Timekeepers of the future

Frequency Ratio of Al⁺and Hg⁺Single-Ion Optical Clocks; Metrology at the 17th Decimal Place

Rosenband, T., Hume, D. B., Schmidt, P. O., Chou, C. W., Brusch, A., Lorini, L., Oskay, W. H., Drullinger, R. E., Fortier, T. M., Stalnaker, J. E., et al. (2008) · Science · doi:10.1126/science.1154622 · Cited by 1,450 · see citing works

Frequency Comparison of Two High-Accuracy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msup> <mml:mi>Al</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> Optical Clocks

Chou, C., Hume, D., Koelemeij, J., Wineland, D., & Rosenband, T. (2010) · Physical Review Letters · doi:10.1103/physrevlett.104.070802 · Cited by 903 · see citing works

An Atomic Clock with 10 ^–18 Instability

Hinkley, N., Sherman, J. A., Phillips, N. B., Schioppo, M., Lemke, N. D., Beloy, K., Pizzocaro, M., Oates, C. W., & Ludlow, A. D. (2013) · Science · doi:10.1126/science.1240420 · Cited by 817 · see citing works

A 920-Kilometer Optical Fiber Link for Frequency Metrology at the 19th Decimal Place

Predehl, K., Grosche, G., Raupach, S. M. F., Droste, S., Terra, O., Alnis, J., Legero, T., Hänsch, T. W., Udem, T., Holzwarth, R., et al. (2012) · Science · doi:10.1126/science.1218442 · Cited by 543 · see citing works

An Atomic Standard of Frequency and Time Interval: A Cæsium Resonator

Essen, L., & PARRY, J. V. L. (1955) · Nature · doi:10.1038/176280a0 · Cited by 303 · see citing works

Progress in atomic fountains at LNE-SYRTE

Guéna, J., Abgrall, M., Rovera, D., Laurent, P., Chupin, B., Lours, M., Santarelli, G., Rosenbusch, P., Tobar, M. E., Li, R., et al. (2012) · IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · doi:10.1109/tuffc.2012.2208 · Cited by 291 · see citing works

Space clocks and fundamental tests: The ACES experiment

Cacciapuoti, L., & Salomon, C. (2009) · The European Physical Journal Special Topics · doi:10.1140/epjst/e2009-01041-7 · Cited by 179 · see citing works

Improved accuracy of the NPL-CsF2 primary frequency standard: evaluation of distributed cavity phase and microwave lensing frequency shifts

Li, R., Gibble, K., & Szymaniec, K. (2011) · Metrologia · doi:10.1088/0026-1394/48/5/007 · Cited by 138 · see citing works

Einstein Gravity Explorer–a medium-class fundamental physics mission

Schiller, S., Tino, G. M., Gill, P. R., Salomon, C., Sterr, U., Peik, E., Nevsky, A. Y., Görlitz, A., Švehla, D., Ferrari, G., et al. (2008) · Experimental Astronomy · doi:10.1007/s10686-008-9126-5 · Cited by 110 · see citing works

Limits to time variation of fundamental constants from comparisons of atomic frequency standards

Lea, S. N. (2007) · Reports on Progress in Physics · doi:10.1088/0034-4885/70/9/r01 · Cited by 73 · see citing works

Geophysical applicability of atomic clocks: direct continental geoid mapping: Atomic clocks map the geoid directly

Bondarescu, R., Bondarescu, M., Hetényi, G., Boschi, L., Jetzer, P., & Balakrishna, J. (2012) · Geophysical Journal International · doi:10.1111/j.1365-246x.2012.05636.x · Cited by 71 · see citing works

Time too good to be true

Kleppner, D. (2006) · Physics Today · doi:10.1063/1.2195297 · Cited by 43 · see citing works

Optical frequency standards and clocks

Margolis, H. S. (2009) · Contemporary Physics · doi:10.1080/00107510903257616 · Cited by 41 · see citing works

Optical frequency combs: Coherently uniting the electromagnetic spectrum

Diddams, S. A., Vahala, K. J., & Udem, T. (2020) · Science · doi:10.1126/science.aay3676 · Cited by 722 · see citing works

Geodesy and metrology with a transportable optical clock

Grotti, J., Koller, S., Vogt, S., Häfner, S., Sterr, U., Lisdat, C., Denker, H., Voigt, C., Timmen, L., Rolland, A., et al. (2018) · Nature Physics · doi:10.1038/s41567-017-0042-3 · Cited by 495 · see citing works

A clock network for geodesy and fundamental science

Lisdat, C., Grosche, G., Quintin, N., Shi, C., Raupach, S. M. F., Grebing, C., Nicolodi, D., Stefani, F., Al-Masoudi, A., Dörscher, S., et al. (2016) · Nature Communications · doi:10.1038/ncomms12443 · Cited by 460 · see citing works

