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Abstract

Microwave trapped-ion quantum logic gates avoid spontaneous emission as a
fundamental source of decoherence. However, microwave two-qubit gates are still
slower than laser-induced gates and hence more sensitive to fluctuations and
noise of the motional mode frequency. We propose and implement amplitude-shaped
gate drives to obtain resilience to such frequency changes without increasing
the pulse energy per gate operation. We demonstrate the resilience by noise
injection during a two-qubit entangling gate with $^9$Be$^+$ ion qubits. In
absence of injected noise, amplitude modulation gives an operation infidelity
in the $10^{-3}$ range.