"Laser writing in glass for dense, fast and efficient archival data storage" (opens in new tab)

I will note that 1.6 Gbit/mm2 in 301 layers works out to about 5 MBit/mm2 - compare that to mag tape which is 300 MBit/mm2 (30 Gbit/cm2). I bet tape at this areal density would last a long time too...