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:1501.01733

Optical frequency standard based on a two-photon transition in calcium

Amar C. Vutha

Published Jan 8, 2015• 0 citations
arXivHTMLPDF

Abstract

A two-photon transition in laser-cooled and trapped calcium atoms is proposed as the atomic reference in an optical frequency standard. An efficient scheme for interrogation of the frequency standard is described, and the sensitivity of the clock transition to systematic effects is estimated. Frequency standards based on this transition could lead to compact and portable devices that are capable of rapidly averaging down to $< 10^{-16}$.

DOI
10.48550/arxiv.1501.01733

Related papers

Toward a Compact Two-photon Optical Clock based on Calcium

Shira Jackson

This thesis presents details on the design, construction, and characterization of a novel compact optical clock based on a two-photon transition in calcium. Optical atomic clocks have reached unprecedented accuracy and precision and have the potential to revolutionize metrology. However, many of the applications of optical clocks, such as the detection of dark matter and gravitational waves, deep space navigation, measurements of variations in fundamental constants, and precision geodetic measurements, require compact portable clocks. Building optical atomic clocks on a scale suitable for most field applications is an ongoing challenge in the precision metrology community. This work describes a clock that can be made smaller and simpler than most existing optical clocks, while still operating with state-of-the-art precision. The basis for these improvements is using a two-photon transition, which eliminates the need for sub-Doppler cooling and tight confinement of the atoms. The design for the calcium two-photon clock is given, and the construction of the clock components is described. Experimental results are presented for the search for the clock transition frequency, which has never before been precisely determined. A detailed uncertainty budget is given, showing that this clock should be able to achieve a fractional frequency uncertainty of $\sim 10^{-17}$. In addition, a novel technique of ``magic polarization'' is presented which can be implemented to mitigate probe laser light shifts, long thought to be a serious impediment to precision two-photon clocks. An experiment in which a two-photon clock based on rubidium was launched and operated on a stratospheric balloon and subsequently recovered is also described. This work represents an advancement in the development of compact portable optical clocks which will further push the boundaries of precision measurement and our understanding of the universe.

•Jun 1, 2023•0 citations

Optical frequency standard based on a single 40Ca+

Kelin Gao

Research on the development of the optical frequency standard based on trapped and cold 40 Ca + with the 4s 2 S 1/2 -3d 2 D 5/2 clock transition at 729 nm is reported. A single calcium ion was trapped and laser cooled in the Paul trap and stay in trap for more than 15 days. The linewidth of a 729 nm laser was reduced to less than 10 Hz by locking to a cavity for longer than 50 hours uninterruptedly. The overall systematic uncertainty of the clock transition has been characterized to be better than 6.5×10 −16 . The absolute frequency of the clock transition was measured at 10 −15 level using an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the global positioning system (GPS). The frequency value was 411042129776393.0(1.6) Hz after the correction of the systematic shifts.

Chinese Science Bulletin•Mar 1, 2013•9 citations

Progress Towards the Development of a Portable All-optical Atomic Clock Based on a Two-photon Transition in Warm Atomic Vapor

S. Jana, B. K. Sahoo, Arijit Sharma

Optical clocks represent the hallmark of precise timekeeping. The most precise atomic clocks are laboratory-based ones that utilize transitions in the microwave/optical domain of neutral atoms or trapped ions. These clocks define an international time scales, confirm the consistency of physical constants and stimulate the search for new physics outside the Standard Model. The other area is the regime of portable atomic clocks based on warm atomic vapor, which is small, power-efficient and deployable in the field with a variety of civilian applications, including sensing, communication and navigation. Two-photon resonance and optical transition based field deployable clocks present a viable alternative that may outperform current commercial chip scale clocks by at least a factor of 10 in terms of both long-term and short-term stability. For portable clocks, two-photon transitions in alkaline earth metals are of special interest. One of the systematic inaccuracies in the optical reference is eliminated by using counter-propagating laser beams to create Doppler-free spectroscopy. At IIT Tirupati, we are engaged in developing the next generation of atomic vapor based portable frequency standard using two-photon transition in Rubidium (Rb) for atomic sensing and quantum positioning applications. This article discusses the physics behind the two-photon transition in Rubidium atoms suitable for a clock reference. Briefly, it discusses the experimental methodology for realizing an optical clock using warm rubidium vapor.

