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arXiv · 1406.4295

Deterministic photon-emitter coupling in chiral photonic circuits

Immo Söllner·Sahand Mahmoodian·Sofie Lindskov Hansen·Leonardo Midolo·Alisa Javadi·Gabija Kiršanskė·Tommaso Pregnolato·Haitham El-Ella·Eun Hye Lee·Jin Dong Song·Søren Stobbe·Peter Lodahl
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Abstract

The ability to engineer photon emission and photon scattering is at the heart of modern photonics applications ranging from light harvesting, through novel compact light sources, to quantum-information processing based on single photons. Nanophotonic waveguides are particularly well suited for such applications since they confine photon propagation to a 1D geometry thereby increasing the interaction between light and matter. Adding chiral functionalities to nanophotonic waveguides lead to new opportunities enabling integrated and robust quantum-photonic devices or the observation of novel topological photonic states. In a regular waveguide, a quantum emitter radiates photons in either of two directions, and photon emission and absorption are reverse processes. This symmetry is violated in nanophotonic structures where a non-transversal local electric field implies that both photon emission and scattering may become directional. Here we experimentally demonstrate that the internal state of a quantum emitter determines the chirality of single-photon emission in a specially engineered photonic-crystal waveguide. Single-photon emission into the waveguide with a directionality of more than 90\% is observed under conditions where practically all emitted photons are coupled to the waveguide. Such deterministic and highly directional photon emission enables on-chip optical diodes, circulators operating at the single-photon level, and deterministic quantum gates. Based on our experimental demonstration, we propose an experimentally achievable and fully scalable deterministic photon-photon CNOT gate, which so far has been missing in photonic quantum-information processing where most gates are probabilistic.

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Immo Söllner, Sahand Mahmoodian, Sofie Lindskov Hansen, Leonardo Midolo, Alisa Javadi, Gabija Kiršanskė, Tommaso Pregnolato, Haitham El-Ella, Eun Hye Lee, Jin Dong Song, Søren Stobbe, Peter Lodahl. 2015-01-12. Deterministic photon-emitter coupling in chiral photonic circuits. https://doi.org/10.1038/nnano.2015.159

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