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:2301.08172 · Physical Review A

Rapid generation and number-resolved detection of spinor rubidium Bose-Einstein condensates

Cebrail Pür, Mareike Hetzel, Martin Quensen, Andreas Hüper, Jiao Geng, J. Kruse, Wolfgang A. Ertmer, Carsten Klempt

Published Mar 6, 2023• 4 citations
arXivHTMLPDF

Abstract

High data acquisition rates and low-noise detection of ultracold neutral atoms present important challenges for the state tomography and interferometric application of entangled quantum states in Bose-Einstein condensates. In this paper, we present a high-flux source of $^{87}\mathrm{Rb}$ Bose-Einstein condensates combined with a number-resolving detection. We create Bose-Einstein condensates of $2\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms with no discernible thermal fraction within 3.3 s using a hybrid evaporation approach in a magnetic and optical trap. For the high-fidelity tomography of many-body quantum states in the spin degree of freedom [M. Hetzel, et al., arXiv:2207.01270], it is desirable to select a single mode for a number-resolving detection. We demonstrate the low-noise selection of subsamples of up to 16 atoms and their subsequent detection with a counting noise below 0.2 atoms. The presented techniques offer an exciting path towards the creation and analysis of mesoscopic quantum states with improved fidelities and towards their exploitation for fundamental and metrological applications.

DOI
10.1103/physreva.107.033303

Related papers

Accurate atom counting for entanglement-enhanced atom interferometry

Andreas Hüper

Atom interferometers belong among today's most precise sensors and offer a broad range of possible metrological applications. Given their ability to measure accelerations and rotations precisely, they are suitable for inertial sensing, navigation and geodesy. Beyond this, they proved indispensible for time-keeping as well as fundamental research. This explains why the improvement of achievable sensitivities of atom interferometers is of particular interest. However the sensitivity of atom interferometers is fundamentally restricted by the standard quantum limit. The standard quantum limit can only be surpassed by employing entangled many-partice states. Entangled states, such as the twin-Fock state, allow atom interferometers to improve the phase sensitivity beyond the standard quantum limit, but they are reliant on an accurate detection of the interferometric out come. In this work, an experimental apparatus is designed and set up that will allow for routine generation of highly entangled twin-Fock states in a Rubidium-87 spinor Bose-Einstein condensate. As the main feature of this apparatus, an accurate atom counting fluorescence detection has been implemented. This detection achieves single-particle resolving fluorescence measurements for 1 up to 30 atoms. According to the noise analysis the single-atom resolution extends to a limiting atom number of 390(20) atoms. The implemented quadrupole coils with their strong gradient of up to 300 G/cm offer a tight confinement that in combination with the 55 W optical dipole trap laser will enable a fast repetition rate of the creation of highly entangled quantum states.

•Jan 1, 2020•0 citations

Analyzing spin states of a Bose-Einstein condensate with number-resolved counting

Carsten Klempt, Mareike Hetzel, Lucca Pezzè +5 more

A tomography of many-body quantum states of indistinguishable particles is generally performed by engineering couplings between the involved states and a subsequent counting of the occupation numbers. While precise couplings belong to the standard experimental toolbox, an accurate number counting presents a considerable challenge for both photonic and atomic quantum states. Here we present an application of a number-resolving atom counting [New J. Phys. 23, 113046 (2021)] for the state reconstruction of an atomic coherent spin state. We generate the coherent spin state by driving a Rabi frequency between two hyperfine states of an ultracold Rubidium ensemble.The result is analyzed by a number-resolving fluoresence detection setup. We characterize the fidelity of our detector and show that a negative-valued Wigner function is associated with it. The results offer an exciting perspective for a high-fidelity tomography of entangled states and can be applied for the future demonstration of Heisenberg-limited atom interferometry.

