transition in Sr

Alkaline-earth atoms have ultranarrow optical transitions between their ¹S₀ ground state and metastable triplet states. The frequency of the transition to the ³P₀ state is the basis of optical lattice clocks, due to its insensitivity to magnetic fields. In contrast, the ³P₂ state possesses a large magnetic moment, which is advantageous for proposed quantum simulation and computation schemes with neutral atoms.

Here, we report on the first absolute frequency measurement of the ¹S₀-³P₂ magnetic quadrupole transition in strontium by performing Doppler-free spectroscopy in a Stark-shift-cancelled "magic" optical lattice. We obtain the magic condition in a 1064 nm lattice by adjusting the lattice polarization to tune the vector light shift of the ³P₂ state. Besides the absolute transition frequency, we measure the vector polarizability and the isotope shift between ⁸⁷Sr and ⁸⁸Sr. As a proof-of-principle, we demonstrate first results aimed at isolating a single layer of an optical lattice in a magnetic field gradient in preparation for applications in quantum simulation and quantum computation schemes.