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

Optics Express

Proposal for a hybrid clock system consisting of passive and active optical clocks and a fully stabilized microcomb

Deshui Yu, Frank Vollmer, Pascal Del’Haye, Shougang Zhang

Published Jan 26, 2023• 6 citations
Publisher

Abstract

Optical atomic clocks produce highly stable frequency standards and frequency combs bridge clock frequencies with hundreds of terahertz difference. In this paper, we propose a hybrid clock scheme, where a light source pumps an active optical clock through a microresonator-based nonlinear third harmonic process, serves as a passive optical clock via indirectly locking its frequency to an atomic transition, and drives a chip-scale microcomb whose mode spacing is stabilized using the active optical clock. The operation of the whole hybrid system is investigated through simulation analysis. The numerical results show: (i) The short-term frequency stability of the passive optical clock follows an Allan deviation of σ y ( τ ) = 9.3 × 10 −14 τ −1/2 with the averaging time τ , limited by the population fluctuations of interrogated atoms. (ii) The frequency stability of the active optical clock reaches σ y ( τ ) = 6.2 × 10 −15 τ −1/2 , which is close to the quantum noise limit. (iii) The mode spacing of the stabilized microcomb has a shot-noise-limited Allan deviation of σ y ( τ ) = 1.9 × 10 −11 τ −1/2 . Our hybrid scheme may be realized using recently developed technologies in (micro)photonics and atomic physics, paving the way towards on-chip optical frequency comparison, synthesis, and synchronization.

DOI
10.1364/oe.482722

Related papers

Proposal for an active whispering-gallery microclock

Deshui Yu, Frank Vollmer, Shougang Zhang

Abstract Optical atomic clocks with compact size, reduced weight and low power consumption have broad out-of-the-lab applications such as satellite-based geo-positioning and communication engineering. Here, we propose an active optical microclock based on the lattice-trapped atoms evanescently interacting with a whispering-gallery-mode microcavity. Unlike the conventional passive clock scheme, the active operation directly produces the optical frequency standard without the need of extra laser stabilization, substantially simplifying the clock configuration. The numerical simulation illustrates that the microclock’s frequency stability reaches 1.5 × 10 − 14 at 1 s of averaging, over one order of magnitude better than the recently demonstrated chip-scale optical clock that is built upon rubidium vapor cell and also more stable than current cesium fountain clocks and hydrogen masers. Our work extends the chip-scale clocks to the active fashion, paving the way towards the on-chip quantum micro-metrology, for example, the optical frequency comparison and synchronization between multiple microclocks through frequency microcombs.

Quantum Science and Technology•Jan 17, 2023•8 citations

Stabilizing 459 nm passive optical clock for pumping 1470 nm active optical clock

Haoyang Wu, Zhiqiang 智强 Wen 温, Chen Wang +4 more

Abstract Optical clocks with thermal atoms are characterized by compact size, simple structure, reduced weight, and low power consumption and have the potential for broad out-of-the-lab and commercial applications. Here, we demonstrate a 459 nm optical clock based on the 6S 1/2 –7P 1/2 transition in thermal 133 Cs atoms. Two methods, modulation transfer spectroscopy (MTS) and frequency modulation spectroscopy (FMS), are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition. The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of 3.7 × 10 − 13 / τ and 6.4 × 10 − 13 / τ , respectively, at the averaging time τ . The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing. The resultant 1470 nm output power reaches over 10 μW and the pump-beam-induced light shift is estimated to be 2 π × 11 Hz with a fractional uncertainty of 2.4 × 10 −18 . These results demonstrate the feasibility of hybridizing passive and active optical clocks, providing a promising route toward compact multi-wavelength optical frequency standards.

Chinese Physics B•Aug 26, 2025•3 citations

A photonic integrated comb engine for ultracold quantum gases

Wei Sun, Xiaoying Yan, Jinbao Long +18 more

Cold atoms underpin quantum sensing, simulation and computation, but their coherent control demands highly stable optical fields whose generation, referencing and power scaling remain formidable integration challenges. While photonic integrated circuits have yielded compact visible lasers and high-$Q$ microresonators have enabled chip-scale optical frequency combs, these crucial technologies have largely remained functionally fragmented. Consequently, the coherent manipulation of ultracold quantum gases using a fully integrated laser-comb source has yet to be realized. Here we demonstrate a scalable, hybrid-integrated microcomb engine at 780 nm that seamlessly bridges frequency synthesis, atomic referencing and power amplification to achieve quantum state control of a Bose--Einstein condensate. By self-injection locking of electrically driven III--V lasers to high-$Q$ Si$_3$N$_4$ microresonators, we generate coherent platicon microcombs featuring 20- and 100-GHz mode spacings. Absolute referencing of the microcomb to an $^{85}$Rb transition actively suppresses long-term frequency drift from over 200 MHz to the 100-kHz level across 2,000 s. A selected comb tooth is subsequently injection-amplified to 102 mW, entirely preserving the microcomb's pristine coherence and stability. We utilize this synthesized field to construct an optical lattice, drive coherent two-photon Raman transitions, and prepare stationary spin--orbit-coupled and Raman-lattice states within an $^{87}$Rb condensate. By providing a synchronized optical grid, this atom-referenced microcomb can allow multiple optical-control channels to scale without a proportional multiplication of independent frequency references. Our work establishes a fully integrated frequency-synthesis architecture essential for realizing deployable, large-scale atomic quantum systems.