Optical and Quantum Sensing and Precision Metrology II•Mar 9, 2022•0 citations

Magnetic transport and Bose-Einstein condensation of rubidium atoms

Benjamin Thomas Sheard, Sheard, Benjamin

This thesis describes the design, construction and optimisation of a new apparatus to produce Bose-Einstein condensates (BECs) of 87Rb atoms. The main aim in building this system was to include a high resolution imaging system capable of resolving single atoms. Optical access for the imaging system was created by including a stage of atom transport in which the atoms are magnetically transferred ~50 cm from a magneto-optical trap (MOT), where they are initially collected, to a glass science cell where experiments are carried out and imaging takes place. Two magnetic transport schemes have been demonstrated, based on approaches first used in other laboratories. First, a scheme in which the atoms are transferred in a moving pair of magnetic trapping coils. Second, a hybrid scheme where the atoms are translated part of the distance in the moving coils, and the rest of the way by switching the current in a chain of fixed coils. This second scheme was designed to allow optical access for a high numerical aperture microscope objective to be placed immediately next to the science cell for high resolution imaging.The atoms were first collected in a large pyramid MOT which can be loaded with 3 × 10^9 atoms in a time of 20 s. Around half of these atoms – those in the |F = 1, mF = −1> magnetic substate – were then magnetically trapped prior to transport. The typical fraction of the trapped atoms transferred to the science cell was ~30% and ~18% for the moving coils and hybrid schemes respectively.Evaporative cooling was carried out on the atom cloud following transport with the moving coils and loading into a time-orbiting potential trap. The optimised cooling sequence lasted for 28 s and consistently produced a pure condensate with 5 × 10^5 atoms. A BEC has also been produced by evaporative cooling following hybrid transport. The next experimental steps will be to optimise the hybrid transfer approach further and install the high resolution imaging system.The system is well-placed to continue an ongoing series of experiments in which ultracold atoms are trapped in RF-dressed potentials. These potentials will be used to study low-dimensional quantum gases as well as in experiments where small atom number BECs are rapidly rotated to enter the fractional quantum Hall regime.

•Jan 1, 2010•1 citation

Interferometry and precision measurements with Bose-condensed atoms

D. Döring

Bose-Einstein condensates are coherent matter waves, produced by cooling gaseous atomic clouds to ultra-low temperatures. For applications in atom interferometry and precision measurements, Bose-condensed sources present an intriguing alternative to thermal atoms. Although the current sensitivity achievable with interferometers using coherent atoms is not comparable to thermal beam machines (mainly due to the lower flux), there are promising ways to utilise the potential of Bose-condensed sources for atom interferometry. Among those is the low momentum width of Bose-Einstein condensates, which can generally be well controlled and is advantageous for increased interferometric sensitivities by implementing large momentum transfer beam splitters. As part of this thesis, experimental and theoretical investigations are presented to investigate the potential of Bose-Einstein condensates for such applications. We shall present the quantum projection noise limited performance of a Ramsey interferometer operating on the atomic clock transition of a freely expanding cloud of Bose-condensed rubidium 87 atoms. The results include Ramsey fringes of high visibility, not measurably affected by atomic interaction-induced dephasing effects. The achievement and detection of the quantum projection noise limit rely critically on the precision and accuracy of both the imaging setup and the coupling scheme in the interferometric beam splitters. The stabilisation of the beam splitters via an optical Sagnac interferometer is the basis for the quantum projection noise limited performance of the interferometer presented. For an increase of bandwidth and flux in atom interferometric measurements, it is advantageous to use a continuous atomic beam. A truly continuous coherent atom source has not been realised to date, and we present results on a pumping mechanism in this thesis, as a decisive step towards a continuous atom laser. By the investigation of different momentum resonances, we find that the pumping scheme relies on a Raman superradiance-like process. Finally, the thesis demonstrates two interaction measurements in rubidium. The strong mean field interactions due to the high densities in Bose-Einstein condensates are used to probe the potential of a rubidium 87 condensate with an atom laser. The measurement allows a determination of the scattering length between the two atomic states involved. In addition to this two-body scattering scheme, we present a measurement of three-body loss coefficients, extracted from loss curves in rubidium 85 Bose-Einstein condensates. The measurement provides new upper bounds on the three-body loss coefficients at the scattering lengths considered.

