Quantum interference effects in linear and nonlinear optics

Bin Wu, John F. Hulbert, Aaron R. Hawkins +1 more

Harnessing the unique optical quantum interference effects associated with electromagnetically induced transparency (EIT) on a chip promises new opportunities for linear and nonlinear optical devices. Here, we review the status of integrated atomic spectroscopy chips that could replace conventional rubidium spectroscopy cells. Both linear and nonlinear absorption spectroscopy with excellent performance are demonstrated on a chip using a self-contained Rb reservoir and exhibiting a footprint of only 1.5cm x 1cm. In addition, quantum interference effects including V-scheme and Λ-scheme EIT are observed in miniaturized rubidium glass cells whose fabrication is compatible with on-chip integration.

Kazuhiko Misawa

高志 近藤

Chao Chen, Shu-Tian Xue, Shi, Yu-Peng +8 more

The Hong-Ou-Mandel effect is a paradigmatic quantum phenomenon demonstrating the interference of two indistinguishable photons that are linearly coupled at a 50:50 beam splitter. Here, we transpose such a two-particle quantum interference effect to the nonlinear regime, when two single photons are impinging on a parametric down-conversion crystal. Formally, this transposition amounts to exchanging space and time variables, giving rise to an unknown form of timelike quantum interference. The two-photon component of the output state is a superposition of the incident photons being either transmitted or reborn, that is, replaced by indistinguishable substitutes due to their interaction with the nonlinear crystal. We experimentally demonstrate the suppression of the probability of detecting precisely one photon pair when the amplification gain is tuned to 2, which arises from the destructive interference between the transmitted and reborn photon pairs. This heretofore unobserved quantum manifestation of indistinguishability in time pushes nonlinear quantum interference towards a new regime with multiple photons. Hence, composing this effect with larger linear optical circuits should provide a tool to generate multimode quantum non-Gaussian states, which are essential resources for photonic quantum computers.

Xuesong Gao

Anna Sitek, Paweł Machnikowski

We calculate the linear optical response from a single quantum dot molecule and the nonlinear, four-wave-mixing response from an inhomogeneously broadened ensemble of such molecules.We show that both optical signals are affected by the coupling-dependent superradiance effect and by optical interference between the two polarizations.As a result, the linear and nonlinear responses are not identical.