Detection of single ions in a nanoparticle coupled to a fiber cavity

• Published in: Optica 2023-10, Vol.10 (10), p.1339-1344
• Main Authors: Deshmukh, Chetan, Beattie, Eduardo, Casabone, Bernardo, Grandi, Samuele, Serrano, Diana, Ferrier, Alban, Goldner, Philippe, Hunger, David, de Riedmatten, Hugues
• Format: Article
• Language: English
• Subjects: Atomic Physics; Engineering Sciences; Optics; Photonic; Physics; Quantum Physics
• ISSN: 2334-2536; 2334-2536
• DOI: 10.1364/OPTICA.491692

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.