Nanophotonic systems offer unique opportunities for controlling and stimulating light-matter coupling. One of the important topics which drags the interest of the researchers is artificial chirality in quantum sources interaction with surface photonic or plasmonic modes. The presence of the transverse optical spin component of guided modes opens the possibility to control their direction of propagation by means of the so called spin-locking effect. The atom transition with nonzero spin moment (chiral atoms) can excite surface modes in preferable direction, or, on the contrary, the scattering of surface mode is very sensitive to chirality of atomic transitions.
In this work we present a brief overview of the current progress in the field of quantum chiral optics. We will discuss our theoretical results on coupling of chiral atoms with surface guiding modes. In particular, we consider the scattering of a nanofiber guided mode (Fig. 1) on ensemble of atoms with chiral transitions, and show how the spin of nanofiber modes governs the scattering spectrum [1]. Moreover, we propose a model of atomic ensemble of chiral atoms with perfect unidirectional coupling, and suggest a rigorous solution in such system [2], which demonstrates the main features of unidirectional coupling (Fig. 2). Such a system can be implemented with a simple metal nanowire, where the spin-locking effect is extremely strong. Finally, we will discuss the effect of quantum anisotropy, which allows coupling of orthogonal quantum states close to a nanophotonics systems. We show by using anisotropic metasurfaces (Fig 3 a) that one can couple two atomic levels with chiral transition, which may result in non-inverse Rabi oscillation between two quantum states in a single atom (Fig 3 b).
[1] D. F. Kornovan, A. S. Sheremet, and M. I. Petrov, “Collective polaritonic modes in an array of two-level quantum emitters coupled to optical nanofiber,” Phys. Rev. B, vol. 94, p. 245416, 2016.
[2] D. Kornovan, M. Petrov, and I. Iorsh, “Transport and collective radiance in a basic quantum chiral optical model,” Phys. Rev. B, vol. 96, p. 115162, 2017.
