Quantum-logic spectroscopy of forbidden vibrational transitions in single nitrogen molecular ions

TL;DR

This paper demonstrates the first coherent manipulation of forbidden vibrational transitions in a single nitrogen molecular ion using quantum-logic spectroscopy, advancing molecular quantum control and precision measurement.

Contribution

It reports the observation and coherent control of electric-quadrupole vibrational transitions in N₂⁺ molecules, a significant step in molecular quantum technologies.

Findings

Identified hyperfine-Zeeman-rotational components of N₂⁺ vibrational transition

Achieved coherent population transfer between molecular energy levels

Paves the way for molecular clocks and quantum sensors

Abstract

Electric-dipole forbidden spectroscopic transitions in atoms form the basis of many advanced implementations of quantum computers, atomic clocks and quantum sensors. Coherently addressing such transitions in molecules which are among the most ubiquitous and versatile quantum objects has remained a long-standing challenge owing to their complex energy-level structure. Here, we report the search, observation and coherent manipulation of electric-quadrupole rotational-vibrational transitions in single trapped molecules using a quantum-logic-spectroscopy protocol. We identified individual hyperfine-Zeeman-rotational components of the fundamental vibrational transition of the nitrogen molecular ion, N$_2^+$, and performed coherent population transfer between energy levels. Our work opens up new perspectives for precision molecular spectroscopy, for high-fidelity qubits encoded in the rotational-vibrational motion of molecules, for precise infrared molecular clocks and for searches for new physics