Dynamic control of Purcell enhanced emission of erbium ions in nanoparticles

The interaction of single quantum emitters with an optical cavity enables the realization of
efficient spin-photon interfaces, an essential resource for quantum networks. The dynamical
control of the spontaneous emission rate of quantum emitters in cavities has important
implications in quantum technologies, e.g., for shaping the emitted photons’ waveform or for
driving coherently the optical transition while preventing photon emission. Here we
demonstrate the dynamical control of the Purcell enhanced emission of a small ensemble of
erbium ions doped into a nanoparticle. By embedding the nanoparticles into a fully tunable
high finesse fiber based optical microcavity, we demonstrate a median Purcell factor of 15 for
the ensemble of ions. We also show that we can dynamically control the Purcell enhanced
emission by tuning the cavity on and out of resonance, by controlling its length with subnanometer
precision on a time scale more than two orders of magnitude faster than the
natural lifetime of the erbium ions. This capability opens prospects for the realization of
efficient nanoscale quantum interfaces between solid-state spins and single telecom photons
with controllable waveform, for non-destructive detection of photonic qubits, and for the
realization of quantum gates between rare-earth ion qubits coupled to an optical cavity.