•Jan 1, 2011•0 citations

A simple recipe for rapid all-optical formation of spinor Bose–Einstein condensates

Chih-Yuan Huang, Chun-Chia Chen, Li-An Sun +4 more

Abstract We present a simple recipe for the rapid formation of spinor Bose–Einstein condensates of 87 Rb atoms in a three-beam crossed optical dipole trap (ODT). Two laser Gaussian beams were crossed at a small angle to form an effective single potential in the intersection region with an independent and widely tunable trap volume and aspect ratio, for both efficient atom loading and number density enhancement. A third Gaussian beam was then introduced to create a potential dimple at the trap center to further increase the atom number density and collision rate, which enabled rapid evaporation to a Bose condensation. In this configuration, 2 × 10 6 atoms were loaded into the three-beam crossed trap from a vapor cell magneto-optical trap, and condensates of 3 × 10 4 – 4.5 × 10 4 atoms were created after 3–5 s of rapid evaporation. The demonstration of efficient and robust BEC production in this ODT suggests the applicability of this trapping geometry to lasers with any far off-resonant wavelengths. To prepare the spinor condensates with a wide tunability of spin population, control of the magnetic fields was first employed during evaporation to polarize the spin states, and the tuning mechanism is discussed. Spinor condensates with an arbitrary spin population were then created via multiple microwave pulses driving the ground hyperfine transitions.

Journal of Physics B Atomic Molecular and Optical Physics•Jun 14, 2017•8 citations

Rapid generation of all-optical K39 Bose-Einstein condensates using a low-field Feshbach resonance

Alexander Herbst, H. Albers, Knut Stolzenberg +2 more

Ultracold potassium is an interesting candidate for quantum technology applications and fundamental research as it allows controlling intra-atomic interactions via low-field magnetic Feshbach resonances. However, the realization of high-flux sources of Bose-Einstein condensates remains challenging due to the necessity of optical trapping to use magnetic fields as free parameters. We investigate the production of all-optical $^{39}\mathrm{K}$ Bose-Einstein condensates with different scattering lengths using a Feshbach resonance near 33 G. By tuning the scattering length in a range between $75{a}_{0}$ and $300{a}_{0}$ we demonstrate a tradeoff between evaporation speed and final atom number and decrease our evaporation time by a factor of 5 while approximately doubling the evaporation flux. To this end, we are able to produce fully condensed ensembles with $5.8\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms within $850\text{\ensuremath{-}}\mathrm{ms}$ evaporation time at a scattering length of $232{a}_{0}$ and $1.6\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms within $3.9\phantom{\rule{0.16em}{0ex}}\mathrm{s}$ at $158{a}_{0}$, respectively. We deploy a numerical model to analyze the flux and atom number scaling with respect to scattering length, identify current limitations, and simulate the optimal performance of our setup. Based on our findings we describe routes towards high-flux sources of ultracold potassium for inertial sensing.

