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High-fidelity indirect readout of trapped-ion hyperfine qubits



Stephen Erickson, Jenny Wu, Panyu Hou, Daniel Cole, Shawn Geller, Alexander Kwiatkowski, Scott Glancy, Emanuel Knill, Daniel Slichter, Andrew C. Wilson, Dietrich Leibfried


We propose and demonstrate a protocol for high-fidelity indirect readout of trapped ion hyperfine qubits, where the state of a 9Be+ qubit ion is mapped to a 25Mg+ readout ion using laser-driven Raman transitions. By partitioning the 9Be+ ground-state hyperfine manifold into two subspaces representing the two qubit states and choosing appropriate laser parameters, the protocol can be made robust to spontaneous photon scattering errors on the Raman transitions, enabling repetition for increased readout fidelity. We demonstrate combined readout and back-action errors for the two subspaces of 1.2(+1.1/−0.6)×10^−4 and 0(+1.9/−0)×10^−5 with 68% confidence while avoiding decoherence of spectator qubits due to stray resonant light that is inherent to direct fluorescence detection.
Physical Review Letters


quantum information, trapped ions, high-fidelity measurement, quantum logic spectroscopy


Erickson, S. , Wu, J. , Hou, P. , Cole, D. , Geller, S. , Kwiatkowski, A. , Glancy, S. , Knill, E. , Slichter, D. , Wilson, A. and Leibfried, D. (2022), High-fidelity indirect readout of trapped-ion hyperfine qubits, Physical Review Letters, [online], (Accessed March 5, 2024)
Created April 21, 2022, Updated January 2, 2024