International timescales with optical clocks (ITOC)

A new collaborative European project “International timescales with optical clocks” (ITOC) aims to tackle the key challenges that must be addressed prior to a redefinition of the SI second. A coordinated programme of comparisons will be carried out between European optical clocks developed in five different laboratories, enabling their performance levels to be validated at an unprecedented level of accuracy. Supporting work will be carried out to evaluate relativistic effects that influence the comparisons, including the gravitational redshift of the clock transition frequencies. A proof-of-principle experiment will also be performed to demonstrate that optical clocks could be used to make direct measurements of the Earth's gravity potential with high temporal resolution.

[1]  Scott A. Diddams,et al.  Optical Frequency Synthesis and Comparison with Uncertainty at the 10-19 Level , 2004, Science.

[2]  H. Schnatz,et al.  The 87Sr optical frequency standard at PTB , 2011, 1104.4850.

[3]  T. Hänsch,et al.  A 920-Kilometer Optical Fiber Link for Frequency Metrology at the 19th Decimal Place , 2012, Science.

[4]  Patrick Gill,et al.  When should we change the definition of the second? , 2011, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[5]  H. Inaba,et al.  Measuring the frequency of a Sr optical lattice clock using a 120 km coherent optical transfer. , 2008, Optics letters.

[6]  D. Piester,et al.  Remote atomic clock synchronization via satellites and optical fibers , 2011 .

[7]  Davide Calonico,et al.  IEN-CsF1 primary frequency standard at INRIM: accuracy evaluation and TAI calibrations , 2006 .

[8]  D. Wineland,et al.  Frequency comparison of two high-accuracy Al+ optical clocks. , 2009, Physical review letters.

[9]  Ruoxin Li,et al.  Improved accuracy of the NPL-CsF2 primary frequency standard: evaluation of distributed cavity phase and microwave lensing frequency shifts , 2011, 1107.2412.

[10]  Jun Ye,et al.  The absolute frequency of the 87Sr optical clock transition , 2008, 0804.4509.

[11]  J. Guéna,et al.  Progress in atomic fountains at LNE-SYRTE , 2012, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[12]  P. Rosenbusch,et al.  Experimental realization of an optical second with strontium lattice clocks , 2013, Nature Communications.

[13]  Jun Ye,et al.  Sr Lattice Clock at 1 × 10–16 Fractional Uncertainty by Remote Optical Evaluation with a Ca Clock , 2008, Science.

[14]  Jon H. Shirley,et al.  NIST-F1: recent improvements and accuracy evaluations , 2005 .

[15]  K. Gibble,et al.  Distributed cavity phase frequency shifts of the caesium fountain PTB-CSF2 , 2011, 1110.2590.

[16]  Thomas E Parker,et al.  Invited review article: The uncertainty in the realization and dissemination of the SI second from a systems point of view. , 2012, The Review of scientific instruments.

[17]  Christian Chardonnet,et al.  High-resolution optical frequency dissemination on a telecommunications network with data traffic. , 2009, Optics letters.

[18]  P. Gill,et al.  Absolute frequency measurement of the 2S1/2–2F7/2 electric octupole transition in a single ion of 171Yb+ with 10−15 fractional uncertainty , 2012 .

[19]  M. Okhapkin,et al.  High-accuracy optical clock based on the octupole transition in 171Yb+. , 2011, Physical review letters.

[20]  Zichao Zhou,et al.  88Sr+ 445-THz single-ion reference at the 10(-17) level via control and cancellation of systematic uncertainties and its measurement against the SI second. , 2012, Physical review letters.

[21]  Paul A. Williams,et al.  High-stability transfer of an optical frequency over long fiber-optic links , 2008 .