Engineering of Quantum Emitter Properties

We investigate trivalent thulium ions embedded in a lithium niobate crystal (Tm$^{3+}$:LiNbO$_3$) as a platform for quantum information applications, including single and entangled photon sources, quantum memories, and quantum gates.

For this, we consider three infrared zero-phonon lines in (Tm$^{3+}$:LiNbO$_3$), corresponding to wavelengths of 795 nm, 1450 nm, and 1765 nm. We first describe how to realize a quantum repeater (including source and memory) either using 795 nm photons or using energy-time entangled 1450 nm and 1765 nm photons. All photon sources rely on individual Tm ions and nanophotonic cavities that allow increasing the light-matter interaction by means of the Purcell effect, and the required quantum memories are based on large ensembles of Tm ions and mm-sized cavities. In addition, we also discuss the realization of qubits using Zeeman levels of a single Tm ion, and single and two-qubit gates that exploit the 795 and 1765 nm transitions.