Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 55: Quantum Effects

Q 55.4: Talk

Thursday, March 8, 2018, 11:30–11:45, K 1.013

Few-photon nonlinear optics using chirally-coupled two-level atoms — •Sahand Mahmoodian¹, Mantas Čepulkovskis², Sumanta Das², Peter Lodahl², Klemens Hammerer¹, and Anders Sørensen² — ¹Institute for Theoretical Physics, Institute for Gravitational Physics (Albert Einstein Institute), Leibniz University Hannover, Appelstraße 2, 30167 Hannover, Germany — ²Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark

Waveguide quantum electrodynamics studies the interaction between a quantum emitter coupled to a 1D photonic reservoir. It has been recently demonstrated that when quantum emitters couple to tightly-confined optical waveguide modes the light--matter interaction can become chiral leading to directional spontaneous emission and direction-dependent scattering of light. In this talk I discuss using a chain of N chirally-coupled two-level emitters driven by a resonant weak to mediate strong photon--photon interactions. By solving for the one- and two-photon dynamics analytically, we show that the physics of this system is governed by the interplay of nonlinear interactions and photon losses due to coupling to an external reservoir. For large optical depths the system evolves into a state that has a strongly bunched second-order correlation function and the output power exhibits a sub-exponential (inverse polynomial) scaling with N. By using an asymptotic expansion we describe these effects analytically. These dynamics can be demonstrated in state-of-the-art tapered fiber setups with trapped atoms.