title: Photon-assisted tunnelling with nonclassical light.
abstract: Among the most exciting recent advances in the field of superconducting quantum circuits is the ability to coherently couple microwave photons in low-loss cavities to quantum electronic conductors. These hybrid quantum systems hold great promise for quantum information-processing applications; even more strikingly, they enable exploration of new physical regimes. Here we study theoretically the new physics emerging when a quantum electronic conductor is exposed to nonclassical microwaves (for example, squeezed states, Fock states). We study this interplay in the experimentally relevant situation where a superconducting microwave cavity is coupled to a conductor in the tunnelling regime. We find that the conductor acts as a nontrivial probe of the microwave state: the emission and absorption of photons by the conductor is characterized by a nonpositive definite quasi-probability distribution, which is related to the Glauber-Sudarshan P-function of quantum optics. These negative quasi-probabilities have a direct influence on the conductance of the conductor.
authors.affiliation: 1] Laboratoire de Physique des Solides, Université Paris-Sud, Orsay 91405, France [2] Department of Physics, McGill University, Montréal, Quebec, Canada.
authors.forename: J-R
authors.initials: JR
authors.lastname: Souquet
authors.affiliation: School of Engineering and Information Technology, University of New South Wales, ADFA, Canberra, Australian Capital Territory 2600, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Woolley
authors.affiliation: Laboratoire de Physique des Solides, Université Paris-Sud, Orsay 91405, France.
authors.forename: J
authors.initials: J
authors.lastname: Gabelli
authors.affiliation: Laboratoire de Physique des Solides, Université Paris-Sud, Orsay 91405, France.
authors.forename: P
authors.initials: P
authors.lastname: Simon
authors.affiliation: Department of Physics, McGill University, Montréal, Quebec, Canada.
authors.forename: A A
authors.initials: AA
authors.lastname: Clerk