title: Vacuum-assisted generation and control of atomic coherences at x-ray energies.
abstract: The control of light-matter interaction at the quantum level usually requires coherent laser fields. But already an exchange of virtual photons with the electromagnetic vacuum field alone can lead to quantum coherences, which subsequently suppress spontaneous emission. We demonstrate such spontaneously generated coherences (SGC) in a large ensemble of nuclei operating in the x-ray regime, resonantly coupled to a common cavity environment. The observed SGC originates from two fundamentally different mechanisms related to cooperative emission and magnetically controlled anisotropy of the cavity vacuum. This approach opens new perspectives for quantum control, quantum state engineering and simulation of quantum many-body physics in an essentially decoherence-free setting.
authors.affiliation: Max-Planck-Institut für Kernphysik, Heidelberg, Germany.
authors.forename: Kilian P
authors.initials: KP
authors.lastname: Heeg
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Wille
authors.forename: Kai
authors.initials: K
authors.lastname: Schlage
authors.forename: Tatyana
authors.initials: T
authors.lastname: Guryeva
authors.forename: Daniel
authors.initials: D
authors.lastname: Schumacher
authors.forename: Ingo
authors.initials: I
authors.lastname: Uschmann
authors.forename: Kai S
authors.initials: KS
authors.lastname: Schulze
authors.forename: Berit
authors.initials: B
authors.lastname: Marx
authors.forename: Tino
authors.initials: T
authors.lastname: Kämpfer
authors.forename: Gerhard G
authors.initials: GG
authors.lastname: Paulus
authors.forename: Ralf
authors.initials: R
authors.lastname: Röhlsberger
authors.forename: Jörg
authors.initials: J
authors.lastname: Evers