2025/09/01 by Julia M. Brevoord, Jan Fabian Geus, Brevoord, Julia M. +16 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Fiber Laser Technologies #Diamond and Carbon-based Materials Research #FOS: Physical sciences #Quantum Physics (quant-ph) #Quantum optics and atomic interactions
paper · doi:10.48550/arxiv.2509.01661
openalex publication_date 2025/09/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Diamond tin-vacancy (SnV) centers are promising candidates for building quantum network nodes. However, their native photon emission at 619 nm is incompatible with metropolitan-scale networks operating at low-loss telecom wavelengths. To address this, we demonstrate highly efficient, low-noise quantum frequency conversion (QFC) of 619 nm photons to the telecom S-band at 1480 nm. The conversion process combines 619 nm photons with 1064 nm pump light in an actively stabilized cavity containing a bulk monocrystalline potassium titanyl arsenate (KTA) crystal. We achieve an internal (external) conversion efficiency of (48 +/- 3)% ((28 +/- 2)%) and a noise photon rate per wavelength of 2.2 +/- 0.9 cts/s/pm, which is spectrally flat in the investigated frequency range of 40 GHz. Furthermore, we demonstrate that the efficiency remains above 80% of its maximum over a frequency range of 70 GHz. Finally, we generate a string of photons from a single waveguide-embedded SnV center using a train of excitation pulses and send these through the QFC. After the QFC, we observe a string of telecom photons displaying the SnV lifetime, confirming successful conversion. These results represent a critical step towards metropolitan-scale fiber-based quantum networks using SnV centers.