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

Conference on Precision Electromagnetic Measurements

Optical Frequency Stabilization at the 10−16 Fractional Level Utilizing Ramsey-Borde Atom Interferometry

Judith Olson, Richard W. Fox, Tara M. Fortier, Chris W. Oates, Andrew D. Ludlow

Published Jul 1, 2018• 1 citation
Publisher

Abstract

We demonstrate laser frequency stabilization at the 10-16fractional frequency level in one second through spectroscopy on a 650 °C calcium atomic beam. The calcium beam is interrogated with a cavity stabilized 657 nm laser arranged in a Ramsey-Borde configuration. A second laser at 431 nm reads off the final atomic state populations while allowing for high signal-to-noise. Limitations of this method are being explored and, and, based on current noise analysis, there is potential to achieve fractional frequency stabilities in the 10-17range or below.

DOI
10.1109/cpem.2018.8500877

Related papers

Ramsey-Bordé Matter-Wave Interferometry for Laser Frequency Stabilization at 10 − 16 Frequency Instability and Below

Judith Olson, Richard W. Fox, Tara M. Fortier +6 more

We demonstrate Ramsey-Bordé (RB) atom interferometry for high performance laser stabilization with fractional frequency instability <2×10^{-16} for timescales between 10 and 1000s. The RB spectroscopy laser interrogates two counterpropagating ^{40}Ca beams on the ^{1}S_{0}-^{3}P_{1} transition at 657 nm, yielding 1.6 kHz linewidth interference fringes. Fluorescence detection of the excited state population is performed on the (4s4p) ^{3}P_{1}-(4p^{2}) ^{3}P_{0} transition at 431 nm. Minimal thermal shielding and no vibration isolation are used. These stability results surpass performance from other thermal atomic or molecular systems by 1 to 2 orders of magnitude, and further improvements look feasible.

arXiv:1907.06774•Physical Review Letters•Aug 13, 2019•61 citations

Ramsey-Borde Matter-Wave Interferometry with a Thermal Calcium Beam for Optical Frequency Stabilization ≤ 10-16

Judith Olson

This dissertation details the developments of a calcium thermal beam atom interferometer designed to act as an ultra-stable frequency reference over a broad range of timescales. The obtained fractional frequency instabilities of the final apparatus reached ≤ 10−16 after 10's of seconds of averaging without the aid of vibration isolation or significant apparatus temperature stabilization. The vastly superior stability performance of this calcium system compared to other thermal atomic references was facilitated by the enormous atom numbers from the thermal beam, which can be efficiently addressed with Bord\'e-Ramsey spectroscopy on the well-studied (4s2)1S0-(4s4p)3P1 (m=0) clock transition in neutral 40Ca. This method yields interrogation laser frequency dependent interference fringes with a linewidth of 1.6 kHz. This measurement is further enhanced with an electron-shelving detection scheme used for state detection after the interferometry process, causing each excited state atom to emit many hundreds of photons in the detection region. The exceptional instability results from this atom interferometer highlight an underutilized realm of precision measurement science based on relatively simple thermal ensembles. An intuitive understanding of the Bordé-Ramsey process is presented and relevant experimental techniques explained such that this dissertation should prove useful to a broad readership.

•Jan 1, 2019•0 citations

Fractional frequency instability in the 10^−14 range with a thermal beam optical frequency reference

John J. McFerran, Andre Nicholas Luiten

We demonstrate a means of increasing the signal-to-noise ratio in a Ramsey-Bordé interferometer with spatially separated oscillatory fields on a thermal atomic beam. The S01↔P13 intercombination line in neutral Ca40 is used as a frequency discriminator, with an extended cavity diode laser at 423 nm probing the ground state population after a Ramsey-Bordé sequence of 657 nm light-field interactions with the atoms. Evaluation of the instability of the Ca frequency reference is carried out by comparison with (i) a hydrogen-maser and (ii) a cryogenic sapphire oscillator. In the latter case the Ca reference exhibits a square-root Λ variance of 9.2×10−14 at 1 s and 2.0×10−14 at 64 s. This is an order-of-magnitude improvement for optical beam frequency references, to our knowledge. The shot noise of the readout fluorescence produces a limiting square-root Λ variance of 7×10−14/√τ, highlighting the potential for improvement. This work demonstrates the feasibility of a portable frequency reference in the optical domain with 10−14 range frequency instability.

