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Quantum Projection Noise in an Atomic Fountain: A High Stability Cesium Frequency Standard

G. Santarelli, Ph. Laurent, P. Lemonde, A. Clairon, A. G. Mann, S. Chang, A. N. Luiten, and C. Salomon
Phys. Rev. Lett. 82, 4619 – Published 7 June 1999
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Abstract

We describe the operation of a laser cooled cesium fountain clock in the quantum limited regime. An ultrastable cryogenic sapphire oscillator is used to measure the short-term frequency stability of the fountain as a function of the number of detected atoms Nat. For Nat varying from 4×104 to 6×105 the Allan standard deviation of the frequency fluctuations is in excellent agreement with the Nat1/2 law of atomic projection noise. With 6×105 atoms, the relative frequency stability is 4×1014τ1/2, where τ is the integration time in seconds. This is the best short-term stability ever reported for primary frequency standards, a factor of 5 improvement over previous results.

  • Received 29 October 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.4619

©1999 American Physical Society

Authors & Affiliations

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon

  • BNM-LPTF, Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France

A. G. Mann, S. Chang, and A. N. Luiten

  • Physics Department, University of Western Australia, Nedlands, 6907 Western Australia, Australia

C. Salomon

  • Laboratoire Kastler Brossel, ENS, 24 rue Lhomond, 75005 Paris, France

See Also

Fountain Clock Keeps Good Time

Phys. Rev. Focus 3, 32 (1999)

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Issue

Vol. 82, Iss. 23 — 7 June 1999

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