Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 28: Quantum information: Atoms and ions IV

Q 28.5: Vortrag

Dienstag, 18. März 2014, 15:00–15:15, UDL HS3038

Demonstration of a single photon optical Kerr nonlinearity — •Jürgen Volz, Michael Scheucher, Christian Junge, and Arno Rauschenbeutel — Vienna Center for Quantum Science and Technology, TU Wien – Atominstitut, Vienna, Austria

The possibility to generate a controlled interaction between individual photons is one of the the key ingredients of future photon-based quantum applications. Since photons do not interact directly, this interaction can be facilitated by a medium with a high optical nonlinearity. Here we demonstrate the experimental realization of such an optical Kerr nonlinearity on the single photon level. Our system is based on a bottle-microresonator [1] – a novel type of whispering-gallery-mode resonator – interfaced by an optical nanofiber. The presence of a single ⁸⁵Rb-atom in the evanescent field of the resonator [2] in the overcoupled regime results in a strong nonlinear response of the resonator to the photon number in the incident light field. As a consequence, this imprints a photon number dependent phase shift on the light passing the resonator. Analyzing the transmitted light, we observe a phase shift close to the maximum value of π between the case where one or two photons pass the resonator. This nonlinear phase shift results in large entanglement between the two previously independent fiber guided photons, which we verify by performing a full quantum state tomography of the transmitted two-photon state.

[1] Pöllinger et al., PRL 103, 053901 (2009)

[2] Junge et al., PRL 110, 213604 (2013)