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arXiv · 2309.02581

Rapid Exchange Cooling with Trapped Ions

Spencer D. Fallek·Vikram S. Sandhu·Ryan A. McGill·John M. Gray·Holly N. Tinkey·Craig R. Clark·Kenton R. Brown
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Abstract

The trapped-ion quantum charge-coupled device (QCCD) architecture is a leading candidate for advanced quantum information processing. In current QCCD implementations, imperfect ion transport and anomalous heating can excite ion motion during a calculation. To counteract this, intermediate cooling is necessary to maintain high-fidelity gate performance. Cooling the computational ions sympathetically with ions of another species, a commonly employed strategy, creates a significant runtime bottleneck. Here, we demonstrate a different approach we call exchange cooling. Unlike sympathetic cooling, exchange cooling does not require trapping two different atomic species. The protocol introduces a bank of "coolant" ions which are repeatedly laser cooled. A computational ion can then be cooled by transporting a coolant ion into its proximity. We test this concept experimentally with two $^{40}\mathrm{Ca}^{+}$ ions, executing the necessary transport in 107 $\mathrm{\mu s}$, an order of magnitude faster than typical sympathetic cooling durations. We remove over 96%, and as many as 102(5) quanta, of axial motional energy from the computational ion. We verify that re-cooling the coolant ion does not decohere the computational ion. This approach validates the feasibility of a single-species QCCD processor, capable of fast quantum simulation and computation.

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Spencer D. Fallek, Vikram S. Sandhu, Ryan A. McGill, John M. Gray, Holly N. Tinkey, Craig R. Clark, Kenton R. Brown. 2023-09-05. Rapid Exchange Cooling with Trapped Ions. https://doi.org/10.1038/s41467-024-45232-z

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