Journal of the Optical Society of America B•Jan 22, 2010•37 citations

An optical beam frequency reference with 10−14 range frequency instability

John J. McFerran, John Gideon Hartnett, Andre Nicholas Luiten

The authors report on a thermal beam optical frequency reference with a fractional frequency instability of 9.2×10−14 at 1 s reducing to 2.0×10−14 at 64 s before slowly rising. The 1S0↔3P1 intercombination line in neutral 40Ca is used as a frequency discriminator. A diode laser at 423 nm probes the ground state population after a Ramsey–Bordé sequence of 657 nm light-field interactions on the atoms. The measured fractional frequency instability is an order of magnitude improvement on previously reported thermal beam optical clocks. The photon shot-noise of the read-out produces a limiting square root Λ-variance of 7×10−14/.

Applied Physics Letters•Jul 20, 2009•10 citations

An all-diode-laser optical frequency reference using laser-trapped calcium

Chris W. Oates, Michelle S. Stephens, Leo W. Hollberg

The 657 nm calcium intercombination line is an attractive optical frequency/length reference due to its high line Q (10/sup 12/) and insensitivity to external perturbations. In this paper we describe progress towards an all-diode-laser-based reference using laser-trapped Ca. To generate 35 mW of 423 nm trap light, we double the frequency of a 150 mW, 846 nm diode laser with a nonlinear crystal (KNbO/sub 3/) inside a resonant build-up cavity. We use this light to trap 2/spl times/10/sup 7/ atoms in a compact, magneto-optic trap. Spectroscopy of the narrow 657 nm transition is performed with a frequency-stabilized diode laser system. With the trapped atoms we have measured optical Ramsey fringes with a linewidth of 6 kHz. We discuss future improvements as well as potential performance which could achieve a fractional frequency instability of <3/spl times/10/sup -15/.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Nov 23, 2002•7 citations

Cold Beam Optical Clock with Multifrequency Spectroscopy

William G. Tobias, Bryan Hemingway, Steven Peil

We demonstrate an optical clock based on Ramsey-Bordé interferometry in a laser-cooled ^{40}Ca beam. The mean velocity is reduced by an order of magnitude relative to a thermal beam and the transverse temperature approaches the Doppler limit, enabling the measurement of sub-kHz linewidth fringes in a compact interferometer. Using tailored phase and intensity modulation of the spectroscopy laser to add uniform frequency sidebands, we interrogate atoms throughout the transverse velocity distribution, increasing the Ramsey-Bordé fringe amplitude by a factor of 14 and improving the Allan deviation to 3.4×10^{-15} at one second averaging time.

