Ultrastable optical clock with two cold-atom ensembles

ABSTRACT Atomic clocks based on optical transitions are the most stable, and therefore precise, timekeepers available. These clocks operate by alternating intervals of atomic interrogation

with the ‘dead’ time required for quantum state preparation and readout. This non-continuous interrogation of the atom system results in the Dick effect, an aliasing of frequency noise from

the laser interrogating the atomic transition1,2. Despite recent advances in optical clock stability that have been achieved by improving laser coherence, the Dick effect has continually

limited the performance of optical clocks. Here we implement a robust solution to overcome this limitation: a zero-dead-time optical clock that is based on the interleaved interrogation of

two cold-atom ensembles3. This clock exhibits vanishingly small Dick noise, thereby achieving an unprecedented fractional frequency instability assessed to be for an averaging time _τ_ in

seconds. We also consider alternate dual-atom-ensemble schemes to extend laser coherence and reduce the standard quantum limit of clock stability, achieving a spectroscopy line quality

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our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS MULTI-ENSEMBLE METROLOGY BY PROGRAMMING LOCAL ROTATIONS WITH ATOM MOVEMENTS Article Open access 15 January 2024

DYNAMICAL DECOUPLING OF LASER PHASE NOISE IN COMPOUND ATOMIC CLOCKS Article Open access 20 October 2020 ENTANGLEMENT ON AN OPTICAL ATOMIC-CLOCK TRANSITION Article 16 December 2020 REFERENCES

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Download references ACKNOWLEDGEMENTS The authors acknowledge the Defense Advanced Research Projects Agency (DARPA) Quantum Assisted Sensing and Readout (QuASAR) programme, the NASA

Fundamental Physics programme and the National Institute of Standards and Technology for financial support. R.C.B. acknowledges support from the National Research Council Research

Associateship programme. We also thank T. Fortier, F. Quinlan and S. Diddams for femtosecond optical frequency comb measurements. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * National

Institute of Standards and Technology, 325 Broadway, Boulder, 80305, Colorado, USA M. Schioppo, R. C. Brown, W. F. McGrew, N. Hinkley, R. J. Fasano, K. Beloy, T. H. Yoon, G. Milani, D.

Nicolodi, J. A. Sherman, N. B. Phillips, C. W. Oates & A. D. Ludlow * Department of Physics, University of Colorado, Boulder, 80309, Colorado, USA M. Schioppo, W. F. McGrew, N. Hinkley 

& R. J. Fasano * Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany M. Schioppo * Department of Physics, Korea University, 145 Anam-ro,

Seongbuk-gu, 02841, Seoul, South Korea T. H. Yoon * Instituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, Torino, 10135, Italy G. Milani * Politecnico di Torino, Corso duca

degli Abruzzi 24, Torino, 10125, Italy G. Milani Authors * M. Schioppo View author publications You can also search for this author inPubMed Google Scholar * R. C. Brown View author

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this author inPubMed Google Scholar CONTRIBUTIONS M.S., R.C.B., W.F.M., R.J.F., G.M., D.N. and A.D.L. carried out the instability measurements. M.S. and A.D.L. constructed the clock laser.

W.F.M., T.H.Y and A.D.L. contributed to the optimization of the clock laser performance. J.A.S. constructed the DDS system for precise cavity drift compensation. R.C.B., N.H., T.H.Y.,

W.F.M., R.J.F., G.M. and A.D.L. were responsible for the operation of Yb-1 and Yb-2 systems and the phase noise cancellation. K.B. contributed to the evaluation of the instability budget.

C.W.O. and A.D.L. supervised this work. All authors contributed to the final manuscript. CORRESPONDING AUTHOR Correspondence to A. D. Ludlow. ETHICS DECLARATIONS COMPETING INTERESTS The

authors declare no competing financial interests. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Supplementary information (PDF 186 kb) RIGHTS AND PERMISSIONS Reprints and permissions

ABOUT THIS ARTICLE CITE THIS ARTICLE Schioppo, M., Brown, R., McGrew, W. _et al._ Ultrastable optical clock with two cold-atom ensembles. _Nature Photon_ 11, 48–52 (2017).

https://doi.org/10.1038/nphoton.2016.231 Download citation * Received: 16 June 2016 * Accepted: 17 October 2016 * Published: 28 November 2016 * Issue Date: January 2017 * DOI:

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