High-fidelity molecular quantum logic gates resilient to interaction fluctuation

Optically trapped polar molecules are promising for quantum information processing, yet the accuracy of an entangling molecular gate is limited by the uncertainty of dipole-dipole interactions (DDI) from the molecular motion in traps. We show that two π pulses of global microwave excitation can yield a high-fidelity controlled-phase gate when assisted by two single-qubit gates. The gate is resilient to the uncertainty of DDI because it does not rely on populating DDI-coupled states. Further, the controlled phase is fully tunable by varying the relative phase of the two global microwave pulses, and, hence, the gate can find applications in a wide range of quantum algorithms involving quantum Fourier transform. Moreover, we introduce a motional-mode separation technique to quantum mechanically study the influence of the molecular motion, which shows that the gate fidelity can be over 0.9999 with typical experimental conditions.