URSI Regional Conference on Radio Science (URSI-RCRS)•Dec 1, 2022•1 citation

Blue laser for precision spectroscopy: toward optical frequency standard referenced to laser cooled calcium atoms

Vera Grishina

Optical frequency standards with the reference to a narrow electronic transition of a laser-cooled collection of neutral atomic particles are becoming essential tools of research in modern precision physics experiments. In the core of a building block of an optical frequency standard is the optical continuous wave laser that has a good spectral purity of the emitted light. Such a stable optical oscillator is highly desirable in high resolution spectroscopy, if it emits in a good quality beam at a short visible wavelength. This Master thesis explores efficient techniques for building such an optical frequency source intended for use in the cooling and trapping of Calcium atoms scheme. The strong dipole transition at the blue wavelength in the atomic Calcium is needed to reduce the kinetic energy of atoms by nearly six orders of magnitude. A further reduction in the thermal energy of the laser cooled atoms is required to locate with ultra-high precision the 400 Hz narrow clock transition of the stable 40Ca isotope. The experimental methods that achieve this and approach sub-microkelvin temperature of the laser cooled bosonic isotopes of alkaline earths are inspected. The blue laser with a uniform intensity distribution in the beam is useful to maintain the trapped number of cold atoms during these experiments. The spectroscopic properties of the relative transitions in Calcium atom are also reviewed following relevant publications in the area. The constructed blue laser can be used as a primary wavelength source in the lasers network for cooling and trapping of Calcium atoms. These experiments will constitute part of the project to build an optical atom clock referenced to 40Ca narrow linewidth transition. The blue laser is constructed by generating second harmonic in a Potassium Niobate crystal, which is temperature controlled to use a type-I noncritical phase-matching of the optical nonlinear process. The power of the intracavity-generated second harmonic depends on the resonance properties of the optical resonator where this nonlinear crystal is placed. The study is aimed at characterising the designed optical resonator and the experimental parameters that describe it. The formula is derived that relates the resonance power enhancement coefficient with finesse and the power coupling contrast of a passive optical cavity. The obtained relationship is verfied during the experiments. The produced efficiency of the intracavity second harmonic generation is approx. 0.0023 mWblue/(mWred)2. The research work also examines the noise characteristics of the infrared diode laser that is used as a pump source for the intracavity generated second harmonic and determines the spectroscopic precision of the produced blue light. The frequency locking experiment is analysed using the unbalanced scheme of the polarisation stabilisation technique. The designed optical buildup cavity became a part of the unbalanced frequency discriminator in such a scheme. The results demonstrate high gain of frequency noise suppression of the stabilised laser. The unbalanced arrangement of the H}ansch-Couillaud technique has been possible due to a very low amplitude noise of semiconductor lasers.

•Jan 1, 2008•0 citations

Miniaturized optical frequency reference for next-generation portable optical clocks

Vincent N. Maurice, Zachary L. Newman, Susannah M. Dickerson +7 more

Optical frequency standards, or lasers stabilized to atomic or molecular transitions, are widely used in length metrology and laser ranging, provide a backbone for optical communications and lie at the heart of next-generation optical atomic clocks. Here we demonstrate a compact, low-power optical frequency reference based on the Doppler-free, two-photon transition in rubidium-87 at 778 nm implemented on a micro-optics breadboard. Our optical reference achieves a fractional frequency instability of 2.9×10−12/ τ for averaging times τ less than 103 s, has a volume of ≈35 cm3 and operates on ≈450 mW of electrical power. The advanced optical integration presented here demonstrates a key step towards the development of compact optical clocks and the broad dissemination of SI-traceable wavelength references.

arXiv:2003.13172•Optics Express•Jul 15, 2020•71 citations

Single Trapped 171Yb+ for Optical Frequency Standards

Atish Roy, Lakhi Sharma, Harish Kumar Rathore +5 more

An optical clock or frequency standard based on the interrogation of an atomic transition in the optical domain, operates at ~1014Hz is capable of providing orders of magnitude better accuracy than the present primary standard of frequency or time operating in the microwave range. Optical transitions of an ions, confined within a radio frequency ion trap and laser cooled to ~mK temperature, provides better long term stability since they are free from Coulomb and intra-atomic interactions. Optical frequency standards have been realized with several ions, e.g.,199Hg+,171Yb+,115In+,88Sr+,40Ca+,27Al+and among those171Y+has multiple ultra-narrow optical transitions suitable for serving as frequency standards [1-2].

