Internship: IRare-earth doped oxide thin films for on-chip optical quantum technologies

Rare-earth ions (REI) present a strong interest for quantum technologies due to their ability to show long-lived quantum superposition states both in their optical and spin transitions. The perspective of using them for applications such as quantum information processing, quantum memories and indistinguishable photon sources, however, relies on developing host materials in which their outstanding quantum properties are preserved, while enabling integration into nanophotonic devices. Several proof-of-concept experiments based on rare-earth doped oxide crystals have been reported [1], [2], yet, integration into practical and scalable quantum devices has still not been stablished. In particular, specific designs compatible with both optical cavities and MW architectures are generally needed [3], [4]. In this context, the ability to host REI into thin oxide films deposited on a scalable substrate such as silicon would greatly facilitate the development of such resonators. A thin film architecture also allows flexibility in material composition or dopant spatial localization and offers integration perspectives with silicon photonic chips by standard clean room processing technologies [5], [6]. As a drawback, the obtention of high-crystalline quality oxide films on silicon is very challenging with most deposition techniques. Moreover, the optical and spin properties of REIs in thin films tend to lag behind that of their bulk counterpart, mainly due to the close proximity of surface and the presence of interfacial defects. To overcome these challenges, we have developed a hybrid thin film fabrication approach combining MBE [5] and CVD [7] deposition techniques to obtain epitaxial rare-earth oxide thin films on silicon (Fig. 1). The optical properties of europium ions embedded in this film matrix have already shown promising results with sub-MHz homogeneous linewidths measured.

This internship will have two main objectives: (i) the optimisation of the thin-film deposition conditions towards the reproducible obtention of smooth epitaxial Y2O3 thin films doped with REI. (ii) the fabrication of Y2O3 membranes by both dry and wet chemical etching techniques. The deposited thin films, and membranes quality and eligibility for quantum technology applications will be assessed by the candidate using different morphological and optical characterizations.
Techniques/methods in use: Chemical Vapor Deposition (DPC), DRX, SEM, chemical etching, fluorescence and absorption spectroscopy.
Applicant skills: Interest on thin-film deposition and nanofabrication techniques. Basic knowledge about light-matter interactions, optics, data collection and treatment.
Internship duration: 6 months
Internship supervisor(s)
Alexandre Tallaire, alexandre.tallaire@chimieparistech.psl.eu
Diana Serrano, diana.serrano@chimieparistech.psl.eu

Bibliography

[1] A. M. Dibos, M. Raha, C. M. Phenicie, and J. D. Thompson, “Atomic Source of Single Photons in the Telecom Band,” Phys. Rev. Lett., vol. 120, no. 24, p. 243601, Jun. 2018, doi: 10.1103/PhysRevLett.120.243601.
[2] T. Zhong et al., “Nanophotonic rare-earth quantum memory with optically controlled retrieval,” Science, vol. 357, no. 6358, pp. 1392–1395, Sep. 2017, doi: 10.1126/science.aan5959. [3] B. Casabone et al., “Dynamic control of Purcell enhanced emission of erbium ions in nanoparticles,” Nat Commun, vol. 12, no. 1, Art. no. 1, Jun. 2021, doi: 10.1038/s41467-021- 23632-9.
[4] Z. Wang et al., “Single electron-spin-resonance detection by microwave photon counting,” Jan. 06, 2023, arXiv: arXiv:2301.02653. doi: 10.48550/arXiv.2301.02653.
[5] S. Gupta et al., “Dual epitaxial telecom spin-photon interfaces with correlated long-lived coherence,” Oct. 10, 2023, arXiv: arXiv:2310.07120. doi: 10.48550/arXiv.2310.07120.
[6] M. K. Singh et al., “Epitaxial Er-doped Y2O3 on silicon for quantum coherent devices,” APL Materials, vol. 8, no. 3, p. 031111, Mar. 2020, doi: 10.1063/1.5142611.
[7] N. Harada et al., “Chemically vapor deposited Eu3+:Y2O3 thin films as a material platform for quantum technologies,” Journal of Applied Physics, vol. 128, no. 5, p. 055304, Aug. 2020, doi: 10.1063/5.0010833.