The preeminent challenge of quantum technologies is the ability to accurately control the elementary quantum systems, while protecting them from unwanted interactions with their environment. On the one hand, single photons possess a natural advantage as carriers of quantum information because they are highly immune to external disturbances and travel at the speed of light. On the other hand, it is notoriously difficult to perform operations between single photons due to the relatively weak level of interaction between them that one can achieve in practice. The enhancement and flexible control of light-matter interaction on the nanoscale is the central purpose of nanophotonics.
This enhancement can be achieved by two complementary methods. In one approach, one aims at increasing the time for the interaction to take place by using high-quality resonators such as dielectric photonic cavities. This approach usually requires high level of coherence in matter and is therefore often associated with cryogenic temperatures and/or other methods to increase coherence.
An alternative approach consists in tightly concentrating the optical modes, thus intensifying the light-matter interaction. This type of mode concentration is offered by plasmonic nanoresonators, where light can be coupled to a free-electron plasma at optical frequencies. As a result of this coupling, hybrid particles termed plasmon-polaritons arise, having a much smaller wavelength than optical photons. The mode volumes can be made as small as a few cubic nanometers. The achieved interaction rates may exceed the decoherence rates in matter even at cryo-free temperatures. Quantum photonics in the ultrafast, sub-ps regime points a way towards cryo-free quantum photonics operating at THz rates [1,2]. It promises practically usable quantum communication networks and distributed quantum computing architectures.
We have previously used plasmonic enhancement of light-matter interaction to demonstrate the world’s brightest room-temperature single-photon source based on a quantum emitter . We have recently also realized an integration-friendly version of such a source. We have also developed methods for the deterministic assembly of such sources from automatically preselected nanoscale constituents .
 S.I. Bogdanov, A. Boltasseva and V.M. Shalaev, Science, 364, 532 (2019)
 S.I. Bogdanov, O.A. Makarova, X. Xu, Z.O. Martin, A.S. Lagutchev, M. Olinde, D. Shah, S.N. Chowdhuri, A.R. Gabidullin, I.A. Ryzhikov, I.A. Rodionov, A.V. Kildishev, S.I. Bozhevolnyi, A. Boltasseva, V.M. Shalaev and J.B. Khurgin, Optica, 7, 463 (2020)
 S.I. Bogdanov, M.Y. Shalaginov, A.S. Lagutchev, C.-C. Chiang, D. Shah, A.S. Baburin, I.A. Ryzhikov, I.A. Rodionov, A.V. Kildishev, A. Boltasseva, and V.M. Shalaev, Nano Letters, 18, 4837 (2018)
 C.-C. Chiang, S. I. Bogdanov, O. A. Makarova, X. Xu, S. Saha, D. Shah, D. Wang, A. S. Lagutchev, A. V. Kildishev, A. Boltasseva, and V. M. Shalaev, Adv. Opt. Mater., 2000889 (2020)
 S.I. Bogdanov, O.A. Makarova, A.S. Lagutchev, D. Shah, C.-C. Chiang, S. Saha, A.S. Baburin, I.A. Ryzhikov, I.A. Rodionov, A.V. Kildishev, A. Boltasseva and V.M. Shalaev, preprint available on arXiv at http://arxiv.org/abs/1902.05996