Scalable and telecom single-erbium system with record-long room-temperature quantum coherence

Abstract:Achieving long-lived ({\mu}s-scale) quantum coherence at room temperature in the telecom C band remains a central unsolved challenge for solid-state quantum platforms, with coherence at this timescale previously demonstrated only under vacuum cryogenic conditions at temperatures over 600 times lower. To this end, we introduce a CMOS-compatible nanoengineering approach that deterministically controls the number of Er ions within a nanoscale volume and their electromagnetic environment using sub-5 nm silicon-based hollow nanopillars, which achieves the first deterministic spatial isolation of single erbium ions. This nanostructure-enabled isolation suppresses ion-ion interactions and local electromagnetic field noise, enabling single-erbium-ion operation under ambient conditions. The resulting individually addressable single-ion devices exhibit record room temperature optical coherence times of T2*= 32 {\mu}s and T2 > 100 {\mu}s in the telecom C-band. We further present the first demonstration of background-free, upconversion-enabled single photon emission from multilevel erbium qudits, providing high contrast coherent optical readout. Beyond these performance gains, our work, through sub-5-nm nanoscale engineering, establishes isolated single-ion environments as a viable route to room-temperature operation for solid-state quantum systems. This approach has the potential to address the long-standing barrier of room-temperature decoherence and open a manufacturable, telecom-compatible pathway toward scalable quantum networks, distributed sensing, and cryogenic-free quantum photonic integrated circuits.

arXiv:2601.11879 [quant-ph]

(or arXiv:2601.11879v3 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2601.11879 Focus to learn more arXiv-issued DOI via DataCite

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