arXiv:2201.04544•Physical Review A•Oct 21, 2022•8 citations
High data acquisition rates and low-noise detection of ultracold neutral atoms present important challenges for the state tomography and interferometric application of entangled quantum states in Bose-Einstein condensates. In this paper, we present a high-flux source of 87Rb^{87}\mathrm{Rb}87Rb Bose-Einstein condensates combined with a number-resolving detection. We create Bose-Einstein condensates of 2\ifmmode×\else\texttimes\fi1052\ifmmode\times\else\texttimes\fi{}{10}^{5}2\ifmmode×\else\texttimes\fi105 atoms with no discernible thermal fraction within 3.3 s using a hybrid evaporation approach in a magnetic and optical trap. For the high-fidelity tomography of many-body quantum states in the spin degree of freedom [M. Hetzel, et al., arXiv:2207.01270], it is desirable to select a single mode for a number-resolving detection. We demonstrate the low-noise selection of subsamples of up to 16 atoms and their subsequent detection with a counting noise below 0.2 atoms. The presented techniques offer an exciting path towards the creation and analysis of mesoscopic quantum states with improved fidelities and towards their exploitation for fundamental and metrological applications.
Atom interferometers belong among today's most precise sensors and offer a broad range of possible metrological applications. Given their ability to measure accelerations and rotations precisely, they are suitable for inertial sensing, navigation and geodesy. Beyond this, they proved indispensible for time-keeping as well as fundamental research. This explains why the improvement of achievable sensitivities of atom interferometers is of particular interest. However the sensitivity of atom interferometers is fundamentally restricted by the standard quantum limit. The standard quantum limit can only be surpassed by employing entangled many-partice states. Entangled states, such as the twin-Fock state, allow atom interferometers to improve the phase sensitivity beyond the standard quantum limit, but they are reliant on an accurate detection of the interferometric out come. In this work, an experimental apparatus is designed and set up that will allow for routine generation of highly entangled twin-Fock states in a Rubidium-87 spinor Bose-Einstein condensate. As the main feature of this apparatus, an accurate atom counting fluorescence detection has been implemented. This detection achieves single-particle resolving fluorescence measurements for 1 up to 30 atoms. According to the noise analysis the single-atom resolution extends to a limiting atom number of 390(20) atoms. The implemented quadrupole coils with their strong gradient of up to 300 G/cm offer a tight confinement that in combination with the 55 W optical dipole trap laser will enable a fast repetition rate of the creation of highly entangled quantum states.
A tomography of many-body quantum states of indistinguishable particles is generally performed by engineering couplings between the involved states and a subsequent counting of the occupation numbers. While precise couplings belong to the standard experimental toolbox, an accurate number counting presents a considerable challenge for both photonic and atomic quantum states. Here we present an application of a number-resolving atom counting [New J. Phys. 23, 113046 (2021)] for the state reconstruction of an atomic coherent spin state. We generate the coherent spin state by driving a Rabi frequency between two hyperfine states of an ultracold Rubidium ensemble.The result is analyzed by a number-resolving fluoresence detection setup. We characterize the fidelity of our detector and show that a negative-valued Wigner function is associated with it. The results offer an exciting perspective for a high-fidelity tomography of entangled states and can be applied for the future demonstration of Heisenberg-limited atom interferometry.
This thesis describes the design, construction and optimisation of a new apparatus to produce Bose-Einstein condensates (BECs) of 87Rb atoms. The main aim in building this system was to include a high resolution imaging system capable of resolving single atoms. Optical access for the imaging system was created by including a stage of atom transport in which the atoms are magnetically transferred ~50 cm from a magneto-optical trap (MOT), where they are initially collected, to a glass science cell where experiments are carried out and imaging takes place. Two magnetic transport schemes have been demonstrated, based on approaches first used in other laboratories. First, a scheme in which the atoms are transferred in a moving pair of magnetic trapping coils. Second, a hybrid scheme where the atoms are translated part of the distance in the moving coils, and the rest of the way by switching the current in a chain of fixed coils. This second scheme was designed to allow optical access for a high numerical aperture microscope objective to be placed immediately next to the science cell for high resolution imaging.The atoms were first collected in a large pyramid MOT which can be loaded with 3 × 10^9 atoms in a time of 20 s. Around half of these atoms – those in the |F = 1, mF = −1> magnetic substate – were then magnetically trapped prior to transport. The typical fraction of the trapped atoms transferred to the science cell was ~30% and ~18% for the moving coils and hybrid schemes respectively.Evaporative cooling was carried out on the atom cloud following transport with the moving coils and loading into a time-orbiting potential trap. The optimised cooling sequence lasted for 28 s and consistently produced a pure condensate with 5 × 10^5 atoms. A BEC has also been produced by evaporative cooling following hybrid transport. The next experimental steps will be to optimise the hybrid transfer approach further and install the high resolution imaging system.The system is well-placed to continue an ongoing series of experiments in which ultracold atoms are trapped in RF-dressed potentials. These potentials will be used to study low-dimensional quantum gases as well as in experiments where small atom number BECs are rapidly rotated to enter the fractional quantum Hall regime.
