Frequency metrology at the 10^−18 level with an ytterbium ion optical clock
<p>Atomic clocks, the most accurate instruments in existence, are reaching new levels of precision. These devices now find novel uses—from the exploration of relativity [1] to the detection of dark matter [2, 3]—all from same principle: measurement of the frequency of the light that excites a...
| প্রধান লেখক: | |
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| অন্যান্য লেখক: | |
| বিন্যাস: | গবেষণাপত্র |
| ভাষা: | English |
| প্রকাশিত: |
2018
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| বিষয়গুলি: |
| _version_ | 1826297269795684352 |
|---|---|
| author | Baynham, C |
| author2 | Baird, P |
| author_facet | Baird, P Baynham, C |
| author_sort | Baynham, C |
| collection | OXFORD |
| description | <p>Atomic clocks, the most accurate instruments in existence, are reaching new levels of precision. These devices now find novel uses—from the exploration of relativity [1] to the detection of dark matter [2, 3]—all from same principle: measurement of the frequency of the light that excites a reference atomic transition. The <sup>2</sup>S<sub>1/2</sub> (F 0) → <sup>2</sup>F<sub>7/2</sub> (F 3) electric octupole (E3) transition in <sup>171</sup>Yb<sup>+</sup>, with its Δν ≈ 1 nHz [4] linewidth and low sensitivity to external electromagnetic fields, lends itself to this usage [5]. </p> <p>We probe this transition in a single <sup>171</sup>Yb<sup>+</sup> ion held in a newly-designed endcap RF trap [6]. This design achieves a low temperature rise of 0.14(14)K. Excess micromotion in the trap is automatically compensated, resulting in a fractional frequency uncertainty of the combined RF-Stark and 2<sup>nd</sup> order Doppler shifts of 3.6 × 10<sup>−19</sup>. Anomalous phonon heating rates in the radial plane were measured as (−4.9 ± 5.2) s<sup>−1</sup> and (−1.3 ± 3.6) s<sup>−1</sup> for secular frequencies of 446 kHz and 470 kHz. </p> <p>The ion’s differential polarisability at λ = 7 μm has been measured, suggesting a reduction in the BBR-related systematic error of the electric quadrupole (E2) transition by a factor of 5 and confirming the results of a previous measurement for the E3, performed using a different method [7]. However, a limitation prevented full confidence in our uncertainty levels. </p> <p>To pre-stabilize the frequency of our laser a 28 cm long, ultra-stable Fabry-Pérot cavity was constructed and used to drive the E3 atomic resonance with a linewidth of 1.64(2) Hz. Its finesse was measured as 458 000 and, in an atomic lock, a clock stability of 1.9 × 10<sup>−15</sup> (τ/1 s)<sup>−1/2</sup> was observed. The laser’s frequency was measured and its stability transferred to other wavelengths via a femtosecond optical frequency comb. </p> <p>An international clock comparison campaign was carried out via satellite-mediated microwave links: the first of its scale, involving 4 National Measurement Institutes (NMIs) and 5 optical atomic clocks. A new technique was developed to analyse the resulting data and to characterize its uncertainty. The lowest fractional uncertainty in the comparison between any pair of clocks was 2.8 × 10<sup>−16</sup>. </p> <p>Finally, an absolute measurement of the E3 transition has been carried out through a link to International Atomic Time (TAI), without a local primary standard. The transition frequency was measured to be 642 121 496 772 645.17(22) Hz: the best measurement of this transition to date [8, 9].</p> |
| first_indexed | 2024-03-07T04:29:00Z |
| format | Thesis |
| id | oxford-uuid:cdab6fc3-d535-4173-bb56-f01a3f1896f7 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:29:00Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | oxford-uuid:cdab6fc3-d535-4173-bb56-f01a3f1896f72022-03-27T07:30:14ZFrequency metrology at the 10^−18 level with an ytterbium ion optical clockThesishttp://purl.org/coar/resource_type/c_db06uuid:cdab6fc3-d535-4173-bb56-f01a3f1896f7atomic physicstrapped ionsfrequency metrologyEnglishORA Deposit2018Baynham, CBaird, PGodun, R<p>Atomic clocks, the most accurate instruments in existence, are reaching new levels of precision. These devices now find novel uses—from the exploration of relativity [1] to the detection of dark matter [2, 3]—all from same principle: measurement of the frequency of the light that excites a reference atomic transition. The <sup>2</sup>S<sub>1/2</sub> (F 0) → <sup>2</sup>F<sub>7/2</sub> (F 3) electric octupole (E3) transition in <sup>171</sup>Yb<sup>+</sup>, with its Δν ≈ 1 nHz [4] linewidth and low sensitivity to external electromagnetic fields, lends itself to this usage [5]. </p> <p>We probe this transition in a single <sup>171</sup>Yb<sup>+</sup> ion held in a newly-designed endcap RF trap [6]. This design achieves a low temperature rise of 0.14(14)K. Excess micromotion in the trap is automatically compensated, resulting in a fractional frequency uncertainty of the combined RF-Stark and 2<sup>nd</sup> order Doppler shifts of 3.6 × 10<sup>−19</sup>. Anomalous phonon heating rates in the radial plane were measured as (−4.9 ± 5.2) s<sup>−1</sup> and (−1.3 ± 3.6) s<sup>−1</sup> for secular frequencies of 446 kHz and 470 kHz. </p> <p>The ion’s differential polarisability at λ = 7 μm has been measured, suggesting a reduction in the BBR-related systematic error of the electric quadrupole (E2) transition by a factor of 5 and confirming the results of a previous measurement for the E3, performed using a different method [7]. However, a limitation prevented full confidence in our uncertainty levels. </p> <p>To pre-stabilize the frequency of our laser a 28 cm long, ultra-stable Fabry-Pérot cavity was constructed and used to drive the E3 atomic resonance with a linewidth of 1.64(2) Hz. Its finesse was measured as 458 000 and, in an atomic lock, a clock stability of 1.9 × 10<sup>−15</sup> (τ/1 s)<sup>−1/2</sup> was observed. The laser’s frequency was measured and its stability transferred to other wavelengths via a femtosecond optical frequency comb. </p> <p>An international clock comparison campaign was carried out via satellite-mediated microwave links: the first of its scale, involving 4 National Measurement Institutes (NMIs) and 5 optical atomic clocks. A new technique was developed to analyse the resulting data and to characterize its uncertainty. The lowest fractional uncertainty in the comparison between any pair of clocks was 2.8 × 10<sup>−16</sup>. </p> <p>Finally, an absolute measurement of the E3 transition has been carried out through a link to International Atomic Time (TAI), without a local primary standard. The transition frequency was measured to be 642 121 496 772 645.17(22) Hz: the best measurement of this transition to date [8, 9].</p> |
| spellingShingle | atomic physics trapped ions frequency metrology Baynham, C Frequency metrology at the 10^−18 level with an ytterbium ion optical clock |
| title | Frequency metrology at the 10^−18 level with an ytterbium ion optical clock |
| title_full | Frequency metrology at the 10^−18 level with an ytterbium ion optical clock |
| title_fullStr | Frequency metrology at the 10^−18 level with an ytterbium ion optical clock |
| title_full_unstemmed | Frequency metrology at the 10^−18 level with an ytterbium ion optical clock |
| title_short | Frequency metrology at the 10^−18 level with an ytterbium ion optical clock |
| title_sort | frequency metrology at the 10 18 level with an ytterbium ion optical clock |
| topic | atomic physics trapped ions frequency metrology |
| work_keys_str_mv | AT baynhamc frequencymetrologyatthe1018levelwithanytterbiumionopticalclock |