У оквиру традиционалног колоквијума Института за физику у Београду, у чевртак, 25. децембра 2025. године у 14 часова у сали „Звонко Марић“ предавање под насловом:
GaN-Based Single-Photon Sources and Their Potential for Quantum Key Distribution
одржаће проф. Жарко Гачевић (Технички универзитет у Мадриду).
САЖЕТАК:
For more than two decades, the quest for practical, stable, and scalable single-photon sources has been at the forefront of quantum photonics research. While numerous material platforms, such as quantum dots, color centers, and two-dimensional materials, have demonstrated promising performance, many still face limitations including cryogenic operation, spectral instability, or technological incompatibility with established semiconductor processes. In this context, the III-nitride material system, and GaN in particular, has recently emerged as a highly compelling candidate for SPS technologies thanks to its robustness, wide bandgap, mature industrial ecosystem, and compatibility with visible and telecom-wavelength emission.
This colloquium reviews the current state of semiconductor single-photon sources, highlighting recent advances achieved in the development of InGaN/GaN nanowire–based emitters grown by molecular beam epitaxy at ISOM-UPM [1–3]. These nanostructures naturally host localized quantum emitters capable of producing antibunched light with good stability. The talk will highlight the underlying physical mechanisms leading to single-photon generation, the role of nanoscale composition and strain fluctuations, and the fabrication strategies to improve control of emitter formation. Building on this quantum-light platform, the seminar will then introduce the principles of quantum key distribution, focusing on hybrid time-bin/phase encoding architecture for fiber-based communication. Together, these developments illustrate a coherent path toward single photon driven photonic quantum technologies.
[1] Ž. Gačević, N. Vukmirović, N. García-Lepetit, A. Torres-Pardo, M. Müller, S. Metzner, S. Albert, A. Bengoechea-Encabo, F. Bertram, P. Veit, J. Christen, J. M. González-Calbet, and E. Calleja, “Influence of
composition, strain, and electric field anisotropy on different emission colors and recombination dynamics from InGaN nanodisks in pencil-like GaN nanowires”, Phys. Rev. B 93, 125436 (2016).
[2]Ž. Gačević, M. Holmes, E. Chernysheva, M. Müller, A. Torres-Pardo, P. Veit, F. Bertram, J. Christen, J. M. González-Calbet, Y. Arakawa, E. Calleja, and S. Lazić, “Emission of linearly polarized single photons from quantum dots contained in nonpolar, semipolar, and polar sections of pencil-like InGaN/GaN nanowires”, ACS Photonics 4, 657–664 (2017).
[3] J. Obradović, M. Tinoco, L. Monge Bartolomé, V. J. Gómez Hernández, A. Torres-Pardo, S. Fernández-Garrido, Á. de Guzmán, and Ž. Gačević, “Formation mechanisms of (In,Ga)N nanoshells conformally grown around pencil-like GaN nanowires”, Cryst. Growth Des. (2026, accepted for publication).
* Посета проф. Жарка Гачевића подржана је од стране Фонда за науку Републике Србије (Development of GaN Nanowire Based Quantum Light Emitters – PhotonGaN)