscillations in an optical lattice is demonstrated, together with the enhanced sensitivity offered by an ion-detector based detection scheme that is unique to metastable helium (He*). The experiments are performed in a setup that was built to produce, slow down and trap ultracold (~0.2 μK) He-4 atoms. The approach to realising an ultracold sample of He* atoms consists of a sequence of trapping and cooling stages. The experiment starts at the plasma discharge source, where helium atoms are excited to the so-called metastable 2-3S1 state, with a lifetime of ~7800 seconds, 20 eV above the atomic ground state. The atomic beam exiting from the source is 2-D collimated by 1083 nm laser light, resonant to the closed 2-3S1 - 2-3P2 cooling transition. Next, the atoms are slowed down from about 1000- to 50 m/s in a two meter long Zeeman slower through continuous absorption of resonant 1083 nm light. The slowed atoms are captured in a Magneto-Optical Trap (MOT), that holds up to 5x10^8 atoms at a temperature of 1 mK. The MOT cloud is compressed, spin-polarised and transferred to a cloverleaf Magnetic Trap (MT), which provides both axial and radial trapping through a set of coils outside the vacuum. In the MT, 1D-Doppler cooling is applied to the atomic sample to reduce the temperature to about 150 μK. Following this step, the temperature is reduced further by forced evaporative radio-frequency cooling, resulting in the onset of a Bose-Einstein Condensate (BEC). The atoms are transferred from the MT to a crossed horizontal optical dipole trap (ODT), in which the sample is further evaporatively cooled to produce a BEC of 5x10^6 atoms. The BEC is then transferred from the ODT to either a horizontal or vertical optical lattice, consisting of two counter-propagating laser beams at 1557 nm. By detuning the frequency of one of the lattice beams, the standing wave can be accelerated. The trapped helium atoms can follow the accelerating lattice through a process called Bloch oscillations (BO's), which describes the behaviour of particles in a periodic potential that are subjected to a force. Specifically, in this scenario, particles' velocities increase in increments of two recoil velocities, instead of continuously. Bloch oscillations of cold atoms in periodic potentials formed by optical lattices were first studied in 1996. Importantly, BO’s provide a way to efficiently accelerate atoms by coherently transferring a well controlled, large number of photon momenta, which has been used to increase the resolution of recoil measurements with caesium and rubidium atoms. In this thesis, Bloch oscillations with a metastable helium BEC are demonstrated. Due to its light mass, helium can be efficiently accelerated to high velocities which makes it a candidate for experiments that benefit from splitting the atomic wave-function over large distances. Additionally, Rabi-oscillations in an optical lattice are shown, which serve to probe the depth of the lattice, and a measurement of gravity through Bloch oscillations in a static vertical optical lattice is demonstrated, with a statistical uncertainty of 4x10^-5. Finally, the first proof of principle demonstration of a pulsed light He* atom interferometer is shown. The measurements illustrate the high signal-to-noise that can be obtained using an MCP detector. Next to that, we have demonstrated a method for determining the polarizability of atoms at specific wavelengths, by observing the induced change of the characteristic Bloch oscillation frequency by introducing that wavelength to the system.

•Mar 17, 2021•0 citations

Multi-pulse Ramsey interferometry of a double-well Bose–Einstein condensate in a cavity

Yuxiang Liu, Pei-Sen He, Sheng-Chang Li

Ramsey interferometry as one of the most important high-precision measurement methods has prospects for inferring various properties of ultracold atoms and molecules. We investigate the multi-pulse Ramsey interferometry of a double-well Bose–Einstein condensate (BEC) in an optical cavity. Compared with the standard two-pulse Ramsey scheme, our multi-pulse Ramsey proposal greatly relaxes the requirements for both intensity and width of the pulses, allowing the interferometry to be achieved using weak and narrow pulses. When the pumping pulses characterizing the coupling between the cavity field and the atomic BEC are applied to the zero background field, we demonstrate the atomic Ramsey fringes in the time domain for different pulse numbers and different pulse widths. We find that although the multi-pulse Ramsey fringes are no longer sensitive to cavity-pump detuning, they can still record the information of the interaction between coherent atoms. We obtain the fundamental frequency of the multi-pulse Ramsey fringes analytically and find that it is proportional to the number of pulses. Particularly, it is shown that the minimum of the fundamental frequency is exactly the critical point of the phase transition of the system. For a nonzero background field, the results indicate that a nondestructive observation of atomic Ramsey fringes by cavity transmission spectroscopy is feasible. Our findings provide insights for improving the accuracy of Ramsey interferometry and for using interferometry to observe phase transitions.

