Single-qubit quantum memory exceeding ten-minute coherence time

By Ye Wang, M. Um, Junhua Zhang, S. An, Ming Lyu, Jing-Ning Zhang, Luming Duan, Dahyun Yum, Kihwan Kim. 2017

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A long-time quantum memory capable of storing and measuring quantum information at the single-qubit level is an essential ingredient for practical quantum computation and communication1,2. Currently, the coherence time of a single qubit is limited to less than 1 min, as demonstrated in trapped ion systems3–5, although much longer coherence times have been reported in ensembles of trapped ions6,7 and nuclear spins of ionized donors8,9. Here, we report the observation of a coherence time of over 10 min for a single qubit in a 171Yb+ ion sympathetically cooled by a 138Ba+ ion in the same Paul trap, which eliminates the problem of qubit-detection inefficiency from heating of the qubit ion10,11. We also apply a few thousand dynamical decoupling pulses to suppress ambient noise from magnetic-field fluctuations and phase noise from the local oscillator8,9,12–16. The long-time quantum memory of the single trapped ion qubit would be the essential component of scalable quantum computers1,17,18, quantum networks2,19,20 and quantum money21,22.The longest coherence time of a single qubit of more than ten minutes is observed in a 171Yb+ ion. After sympathetically cooling the 171Yb+ ion qubit with a 138Ba+ ion, noise from magnetic-field fluctuations and the local oscillator is suppressed by a dynamic decoupling scheme.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/7f1ca1005689f4e6473691e0efe37516702b6883