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

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)

Progress towards the second-generation atomic fountain clock at NIST

Elizabeth A. Donley, Thomas P. Heavner, M. O. Tataw, Filippo Levi, Steven R. Jefferts

Published Jan 18, 2006• 4 citations
Publisher

Abstract

We present results on the performance of two important subsystems for NIST-F2 - the second-generation atomic fountain clock at NIST. Firstly, we demonstrate the efficient capture of cesium atoms from a low-velocity intense source (LVIS) of atoms into an optical molasses. Our typical LVIS flux was 10/sup 10/ s/sup -1/. The initial molasses fill rate was R/sub t=0/ = 3.8(5)/spl times/10/sup 9/ s/sup -1/, which is consistent with 100% atom capture given the lifetime of our vacuum system. Secondly, recent results for our launch performance in the (1,1,1) fountain geometry are presented. We were able to cool the atoms to a temperature of 1.5 /spl mu/K with our current design. Our plans for improving the laser cooling performance are also presented.

DOI
10.1109/freq.2004.1573617

Related papers

Optical molasses loaded from a low-velocity intense source of atoms: an atom source for improved atomic fountains

Elizabeth A. Donley, Thomas P. Heavner, Steven R. Jefferts

We demonstrate the efficient capture of cesium atoms from a low-velocity intense source (LVIS) of atoms into an optical molasses. The high load rates that are achievable with the technique can potentially improve the stability of and reduce collisional shifts in atomic fountain clocks. An LVIS is an atomic beam created from a small hole in one of the retroreflectors in an otherwise ordinary magnetooptical trap (MOT). Our typical LVIS flux was 10/sup 10/ atoms/s. The asymptotic value for the number of atoms captured in the optical molasses was 1.1(1) /spl times/ 10/sup 9/ atoms, and the fill time constant was /spl tau/ = 290(30) ms. The initial molasses fill rate was R/sub t=0/ = 3.8(5) /spl times/ 10/sup 6/ atoms/ms. At this rate, it would require 24 ms to capture and launch 10/sup 7/ state-selected atoms in an atomic fountain. The fill rate at short times indicates that approximately 40% of the LVIS atoms were being captured in the optical molasses.

IEEE Transactions on Instrumentation and Measurement•Oct 1, 2005•11 citations

Study of a bright, slow, and cold cesium source for a continuous beam frequency standard

P. Berthoud, E. Fretel, P. Thomann

To achieve a primary frequency standard based on a continuous fountain of laser cooled cesium atoms, we report on the production of a bright, slow and cold continuous atomic beam. Atoms are cooled from a thermal vapor in a 45/spl deg/ laser geometry and launched directly from the optical molasses by the moving molasses technique. The effects of the source fluorescence on the continuous beam (average velocity, temperature and flux) have been observed, and ways to optimize simultaneously the atomic capture and the continuous beam are presented. Flux measurements rise to 2/spl times/10/sup 8/ at/s from a 2D magneto-optical trap at 7 m/s. The initial velocity is easily tunable from 1 to 10 m/s. If the longitudinal temperature is about 70 /spl mu/K, additional transverse cooling even reduces the transverse temperature in one dimension below 30 /spl mu/K. By extrapolating the obtained atomic flux to the continuous fountain under construction, we expect a short-term stability of 7/spl times/10/sup -14//spl tau//sup -1/2/. Other applications of continuous beams of cold atoms are suggested.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Jan 22, 2003•2 citations

Laser cooling and launching performance in a (1,1,1)-geometry atomic fountain

Elizabeth A. Donley, Thomas P. Heavner, J.W. O'Brien +2 more

We have successfully cooled and launched cesium atoms in the (1,1,1) atomic fountain geometry at temperatures as low as 0.8 /spl mu/K. This corresponds to a root-mean-square thermal velocity of 0.7 cm/s, which is two times the photon recoil velocity of 0.35 cm/s. Factors that limit the final temperature are presented in detail.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Jan 18, 2006•5 citations

