Frequency tunable, cavity-enhanced single erbium quantum emitter in the telecom band

Understand

Single quantum emitters embedded in solid-state hosts are an ideal platform for realizing quantum information processors and quantum network nodes.

• Among the currently-investigated candidates, Er$^{3+}$ ions are particularly appealing due to their 1.5 $\mu$m optical transition in the telecom band as well as their long spin coherence times.
• However, the long lifetimes of the excited state -- generally in excess of 1 ms -- along with the inhomogeneous broadening of the optical transition result in significant challenges.
• Photon emission rates are prohibitively small, and different emitters generally create photons with distinct spectra, thereby preventing multi-photon interference -- a requirement for building large-scale, multi-node quantum networks.