Hannover 2013 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 68: Quantum information: Photons and nonclassical light II

Q 68.6: Vortrag

Freitag, 22. März 2013, 15:15–15:30, F 142

Entangling photons via the quantum Zeno effect — •Nicolai ten Brinke, Andreas Osterloh, and Ralf Schüztzhold — Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, D-47057 Duisburg, Germany

The quantum Zeno effect describes the inhibition of quantum evolution by frequent measurements. In this talk, we propose a scheme for entangling two given photons based on this effect. We consider a linear-optics set-up with an absorber medium whose two-photon absorption rate ξ_2γ exceeds the one-photon loss rate ξ_1γ. In order to reach an error probability P_error, we need ξ_1γ/ξ_2γ<2P_error²/π² [1], which is a factor of 64 better than previous approaches, e.g., [2]. Since typical media have ξ_2γ<ξ_1γ, we discuss mechanisms for enhancing two-photon absorption as compared to one-photon loss. In particular, we present a mechanism which envisages three-level systems where the middle level is meta-stable (Λ-system). In this case, ξ_1γ is more strongly reduced than ξ_2γ and thus it should be possible to achieve ξ_2γ/ξ_1γ≫1. In conclusion, although our scheme poses serious experimental challenges, we find that a two-photon gate with an error probability P_error below 25% might be feasible using present-day technology [3].

[1] N. ten Brinke, A. Osterloh, and R. Schützhold, Phys. Rev. A 84, 022317 (2011).

[2] J. D. Franson, B. C. Jacobs, and T. B. Pittman, Phys. Rev. A 70, 062302 (2004).

[3] N. ten Brinke, A. Osterloh, and R. Schützhold, arXiv:1212.1309.