Article

Marie-Claude Gagné, J.-S. Boulanger, R J W Douglas

The accelerated development of laser methods for manipulating the internal state and motion of atoms, and the recent primary evaluation in France of a cesium frequency standard using cold atoms in an atomic fountain configuration, allow the frontiers of time metrology, accuracy, and stability to be pushed near parts in the 1016 level, a factor of 100 over the present primary laboratory clocks. These positive results revived the development of more accurate cesium atomic clocks, and the Institute of National Measurement Standards (INMS), of the National Research Council of Canada (NRC) is undertaking a cesium-fountain project aimed at reaching these new levels of accuracy and stability. This paper reviews its present status. To appreciate the considerable impact of cold atoms in time and frequency metrology, we begin by recalling the background principles of traditional cesium frequency standards, their typical performance and main limitations. After introducing the important theoretical results essential to understanding the techniques of laser cooling and magneto-optical trapping, we focus on describing the characterization and control of our magneto-optical trap (MOT) and report the parameters that allow us to fill the trap with a few million atoms in less than a second and cool them to a temperature lower than 5 muK using optical molasses. We will describe the specifics of our cesium-fountain prototype, which operates with a 2-dimensional moving molasses. This special configuration is applicable for multipulse operation of the fountain, which can greatly relax the local oscillator requirements for time keeping. Finally, progress toward our objective of launching cooled atoms, at a rate of one ensemble per second, at speeds of 7 m/s, for a fountain with an interrogation time of about 1 s, will be analysed.PACS Nos.: 06.20, 06.30, and 32.80P

Canadian Journal of Physics•Aug 1, 1998•0 citations

Cold atoms and cesium fountains at NRC

J.-S. Boulanger, Marie-Claude Gagné, R.J. Douglas

We present a progress report on laser-cooled cesium atoms at NRC, work which was started a few years ago in order to realize a cesium fountain frequency standard. We selected an acceleration with two-dimensional moving molasses, which can increase both the force and the interaction time by a factor of /spl radic/2 over the more common 1-D molasses scheme. This configuration also allows for trapping and cooling of atoms while previously launched atoms are still moving in the clock section of the system. We report measurements on the number of atoms, temperature, friction coefficient and spring constant of our magneto-optical trap and 1-D molasses for various conditions.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Dec 24, 2002•4 citations