Transportable Optical Lattice Clock with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>7</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>17</mml:mn> </mml:mrow> </mml:msup> </mml:math> Uncertainty

Koller, S. B., Grotti, J., Vogt, S., Al-Masoudi, A., Dörscher, S., Häfner, S., Sterr, U., & Lisdat, C. (2017) · Physical Review Letters · doi:10.1103/physrevlett.118.073601 · Cited by 238 · see citing works

Realization of a timescale with an accurate optical lattice clock

Grebing, C., Al-Masoudi, A., Dörscher, S., Häfner, S., Gerginov, V., Weyers, S., Lipphardt, B., Riehle, F., Sterr, U., & Lisdat, C. (2016) · Optica · doi:10.1364/optica.3.000563 · Cited by 149 · see citing works

Geodetic methods to determine the relativistic redshift at the level of 10 $$^{-18}$$ - 18 in the context of international timescales: a review and practical results

Denker, H., Timmen, L., Voigt, C., Weyers, S., Peik, E., Margolis, H. S., Delva, P., Wolf, P., & Petit, G. (2018) · Journal of Geodesy · doi:10.1007/s00190-017-1075-1 · Cited by 91 · see citing works

A window on the deep ocean: The special value of ocean bottom pressure for monitoring the large-scale, deep-ocean circulation

Hughes, C. W., Williams, J., Blaker, A. T., Coward, A. C., & Степанов, В. Н. (2018) · Progress In Oceanography · doi:10.1016/j.pocean.2018.01.011 · Cited by 65 · see citing works

On a definition of the SI second with a set of optical clock transitions

Lodewyck, J. (2019) · Metrologia · doi:10.1088/1681-7575/ab3a82 · Cited by 65 · see citing works

Time-variable gravity potential components for optical clock comparisons and the definition of international time scales

Voigt, C., Denker, H., & Timmen, L. (2016) · Metrologia · doi:10.1088/0026-1394/53/6/1365 · Cited by 50 · see citing works

Optical injection locking-based amplification in phase-coherent transfer of optical frequencies

Kim, J.-Y., Schnatz, H., Wu, D. S., Marra, G., Richardson, D. J., & Slavı́k, R. (2015) · Optics Letters · doi:10.1364/ol.40.004198 · Cited by 38 · see citing works

On the Compton clock and the undulatory nature of particle mass in graphene systems

Donatello Dolce, B., & Perali, A. (2015) · The European Physical Journal Plus · doi:10.1140/epjp/i2015-15041-5 · Cited by 33 · see citing works

Optical frequency standards for gravitational wave detection using satellite Doppler velocimetry

Vutha, A. C. (2015) · New Journal of Physics · doi:10.1088/1367-2630/17/6/063030 · Cited by 30 · see citing works

Chronometric Geodesy: Methods and Applications

Delva, P., Denker, H., & Lion, G. (2019) · Fundamental Theories of Physics · doi:10.1007/978-3-030-11500-5_2 · Cited by 28 · see citing works

Collisional frequency shift of a trapped-ion optical clock

Vutha, A. C., Kirchner, T., & Dubé, P. (2017) · Physical Review A · doi:10.1103/physreva.96.022704 · Cited by 25 · see citing works

Compact Yb+optical atomic clock project: design principle and current status

Lacroûte, C., Souidi, M., Bourgeois, P.-Y., Millo, J., Saleh, K., Bigler, E., Boudot, R., Giordano, V., & Kersalé, Y. (2016) · Journal of Physics Conference Series · doi:10.1088/1742-6596/723/1/012025 · Cited by 20 · see citing works

Field deployable atomics package for an optical lattice clock

Kale, Y. B., Singh, A. K., Gellesch, M., Jones, J. M., Morris, D. C., Aldous, M., Bongs, K., & Singh, Y. (2022) · Quantum Science and Technology · doi:10.1088/2058-9565/ac7b40 · Cited by 18 · see citing works

A proof-of-concept model of compact and high-performance 87Sr optical lattice clock for space

Guo, F., Tan, W., Zhou, C.-H., Xia, J., Chen, Y.-X., Liang, T., Liu, Q., Liu, Y., He, D.-J., Zhou, Y.-Z., et al. (2021) · AIP Advances · doi:10.1063/5.0064087 · Cited by 16 · see citing works

Relativistic tidal effects on clock-comparison experiments

Qin, C.-G., Tan, Y.-J., & Shao, C.-G. (2019) · Classical and Quantum Gravity · doi:10.1088/1361-6382/ab01ae · Cited by 15 · see citing works

