Zeeman-level lifetimes in Er 3+ :Y 2 SiO 5

We present measurements of Zeeman-level population lifetimes in Er3+:Y2SiO5 at low magnetic fields and low temperatures. Using spectral hole burning spectroscopy, we investigate the dynamics and temperature dependence of the hole structure due to the Zeeman interaction. Evidence for population storage in Zeeman levels with lifetimes of up to 130 ms is found in the form of long-lived spectral holes and antiholes. We also observe that a subset of the erbium ions exhibit very long-lived holes with lifetimes as long as 60 s at 2.8 K.