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:2206.09056 · Physical Review Letters

Subrecoil Clock-Transition Laser Cooling Enabling Shallow Optical Lattice Clocks

Xiaogang Zhang, K. Beloy, Youssef S. Hassan, William F. McGrew, Chun-Chia Chen, Jacob L. Siegel, Tanner Grogan, Andrew D. Ludlow

Published Sep 8, 2022• 26 citations
arXivHTMLPDF

Abstract

Laser cooling is a key ingredient for quantum control of atomic systems in a variety of settings. In divalent atoms, two-stage Doppler cooling is typically used to bring atoms to the μK regime. Here, we implement a pulsed radial cooling scheme using the ultranarrow ^{1}S_{0}-^{3}P_{0} clock transition in ytterbium to realize subrecoil temperatures, down to tens of nK. Together with sideband cooling along the one-dimensional lattice axis, we efficiently prepare atoms in shallow lattices at an energy of 6 lattice recoils. Under these conditions key limits on lattice clock accuracy and instability are reduced, opening the door to dramatic improvements. Furthermore, tunneling shifts in the shallow lattice do not compromise clock accuracy at the 10^{-19} level.

DOI
10.1103/physrevlett.129.113202

Related papers

Clock-Line-Mediated Sisyphus Cooling

Chun-Chia Chen, Jacob L. Siegel, B. D. Hunt +6 more

We demonstrate subrecoil Sisyphus cooling using the long-lived ^{3}P_{0} clock state in alkaline-earth-like ytterbium. A 1388-nm optical standing wave nearly resonant with the ^{3}P_{0}→^{3}D_{1} transition creates a spatially periodic light shift of the ^{3}P_{0} clock state. Following excitation on the ultranarrow clock transition, we observe Sisyphus cooling in this potential, as the light shift is correlated with excitation to ^{3}D_{1} and subsequent spontaneous decay to the ^{1}S_{0} ground state. We observe that cooling enhances the loading efficiency of atoms into a 759-nm magic-wavelength one-dimensional (1D) optical lattice, as compared to standard Doppler cooling on the ^{1}S_{0}→^{3}P_{1} transition. Sisyphus cooling yields temperatures below 200 nK in the weakly confined, transverse dimensions of the 1D optical lattice. These lower temperatures improve optical lattice clocks by facilitating the use of shallow lattices with reduced light shifts while retaining large atom numbers to reduce the quantum projection noise. This Sisyphus cooling can be pulsed or continuous and is applicable to a range of quantum metrology applications.

arXiv:2406.13782•Physical Review Letters•Jul 31, 2024•12 citations

Advancing optical lattice clock performance with novel clock-line laser cooling techniques

Chun-Chia Chen, Jacob L. Siegel, B. D. Hunt +6 more

Optical lattice clocks have demonstrated unprecedented performance below the 10^-18 fractional level, advancing towards new standards of timekeeping and sensitive probes in fundamental physics. To further advance optical lattice clocks performance, it is crucial to attain lower temperatures which facilitates the use of shallow lattices with reduced light shifts, while retaining large atom numbers to reduce the quantum projection noise. Here, we present Sisyphus cooling using the long-lived 3P0 clock state in alkaline-earth-like ytterbium. Upon excitation on the ultranarrow clock transition, Sisyphus cooling is observed within a spatially periodic potential induced by a 1388-nm optical standing wave that is nearly resonant with the 3P0 → 3D1 transition. Our cooling demonstrates versatility, working both in free space and in a magic-wavelength lattice. It offers the flexibility of being employed in either pulsed or continuous modes, making it suitable to a range of quantum metrology applications.