Journal of the Optical Society of America B•Apr 4, 2024•1 citation
We report on interference studies in the internal and external degrees of freedom of metastable triplet helium atoms trapped near quantum degeneracy in a 1.5 \upmum1.5 \,\upmu {\mathrm{m}}1.5\upmum optical dipole trap. Applying a single π/2\pi /2π/2 rf pulse we demonstrate that 50% of the atoms initially in the m=+1m=+1m=+1 state can be transferred to the magnetic field insensitive m=0m=0m=0 state. Two π/2\pi /2π/2 pulses with varying time delay allow a Ramsey-type measurement of the Zeeman shift for a high precision measurement of the 2 3S12\,^3S_123S1​ – 2 1S02\,^1S_021S0​ transition frequency. We show that this method also allows strong suppression of mean-field effects on the measurement of the Zeeman shift, which is necessary to reach the accuracy goal of 0.1 kHz on the absolute transition frequencies. Theoretically the feasibility of using metastable triplet helium atoms in the m=0m=0m=0 state for atom interferometry is studied demonstrating favorable conditions, compared to the alkali atoms that are used traditionally, for a non-QED determination of the fine structure constant.
Abstract We report on interference studies in the internal and external degrees of freedom of metastable triplet helium atoms trapped near quantum degeneracy in a $$ 1.5\kern0.166667em \upmu \mathrm{m} $$ 1.5 μ m optical dipole trap. Applying a single π/2 \pi /2 π/2 π / 2 rf pulse we demonstrate that 50% of the atoms initially in the m=+1 m=+1 m=+1 m = + 1 state can be transferred to the magnetic field insensitive m=0 m=0 m=0 m = 0 state. Two π/2 \pi /2 π/2 π / 2 pulses with varying time delay allow a Ramsey-type measurement of the Zeeman shift for a high precision measurement of the 23S1 {2}^3{S}_1 23S1​ 2 3 S 1 – 21S0 {2}^1{S}_0 21S0​ 2 1 S 0 transition frequency. We show that this method also allows strong suppression of mean-field effects on the measurement of the Zeeman shift, which is necessary to reach the accuracy goal of 0.1 kHz on the absolute transition frequencies. Theoretically the feasibility of using metastable triplet helium atoms in the m=0 m=0 m=0 m = 0 state for atom interferometry is studied demonstrating favorable conditions, compared to the alkali atoms that are used traditionally, for a non-QED determination of the fine structure constant.
The thematics treated in this manuscript illustrate two specificities of ultracold metastable Helium gases: the ability to compare experimental measurement with precise theoretical evaluations (simplicity of the atomic structure) and to easily detect products of Penning ionisations. We present the building and the characterisation of a novel magnetic trap with large optical access, allowing to combine the production of a Bose-Einstein condensate with its in situ loading into a 3D optical lattice. The theoretical fundaments of the experiments planned in those optical potentials are then detailed. In a crossed dipole trap, the influence of the magnetic field, now a free parameter, on the Penning collision rates can be measured and compared to a new theoretical evaluation. Concerning Helium in optical lattices, two subjects are developped: the effect of the confinement on the inelastic Penning collisions (1D optical lattice) and the modelisation of the Penning losses via a dissipative Bose-Hubbard model (3D lattice). Finally we present the first direct measurement of the dipolar magnetic transition 23S1 to 23P2, linking the singlet and triplet families in Helium 4. This spectroscopy experiment, realised in collaboration with the group of W. Vassen (LaserLab - Amsterdam), combines cold atoms knowledge with the frequency comb technique, in order to reach an accuracy of 5 kHz.
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.
Electric Rydberg-atom interferometry has been performed with helium atoms in coherent superpositions of the 1s56s3S11s56s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}1s56s3S1​ and 1s57s3S11s57s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}1s57s3S1​ Rydberg levels. The experiments were carried out in a longitudinal geometry with the atoms traveling at 2000 m/s in pulsed supersonic beams. After laser photoexcitation from the 1s2s3S11s2s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}1s2s3S1​ metastable level, coherent manipulation of the population of the Rydberg states was achieved using sequences of microwave pulses. The difference in the static electric dipole polarizabilities of the 1s56s3S11s56s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}1s56s3S1​ and 1s57s3S11s57s\phantom{\rule{0.16em}{0ex}}^{3}S_{1}1s57s3S1​ levels allowed superpositions of external momentum states to be generated when inhomogeneous electric fields were used to exerted forces on the atoms prepared in superpositions of these internal states. Interference fringes, with contributions arising from the spatial separation of these Rydberg-atom wave packets in the direction of propagation of the atomic beam, were identified through changes in the internal-state populations as the magnitudes and durations of the time-dependent electric-field gradient pulses were adjusted. The maximal displacement of the atomic wave packets for which interference fringes were observed was $\ensuremath{\sim}0.75\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$, limited by the longitudinal velocity spread in the atomic beam and the characteristics of the inhomogeneous electric-field distribution in the apparatus. The experimental data are in good quantitative agreement with the results of numerical calculations of the time evolution of the atomic states under the experimental conditions.
