title: Microcavity controlled coupling of excitonic qubits.
abstract: Controlled non-local energy and coherence transfer enables light harvesting in photosynthesis and non-local logical operations in quantum computing. This process is intuitively pictured by a pair of mechanical oscillators, coupled by a spring, allowing for a reversible exchange of excitation. On a microscopic level, the most relevant mechanism of coherent coupling of distant quantum bits--like trapped ions, superconducting qubits or excitons confined in semiconductor quantum dots--is coupling via the electromagnetic field. Here we demonstrate the controlled coherent coupling of spatially separated quantum dots via the photon mode of a solid state microresonator using the strong exciton-photon coupling regime. This is enabled by two-dimensional spectroscopy of the sample's coherent response, a sensitive probe of the coherent coupling. The results are quantitatively understood in a rigorous description of the cavity-mediated coupling of the quantum dot excitons. This mechanism can be used, for instance in photonic crystal cavity networks, to enable a long-range, non-local coherent coupling.
authors.affiliation: Technische Physik, Physikalisches Institut, and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Albert
authors.forename: K
authors.initials: K
authors.lastname: Sivalertporn
authors.forename: J
authors.initials: J
authors.lastname: Kasprzak
authors.forename: M
authors.initials: M
authors.lastname: Strauß
authors.forename: C
authors.initials: C
authors.lastname: Schneider
authors.forename: S
authors.initials: S
authors.lastname: Höfling
authors.forename: M
authors.initials: M
authors.lastname: Kamp
authors.forename: A
authors.initials: A
authors.lastname: Forchel
authors.forename: S
authors.initials: S
authors.lastname: Reitzenstein
authors.forename: E A
authors.initials: EA
authors.lastname: Muljarov
authors.forename: W
authors.initials: W
authors.lastname: Langbein