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TT: Fachverband Tiefe Temperaturen

TT 105: Focus Session: Mesoscopic Superconductivity and Quantum Circuits

TT 105.8: Talk

Friday, March 16, 2018, 12:50–13:05, H 0104

Quantum microwaves with a DC-biased Josephson junction — •Fabien Portier, Ambroise Peugeot, Iouri Moukharski, Phillipe Joyez, Denis Vion, Daniel Estève, Patrice Roche, Carles Altimiras, Marc Westig, Max Hofheinz, and Olivier Parlavecchio — NanoElectronics and Quantronics groups, SPEC, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France

Tunneling of a Cooper pair through a dc-biased Josephson junction is possible if collective excitations (photons) are produced in the rest of the circuit to conserve the energy. The probability of tunneling and photon creation, well described by the theory of dynamical Coulomb blockade, increases with the coupling strength between the tunneling charge and the circuit mode, which scales as the mode impedance. Using very simple circuits with only one or two high impedance series resonators, we first show the equality between Cooper pair tunneling rate and photon production rate [1]. Then we demonstrate a blockade regime for which the presence of a single photon blocks the next tunneling event and the creation of a second photon. Finally, using two resonator with different frequencies, we demonstrate photon pair production [2], two-mode squeezing, and entanglement between the two modes leaking out of the resonators.
M. Hofheinz et al., Phys. Rev. Lett. 106, 217005 (2011)
M. Westig et al., arXiv:1703.05009 (2017)