Dipolar exchange quantum logic gate with polar molecules

Kang-Kuen Ni; Till Rosenband; David D Grimes

doi:10.1039/c8sc02355g

Dipolar exchange quantum logic gate with polar molecules

Chem Sci. 2018 Jul 13;9(33):6830-6838. doi: 10.1039/c8sc02355g. eCollection 2018 Sep 7.

Authors

Kang-Kuen Ni^{1

2

3}, Till Rosenband², David D Grimes^{1

2

3}

Affiliations

¹ Department of Chemistry and Chemical Biology , Harvard University , Cambridge , Massachusetts 02138 , USA . Email: ni@chemistry.harvard.edu.
² Department of Physics , Harvard University , Cambridge , Massachusetts 02138 , USA.
³ Harvard-MIT Center for Ultracold Atoms , Cambridge , Massachusetts 02138 , USA.

Abstract

We propose a two-qubit gate based on dipolar exchange interactions between individually addressable ultracold polar molecules in an array of optical dipole traps. Our proposal treats the full Hamiltonian of the ¹Σ⁺ molecule NaCs, utilizing a pair of nuclear spin states as storage qubits. A third rotationally excited state with rotation-hyperfine coupling enables switchable electric dipolar exchange interactions between two molecules to generate an iSWAP gate. All three states are insensitive to external magnetic and electric fields. Impacts on gate fidelity due to coupling to other molecular states, imperfect ground-state cooling, blackbody radiation and vacuum spontaneous emission are small, leading to potential fidelity above 99.99% in a coherent quantum system that can be scaled by purely optical means.