In December 2022, IonQ announced that it was researching the use of barium instead of ytterbium for a future generation machine. Barium has certain potential advantages in an ion trap machine because it is more compatible with telecom wavelengths for control and also allows the use of higher power lasers which can improve gate delays. But, up until now, none of the IonQ publicly announced machines had yet switched to using barium. The previous Harmony, Aria, and Forte machines and also the upcoming Tempo processor announced last month will continue to use ytterbium.
However, in a clear sign the company is making progress, they have announced been able to achieve a performance metric of #AQ29 on a prototype machine they have developed that uses barium. Although that level is not quite as good as the latest #AQ35 performance metric they have seen with the ytterbium based IonQ Forte Enterprise systems, one should remember that the barium processors are still at the very early stage of their lifecycle. So it is very likely IonQ will be able to make many more optimizations to the designs in the future that will allow the barium based platforms to ultimately surpass the ytterbium ones.
IonQ has issued a press release announcing their progress with barium which be seen here.
October 25, 2023