Detection of single ions in a nanoparticle coupled to a fiber cavity
Chetan Deshmukh, Eduardo Beattie, Bernardo Casabone, Samuele Grandi, Diana Serrano, Alban Ferrier, Philippe Goldner, David Hunger, Hugues de Riedmatten
Abstract
Many quantum information protocols require the storage and manipulation of information over long times, and its exchange between nodes of a quantum network across long distances. Implementing these protocols requires an advanced quantum hardware, featuring, for example, a register of long-lived and interacting qubits with an efficient optical interface in the telecommunication band. Here we present the Purcell-enhanced detection of single solid-state ions in erbium-doped nanoparticles placed in a fiber cavity, emitting photons at 1536 nm. The open-access design of the cavity allows for complete tunability in both space and frequency, selecting individual particles and ions. The ions are confined in a volume two orders of magnitude smaller than in previous realizations, increasing the probability of finding ions separated by only a few nanometers, which could then interact. We report the detection of individual spectral features presenting saturation of the emission count rate and linewidth, as expected for two-level systems. We also report an uncorrected g (2) (0) of 0.24(5) for the emitted field, confirming the presence of a single emitter. Our fully fiber-integrated system is an important step towards the realization of the initially envisioned quantum hardware.