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Lifetime-Limited Interrogation of Two Independent 27Al+ Clocks using Correlation Spectroscopy



Ethan Clements, May E. Kim, Kaifeng Cui, Aaron M. Hankin, Samuel M. Brewer, Jose Valencia, Jwo-Sy Chen, Chin-wen Chou, David Leibrandt, David Hume


Laser decoherence limits the stability of optical clocks by broadening the observable resonance linewidths and adding noise during the dead time between clock probes. Correlation spectroscopy avoids these limitations by measuring correlated atomic transitions between two ensembles, which provides a frequency difference measurement independent of laser noise. Here, we apply this technique to perform stability measurements between two independent clocks based on the 1S0↔3P0 transition in 27Al+. By stabilizing the dominant sources of differential phase noise between the two clocks, we observe coherence between them during synchronous Ramsey interrogations as long as 8 s at a frequency of 1.12×1015Hz. The observed contrast in the correlation spectroscopy signal is consistent with the 20.6 s 3P0 state lifetime and supports a measurement instability of (1.8±0.5)×10−16/√(τ/s) for averaging periods longer than the probe duration.
Physical Review Letters


atomic clocks, trapped ions, optical clocks, precision measurements, quantum metrology


Clements, E. , Kim, M. , Cui, K. , Hankin, A. , Brewer, S. , Valencia, J. , Chen, J. , Chou, C. , Leibrandt, D. and Hume, D. (2020), Lifetime-Limited Interrogation of Two Independent 27Al+ Clocks using Correlation Spectroscopy, Physical Review Letters, [online], (Accessed June 18, 2024)


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Created December 9, 2020, Updated April 23, 2021