Quantum optics with emergent materials.

Place: conference room, IMDEA Nanociencia.

Abstract:

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Weak light-matter coupling conditions allow to generate bright single photon emission from solid-state sources.
In this talk we will present results on quantum dots in monolayers of WSe2, and defects in hexagonal Boron Nitride, that are coupled to a tunable Fabry-Pérot microcavity, rendering a bright single photon emission.

The nanoscale control of light-matter interactions allows to create new optoelectronic devices for a wide span of nonlinear and quantum photonic applications [1]. A key part of this endeavour is the exploration of novel materials,which reveal unique properties that can be tailored to specific applications. Regarding the implementation of solid-state single photon sources, relevant emergent materials for quantum light emission are quantum dots in transitionmetal dichalcogenides monolayers, perovskite quantum dots, or also defects in hexagonal boron nitride
nanocrystals. [2]

An optimal single-photon source should satisfy three essential criteria: (1) the emission of photons "on demand", (2) emit one photon at a time, and (3) high degree of temporal coherence and uniformity in the properties of emitted photons (spectrum, polarization, spatial mode). Achieving this ideal quantum performance relies on using a resonant cavity to enhance the emitter's spontaneous decay rate via the Purcell effect.

In the first part of this talk, we will present recent advancements in generating single photons from atomically thin WSe2 monolayers. Local stress within these monolayers creates a confining potential that traps single excitons,resulting in single-photon emission. By embedding these quantum dots in a cryogenic Fabry-Pérot optical cavity, we achieve record emission-efficiency levels. [3] We also study the filtering cavity effects on the temporal coherence of the emitted single photons via Michelson interferometry. [4] Initial quantum communication tests with these sources
further demonstrate their viability for single-photon applications. [5]In the latter part of the talk, I will discuss our experimental progress with an alternative material platform: single defects in hexagonal boron nitride. [6] This emitter, operable at ambient conditions and integrated with a Fabry-Pérot cavity, offers a promising option for cryogenic-free quantum optical applications, including free-space quantum key distribution. [7]

References

[1] H. Wang, T. C. Ralph, J. J. Renema, C.-Y. Lu, and J.-W. Pan, Scalable photonic quantum technologies, Nat. Mater. 1
(2025).

[2] M. Esmann, S. C. Wein, and C. Antón-Solanas, Solid-State Single-Photon Sources: Recent Advances for Novel Quantum Materials, Advanced Functional Materials 34, 2315936 (2024).

[3] J.-C. Drawer et al., Monolayer-Based Single-Photon Source in a Liquid-Helium-Free Open Cavity Featuring 65% Brightness and Quantum Coherence, Nano Lett. 23, 8683 (2023).

[4] V. N. Mitryakhin et al., Engineering the Impact of Phonon Dephasing on the Coherence of a ${\mathrm{WSe}}_{2}$ Single-Photon Source via Cavity Quantum Electrodynamics, Phys. Rev. Lett. 132, 206903 (2024).

[5] T. Gao, M. von Helversen, C. Antón-Solanas, C. Schneider, and T. Heindel, Atomically-thin single-photon sources forquantum communication, Npj 2D Mater Appl 7, 1 (2023).

[6] J. Vidal Martínez-Pons, S. K. Kim, M. Behrens, A. Izquierdo-Molina, A. Menendez Rua, S. Paçal, S. Ateş, L. Viña, and C. Antón-Solanas, Temporal Coherence of Single Photons Emitted by Hexagonal Boron Nitride Defects at Room Temperature, ACS Photonics 13, 282 (2026).

[7] Ö. S. Tapşın, F. Ağlarcı, R. G. Pousa, D. K. L. Oi, M. Gündoğan, and S. Ateş, Secure Quantum Key Distribution Using a Room-Temperature Quantum Emitter, arXiv:2501.13902.

Short bio:

Zaragoza, 1987. Bachelor's degree in Physics (2010), Master's degree in Photonics (2011), and PhD in Physics (2015) from the Autonomous University of Madrid. He completed postdoctoral fellowships at the CNRS (France, Marie Curie-IF grant) and at the universities of Würzburg and Oldenburg (Germany). Since 2022, he has been a tenure track "Talent Attraction" researcher at the UAM. He has been the principal investigator of several competitive projects, including a project coordinated in the European QuantERA 2023 call for proposals on quantum communications. His research focuses on solid-state quantum optics, especially single-photon sources and quantum states of light based on semiconductor quantum dots and emerging materials (defects in hBN, TMDs) coupled to photonic cavities. He is the author of more than 50 publications, mainly on light-matter coupling, nanophotonics, and quantum photonics. UAM Young Researchers Award (2024)

This seminar is hosted by Roberto Otero (Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.).

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