Cesium fountain development at USNO

Eric A. Burt, Thomas B. Swanson, Christopher R. Ekstrom

In this paper we discuss progress made at the U.S. Naval Observatory (USNO) towards building a cesium fountain atomic clock. In particular we will address the efficacy of a 4-beam optical lattice as an atom collection and launch mechanism. To date we have measured temperatures in a 4-beam lattice of 1.4(0.3) /spl mu/K and have launched atoms from this lattice to a height of just under a meter with a temperature of 1.7(0.1) /spl mu/K. We are able to collect 2.4/spl times/10/sup 6/ atoms using only the lattice beams and no magnetic fields. We have completed the design for and are in the process of fabricating all aspects of the fountain device including the collection region, the drift region, the microwave cavity and the magnetic shields. We present our progress to date including a discussion of our launch results and the design and testing of our magnetic shields.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Jan 22, 2003•6 citations
We present results on the performance of two important subsystems for NIST-F2 - the second-generation atomic fountain clock at NIST. Firstly, we demonstrate the efficient capture of cesium atoms from a low-velocity intense source (LVIS) of atoms into an optical molasses. Our typical LVIS flux was 10/sup 10/ s/sup -1/. The initial molasses fill rate was R/sub t=0/ = 3.8(5)/spl times/10/sup 9/ s/sup -1/, which is consistent with 100% atom capture given the lifetime of our vacuum system. Secondly, recent results for our launch performance in the (1,1,1) fountain geometry are presented. We were able to cool the atoms to a temperature of 1.5 /spl mu/K with our current design. Our plans for improving the laser cooling performance are also presented.
We demonstrate the efficient capture of cesium atoms from a low-velocity intense source (LVIS) of atoms into an optical molasses. The high load rates that are achievable with the technique can potentially improve the stability of and reduce collisional shifts in atomic fountain clocks. An LVIS is an atomic beam created from a small hole in one of the retroreflectors in an otherwise ordinary magnetooptical trap (MOT). Our typical LVIS flux was 10/sup 10/ atoms/s. The asymptotic value for the number of atoms captured in the optical molasses was 1.1(1) /spl times/ 10/sup 9/ atoms, and the fill time constant was /spl tau/ = 290(30) ms. The initial molasses fill rate was R/sub t=0/ = 3.8(5) /spl times/ 10/sup 6/ atoms/ms. At this rate, it would require 24 ms to capture and launch 10/sup 7/ state-selected atoms in an atomic fountain. The fill rate at short times indicates that approximately 40% of the LVIS atoms were being captured in the optical molasses.
To achieve a primary frequency standard based on a continuous fountain of laser cooled cesium atoms, we report on the production of a bright, slow and cold continuous atomic beam. Atoms are cooled from a thermal vapor in a 45/spl deg/ laser geometry and launched directly from the optical molasses by the moving molasses technique. The effects of the source fluorescence on the continuous beam (average velocity, temperature and flux) have been observed, and ways to optimize simultaneously the atomic capture and the continuous beam are presented. Flux measurements rise to 2/spl times/10/sup 8/ at/s from a 2D magneto-optical trap at 7 m/s. The initial velocity is easily tunable from 1 to 10 m/s. If the longitudinal temperature is about 70 /spl mu/K, additional transverse cooling even reduces the transverse temperature in one dimension below 30 /spl mu/K. By extrapolating the obtained atomic flux to the continuous fountain under construction, we expect a short-term stability of 7/spl times/10/sup -14//spl tau//sup -1/2/. Other applications of continuous beams of cold atoms are suggested.
The accelerated development of laser methods for manipulating the internal state and motion of atoms, and the recent primary evaluation in France of a cesium frequency standard using cold atoms in an atomic fountain configuration, allow the frontiers of time metrology, accuracy, and stability to be pushed near parts in the 1016 level, a factor of 100 over the present primary laboratory clocks. These positive results revived the development of more accurate cesium atomic clocks, and the Institute of National Measurement Standards (INMS), of the National Research Council of Canada (NRC) is undertaking a cesium-fountain project aimed at reaching these new levels of accuracy and stability. This paper reviews its present status. To appreciate the considerable impact of cold atoms in time and frequency metrology, we begin by recalling the background principles of traditional cesium frequency standards, their typical performance and main limitations. After introducing the important theoretical results essential to understanding the techniques of laser cooling and magneto-optical trapping, we focus on describing the characterization and control of our magneto-optical trap (MOT) and report the parameters that allow us to fill the trap with a few million atoms in less than a second and cool them to a temperature lower than 5 muK using optical molasses. We will describe the specifics of our cesium-fountain prototype, which operates with a 2-dimensional moving molasses. This special configuration is applicable for multipulse operation of the fountain, which can greatly relax the local oscillator requirements for time keeping. Finally, progress toward our objective of launching cooled atoms, at a rate of one ensemble per second, at speeds of 7 m/s, for a fountain with an interrogation time of about 1 s, will be analysed.PACS Nos.: 06.20, 06.30, and 32.80P
We present a progress report on laser-cooled cesium atoms at NRC, work which was started a few years ago in order to realize a cesium fountain frequency standard. We selected an acceleration with two-dimensional moving molasses, which can increase both the force and the interaction time by a factor of /spl radic/2 over the more common 1-D molasses scheme. This configuration also allows for trapping and cooling of atoms while previously launched atoms are still moving in the clock section of the system. We report measurements on the number of atoms, temperature, friction coefficient and spring constant of our magneto-optical trap and 1-D molasses for various conditions.
In this paper we discuss progress made at the U.S. Naval Observatory (USNO) towards building a cesium fountain atomic clock. In particular we will address the efficacy of a 4-beam optical lattice as an atom collection and launch mechanism. To date we have measured temperatures in a 4-beam lattice of 1.4(0.3) /spl mu/K and have launched atoms from this lattice to a height of just under a meter with a temperature of 1.7(0.1) /spl mu/K. We are able to collect 2.4/spl times/10/sup 6/ atoms using only the lattice beams and no magnetic fields. We have completed the design for and are in the process of fabricating all aspects of the fountain device including the collection region, the drift region, the microwave cavity and the magnetic shields. We present our progress to date including a discussion of our launch results and the design and testing of our magnetic shields.