High-fidelity molecular quantum logic gates resilient to interaction fluctuation

TL;DR

This paper proposes a high-fidelity, interaction-fluctuation-resilient molecular quantum gate using microwave pulses, achieving over 99.99% fidelity under typical conditions, with tunable phase for quantum algorithms.

Contribution

It introduces a novel microwave pulse scheme and motional-mode separation technique to enhance gate fidelity and robustness against dipole-dipole interaction uncertainties.

Findings

Gate fidelity can exceed 0.9999 with typical experimental parameters.

The controlled phase is fully tunable via the relative phase of microwave pulses.

The method is resilient to interaction fluctuations without populating DDI-coupled states.

Abstract

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 $\pi$ 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.