Title: Enhanced control of single-molecules for quantum technologies

Speaker: Maja Colautti National Institute of Optics (CNR-INO)

Time: 2025-10-14 4:00 pm

Venue: Room W105, Physics Building

Abstract: The generation and manipulation of quantum states of light is required for key applications, such as photonic quantum simulation, linear optical quantum computing, quantum communication protocols, and quantum metrology. In this context, I will present our recent advancements in using single organic molecules at cryogenic temperature as bright and stable sources of coherent single photons in the solid state [1]. In particular, I will focus on our results on two-photon interference (TPI) experiments performed between distinct molecules on the same chip [2], and our recent insights on how to mitigate the practical limitations on the TPI among distinct emitters via the control of the electrical environment at the nanoscale. Indeed, we recently provided experimental demonstration of a hybrid tuning method for controlling the frequency of quantum emitters and at the same time to reduce the emitter sensitivity to charge noise, controlling spectral fluctuations [3]. This successful strategy is based on the combined use of the electric field generated by electrodes and of optically excited long-lived charge states [4], which provide two efficient knobs for enhanced control of single-molecule emitters for quantum photonic experiment.Dibenzoterrylene-doped nanocrystals of anthracene are dispersed on a glass substrate, nanostructured with 4 μm gap interdigitated gold electrodes. A combination of optical pumping and electrodegenerated electric field is implemented (electrically guided optical Stark shift: EGOSS), yielding a high degree of control on the local applied field with high spatial resolution and out-of-plane orientation. This allows for a reduction of spectral fluctuation (by a factor of 12) for a given frequency shift, with respect to the case of an in-plane-only electric field manipulation. In this way, the emission frequencies of single molecules can be tuned without degrading their spectral stability.

References

[1] Toninelli, C., et al., Nat. Mater. 20, 1615–1628 (2021). [2] Duquennoy, R. et al., Optica 9, 731-737 (2022).

[3] Duquennoy, R. et al., ACS Nano 18 (47), 32508–32516 (2024). [4] Colautti, M. et al., ACS Nano 14 (10), 13584–13592 (2020).

Bio: Maja Colautti did her PhD in atomic and molecular photonics at the European Laboratory for Non-Linear Spectroscopy (LENS) in Florence, from 2016 to 2020, during which she developed hybrid strategies to efficiently integrate organic quantum emitters on chip. In 2021 she was visiting PostDoc Researcher at the Technical University of Denmark and at the Niels Bohr Institute in Copenhagen. During this period, she also worked for the Sparrow Quantum start-up developing quantum dot based devices for quantum technologies applications. Currently, she is a fixed term researcher at the National Institute of Optics in Florence, focusing her research on organic quantum emitters and hybrid nanophotonic strategies for diverse quantum applications.