Optical and Quantum Sensing and Precision Metrology II•Mar 13, 2024•0 citations

Effective sideband cooling in an ytterbium optical lattice clock

Jin-Qi Wang, Ang Zhang, Cong-Cong Tian +6 more

Sideband cooling is a key technique for improving the performance of optical atomic clocks by preparing cold atoms and single ions into the ground vibrational state. In this work, we demonstrate detailed experimental research on pulsed Raman sideband cooling in a 171Yb optical lattice clock. A sequence comprised of interleaved 578 nm cooling pulses resonant on the 1st-order red sideband and 1388 nm repumping pulses is carried out to transfer atoms into the motional ground state. We successfully decrease the axial temperature of atoms in the lattice from 6.5 μK to less than 0.8 μK in the trap depth of 24 μK, corresponding to an average axial motional quantum number 〈 nz 〉 < 0.03. Rabi oscillation spectroscopy is measured to evaluate the effect of sideband cooling on inhomogeneous excitation. The maximum excitation fraction is increased from 0.8 to 0.86, indicating an enhancement in the quantum coherence of the ensemble. Our work will contribute to improving the instability and uncertainty of Yb lattice clocks.

Chinese Physics B•Feb 10, 2022•3 citations

Atomic thermometry in optical lattice clocks: Model discrepancies and their impact on lattice light shifts

Irene Goti, Tommaso Petrucciani, Stefano Condio +3 more

Accurate measurement of atomic temperature is fundamental for a wide range of applications, from quantum sensing to precision metrology. In optical lattice clocks, precise characterization of atomic temperature is required to minimize systematic uncertainties at the $10^{-18}$ level. In this work, we investigate atomic temperature measurements in the ytterbium optical clock developed at INRIM, IT-Yb1, employing sideband and transverse Doppler spectroscopy across a wide range of trapping conditions in a one-dimensional optical lattice. By implementing clock-line-mediated Sisyphus cooling [Phys. Rev. Lett. 133, 053401 (2024)], we reduce the atomic temperature and enable operation at shallower lattice depths down to $D = 50\,E_\text{R}$, where $E_\text{R}$ is the photon recoil energy. We compare temperature estimates obtained from the perturbed harmonic oscillator model with those derived using a Born-Oppenheimer model [Phys. Rev. A 101, 053416 (2020)]. Discrepancies of up to a factor of four are observed between the temperature estimates obtained with the two approximations. We assess the impact of these modeling differences on the evaluation of lattice light shifts and find relative frequency deviations of up to $8\times10^{-17}$. Although sufficiently low atomic temperatures and the consistent use of theoretical models reduce these discrepancies to the low $10^{-18}$ level, these results motivate further investigations that will be relevant to state-of-the-art optical lattice clocks.

arXiv:2508.08164•Physical Review A•Oct 19, 2026•0 citations

Isotope-agnostic motional ground-state cooling of neutral Yb atoms

Ronen M. Kroeze, René A. Villela, Er Zu +2 more

Efficient high-fidelity ground-state cooling of motional degrees of freedom is crucial for applications in quantum simulation, computing, and metrology. Here, we demonstrate direct ground-state cooling of fermionic Yb 171 and bosonic Yb 174 atoms in two- and three-dimensional magic-wavelength optical lattices on the ultranarrow clock transition. Its high spectral resolution offers the potential for reaching extremely low temperatures. To ensure efficient cooling, we develop a chirped sideband cooling scheme, where we sweep the clock-laser frequency to mitigate the effects of spatial trap inhomogeneities. We further generalize the theoretical description of sideband spectra to higher-dimensional lattices for precise thermometry. We achieve 2D ground-state fractions of 97 % for Yb 171 with an average motional occupation of n ¯ ≃ 0.015 and provide a direct comparison with Yb 174 , reaching similar cooling performance. Applying the same scheme in 3D results in n ¯ ≃ 0.15 limited by layer-to-layer inhomogeneities in the vertical direction. These results demonstrate efficient motional ground-state cooling in optical lattices, especially for bosonic alkaline-earth(-like) atoms, where other methods are not applicable, opening the door to novel protocols for quantum science applications with neutral atoms.

