arXiv:1702.07129 · Quantum Science and Technology

Enhanced quantum sensing with multi-level structures of trapped ions

N. Aharon, Michael Drewsen, Alex Retzker

Published Jul 7, 2017• 5 citations

Abstract

Abstract We present a method of enhanced sensing of AC magnetic fields. The method is based on the construction of a robust qubit by the application of continuous driving fields. Specifically, magnetic noise and power fluctuations of the driving fields do not operate within the robust qubit subspace, hence robustness to both external and controller noise is achieved. The scheme is applicable to either a single ion or an ensemble of ions. We consider trapped-ion based implementation via the dipole transitions, which is relevant for several types of ions, such as the 40 Ca + , 88 Sr + and the 138 Ba + ions. Taking experimental errors into account, we conclude that the coherence time of the robust qubit can be improved by up to ∼4 orders of magnitude compared to the coherence time of the bare states. We show how the robust qubit can be utilised for the task of sensing AC magnetic fields in the range ∼ 0.1 − 100 MHz with an improvement of ∼2 orders of magnitude of the sensitivity. In addition, we present a microwave-based sensing scheme that is suitable for ions with a hyperfine structure, such as the 9 Be + , 25 Mg + , 43 Ca + , 87 Sr + , 137 Ba + , 111 Cd + ,

DOI: 10.1088/2058-9565/aa771a

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