URSI Asia-Pacific Radio Science Conference•Mar 1, 2019•0 citations
A two-photon transition in laser-cooled and trapped calcium atoms is proposed as the atomic reference in an optical frequency standard. An efficient scheme for interrogation of the frequency standard is described, and the sensitivity of the clock transition to systematic effects is estimated. Frequency standards based on this transition could lead to compact and portable devices that are capable of rapidly averaging down to <10−16< 10^{-16}<10−16.
This thesis presents details on the design, construction, and characterization of a novel compact optical clock based on a two-photon transition in calcium. Optical atomic clocks have reached unprecedented accuracy and precision and have the potential to revolutionize metrology. However, many of the applications of optical clocks, such as the detection of dark matter and gravitational waves, deep space navigation, measurements of variations in fundamental constants, and precision geodetic measurements, require compact portable clocks. Building optical atomic clocks on a scale suitable for most field applications is an ongoing challenge in the precision metrology community. This work describes a clock that can be made smaller and simpler than most existing optical clocks, while still operating with state-of-the-art precision. The basis for these improvements is using a two-photon transition, which eliminates the need for sub-Doppler cooling and tight confinement of the atoms. The design for the calcium two-photon clock is given, and the construction of the clock components is described. Experimental results are presented for the search for the clock transition frequency, which has never before been precisely determined. A detailed uncertainty budget is given, showing that this clock should be able to achieve a fractional frequency uncertainty of ∼10−17\sim 10^{-17}∼10−17. In addition, a novel technique of ``magic polarization'' is presented which can be implemented to mitigate probe laser light shifts, long thought to be a serious impediment to precision two-photon clocks. An experiment in which a two-photon clock based on rubidium was launched and operated on a stratospheric balloon and subsequently recovered is also described. This work represents an advancement in the development of compact portable optical clocks which will further push the boundaries of precision measurement and our understanding of the universe.
Research on the development of the optical frequency standard based on trapped and cold 40 Ca + with the 4s 2 S 1/2 -3d 2 D 5/2 clock transition at 729 nm is reported. A single calcium ion was trapped and laser cooled in the Paul trap and stay in trap for more than 15 days. The linewidth of a 729 nm laser was reduced to less than 10 Hz by locking to a cavity for longer than 50 hours uninterruptedly. The overall systematic uncertainty of the clock transition has been characterized to be better than 6.5×10 −16 . The absolute frequency of the clock transition was measured at 10 −15 level using an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the global positioning system (GPS). The frequency value was 411042129776393.0(1.6) Hz after the correction of the systematic shifts.
Optical clocks represent the hallmark of precise timekeeping. The most precise atomic clocks are laboratory-based ones that utilize transitions in the microwave/optical domain of neutral atoms or trapped ions. These clocks define an international time scales, confirm the consistency of physical constants and stimulate the search for new physics outside the Standard Model. The other area is the regime of portable atomic clocks based on warm atomic vapor, which is small, power-efficient and deployable in the field with a variety of civilian applications, including sensing, communication and navigation. Two-photon resonance and optical transition based field deployable clocks present a viable alternative that may outperform current commercial chip scale clocks by at least a factor of 10 in terms of both long-term and short-term stability. For portable clocks, two-photon transitions in alkaline earth metals are of special interest. One of the systematic inaccuracies in the optical reference is eliminated by using counter-propagating laser beams to create Doppler-free spectroscopy. At IIT Tirupati, we are engaged in developing the next generation of atomic vapor based portable frequency standard using two-photon transition in Rubidium (Rb) for atomic sensing and quantum positioning applications. This article discusses the physics behind the two-photon transition in Rubidium atoms suitable for a clock reference. Briefly, it discusses the experimental methodology for realizing an optical clock using warm rubidium vapor.
