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arXiv · 1905.06878

Probing Qubit Memory Errors at the Part-per-Million Level

M. A. Sepiol·A. C. Hughes·J. E. Tarlton·D. P. Nadlinger·T. G. Ballance·C. J. Ballance·T. P. Harty·A. M. Steane·J. F. Goodwin·D. M. Lucas
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Abstract

Robust qubit memory is essential for quantum computing, both for near-term devices operating without error correction, and for the long-term goal of a fault-tolerant processor. We directly measure the memory error $\epsilon_m$ for a $^{43}$Ca$^+$ trapped-ion qubit in the small-error regime and find $\epsilon_m<10^{-4}$ for storage times $t\lesssim50\,\mbox{ms}$. This exceeds gate or measurement times by three orders of magnitude. Using randomized benchmarking, at $t=1\,\mbox{ms}$ we measure $\epsilon_m=1.2(7)\times10^{-6}$, around ten times smaller than that extrapolated from the $T_{2}^{\ast}$ time, and limited by instability of the atomic clock reference used to benchmark the qubit.

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M. A. Sepiol, A. C. Hughes, J. E. Tarlton, D. P. Nadlinger, T. G. Ballance, C. J. Ballance, T. P. Harty, A. M. Steane, J. F. Goodwin, D. M. Lucas. 2019-05-16. Probing Qubit Memory Errors at the Part-per-Million Level. https://doi.org/10.1103/physrevlett.123.110503

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