Quantum logic scheme for state detection of molecular ions

Quantum state detection of a single molecular ion can be applied towards precision measurement and controlled studies of cold chemistry. Such detection can be performed using quantum logic techniques, where the internal state of the molecular ion is mapped onto the state of a co-trapped atomic ion by coupling both of them to the common motional modes. The rotational state of the molecular ion can therefore be read out using the fluorescence of the atomic ion. Further, we can use the Zeeman splitting as a signature of different rotational levels due to their different magnetic g-factors. We will report implementation of this scheme using two atomic ions as a proof-of-principle experiment.