Optical frequency standards with the reference to a narrow electronic transition of a laser-cooled collection of neutral atomic particles are becoming essential tools of research in modern precision physics experiments. In the core of a building block of an optical frequency standard is the optical continuous wave laser that has a good spectral purity of the emitted light. Such a stable optical oscillator is highly desirable in high resolution spectroscopy, if it emits in a good quality beam at a short visible wavelength. This Master thesis explores efficient techniques for building such an optical frequency source intended for use in the cooling and trapping of Calcium atoms scheme. The strong dipole transition at the blue wavelength in the atomic Calcium is needed to reduce the kinetic energy of atoms by nearly six orders of magnitude. A further reduction in the thermal energy of the laser cooled atoms is required to locate with ultra-high precision the 400 Hz narrow clock transition of the stable 40Ca isotope. The experimental methods that achieve this and approach sub-microkelvin temperature of the laser cooled bosonic isotopes of alkaline earths are inspected. The blue laser with a uniform intensity distribution in the beam is useful to maintain the trapped number of cold atoms during these experiments. The spectroscopic properties of the relative transitions in Calcium atom are also reviewed following relevant publications in the area. The constructed blue laser can be used as a primary wavelength source in the lasers network for cooling and trapping of Calcium atoms. These experiments will constitute part of the project to build an optical atom clock referenced to 40Ca narrow linewidth transition. The blue laser is constructed by generating second harmonic in a Potassium Niobate crystal, which is temperature controlled to use a type-I noncritical phase-matching of the optical nonlinear process. The power of the intracavity-generated second harmonic depends on the resonance properties of the optical resonator where this nonlinear crystal is placed. The study is aimed at characterising the designed optical resonator and the experimental parameters that describe it. The formula is derived that relates the resonance power enhancement coefficient with finesse and the power coupling contrast of a passive optical cavity. The obtained relationship is verfied during the experiments. The produced efficiency of the intracavity second harmonic generation is approx. 0.0023 mWblue/(mWred)2. The research work also examines the noise characteristics of the infrared diode laser that is used as a pump source for the intracavity generated second harmonic and determines the spectroscopic precision of the produced blue light. The frequency locking experiment is analysed using the unbalanced scheme of the polarisation stabilisation technique. The designed optical buildup cavity became a part of the unbalanced frequency discriminator in such a scheme. The results demonstrate high gain of frequency noise suppression of the stabilised laser. The unbalanced arrangement of the H}ansch-Couillaud technique has been possible due to a very low amplitude noise of semiconductor lasers.
Optical frequency standards, or lasers stabilized to atomic or molecular transitions, are widely used in length metrology and laser ranging, provide a backbone for optical communications and lie at the heart of next-generation optical atomic clocks. Here we demonstrate a compact, low-power optical frequency reference based on the Doppler-free, two-photon transition in rubidium-87 at 778 nm implemented on a micro-optics breadboard. Our optical reference achieves a fractional frequency instability of 2.9×10−12/ τ for averaging times τ less than 103 s, has a volume of ≈35 cm3 and operates on ≈450 mW of electrical power. The advanced optical integration presented here demonstrates a key step towards the development of compact optical clocks and the broad dissemination of SI-traceable wavelength references.
An optical clock or frequency standard based on the interrogation of an atomic transition in the optical domain, operates at ~1014Hz is capable of providing orders of magnitude better accuracy than the present primary standard of frequency or time operating in the microwave range. Optical transitions of an ions, confined within a radio frequency ion trap and laser cooled to ~mK temperature, provides better long term stability since they are free from Coulomb and intra-atomic interactions. Optical frequency standards have been realized with several ions, e.g.,199Hg+,171Yb+,115In+,88Sr+,40Ca+,27Al+and among those171Y+has multiple ultra-narrow optical transitions suitable for serving as frequency standards [1-2].