Ultracold atoms and precise time standards

Campbell, Gretchen K.; Phillips, William D.

doi:10.1098/rsta.2011.0229

Cited by 19 publications

(10 citation statements)

References 48 publications

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“…These fountain clocks are currently used to realize the second to better than 1 part in 10 15 [9][10][11][12][13]. Microwave fountain clocks are discussed in more detail in the paper by Campbell & Phillips [14] in this issue.…”

Section: P Gillmentioning

confidence: 99%

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When should we change the definition of the second?

Gill

2011

Phil. Trans. R. Soc. A.

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The microwave caesium (Cs) atomic clock has formed an enduring basis for the second in the International System of Units (SI) over the last few decades. The advent of laser cooling has underpinned the development of cold Cs fountain clocks, which now achieve frequency uncertainties of approximately 5 × 10 −16 . Since 2000, optical atomic clock research has quickened considerably, and now challenges Cs fountain clock performance. This has been suitably shown by recent results for the aluminium Al + quantum logic clock, where a fractional frequency inaccuracy below 10 −17 has been reported. A number of optical clock systems now achieve or exceed the performance of the Cs fountain primary standards used to realize the SI second, raising the issues of whether, how and when to redefine it. Optical clocks comprise frequency-stabilized lasers probing very weak absorptions either in a single cold ion confined in an electromagnetic trap or in an ensemble of cold atoms trapped within an optical lattice. In both cases, different species are under consideration as possible redefinition candidates. In this paper, I consider options for redefinition, contrast the performance of various trapped ion and optical lattice systems, and point to potential limiting environmental factors, such as magnetic, electric and light fields, collisions and gravity, together with the challenge of making remote comparisons of optical frequencies between standards laboratories worldwide.

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Section: P Gillmentioning

confidence: 99%

“…Neutral atom optical lattice clocks are discussed in another paper in this issue [14]. In the following section, I therefore concentrate on the state of research of single ion optical clocks.…”

Section: Optical Clock Architectures and Candidatesmentioning

confidence: 99%

When should we change the definition of the second?

Gill

2011

Phil. Trans. R. Soc. A.

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“…Atomic clocks, which are based on cold-atom systems, rely on very accurate measurements where a laser is locked to a stable atomic transition [1]. As these devices require extremely high accuracy, the lasers which are used must be optimised in terms of linewidth, stability, wavelength and output power.…”

Section: Introductionmentioning

confidence: 99%

Distributed Feedback Lasers for Quantum Cooling Applications

Watson

Gwyn

Gaetano

et al. 2020

2020 22nd International Conference on Transparent Optical Networks (ICTON)

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There is an ever-growing need for compact sources which can be used for the cooling process in high accuracy atomic clocks. Current systems make use of large, expensive lasers which are power-hungry and often require frequency doubling in order to hit the required wavelengths. Distributed feedback (DFB) lasers have been fabricated at a number of key wavelengths which would allow chip scale atomic devices with very high accuracy to become a reality. Two key atomic transitions analysed here are 88Sr+ and 87Rb which require cooling at 422 nm and 780.24 nm, respectively. The vital parameter of the DFB lasers for this application is the linewidth, as very narrow linewidths are required in order for the atomic cooling process to occur. The lasers realised here produce the required power levels, with high side-mode suppression ratios and show good single mode tuning which is important for hitting precise wavelengths. This work will present the latest techniques and results using the DFB lasers at both wavelengths.

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“…Laser cooling is responsible for many innovations in quantum sensing and atomic metrology [1]. While the pursuit of better performance leads to exciting possibilities [2], it is also important to reduce the complexity of the apparatus in order to bring the benefits of cold atoms to more applications.…”

Section: Introductionmentioning

confidence: 99%

Raman-Ramsey CPT with a grating magneto-optical trap

Elvin

Hoth

Wright

et al. 2018

2018 European Frequency and Time Forum (EFTF)

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We describe an experiment which combines cold 87 Rb atoms from a grating magneto-optical trap (GMOT) with Lin⊥Lin coherent population trapping (CPT) and pulsed Ramsey interrogation. The bichromatic fields required for Lin⊥Lin are generated by combining light from a single external cavity diode laser (ECDL) with an electro-optic modulator (EOM) and an acousto-optic modulator (AOM). With this laser system and the GMOT, we are able to produce Raman-Ramsey fringes using either the F = 1 or the F = 2 excited states of the 87 Rb D1 line. As a step towards realising a frequency standard based on the GMOT, we measure the Ramsey fringe amplitude as a function of the magnetic bias field and the excited state. We observe dark state interference with F = 1 and show that this interference is suppressed with F = 2, as expected from prior work on CPT with 87 Rb in thermal vapour cells.

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Ultracold atoms and precise time standards

Cited by 19 publications

References 48 publications

When should we change the definition of the second?

When should we change the definition of the second?

Distributed Feedback Lasers for Quantum Cooling Applications

Raman-Ramsey CPT with a grating magneto-optical trap

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