arXiv:2506.09031•Physical Review Research•Nov 10, 2025•1 citation

Subrecoil Raman laser cooling of $lt;sup$gt;6$lt;/sup$gt;Li atoms

Liang Zhang, Shichuan Yu, Pengyue Liu +3 more

We realize an efficient one-dimensional Raman cooling of 6Li atoms using 2S→2P Raman transition pulses and 2S→3P ultraviolet (UV) optical repumping. In this cooling scheme, we directly cool an initial cold atomic sample of 350 μK released from a standard magneto-optical trap down to a velocity spread of 0.8 recoil velocity, corresponding to an effective temperature of 4.5 μK, an increase of almost an order of magnitude in the phase space density with respect to ordinary laser sub-Doppler cooling. This technique may provide an ideal initial sub-recoil atomic sample for the application of the large-momentum-transfer in the recoil-sensitive lithium atom interferometers.

Frontiers of Physics•Jan 1, 2025•1 citation
Laser cooling is a key ingredient for quantum control of atomic systems in a variety of settings. In divalent atoms, two-stage Doppler cooling is typically used to bring atoms to the μK regime. Here, we implement a pulsed radial cooling scheme using the ultranarrow ^{1}S_{0}-^{3}P_{0} clock transition in ytterbium to realize subrecoil temperatures, down to tens of nK. Together with sideband cooling along the one-dimensional lattice axis, we efficiently prepare atoms in shallow lattices at an energy of 6 lattice recoils. Under these conditions key limits on lattice clock accuracy and instability are reduced, opening the door to dramatic improvements. Furthermore, tunneling shifts in the shallow lattice do not compromise clock accuracy at the 10^{-19} level.
We demonstrate subrecoil Sisyphus cooling using the long-lived ^{3}P_{0} clock state in alkaline-earth-like ytterbium. A 1388-nm optical standing wave nearly resonant with the ^{3}P_{0}→^{3}D_{1} transition creates a spatially periodic light shift of the ^{3}P_{0} clock state. Following excitation on the ultranarrow clock transition, we observe Sisyphus cooling in this potential, as the light shift is correlated with excitation to ^{3}D_{1} and subsequent spontaneous decay to the ^{1}S_{0} ground state. We observe that cooling enhances the loading efficiency of atoms into a 759-nm magic-wavelength one-dimensional (1D) optical lattice, as compared to standard Doppler cooling on the ^{1}S_{0}→^{3}P_{1} transition. Sisyphus cooling yields temperatures below 200 nK in the weakly confined, transverse dimensions of the 1D optical lattice. These lower temperatures improve optical lattice clocks by facilitating the use of shallow lattices with reduced light shifts while retaining large atom numbers to reduce the quantum projection noise. This Sisyphus cooling can be pulsed or continuous and is applicable to a range of quantum metrology applications.
Optical lattice clocks have demonstrated unprecedented performance below the 10^-18 fractional level, advancing towards new standards of timekeeping and sensitive probes in fundamental physics. To further advance optical lattice clocks performance, it is crucial to attain lower temperatures which facilitates the use of shallow lattices with reduced light shifts, while retaining large atom numbers to reduce the quantum projection noise. Here, we present Sisyphus cooling using the long-lived 3P0 clock state in alkaline-earth-like ytterbium. Upon excitation on the ultranarrow clock transition, Sisyphus cooling is observed within a spatially periodic potential induced by a 1388-nm optical standing wave that is nearly resonant with the 3P0 → 3D1 transition. Our cooling demonstrates versatility, working both in free space and in a magic-wavelength lattice. It offers the flexibility of being employed in either pulsed or continuous modes, making it suitable to a range of quantum metrology applications.
