Trapped-ion qubits are a leading candidate for the realization of large-scale quantum computers thanks to their long coherence time, good environmental isolation, photonic interfacing, and favourable scalability prospects. Although high-fidelity qubit gate operations have been demonstrated in these platforms, these typically require a (near) motional ground-state cooling and leverage the secular confinement frequency of the trapped ions, limiting practical implements to a few tens of microseconds.

We report on progress towards implementing Garcia-Ripoll style fast gates which are not limited by the ion’s confinement though a sequence of counter-propagating $\pi$ pulse pairs onto the trapped-ions. We have demonstrated 94(1)% coherent excitation of $^{171}$Yb$^+$ on the $^2$S$_{1/2}$- $^2$P$_{1/2}$ optical transition at 370 nm using a single near transform limited 2.36(1) ps pulse from a purpose build frequency-multiplied fibre laser. The population transfer is limited by our control over the laser’s detuning and the pulse intensity stability. The laser pulses are monitored in real-time using a 3.6 GHz resolution grating spectrometer for detuning and a scanning Michaelson interferometer for pulse duration.