Long-Lived Coherence on a μHz Scale Optical Magnetic Quadrupole Transition

• Published in: Physical review letters Vol. 132; no. 25; p. 253201
• Main Authors: Klüsener, V, Pucher, S, Yankelev, D, Trautmann, J, Spriestersbach, F, Filin, D, Porsev, S G, Safronova, M S, Bloch, I, Blatt, S
• Format: Journal Article
• Language: English
• Published: United States 21-06-2024
• ISSN: 0031-9007; 1079-7114; 1079-7114
• DOI: 10.1103/PhysRevLett.132.253201

We report on the coherent excitation of the ultranarrow ^{1}S_{0}-^{3}P_{2} magnetic quadrupole transition in ^{88}Sr. By confining atoms in a state insensitive optical lattice, we achieve excitation fractions of 97(1)% and observe linewidths as narrow as 58(1) Hz. With Ramsey spectroscopy, we find coherence times of 14(1) ms, which can be extended to 266(36) ms using a spin-echo sequence. We determine the lifetime of the ^{3}P_{2} level for spontaneous emission of magnetic quadrupole radiation to be 110(31) min, confirming long-standing theoretical predictions. These results establish an additional clock transition in strontium and pave the way for applications of the metastable ^{3}P_{2} state in quantum computing and quantum simulations.