OH hyperfine ground state: From precision measurement to molecular qubits

We perform precision microwave spectroscopy-aided by Stark deceleration-to reveal the low-magnetic-field behavior of OH in its Π 3/2 2 rovibronic ground state, identifying two field-insensitive hyperfine transitions suitable as qubits and determining a differential Landé g factor of 1.267 (5) × 10-3 between opposite-parity components of the Λ doublet. The data are successfully modeled with an effective hyperfine Zeeman Hamiltonian, which we use to make a tenfold improvement of the magnetically sensitive, astrophysically important ΔF=±1 satellite-line frequencies, yielding 1 720 529 887 (10) Hz and 1 612 230 825 (15) Hz.