Bose-Einstein condensates are coherent matter waves, produced by cooling gaseous atomic clouds to ultra-low temperatures. For applications in atom interferometry and precision measurements, Bose-condensed sources present an intriguing alternative to thermal atoms. Although the current sensitivity achievable with interferometers using coherent atoms is not comparable to thermal beam machines (mainly due to the lower flux), there are promising ways to utilise the potential of Bose-condensed sources for atom interferometry. Among those is the low momentum width of Bose-Einstein condensates, which can generally be well controlled and is advantageous for increased interferometric sensitivities by implementing large momentum transfer beam splitters. As part of this thesis, experimental and theoretical investigations are presented to investigate the potential of Bose-Einstein condensates for such applications. We shall present the quantum projection noise limited performance of a Ramsey interferometer operating on the atomic clock transition of a freely expanding cloud of Bose-condensed rubidium 87 atoms. The results include Ramsey fringes of high visibility, not measurably affected by atomic interaction-induced dephasing effects. The achievement and detection of the quantum projection noise limit rely critically on the precision and accuracy of both the imaging setup and the coupling scheme in the interferometric beam splitters. The stabilisation of the beam splitters via an optical Sagnac interferometer is the basis for the quantum projection noise limited performance of the interferometer presented. For an increase of bandwidth and flux in atom interferometric measurements, it is advantageous to use a continuous atomic beam. A truly continuous coherent atom source has not been realised to date, and we present results on a pumping mechanism in this thesis, as a decisive step towards a continuous atom laser. By the investigation of different momentum resonances, we find that the pumping scheme relies on a Raman superradiance-like process. Finally, the thesis demonstrates two interaction measurements in rubidium. The strong mean field interactions due to the high densities in Bose-Einstein condensates are used to probe the potential of a rubidium 87 condensate with an atom laser. The measurement allows a determination of the scattering length between the two atomic states involved. In addition to this two-body scattering scheme, we present a measurement of three-body loss coefficients, extracted from loss curves in rubidium 85 Bose-Einstein condensates. The measurement provides new upper bounds on the three-body loss coefficients at the scattering lengths considered.
Abstract We present a simple recipe for the rapid formation of spinor Bose–Einstein condensates of 87 Rb atoms in a three-beam crossed optical dipole trap (ODT). Two laser Gaussian beams were crossed at a small angle to form an effective single potential in the intersection region with an independent and widely tunable trap volume and aspect ratio, for both efficient atom loading and number density enhancement. A third Gaussian beam was then introduced to create a potential dimple at the trap center to further increase the atom number density and collision rate, which enabled rapid evaporation to a Bose condensation. In this configuration, 2 × 10 6 atoms were loaded into the three-beam crossed trap from a vapor cell magneto-optical trap, and condensates of 3 × 10 4 – 4.5 × 10 4 atoms were created after 3–5 s of rapid evaporation. The demonstration of efficient and robust BEC production in this ODT suggests the applicability of this trapping geometry to lasers with any far off-resonant wavelengths. To prepare the spinor condensates with a wide tunability of spin population, control of the magnetic fields was first employed during evaporation to polarize the spin states, and the tuning mechanism is discussed. Spinor condensates with an arbitrary spin population were then created via multiple microwave pulses driving the ground hyperfine transitions.
Ultracold potassium is an interesting candidate for quantum technology applications and fundamental research as it allows controlling intra-atomic interactions via low-field magnetic Feshbach resonances. However, the realization of high-flux sources of Bose-Einstein condensates remains challenging due to the necessity of optical trapping to use magnetic fields as free parameters. We investigate the production of all-optical 39K^{39}\mathrm{K}39K Bose-Einstein condensates with different scattering lengths using a Feshbach resonance near 33 G. By tuning the scattering length in a range between 75a075{a}_{0}75a0​ and 300a0300{a}_{0}300a0​ we demonstrate a tradeoff between evaporation speed and final atom number and decrease our evaporation time by a factor of 5 while approximately doubling the evaporation flux. To this end, we are able to produce fully condensed ensembles with $5.8\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms within $850\text{\ensuremath{-}}\mathrm{ms}$ evaporation time at a scattering length of 232a0232{a}_{0}232a0​ and $1.6\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms within 3.9s3.9\phantom{\rule{0.16em}{0ex}}\mathrm{s}3.9s at 158a0158{a}_{0}158a0​, respectively. We deploy a numerical model to analyze the flux and atom number scaling with respect to scattering length, identify current limitations, and simulate the optimal performance of our setup. Based on our findings we describe routes towards high-flux sources of ultracold potassium for inertial sensing.