Recent years have seen a growing interest in strong coupling between plasmons and excitons, as a way to generate new quantum optical testbeds and influence chemical dynamics and reactivity. Strong coupling to bright plasmonic modes has been achieved even with single quantum emitters. Dark plasmonic modes fare better in some applications due to longer lifetimes, but are difficult to probe as they are subradiant. Here, we apply electron energy loss (EEL) spectroscopy to demonstrate that a dark mode of an individual plasmonic bowtie can interact with a small number of quantum emitters, as evidenced by Rabi-split spectra. Coupling strengths of up to 85 meV place the bowtie-emitter devices at the onset of the strong coupling regime. Remarkably, the coupling occurs at the periphery of the bowtie gaps, even while the electron beam probes their center. Our findings pave the way for using EEL spectroscopy to study exciton-plasmon interactions involving non-emissive photonic modes.

Central European Institute of Technology Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic

Chemical Research Support Department Weizmann Institute of Science POB 26 7610001 Rehovot Israel

Department of Chemical and Biological Physics Weizmann Institute of Science POB 26 7610001 Rehovot Israel

Institute of Physical Engineering Brno University of Technology Technická 2 616 69 Brno Czech Republic

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Haroche, S. & Raimond, J. M. Exploring the Quantum: Atoms, Cavities and Photons. 1st edn (Oxford University Press, 2006).

Hennessy K, et al. Quantum nature of a strongly coupled single quantum dot-cavity system. Nature. 2007;445:896–899. doi: 10.1038/nature05586. PubMed DOI

Monroe C. Quantum information processing with atoms and photons. Nature. 2002;416:238–246. doi: 10.1038/416238a. PubMed DOI

Lo HK, Chau HF. Unconditional security of quantum key distribution over arbitrarily long distances. Science. 1999;283:2050–2056. doi: 10.1126/science.283.5410.2050. PubMed DOI

Kimble HJ. The quantum internet. Nature. 2008;453:1023–1030. doi: 10.1038/nature07127. PubMed DOI

Zhong XL, et al. Energy transfer between spatially separated entangled molecules. Angew. Chem. Int. Ed. 2017;56:9034–9038. doi: 10.1002/anie.201703539. PubMed DOI PMC

Thomas A, et al. Tilting a ground-state reactivity landscape by vibrational strong coupling. Science. 2019;363:616−+. doi: 10.1126/science.aau7742. PubMed DOI

Halas NJ, Lal S, Chang WS, Link S, Nordlander P. Plasmons in strongly coupled metallic nanostructures. Chem. Rev. 2011;111:3913–3961. doi: 10.1021/cr200061k. PubMed DOI

Haran G, Chuntonov L. Artificial plasmonic molecules and their interaction with real molecules. Chem. Rev. 2018;118:5539–5580. doi: 10.1021/acs.chemrev.7b00647. PubMed DOI

Hugall JT, Singh A, van Hulst NF. Plasmonic cavity coupling. ACS Photonics. 2018;5:43–53. doi: 10.1021/acsphotonics.7b01139. DOI

Santhosh K, Bitton O, Chuntonov L, Haran G. Vacuum Rabi splitting in a plasmonic cavity at the single quantum emitter limit. Nat. Commun. 2016;7:ncomms11823. doi: 10.1038/ncomms11823. PubMed DOI PMC

Groß H, Hamm JM, Tufarelli T, Hess O, Hecht B. Near-field strong coupling of single quantum dots. Sci. Adv. 2018;4:eaar4906. doi: 10.1126/sciadv.aar4906. PubMed DOI PMC

Leng H, Szychowski B, Daniel MC, Pelton M. Strong coupling and induced transparency at room temperature with single quantum dots and gap plasmons. Nat. Commun. 2018;9:4012. doi: 10.1038/s41467-018-06450-4. PubMed DOI PMC

Herzog JB, et al. Dark plasmons in hot spot generation and polarization in interelectrode nanoscale junctions. Nano Lett. 2013;13:1359–1364. doi: 10.1021/nl400363d. PubMed DOI

Gomez DE, et al. The dark side of plasmonics. Nano Lett. 2013;13:3722–3728. doi: 10.1021/nl401656e. PubMed DOI

Garcia de Abajo FJ. Optical excitations in electron microscopy. Rev. Mod. Phys. 2010;82:209–275. doi: 10.1103/RevModPhys.82.209. DOI

Koh AL, et al. Electron energy-loss spectroscopy (EELS) of surface plasmons in single silver nanoparticles and dimers: influence of beam damage and mapping of dark modes. ACS Nano. 2009;3:3015–3022. doi: 10.1021/nn900922z. PubMed DOI

