Low excitation transport of Ba-Sr crystals through an RF Paul trap X-junction

Ongoing efforts to scale up trapped ion QCCD computers are driving the architecture towards sorting ion qubits in a 2D geometry and delivering control beams through integrated photonic structures. The performance and lifespan of these photonic structures generally improve at longer wavelengths. In this latter respect, 137Ba+ and 88Sr+ form a compelling qubit-sympathetic coolant pair as their trapping and manipulation requires no UV light. However, their large mass imbalance poses potential challenges, particularly in transporting Ba-Sr pairs through junctions in two-dimensional surface RF Paul traps. Here, we demonstrate transport of Ba-Sr crystals through such an X-junction and measure that, at 2 m/s, the transport induces an increase in thermal occupation of 0.035 +- 0.005 quanta per round trip in both the axial in-phase and out-of-phase modes with insignificant coherent excitation.