physics.opticsCross-listedarXiv:2609.28294•Sep 24, 2026•0 citations

Active whispering-gallery microclock in pulsed-operation mode

Deshui Yu, Jingbiao Chen, Shougang Zhang

A whispering-gallery-mode microlaser in the bad-cavity limit serves as an active optical clock. In this clock scheme, an ensemble of two-level atoms is trapped in a two-color ring-shaped optical lattice, i.e., Lamb-Dicke regime, and evanescently interacts with an optical microcavity. The microclock is operated in the pulsed mode, where the atoms are periodically pumped into the upper state of the electric-dipole-forbidden clock transition, providing the optical gain. The numerical simulation shows that the fractional frequency instability of the microclock reaches $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}$ at ${10}^{3}$ s of averaging, mainly limited by the lattice-induced frequency shifts. This miniature optical clock owns the high integration and can be potentially used to supply the time standard in a photonic network, paving the way towards the on-chip metrology.

Physical Review A•Apr 26, 2023•4 citations

Enhancing optical clock stability via decoupling laser frequency noise and systematic effects

Qichao Qi, Tao Zhang, Taoyun Jin +10 more

Optical lattice clocks demonstrate advantages in metrology and frontier physics because of their high stability.Here, we present approaches to enhancing the stability by decoupling the noise related to the short-term and long-term stability.For the short-term stability, we optimize the clock laser by decoupling the frequency noise, and optimize each noise contribution individually until it is below the thermal noise limit.For the long-term stability, we introduce a method to decouple the instability caused by systematic effects.Having identified that the collision frequency shift was the main limiting factor in our systems, we thus optimized the atom number fluctuations in optical lattices.Through targeted optimization, we achieve a synchronous comparison of two clocks with an average stability of 3.2 × 10 -16 = τ p and a long-term stability of 2.4 × 10 -18 at 8000 s.This work provides an analytical framework for enhancing optical clock stability.

