Improving a Trapped-Ion Quantum Computer with a Cryogenic Sapphire Oscillator

SummaryWe report an 8.7-second qubit coherence time in a ytterbium ion (
¹⁷¹
Yb
⁺
) using a microwave synthesis system derived from an ultra-low phase noise cryogenic sapphire oscillator (CSO). Our measurement provides evidence that the phase noise of a local oscillator that serves as the master clock plays a significant role in the operation fidelities of a trapped-ion quantum information processor.