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Local detection of quantum correlations with a single trapped ion

Abstract

Quantum correlations are at the heart of quantum information science1,2,3. Their detection usually requires access to all the correlated subsystems4,5. However, in many realistic scenarios this is not feasible, as only some of the subsystems can be controlled and measured. Such cases can be treated as open quantum systems interacting with an inaccessible environment6. Initial system–environment correlations play a fundamental role for the dynamics of open quantum systems6,7,8,9. Following a recent proposal10,11, we exploit the impact of the correlations on the open-system dynamics to detect system–environment quantum correlations without accessing the environment. We use two degrees of freedom of a trapped ion to model an open system and its environment. The present method does not require any assumptions about the environment, the interaction or the initial state, and therefore provides a versatile tool for the study of quantum systems.

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Figure 1: Outline of the local detection protocol.
Figure 2: Description of open system and environment.
Figure 3: Local detection of qubit-motion quantum correlations.
Figure 4: Open-system trace distance for environmental states of different temperatures.
Figure 5: Maximum of the local distance and quantum correlations at the dephasing time.

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Acknowledgements

This work was supported by the NSF CAREER program grant # PHY 0955650. M.G. thanks the German National Academic Foundation for support. M.R. was supported by an award from the Department of Energy Office of Science Graduate Fellowship Program administered by ORISE-ORAU under Contract No. DE-AC05-06OR23100. A.B. acknowledges financial support by DFG and under the EU-COST action ‘Fundamental Problems in Quantum Physics’.

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Contributions

M.G., A.B., H-P.B. and H.H. devised the experiment. M.G., M.R., T.P. and H.H. performed the experiment. M.G. analysed the data. All authors contributed to the discussion of the results and the manuscript preparation.

Corresponding author

Correspondence to M. Gessner.

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The authors declare no competing financial interests.

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Gessner, M., Ramm, M., Pruttivarasin, T. et al. Local detection of quantum correlations with a single trapped ion. Nature Phys 10, 105–109 (2014). https://doi.org/10.1038/nphys2829

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