ECAMP 15

Quantum-logic protocols have emerged as an important tool for characterization of trapped atomic and molecular ions with complex energy-level structures. In such schemes, the internal state of the target ion is mapped onto a state of a co-trapped logic ion with accessible transitions, typically via shared motional modes.

Here, we report on quantum-logic state detection of $N_2^+$ with 99.99% fidelity for as few as nine experimental repetitions - an order-of-magnitude improvement over our previous results [1]. By combining experiments and simulations, we identify the fidelity-limiting role of the population in the motional modes not directly involved in the state readout and associate it with Debye-Waller effects. The enhanced detection fidelity reduces the experimental duty cycle and improves sensitivity towards higher molecular states that could be potentially identified under similar experimental conditions. 

Our current efforts focus on precision spectroscopy and coherent manipulation of single molecules, which can be used to test fundamental and beyond-standard-model theories, develop THz-range molecular clocks, and investigate state-resolved single-molecule collisions. 

[1] 1. M. Sinhal, Z. Meir, K. Najafian, G. Hegi, S. Willitsch, Science. 367, 1213–1218 (2020).