Optical nonlinearity in a system of coupled atoms

Ilan Shlesinger, P. Senellart, L. Lanco +1 more

Optical nonlinearities at the single-photon level are key features to build efficient photon-photon gates and to implement quantum networks. Such optical nonlinearities can be obtained using an ideal two-level system such as a single atom coupled to an optical cavity. While efficient, such atom-photon interface however presents a fixed bandwidth, determined by the spontaneous emission time and thus the spectral width of the cavity-enhanced two-level transition, preventing an efficient transmission to bandwidth-mismatched atomic systems in a single quantum network. In the present work, we propose a tunable atom-photon interface making use of the direct dipole-dipole coupling of two slightly different atomic systems. We show that, when weakly coupled to a cavity mode and directly coupled through dipole-dipole interaction, the subradiant mode of two slightly detuned atomic systems is optically addressable and presents a widely tunable bandwidth and single-photon nonlinearity.

С. А. Бахрамов

A. M. Bonch-Bruevich, Sergey G. Przhibel'skii, V. V. Khromov

Xiuwen Xia, Xinqin Zhang, Jingping Xu +2 more

We consider in this paper the input-output properties of an atom-nanowire coupling system which is composed of two individual terminated metal nanowaveguides and a two-level optical emitter. In detail, four aspects of the input-output properties are studied. First, we discuss in particular the coherent perfect absorber in the linear excitation regime and give the condition to realize it. Second, the transmittivity of the atom-nanowire system in the nonlinear regime is calculated, and a Rabi-like splitting associated with optical nonlinearity is found. Such a result is much different from the Rabi splitting in the atom-cavity system in the low excitation limit. Third, we find that the cooperation of optical nonlinearity and spatial asymmetry can generate optical nonreciprocity. Finally, a negative differential transmittivity is achieved with appropriate parameters. Our findings show promising applications in the full-optical device.

Xiuwen Xia, Xinqin Zhang, Jingping Xu +2 more

Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber (CPA) beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.

A. M. Bonch-Bruevich, Sergey G. Przhibel'skii, V. V. Khromov