Speaker
Description
Towards quantum information processing in silicon-on-insulator (SOI), single photons play an important role as carriers of information. Thereby, a key element is an integrated, efficient single-photon source (SPS) with high purity and fidelity operating on demand. Although sources of entangled photon pairs and heralded single photons have been successfully developed and integrated on SOI photonic chips, such sources are based on non-linear effects, and do not ensure “on demand” emission.
The observation of photon antibunching for the spontaneous emission of isolated color centers in SOI [1] has opened novel opportunities in this context. Among a dozen of other point defects, the W center looks as an attractive candidate because of its zero-phonon line at 1218 nm, which permits low-loss propagation through SOI waveguides, its large Debye-Waller factor (ca. 40%), its radiative quantum efficiency around 0.65 (in SOI membranes) and relative easy selective fabrication process [2]. By integrating an ensemble of W centers inside a SOI “Bullseye” cavity, clear signatures of Purcell enhancement of their emission has been recently reported [3].
Building upon these results, we have recently developed a method to integrate single W centers at the core of SOI bullseye cavities in a deterministic way. Our approach, inspired by ref 4, is based on the implantation of Si ions through a PMMA mask comprising nanoholes defined by electron-beam lithography. The nanoholes have a diameter ranging from 30 nm to 2 µm in small steps, allowing to finely tune the average number of implanted ions per hole. After mask removal and annealing at 250°C, we witness the formation of single W centers with microphotoluminescence spectroscopy at well-defined locations. Then, we fabricate Bullseye cavities, spectrally resonant with the zero-phonon line of the W center, on the same axis as the implantation spots. The observation of photon antibunching with $g^{(2)}(0)<0.05$ shows that the cavity fabrication step does not generate additional color centers. Furthermore, Purcell enhancement is obtained for several cavity-coupled emitters, showing that the W centers are located in the vicinity of the antinode of the resonant mode.
While this contribution focuses on fabrication-related issues, another presentation at EQEP will focus on the advanced characterization of the properties of this on-demand SPS.
[1] Redjem, W. et al. Nat Electron 3, 738–743 (2020); Durand, A. et al, PRL 126, 083602 (2021)
[2] Y. Baron et al., ACS Photonics 9 (7), 2337-2345 (2022).
[3] B. Lefaucher et al., ACS Photonics 11 (1), 24-32 (2024)
[4] M. Hollenbach et al., Nat Commun. 13, 7683 (2022).
