Two-phase driving of a linear radio-frequency ion trap.

A linear radio-frequency Paul trap is traditionally driven with one diagonal pair of electrodes grounded and the other connected to a high-voltage radio-frequency source. This method simplifies impedance matching of the voltage source to the trap. However, for several architectures, it leads to increasing the axial micromotion amplitude, for example, when the capacitance between radio-frequency and end-cap electrodes is not negligible. Here, we present a technique to generate two high-voltage radio-frequency signals 180° out of phase to drive a linear Paul trap with opposite voltages between neighboring electrodes. We have analyzed our technique using an equivalent circuit model and finite-element simulation. By performing Monte-Carlo analysis of the equivalent circuit of our system, we have estimated the phase mismatch between the adjacent electrodes of the linear ion trap to be 179.86(1)°, and the opposite electrodes of the linear ion trap to be 0 ± 0.00 035°. We have observed radial trapping frequencies of over 1.2 MHz for trapped 174Yb ions, corresponding to a voltage peak to peak amplitude of around 800 V. We have observed an excess radio-frequency electric field of less than 120 V/m up to 56 μm from the micro-motion minimum along the axis of the ion trap. Using our new technique, we have successfully trapped and cooled a chain of ytterbium ions in a linear radio-frequency Paul trap.