Clock transition for a future optical frequency standard with trapped atoms

Courtillot, I.; Quessada, A.; Kovacich, R.P.; Brusch, Anders; Kolker, D. B.; Zondy, J.‐J.; Rovera, Daniele; Lemonde, P.

doi:10.1103/physreva.68.030501

Cited by 72 publications

(52 citation statements)

References 20 publications

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“…Higher order frequency shifts due to the trapping light were then also shown to be controllable at that level [5] 1 . Altogether, the accuracy of the frequency measurement of the 1 S 0 − 3 P 0 clock transition of Sr has steadily improved by four orders of magnitude since its first direct measurement in 2003 [8]. Three independent measurements performed in Tokyo university [9], JILA [4] and SYRTE [10] were reported with a fractional uncertainty of 10 −14 giving excellent agreement.…”

Section: Introductionmentioning

confidence: 54%

An optical lattice clock with spin-polarized 87Sr atoms

et al. 2007

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Abstract. We present a new evaluation of an 87 Sr optical lattice clock using spin polarized atoms. The frequency of the 1 S0 → 3 P0 clock transition is found to be 429 228 004 229 873.6 Hz with a fractional accuracy of 2.6 × 10 −15 , a value that is comparable to the frequency difference between the various primary standards throughout the world. This measurement is in excellent agreement with a previous one of similar accuracy [1].

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Section: Introductionmentioning

confidence: 54%

An optical lattice clock with spin-polarized 87Sr atoms

et al. 2007

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“…Recently, its analogous clock transition has been observed and measured [13], and highresolution Doppler-free spectroscopy of lattice-confined 87 Sr atoms has been demonstrated [14]. One of the primary differences between Sr and Yb is their hyperfine structure.…”

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confidence: 99%

“…Lower temperatures aid in the search for absorption on the ultranarrow clock transition because smaller Doppler-widths lead to higher-contrast signals. Courtillot, et al [13] used a novel approach to find the (5s…”

mentioning

confidence: 99%

Observation and Absolute Frequency Measurements of theS01-P03Optical Clock Transition in Neutral Ytterbium

et al. 2005

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We report the direct excitation of the highly forbidden (6s 2 ) 1 S0 ↔ (6s6p) 3 P0 optical transition in two odd isotopes of ytterbium. As the excitation laser frequency is scanned, absorption is detected by monitoring the depletion from an atomic cloud at ∼70 µK in a magneto-optical trap. The measured frequency in 171 Yb (F=1/2) is 518,295,836,593.2 ± 4.4 kHz. The measured frequency in 173 Yb (F=5/2) is 518,294,576,850.0 ± 4.4 kHz. Measurements are made with a femtosecond-laser frequency comb calibrated by the NIST cesium fountain clock and represent nearly a million-fold reduction in uncertainty. The natural linewidth of these J=0 to J=0 transitions is calculated to be ∼10 mHz, making them well-suited to support a new generation of optical atomic clocks based on confinement in an optical lattice.PACS numbers: 32.30. Jc, 06.30.Ft, 32.80.Pj, 39.30.+w Work is underway to realize a high-performance optical clock that combines the best features of state-of-the-art single-ion and neutral atom optical frequency standards [1]. Such a clock system comprises a dipole-force optical lattice trap that confines an ensemble of neutral atoms individually to sub-wavelength sites for Dopplerand recoil-free precision spectroscopy [2,3]. Crucial to this scheme is an atom with a "clock" transition that has both a narrow linewidth and an insensitivity to lattice perturbations. Several groups have recognized ytterbium as an excellent candidate and are pursuing lattice-based optical clocks that will use its narrow 1 S 0 ↔ 3 P 0 transition [3,4,5,6]. However, until now the absolute frequency of this resonance was known in tables [7] to only a few gigahertz. We report the direct excitation of the doubly-forbidden (6s 2 ) 1 S 0 ↔ (6s6p) 3 P 0 optical transition at 578.4 nm in two odd isotopes of ytterbium [8]. Using a femtosecond-laser frequency comb [9], we make precision absolute frequency measurements with an uncertainty of 4.4 kHz -an improvement of nearly 106 . This accurate frequency knowledge will expedite the pursuit of an ytterbium-based optical clock, whose performance can potentially surpass that of the best cesium primary standard [10] by orders of magnitude.The ytterbium 1 S 0 ↔ 3 P 0 resonance is an outstanding potential clock transition, in part because of its narrow natural linewidth (∼10 mHz [3]). This transition is strictly dipole-forbidden from spin and orbital angular momentum considerations. An appreciable excitation probability exists, however, through hyperfine mixing of the 3 P 0 level with nearby states in the odd isotopes. (See the diagram in Fig. 1.) In an optical atomic clock based on confinement to a lattice, the lattice laser wavelength is chosen such that the ac Stark shift of the upper clock energy state matches the shift of the ground state. This results in a vanishing net perturbation to the clock frequency. The shiftcanceling wavelength for ytterbium is calculated to be 752 nm [3], readily accessible by high-power cw titaniumsapphire laser systems. Furthermore, the J=0 to J=0 transitions in Yb repor...

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“…84) Thus far, frequencies of several atom clocks operated at the 10 À15 level have been compared over 87 Sr with a natural linewidth of 1 mHz was first observed in 2003 by two groups simultaneously. The Paris group 86) investigated the transition by saturated absorption spectroscopy in free space to determine its transition frequency with 11 digits, while the Tokyo 9) group observed the transition with a linewidth of 700 Hz in an optical lattice tuned to the magic wavelength, thus opening up a new era for optical lattice clocks. Figure 6 shows the experimental setup used in the early stages of the lattice clock experiments.…”

Section: Atomic Elements Applicable To Optical Lattice Clocksmentioning

confidence: 99%

Frequency Metrology with Optical Lattice Clocks

Hong

Katori

2010

Jpn. J. Appl. Phys.

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The precision measurement of time and frequency is of great interest for a wide range of applications, including fundamental science and technologies that support broadband communication networks and the navigation with global positioning systems (GPSs). The development of optical frequency measurement based on frequency combs has revolutionized the field of frequency metrology, especially research on optical frequency standards. The proposal and realization of the optical lattice clock have further stimulated studies in the field of optical frequency metrology. Optical carrier transfer using optical fibers has been used to disseminate optical frequencies or compare two optical clocks without degrading their stability and accuracy. In this paper, we review the state-of-the-art development of optical frequency combs, standards, and transfer techniques with emphasis on optical lattice clocks. We address recent results achieved at the University of Tokyo and the National Metrology Institute of Japan in respect of frequency metrology with Sr and Yb optical lattice clocks.

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Clock transition for a future optical frequency standard with trapped atoms

Cited by 72 publications

References 20 publications

An optical lattice clock with spin-polarized 87Sr atoms

An optical lattice clock with spin-polarized 87Sr atoms

Observation and Absolute Frequency Measurements of theS01-P03Optical Clock Transition in Neutral Ytterbium

Frequency Metrology with Optical Lattice Clocks

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