Chinese Optics Letters•Jan 1, 2025•2 citations

All-Optical Integrated rubidium Atomic Clock

Lute Maleki, Anatoliy A. Savchenkov, Vladimir S. Ilchenko +7 more

We report on progress in the development of an All-Optical Integrated Micro-Primary Atomic Clock (AO-IMPAC). The operattion of the clock is based on an inhomogeneously broadened rubidium optical transition used for stabilization of a Kerr optical frequency comb generated in a high-Q whispering gallery mode (WGM) microresonator. We have demonstrated the initial operation of this clock built in a physics package with dimensions 5 × 6 × 1.2 cm. The clock's long term stability approaches 3 × 10-13at about 2 × 104s integration time. The measured value is limited by the noise floor of the measurement setup.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•May 1, 2011•17 citations
Optical atomic clocks produce highly stable frequency standards and frequency combs bridge clock frequencies with hundreds of terahertz difference. In this paper, we propose a hybrid clock scheme, where a light source pumps an active optical clock through a microresonator-based nonlinear third harmonic process, serves as a passive optical clock via indirectly locking its frequency to an atomic transition, and drives a chip-scale microcomb whose mode spacing is stabilized using the active optical clock. The operation of the whole hybrid system is investigated through simulation analysis. The numerical results show: (i) The short-term frequency stability of the passive optical clock follows an Allan deviation of σ y ( τ ) = 9.3 × 10 −14 τ −1/2 with the averaging time τ , limited by the population fluctuations of interrogated atoms. (ii) The frequency stability of the active optical clock reaches σ y ( τ ) = 6.2 × 10 −15 τ −1/2 , which is close to the quantum noise limit. (iii) The mode spacing of the stabilized microcomb has a shot-noise-limited Allan deviation of σ y ( τ ) = 1.9 × 10 −11 τ −1/2 . Our hybrid scheme may be realized using recently developed technologies in (micro)photonics and atomic physics, paving the way towards on-chip optical frequency comparison, synthesis, and synchronization.
Abstract Optical atomic clocks with compact size, reduced weight and low power consumption have broad out-of-the-lab applications such as satellite-based geo-positioning and communication engineering. Here, we propose an active optical microclock based on the lattice-trapped atoms evanescently interacting with a whispering-gallery-mode microcavity. Unlike the conventional passive clock scheme, the active operation directly produces the optical frequency standard without the need of extra laser stabilization, substantially simplifying the clock configuration. The numerical simulation illustrates that the microclock’s frequency stability reaches 1.5 × 10 − 14 at 1 s of averaging, over one order of magnitude better than the recently demonstrated chip-scale optical clock that is built upon rubidium vapor cell and also more stable than current cesium fountain clocks and hydrogen masers. Our work extends the chip-scale clocks to the active fashion, paving the way towards the on-chip quantum micro-metrology, for example, the optical frequency comparison and synchronization between multiple microclocks through frequency microcombs.
Abstract Optical clocks with thermal atoms are characterized by compact size, simple structure, reduced weight, and low power consumption and have the potential for broad out-of-the-lab and commercial applications. Here, we demonstrate a 459 nm optical clock based on the 6S 1/2 –7P 1/2 transition in thermal 133 Cs atoms. Two methods, modulation transfer spectroscopy (MTS) and frequency modulation spectroscopy (FMS), are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition. The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of 3.7 × 10 − 13 / τ and 6.4 × 10 − 13 / τ , respectively, at the averaging time τ . The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing. The resultant 1470 nm output power reaches over 10 μW and the pump-beam-induced light shift is estimated to be 2 π × 11 Hz with a fractional uncertainty of 2.4 × 10 −18 . These results demonstrate the feasibility of hybridizing passive and active optical clocks, providing a promising route toward compact multi-wavelength optical frequency standards.
Cold atoms underpin quantum sensing, simulation and computation, but their coherent control demands highly stable optical fields whose generation, referencing and power scaling remain formidable integration challenges. While photonic integrated circuits have yielded compact visible lasers and high-QQQ microresonators have enabled chip-scale optical frequency combs, these crucial technologies have largely remained functionally fragmented. Consequently, the coherent manipulation of ultracold quantum gases using a fully integrated laser-comb source has yet to be realized. Here we demonstrate a scalable, hybrid-integrated microcomb engine at 780 nm that seamlessly bridges frequency synthesis, atomic referencing and power amplification to achieve quantum state control of a Bose--Einstein condensate. By self-injection locking of electrically driven III--V lasers to high-QQQ Si3_33​N4_44​ microresonators, we generate coherent platicon microcombs featuring 20- and 100-GHz mode spacings. Absolute referencing of the microcomb to an 85^{85}85Rb transition actively suppresses long-term frequency drift from over 200 MHz to the 100-kHz level across 2,000 s. A selected comb tooth is subsequently injection-amplified to 102 mW, entirely preserving the microcomb's pristine coherence and stability. We utilize this synthesized field to construct an optical lattice, drive coherent two-photon Raman transitions, and prepare stationary spin--orbit-coupled and Raman-lattice states within an 87^{87}87Rb condensate. By providing a synchronized optical grid, this atom-referenced microcomb can allow multiple optical-control channels to scale without a proportional multiplication of independent frequency references. Our work establishes a fully integrated frequency-synthesis architecture essential for realizing deployable, large-scale atomic quantum systems.
A whispering-gallery-mode microlaser in the bad-cavity limit serves as an active optical clock. In this clock scheme, an ensemble of two-level atoms is trapped in a two-color ring-shaped optical lattice, i.e., Lamb-Dicke regime, and evanescently interacts with an optical microcavity. The microclock is operated in the pulsed mode, where the atoms are periodically pumped into the upper state of the electric-dipole-forbidden clock transition, providing the optical gain. The numerical simulation shows that the fractional frequency instability of the microclock reaches $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}$ at 103{10}^{3}103 s of averaging, mainly limited by the lattice-induced frequency shifts. This miniature optical clock owns the high integration and can be potentially used to supply the time standard in a photonic network, paving the way towards the on-chip metrology.
Optical lattice clocks demonstrate advantages in metrology and frontier physics because of their high stability.Here, we present approaches to enhancing the stability by decoupling the noise related to the short-term and long-term stability.For the short-term stability, we optimize the clock laser by decoupling the frequency noise, and optimize each noise contribution individually until it is below the thermal noise limit.For the long-term stability, we introduce a method to decouple the instability caused by systematic effects.Having identified that the collision frequency shift was the main limiting factor in our systems, we thus optimized the atom number fluctuations in optical lattices.Through targeted optimization, we achieve a synchronous comparison of two clocks with an average stability of 3.2 × 10 -16 = τ p and a long-term stability of 2.4 × 10 -18 at 8000 s.This work provides an analytical framework for enhancing optical clock stability.
We report on progress in the development of an All-Optical Integrated Micro-Primary Atomic Clock (AO-IMPAC). The operattion of the clock is based on an inhomogeneously broadened rubidium optical transition used for stabilization of a Kerr optical frequency comb generated in a high-Q whispering gallery mode (WGM) microresonator. We have demonstrated the initial operation of this clock built in a physics package with dimensions 5 × 6 × 1.2 cm. The clock's long term stability approaches 3 × 10-13at about 2 × 104s integration time. The measured value is limited by the noise floor of the measurement setup.