The main subject of this thesis is to demonstrate that helium is a promising candidate for matter wave interferometry, with the goal of providing an improved value for the fine-structure constant, α. In particular, fast and efficient momentum transfer via Bloch oscillations in an optical lattice is demonstrated, together with the enhanced sensitivity offered by an ion-detector based detection scheme that is unique to metastable helium (He*). The experiments are performed in a setup that was built to produce, slow down and trap ultracold (~0.2 μK) He-4 atoms. The approach to realising an ultracold sample of He* atoms consists of a sequence of trapping and cooling stages. The experiment starts at the plasma discharge source, where helium atoms are excited to the so-called metastable 2-3S1 state, with a lifetime of ~7800 seconds, 20 eV above the atomic ground state. The atomic beam exiting from the source is 2-D collimated by 1083 nm laser light, resonant to the closed 2-3S1 - 2-3P2 cooling transition. Next, the atoms are slowed down from about 1000- to 50 m/s in a two meter long Zeeman slower through continuous absorption of resonant 1083 nm light. The slowed atoms are captured in a Magneto-Optical Trap (MOT), that holds up to 5x10^8 atoms at a temperature of 1 mK. The MOT cloud is compressed, spin-polarised and transferred to a cloverleaf Magnetic Trap (MT), which provides both axial and radial trapping through a set of coils outside the vacuum. In the MT, 1D-Doppler cooling is applied to the atomic sample to reduce the temperature to about 150 μK. Following this step, the temperature is reduced further by forced evaporative radio-frequency cooling, resulting in the onset of a Bose-Einstein Condensate (BEC). The atoms are transferred from the MT to a crossed horizontal optical dipole trap (ODT), in which the sample is further evaporatively cooled to produce a BEC of 5x10^6 atoms. The BEC is then transferred from the ODT to either a horizontal or vertical optical lattice, consisting of two counter-propagating laser beams at 1557 nm. By detuning the frequency of one of the lattice beams, the standing wave can be accelerated. The trapped helium atoms can follow the accelerating lattice through a process called Bloch oscillations (BO's), which describes the behaviour of particles in a periodic potential that are subjected to a force. Specifically, in this scenario, particles' velocities increase in increments of two recoil velocities, instead of continuously. Bloch oscillations of cold atoms in periodic potentials formed by optical lattices were first studied in 1996. Importantly, BO’s provide a way to efficiently accelerate atoms by coherently transferring a well controlled, large number of photon momenta, which has been used to increase the resolution of recoil measurements with caesium and rubidium atoms. In this thesis, Bloch oscillations with a metastable helium BEC are demonstrated. Due to its light mass, helium can be efficiently accelerated to high velocities which makes it a candidate for experiments that benefit from splitting the atomic wave-function over large distances. Additionally, Rabi-oscillations in an optical lattice are shown, which serve to probe the depth of the lattice, and a measurement of gravity through Bloch oscillations in a static vertical optical lattice is demonstrated, with a statistical uncertainty of 4x10^-5. Finally, the first proof of principle demonstration of a pulsed light He* atom interferometer is shown. The measurements illustrate the high signal-to-noise that can be obtained using an MCP detector. Next to that, we have demonstrated a method for determining the polarizability of atoms at specific wavelengths, by observing the induced change of the characteristic Bloch oscillation frequency by introducing that wavelength to the system.
Ramsey interferometry as one of the most important high-precision measurement methods has prospects for inferring various properties of ultracold atoms and molecules. We investigate the multi-pulse Ramsey interferometry of a double-well Bose–Einstein condensate (BEC) in an optical cavity. Compared with the standard two-pulse Ramsey scheme, our multi-pulse Ramsey proposal greatly relaxes the requirements for both intensity and width of the pulses, allowing the interferometry to be achieved using weak and narrow pulses. When the pumping pulses characterizing the coupling between the cavity field and the atomic BEC are applied to the zero background field, we demonstrate the atomic Ramsey fringes in the time domain for different pulse numbers and different pulse widths. We find that although the multi-pulse Ramsey fringes are no longer sensitive to cavity-pump detuning, they can still record the information of the interaction between coherent atoms. We obtain the fundamental frequency of the multi-pulse Ramsey fringes analytically and find that it is proportional to the number of pulses. Particularly, it is shown that the minimum of the fundamental frequency is exactly the critical point of the phase transition of the system. For a nonzero background field, the results indicate that a nondestructive observation of atomic Ramsey fringes by cavity transmission spectroscopy is feasible. Our findings provide insights for improving the accuracy of Ramsey interferometry and for using interferometry to observe phase transitions.