Sideband cooling is a key technique for improving the performance of optical atomic clocks by preparing cold atoms and single ions into the ground vibrational state. In this work, we demonstrate detailed experimental research on pulsed Raman sideband cooling in a 171Yb optical lattice clock. A sequence comprised of interleaved 578 nm cooling pulses resonant on the 1st-order red sideband and 1388 nm repumping pulses is carried out to transfer atoms into the motional ground state. We successfully decrease the axial temperature of atoms in the lattice from 6.5 μK to less than 0.8 μK in the trap depth of 24 μK, corresponding to an average axial motional quantum number 〈 nz 〉 < 0.03. Rabi oscillation spectroscopy is measured to evaluate the effect of sideband cooling on inhomogeneous excitation. The maximum excitation fraction is increased from 0.8 to 0.86, indicating an enhancement in the quantum coherence of the ensemble. Our work will contribute to improving the instability and uncertainty of Yb lattice clocks.
Accurate measurement of atomic temperature is fundamental for a wide range of applications, from quantum sensing to precision metrology. In optical lattice clocks, precise characterization of atomic temperature is required to minimize systematic uncertainties at the 10−1810^{-18}10−18 level. In this work, we investigate atomic temperature measurements in the ytterbium optical clock developed at INRIM, IT-Yb1, employing sideband and transverse Doppler spectroscopy across a wide range of trapping conditions in a one-dimensional optical lattice. By implementing clock-line-mediated Sisyphus cooling [Phys. Rev. Lett. 133, 053401 (2024)], we reduce the atomic temperature and enable operation at shallower lattice depths down to D=50 ERD = 50\,E_\text{R}D=50ER​, where ERE_\text{R}ER​ is the photon recoil energy. We compare temperature estimates obtained from the perturbed harmonic oscillator model with those derived using a Born-Oppenheimer model [Phys. Rev. A 101, 053416 (2020)]. Discrepancies of up to a factor of four are observed between the temperature estimates obtained with the two approximations. We assess the impact of these modeling differences on the evaluation of lattice light shifts and find relative frequency deviations of up to 8×10−178\times10^{-17}8×10−17. Although sufficiently low atomic temperatures and the consistent use of theoretical models reduce these discrepancies to the low 10−1810^{-18}10−18 level, these results motivate further investigations that will be relevant to state-of-the-art optical lattice clocks.
Efficient high-fidelity ground-state cooling of motional degrees of freedom is crucial for applications in quantum simulation, computing, and metrology. Here, we demonstrate direct ground-state cooling of fermionic Yb 171 and bosonic Yb 174 atoms in two- and three-dimensional magic-wavelength optical lattices on the ultranarrow clock transition. Its high spectral resolution offers the potential for reaching extremely low temperatures. To ensure efficient cooling, we develop a chirped sideband cooling scheme, where we sweep the clock-laser frequency to mitigate the effects of spatial trap inhomogeneities. We further generalize the theoretical description of sideband spectra to higher-dimensional lattices for precise thermometry. We achieve 2D ground-state fractions of 97 % for Yb 171 with an average motional occupation of n ¯ ≃ 0.015 and provide a direct comparison with Yb 174 , reaching similar cooling performance. Applying the same scheme in 3D results in n ¯ ≃ 0.15 limited by layer-to-layer inhomogeneities in the vertical direction. These results demonstrate efficient motional ground-state cooling in optical lattices, especially for bosonic alkaline-earth(-like) atoms, where other methods are not applicable, opening the door to novel protocols for quantum science applications with neutral atoms.
Subrecoil Raman laser cooling of lt;suplt;suplt;supgt;6lt;/suplt;/suplt;/supgt;Li atoms
We realize an efficient one-dimensional Raman cooling of 6Li atoms using 2S→2P Raman transition pulses and 2S→3P ultraviolet (UV) optical repumping. In this cooling scheme, we directly cool an initial cold atomic sample of 350 μK released from a standard magneto-optical trap down to a velocity spread of 0.8 recoil velocity, corresponding to an effective temperature of 4.5 μK, an increase of almost an order of magnitude in the phase space density with respect to ordinary laser sub-Doppler cooling. This technique may provide an ideal initial sub-recoil atomic sample for the application of the large-momentum-transfer in the recoil-sensitive lithium atom interferometers.