The latest I read is 3 but that was in Oct. With Lene Hau of Harvard's "frozen light" and with quantum donuts, newer strategies for stabilization are appearing, but the problem of keeping the qubit in superposition for long enough to sample it seems boggling. https://www.sciencedaily.com/releases/2009/03/090309105026.htm
https://groups.seas.harvard.edu/haulab/publications/HauPublications_All.htm