Trapped ion qubits are one of the most promising candidates for scalable quantum computing. Entangling gates with trapped ions are typically performed in an adiabatic regime, where the motional frequencies of the ions in the trap limit the gate speed. Following  we use amplitude-shaped cw-pulses to perform entangling gates significantly faster than the speed limit for conventional gate mechanisms. At these gate speeds, the motional modes are not spectrally isolated, leading to entanglement with both motional modes sensitively depending on the optical phase of the control fields. We demonstrate gates with fidelity F = 99.8% in 1.6 µs  - over an order of magnitude faster than previous trapped ion gates of similar fidelity.
I will further present recent progress on mixed-element entangling gates using 43Ca+ and 88Sr+. Combining different ion species provides crucial advantages for scaling up trapped ion quantum computers. Expanding our work using mixed isotopes , we take advantage of the spectral properties of calcium and strontium to implement entangling gates using only a single pair of Raman lasers, achieving a fidelity of F = 99.5%.
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