Light and the distribution of time

Calonico, D., Inguscio, M., & Levi, F. (2015) · Europhysics Letters (EPL) · doi:10.1209/0295-5075/110/40001 · Cited by 14 · see citing works

On the origin of flicker noise in carrier-envelope phase stabilization

Song, Y., Lücking, F., Borchers, B., & Steinmeyer, G. (2014) · Optics Letters · doi:10.1364/ol.39.006989 · Cited by 9 · see citing works

Optical frequency transfer with below 10−21 uncertainty using a DFB–laser-based fiber Brillouin amplifier

Kadum, J. E., Ji, J., Kühl, A., Misera, M., Waterholter, T., & Koke, S. (2023) · APL Photonics · doi:10.1063/5.0133919 · Cited by 7 · see citing works

Quantum optics route to market

Stühler, J. (2015) · Nature Physics · doi:10.1038/nphys3292 · Cited by 7 · see citing works

Heisenberg-Limited Frequency Estimation via Driving Through Quantum Phase Transitions

Zhuang, M., Huo, H., Qiu, Y., Liu, W., Huang, J., & Lee, C. (2021) · Physical Review Applied · doi:10.1103/physrevapplied.16.064056 · Cited by 7 · see citing works

Wave-front curvature in optical atomic beam clocks

Strathearn, A., Offer, R. F., Hilton, A. P., Klantsataya, E., Luiten, A. N., Anderson, R. P., Sparkes, B. M., & Stace, T. M. (2023) · Physical Review A · doi:10.1103/physreva.108.013105 · Cited by 5 · see citing works

Determination of optimized frequency and frequency ratio values from over-determined sets of clock comparison data

Margolis, H. S., & Gill, P. R. (2016) · Journal of Physics Conference Series · doi:10.1088/1742-6596/723/1/012060 · Cited by 4 · see citing works

Clock frequency estimation under spontaneous emission

Qin, X., Huang, J., Zhong, H., & Lee, C. (2017) · Frontiers of Physics · doi:10.1007/s11467-017-0706-6 · Cited by 3 · see citing works

Thorium-doped CsI: Implications for the thorium nuclear clock transition

Meyer, E., Timmermans, E., Rudin, S. P., Kress, J. D., Collins, L. A., & Zhao, X. (2018) · Physical Review A · doi:10.1103/physreva.97.060503 · Cited by 2 · see citing works

The caesium fountain clock at the NRC

Beattie, S., Jian, B., Alcock, J. A., & Gertsvolf, M. (2022) · Canadian Journal of Physics · doi:10.1139/cjp-2022-0175 · Cited by 2 · see citing works

Unification of Relativistic and Quantum Mechanics from Elementary Cycles TheoryPreprint

Donatello Dolce, B. (2016) · arXiv (Cornell University) · doi:10.48550/arxiv.1606.01918 · Cited by 2 · see citing works

Toward a Thorium-229 Isomer–Based Nuclear Clock: Recent Progress

Kraemer, S., & Duppen, P. V. (2025) · Nuclear Physics News · doi:10.1080/10619127.2025.2483617 · Cited by 1 · see citing works

Augmenting the Time and Frequency Transfer Capabilities of Galileo

Delva, P., Courde, C., Samain, É., & Kostić, U. (2020) · European Navigation Conference (ENC) · doi:10.23919/enc48637.2020.9317454 · Cited by 1 · see citing works

A matter of time

Margolis, H. S. (2017) · Nature Physics · doi:10.1038/nphys4327 · Cited by 1 · see citing works

Paper Laser: a step towards a time scale generation from an ensemble of optical clocks

Ortiz, C. A., Carlos, E., & López, J. M. (2016) · Journal of Physics Conference Series · doi:10.1088/1742-6596/723/1/012062

Towards a redefinition of the second based on optical atomic clocks

Riehle, F. (2015) · Comptes Rendus. Physique · doi:10.1016/j.crhy.2015.03.012 · Cited by 174 · see citing works

Accurate and stable timekeeping

Derevianko, A. (2019) · Nature Reviews Physics · doi:10.1038/s42254-019-0089-4 · Cited by 2 · see citing works

On a Redefinition of the SI Second

Riehle, F. (2017) · Astrophysics and space science proceedings · doi:10.1007/978-3-319-59909-0_18 · Cited by 1 · see citing works

Possibilities for a future redefinition of the second

Gill, P. R., & Riehle, F. (2012) · Conference on Precision Electromagnetic Measurements · doi:10.1109/cpem.2012.6250864

Optical atomic clocksPreprint

Poli, N., Oates, C. W., Gill, P. R., & Tino, G. M. (2014) · arXiv (Cornell University) · doi:10.48550/arxiv.1401.2378 · Cited by 93 · see citing works