Comparison of Two Independent Sr Optical Clocks withStability at
Open Access
- 5 December 2012
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 109 (23), 230801
- https://doi.org/10.1103/physrevlett.109.230801
Abstract
Many-particle optical lattice clocks have the potential for unprecedented measurement precision and stability due to their low quantum projection noise. However, this potential has so far never been realized because clock stability has been limited by frequency noise of optical local oscillators. By synchronously probing two lattice systems using a laser with a thermal noise floor of , we remove classically correlated laser noise from the intercomparison, but this does not demonstrate independent clock performance. With an improved optical oscillator that has a thermal noise floor, we demonstrate an order of magnitude improvement over the best reported stability of any independent clock, achieving a fractional instability of in 1000 s of averaging time for synchronous or asynchronous comparisons. This result is within a factor of 2 of the combined quantum projection noise limit for a 160 ms probe time with atoms in each clock. We further demonstrate that even at this high precision, the overall systematic uncertainty of our clock is not limited by atomic interactions. For the second Sr clock, which has a cavity-enhanced lattice, the atomic-density-dependent frequency shift is evaluated to be with an uncertainty of .
Keywords
Other Versions
Funding Information
- National Institute of Standards and Technology
- National Science Foundation
- Defense Advanced Research Projects Agency
This publication has 33 references indexed in Scilit:
- Operating a 87Sr optical lattice clock with high precision and at high densityIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2012
- High-Accuracy Optical Clock Based on the Octupole Transition inPhysical Review Letters, 2012
- Absolute frequency measurement of the2S1/2–2F7/2electric octupole transition in a single ion of171Yb+with 10−15fractional uncertaintyNew Journal of Physics, 2012
- Suppression of Collisional Shifts in a Strongly Interacting Lattice ClockScience, 2011
- Frequency Comparison of Two High-AccuracyOptical ClocksPhysical Review Letters, 2010
- Long-term comparison of caesium fountain primary frequency standardsMetrologia, 2009
- Sr Lattice Clock at 1 × 10 –16 Fractional Uncertainty by Remote Optical Evaluation with a Ca ClockScience, 2008
- Single-Atom Optical Clock with High AccuracyPhysical Review Letters, 2006
- Electric Quadrupole Shift Cancellation in Single-Ion Optical Frequency StandardsPhysical Review Letters, 2005
- Cold atom clocks and applicationsJournal of Physics B: Atomic, Molecular and Optical Physics, 2005