arXiv:2409.13512•Physical Review Letters•Jan 27, 2025•9 citations
We demonstrate laser frequency stabilization at the 10-16fractional frequency level in one second through spectroscopy on a 650 °C calcium atomic beam. The calcium beam is interrogated with a cavity stabilized 657 nm laser arranged in a Ramsey-Borde configuration. A second laser at 431 nm reads off the final atomic state populations while allowing for high signal-to-noise. Limitations of this method are being explored and, and, based on current noise analysis, there is potential to achieve fractional frequency stabilities in the 10-17range or below.
We demonstrate Ramsey-Bordé (RB) atom interferometry for high performance laser stabilization with fractional frequency instability <2×10^{-16} for timescales between 10 and 1000s. The RB spectroscopy laser interrogates two counterpropagating ^{40}Ca beams on the ^{1}S_{0}-^{3}P_{1} transition at 657 nm, yielding 1.6 kHz linewidth interference fringes. Fluorescence detection of the excited state population is performed on the (4s4p) ^{3}P_{1}-(4p^{2}) ^{3}P_{0} transition at 431 nm. Minimal thermal shielding and no vibration isolation are used. These stability results surpass performance from other thermal atomic or molecular systems by 1 to 2 orders of magnitude, and further improvements look feasible.
This dissertation details the developments of a calcium thermal beam atom interferometer designed to act as an ultra-stable frequency reference over a broad range of timescales. The obtained fractional frequency instabilities of the final apparatus reached ≤ 10−16 after 10's of seconds of averaging without the aid of vibration isolation or significant apparatus temperature stabilization. The vastly superior stability performance of this calcium system compared to other thermal atomic references was facilitated by the enormous atom numbers from the thermal beam, which can be efficiently addressed with Bord\'e-Ramsey spectroscopy on the well-studied (4s2)1S0-(4s4p)3P1 (m=0) clock transition in neutral 40Ca. This method yields interrogation laser frequency dependent interference fringes with a linewidth of 1.6 kHz. This measurement is further enhanced with an electron-shelving detection scheme used for state detection after the interferometry process, causing each excited state atom to emit many hundreds of photons in the detection region. The exceptional instability results from this atom interferometer highlight an underutilized realm of precision measurement science based on relatively simple thermal ensembles. An intuitive understanding of the Bordé-Ramsey process is presented and relevant experimental techniques explained such that this dissertation should prove useful to a broad readership.
We demonstrate a means of increasing the signal-to-noise ratio in a Ramsey-Bordé interferometer with spatially separated oscillatory fields on a thermal atomic beam. The S01↔P13 intercombination line in neutral Ca40 is used as a frequency discriminator, with an extended cavity diode laser at 423 nm probing the ground state population after a Ramsey-Bordé sequence of 657 nm light-field interactions with the atoms. Evaluation of the instability of the Ca frequency reference is carried out by comparison with (i) a hydrogen-maser and (ii) a cryogenic sapphire oscillator. In the latter case the Ca reference exhibits a square-root Λ variance of 9.2×10−14 at 1 s and 2.0×10−14 at 64 s. This is an order-of-magnitude improvement for optical beam frequency references, to our knowledge. The shot noise of the readout fluorescence produces a limiting square-root Λ variance of 7×10−14/√τ, highlighting the potential for improvement. This work demonstrates the feasibility of a portable frequency reference in the optical domain with 10−14 range frequency instability.
The authors report on a thermal beam optical frequency reference with a fractional frequency instability of 9.2×10−14 at 1 s reducing to 2.0×10−14 at 64 s before slowly rising. The 1S0↔3P1 intercombination line in neutral 40Ca is used as a frequency discriminator. A diode laser at 423 nm probes the ground state population after a Ramsey–Bordé sequence of 657 nm light-field interactions on the atoms. The measured fractional frequency instability is an order of magnitude improvement on previously reported thermal beam optical clocks. The photon shot-noise of the read-out produces a limiting square root Λ-variance of 7×10−14/.
The 657 nm calcium intercombination line is an attractive optical frequency/length reference due to its high line Q (10/sup 12/) and insensitivity to external perturbations. In this paper we describe progress towards an all-diode-laser-based reference using laser-trapped Ca. To generate 35 mW of 423 nm trap light, we double the frequency of a 150 mW, 846 nm diode laser with a nonlinear crystal (KNbO/sub 3/) inside a resonant build-up cavity. We use this light to trap 2/spl times/10/sup 7/ atoms in a compact, magneto-optic trap. Spectroscopy of the narrow 657 nm transition is performed with a frequency-stabilized diode laser system. With the trapped atoms we have measured optical Ramsey fringes with a linewidth of 6 kHz. We discuss future improvements as well as potential performance which could achieve a fractional frequency instability of <3/spl times/10/sup -15/.
We demonstrate an optical clock based on Ramsey-Bordé interferometry in a laser-cooled ^{40}Ca beam. The mean velocity is reduced by an order of magnitude relative to a thermal beam and the transverse temperature approaches the Doppler limit, enabling the measurement of sub-kHz linewidth fringes in a compact interferometer. Using tailored phase and intensity modulation of the spectroscopy laser to add uniform frequency sidebands, we interrogate atoms throughout the transverse velocity distribution, increasing the Ramsey-Bordé fringe amplitude by a factor of 14 and improving the Allan deviation to 3.4×10^{-15} at one second averaging time.