Koh AL, Fernandez-Dominguez AI, McComb DW, Maier SA, Yang JKW. High-resolution mapping of electron-beam-excited plasmon modes in lithographically defined gold nanostructures. Nano Lett. 2011;11:1323–1330. doi: 10.1021/nl104410t. PubMed DOI

Cherqui C, Thakkar N, Li GL, Camden JP, Masiello DJ. Characterizing localized surface plasmons using electron energy-loss spectroscopy. Annu. Rev. Phys. Chem. 2016;67:331–357. doi: 10.1146/annurev-physchem-040214-121612. PubMed DOI

Colliex C, Kociak M, Stephan O. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale. Ultramicroscopy. 2016;162:A1–A24. doi: 10.1016/j.ultramic.2015.11.012. PubMed DOI

Losquin A, et al. Unveiling nanometer scale extinction and scattering phenomena through combined electron energy loss spectroscopy and cathodoluminescence measurements. Nano Lett. 2015;15:1229–1237. doi: 10.1021/nl5043775. PubMed DOI

Bernasconi GD, et al. Where does energy go in electron energy loss spectroscopy of nanostructures? ACS Photonics. 2017;4:156–164. doi: 10.1021/acsphotonics.6b00761. DOI

Liu, M. Z., Lee, T. W., Gray, S. K., Guyot-Sionnest, P. & Pelton, M. Excitation of dark plasmons in metal nanoparticles by a localized emitter. Phys. Rev. Lett. 102, 107401 (2009). PubMed

Efros AL, Rosen M. The electronic structure of semiconductor nanocrystals. Annu. Rev. Mater. Sci. 2000;30:475–521. doi: 10.1146/annurev.matsci.30.1.475. DOI

Wu X, Gray SK, Pelton M. Quantum-dot-induced transparency in a nanoscale plasmonic resonator. Opt. Express. 2010;18:23633–23645. doi: 10.1364/OE.18.023633. PubMed DOI

Hohenester U, Trugler A. MNPBEM—A Matlab toolbox for the simulation of plasmonic nanoparticles. Comput. Phys. Commun. 2012;183:370–381. doi: 10.1016/j.cpc.2011.09.009. DOI

Hohenester U. Simulating electron energy loss spectroscopy with the MNPBEM toolbox. Comput. Phys. Commun. 2014;185:1177–1187. doi: 10.1016/j.cpc.2013.12.010. DOI

Wei JK, Jiang N, Xu J, Bai XD, Liu JY. Strong coupling between ZnO excitons and localized surface plasmons of silver nanoparticles studied by STEM-EELS. Nano Lett. 2015;15:5926–5931. doi: 10.1021/acs.nanolett.5b02030. PubMed DOI

Yankovich AB, et al. Visualizing spatial variations of plasmon-exciton polaritons at the nanoscale using electron microscopy. Nano Lett. 2019;19:8171–8181. doi: 10.1021/acs.nanolett.9b03534. PubMed DOI

Li RQ, Garcia-Vidal FJ, Fernandez-Dominguez AI. Plasmon-exciton coupling in symmetry-broken nanocavities. ACS Photonics. 2018;5:177–185. doi: 10.1021/acsphotonics.7b00616. DOI

Demetriadou A, et al. Spatiotemporal dynamics and control of strong coupling in plasmonic nanocavities. ACS Photonics. 2017;4:2410–2418. doi: 10.1021/acsphotonics.7b00437. DOI

Ramezani M, et al. Plasmon-exciton-polariton lasing. Optica. 2017;4:31–37. doi: 10.1364/OPTICA.4.000031. DOI

Torma, P. & Barnes, W. L. Strong coupling between surface plasmon polaritons and emitters: a review. Rep. Prog. Phys.78, 013901 (2015). PubMed

Miri MA, Alu A. Exceptional points in optics and photonics. Science. 2019;363:42. doi: 10.1126/science.aar7709. PubMed DOI

Rodriguez Said Rahimzadeh-Kalaleh. Classical and quantum distinctions between weak and strong coupling. European Journal of Physics. 2016;37(2):025802. doi: 10.1088/0143-0807/37/2/025802. DOI

Schwartz I, et al. Deterministic generation of a cluster state of entangled photons. Science. 2016;354:434–437. doi: 10.1126/science.aah4758. PubMed DOI

Meuret S, et al. Complementary cathodoluminescence lifetime imaging configurations in a scanning electron microscope. Ultramicroscopy. 2019;197:28–38. doi: 10.1016/j.ultramic.2018.11.006. PubMed DOI

Johnson PB, Christy RW. Optical constants of the noble metals. Phys. Rev. B. 1972;6:4370–4379. doi: 10.1103/PhysRevB.6.4370. DOI

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