Demonstration of Mølmer–Sørensen Gates Robust to 10 kHz Trap Frequency Error

Trapped ions are leading candidates for useful quantum computation in the near term. While reliable single-qubit operations are routine on trapped ion platforms, two-qubit operations are more difficult. Two-qubit entangling gates are strongly susceptible to technical noise, and achieving those that are robust to such noise is an outstanding challenge. Drift in trap frequencies is a prevalent error mechanism and leads to infidelity in entangling gates, such as the Mølmer–Sørensen gate, that are operated through motional modes. We propose and experimentally demonstrate that by using a Gaussian pulse shape to exponentially suppress displacement error and balancing the contribution of multiple motional modes to suppress gate angle error, we can implement a Mølmer–Sørensen gate that is robust to order 10 kHz drift in trap frequency. Further, our gate is technically simple to implement and requires no lengthy optimization, enabling straightforward integration on contemporary systems.