title: Coherently opening a high-Q cavity.
abstract: We propose a general framework to effectively "open" a high-Q resonator, that is, to release the quantum state initially prepared in it in the form of a traveling electromagnetic wave. This is achieved by employing a mediating mode that scatters coherently the radiation from the resonator into a one-dimensional continuum of modes such as a waveguide. The same mechanism may be used to "feed" a desired quantum field to an initially empty cavity. Switching between an open and "closed" resonator may then be obtained by controlling either the detuning of the scatterer or the amount of time it spends in the resonator. First, we introduce the model in its general form, identifying (i) the traveling mode that optimally retains the full quantum information of the resonator field and (ii) a suitable figure of merit that we study analytically in terms of the system parameters. Then, we discuss two feasible implementations based on ensembles of two-level atoms interacting with cavity fields. In addition, we discuss how to integrate traditional cavity QED in our proposal using three-level atoms.
authors.affiliation: QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Tufarelli
authors.affiliation: School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ferraro
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
authors.forename: Alessio
authors.initials: A
authors.lastname: Serafini
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
authors.forename: Sougato
authors.initials: S
authors.lastname: Bose
authors.affiliation: QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom.
authors.forename: M S
authors.initials: MS
authors.lastname: Kim