Vion, Denis

Date:  Wednesday, January 31, 2018
Time:  11:00
Place:  ETH Zurich, Hönggerberg, HPF G 6
Host:  Andreas Wallraff

Quantum microwaves with a DC-biased Josephson junction 

Denis Vion
SEA Saclay, Gif-sur-Yvette Cedex, France

Tunneling of a Cooper pair through a dc-biased Josephson junction is possible only 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 modes, 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 [2]. Finally, using two resonator with different frequencies, we demonstrate photon pair production [3], two-mode squeezing, and entanglement between the two modes leaking out of the resonators.

[1] M. Hoffheinz et al., Phys. Rev. Lett.  106, 217005 (2011)
[2] In preparation
[3] M. Westig et al., Phys. Rev. Lett.  119, 137001 (2017)