Intermittent optical frequency measurements to reduce the dead time uncertainty of frequency link

Hachisu, Hidekazu; Ido, T.

doi:10.7567/jjap.54.112401

Cited by 46 publications

(83 citation statements)

References 39 publications

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“…The instability of the TOC is dominated by the performance of the interrogation laser [38] through the Dick effect [44]. This instability is lower than achieved in typical single ion clocks [3,13,29,45], and comparable to many high perfromance lattice clocks [11,30,46,47].…”

Section: This Clock Uses the (5smentioning

confidence: 99%

Transportable Optical Lattice Clock with7×10−17Uncertainty

et al. 2017

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We present a transportable optical clock (TOC) with 87 Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of 7.4 × 10 −17 which is currently limited by the statistics of the determination of the residual lattice light shift. The measurements confirm that the systematic uncertainty is reduceable to below the design goal of 1 × 10 −17 . The instability of our TOC is 1.3 × 10 −15 / √ τ . Both, the systematic uncertainty and the instability are to our best knowledge currently the best achieved with any type of transportable clock. For autonomous operation the TOC is installed in an air-conditioned car-trailer. It is suitable for chronometric leveling with sub-meter resolution as well as intercontinental cross-linking of optical clocks, which is essential for a redefiniton of the SI second. In addition, the TOC will be used for high precision experiments for fundamental science that are commonly tied to precise frequency measurements and it is a first step to space borne optical clocks. PACS numbers:The best clocks in the world reach a fractional systematic uncertainty at the low 10 −18 level [1-4] and instabilities near or even below 10 2,[4][5][6], surpassing the clocks realizing the SI second in both by two orders of magnitude. This has triggered a discussion about a redefinition of the SI second [7,8], pushes the frontiers of precision spectroscopy and tests fundamental physics [9][10][11][12][13][14], and enables chronometric leveling [15][16][17][18][19], where gravitational redshifts are exploited to measure height differences.So far, the operation of optical clocks has been constrained to laboratories. However, transportable clocks are required for the necessary flexibility in the choice of measurement sites for applications like chronometric leveling. Also, they are highly interesting for frequency metrology and time keeping in creating a consistent worldwide network of the next-generation ultraprecise clocks. Although comparisons at the full performance level of state-of-the-art optical clocks are possible on a continental scale [18,19] through a few specialized optical fiber links [20][21][22], intercontinental links are so far restricted to satellite-based methods that cannot fully exploit the clock performance [23]. A transfer standard enables world-wide interconnections between optical clocks and will thus benefit the efforts towards a redefinition of the SI second.Making laboratory setups compact and robust for transport is also the first step towards granting a wide community of users access to these devices [24][25][26]. Furthermore, transportability is a first step towards applications of optical clocks in space. Developments in these directions are ongoing for optical lattice clocks (OLCs) with strontium [27,28]; however, to our knowledge the single-ion clock reported recently [29] is the only other transportable clock with uncertainty below 10 −16 .The requirements on such a TOC are challenging indeed: To enable comparisons of other optical cl...

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Section: This Clock Uses the (5smentioning

confidence: 99%

Transportable Optical Lattice Clock with7×10−17Uncertainty

et al. 2017

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“…The instability of the TOC is dominated by the performance of the interrogation laser [45] through the Dick effect [50]. It is lower than achieved in typical single ion clocks [3,12,31,51], and comparable to many high performance lattice clocks [2,32,[52][53][54][55][56].…”

Section: Selected For a Viewpoint In Physics P H Y S I C A L R E V I mentioning

confidence: 99%

Transportable Clocks Move with the Times

Godun

2017

Physics

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We present a transportable optical clock (TOC) with 87 Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of 7.4 × 10 −17 , which is currently limited by the statistics of the determination of the residual lattice light shift, and an instability of 1.3 × 10 −15 = ffiffi ffi τ p with an averaging time τ in seconds. Measurements confirm that the systematic uncertainty can be reduced to below the design goal of 1 × 10 −17 . To our knowledge, these are the best uncertainties and instabilities reported for any transportable clock to date. For autonomous operation, the TOC has been installed in an airconditioned car trailer. It is suitable for chronometric leveling with submeter resolution as well as for intercontinental cross-linking of optical clocks, which is essential for a redefinition of the International System of Units (SI) second. In addition, the TOC will be used for high precision experiments for fundamental science that are commonly tied to precise frequency measurements and its development is an important step to space-borne optical clocks. DOI: 10.1103/PhysRevLett.118.073601 The best clocks reach fractional systematic uncertainties of a few 10 −18 [1-3] and instabilities near or even below 10 ,4-6], surpassing the clocks realizing the International System of Units (SI) second in both aspects by 2 orders of magnitude. These achievements have triggered a discussion about a redefinition of the SI second [7,8] and push the frontiers of precision spectroscopy [2,9,10] as well as tests of fundamental physics [10][11][12][13]. Further, these clocks enable chronometric leveling [14][15][16][17][18] with relevant resolution, where gravitational redshifts are exploited to measure height differences.So far, the operation of optical clocks has been constrained to laboratories. However, applications like chronometric leveling require transportable clocks to provide the necessary flexibility in the choice of measurement sites. Transportable optical clocks (TOCs) are highly interesting for frequency metrology and time keeping as well, enabling a consistent worldwide network of ultraprecise clocks. Although comparisons at the full performance level of state-of-the-art optical clocks are possible through a few specialized optical fiber links [19][20][21][22] on a continental scale [17,23], intercontinental links are restricted to satellite-based methods that do not reach the clock performance [24]. In contrast, a transfer standard enables world-wide interconnections between optical clocks exploiting their exquisitely small uncertainty and low instability. It will thus benefit the efforts towards a redefinition of the SI second.Making optical clocks compact and robust for transport is the first phase in granting a wide community of users access to these devices [25][26][27]. Furthermore, transportability is a relevant step towards applications of optical clocks in space. Although developments in these directions are ongoing [28][29][30][31], to our knowledge, the o...

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“…As well as the five direct optical frequency ratio measurements already discussed, these included 16 new absolute frequency measurements: one each of the 1S-2S transition in 1 H [18], the optical clock transitions in 171 Yb [19] and 88 Sr + [20] and the ground state hyperfine transition in 87 Rb [21], two each of the E2 [9,14] and E3 [9,15] transitions in 171 Yb + and the reference transition in 40 Ca + [22], and six of the optical clock transition in 87 Sr [23,24,25,26,27,28]. In addition, a correction [29] was submitted to a previously-used absolute frquency measurement of the optical clock transition in 199 Hg [30] and one earlier absolute frequency measurement of the reference transition in 40 Ca + [31] was withdrawn as new data from the same group suggested that the systematic frequency shifts may have been underestimated in this measurement [22].…”

Section: Analysis Of Data Available In September 2015mentioning

confidence: 99%

“…The sole exception was a directly measured optical frequency ratio between the clock transitions in 27 Al + and 199 Hg + [6], which was used to derive a second absolute frequency value for 27 Al + with much lower uncertainty than the directly measured absolute frequency value [7].…”

Section: Introductionmentioning

confidence: 99%