Enriching the quantum toolbox of ultracold molecules with Rydberg atoms

Conner P. Williams, Kenneth Wang, Lewis R. B. Picard, Norman Y. Yao, and Kang-Kuen Ni
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

Assembly of rovibrational ground-state NaCs molecules in an optical tweezer array allows for high-fidelity quantum computation and the exploration of rich dipolar exchange Hamiltonians. Currently, these systems are limited by a minimum tweezer separation, which sets a hard cap on the interaction strength and increases the characteristic time for interesting physics. Further, readout requires re-separation into the component atoms, which is destructive and error-prone. We propose a hybrid array of optically-trapped molecules and atoms to solve these problems. By leveraging the large dipole moment of resonant Cesium Rydberg levels, we can increase the effective molecular coupling and achieve fast high-fidelity gates. The atoms can then be used as auxiliary qubits for entanglement and projective measurement, giving us a path towards nondestructive molecular readout. A near-term implementation of this scheme in our molecular qubit array can carry out 300ns entangling gates with potential gate and readout fidelities higher than 99.9%.